| 1. |
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| 2. |
- Andersson, Jens, et al.
(författare)
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Plastic reources polymorphism : effects or resource availability on Arctic char (Salvelinus alpinus) morphology
- 2005
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Ingår i: Biological Journal of the Linnean Society. - London : Acad. P.. - 0024-4066 .- 1095-8312. ; 85:3, s. 341-351
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Tidskriftsartikel (refereegranskat)abstract
- Resource polymorphism has been suggested to be a platform for speciation. In some cases resource polymorphism depends on phenotypic plasticity but in other cases on genetic differences between morphotypes, which in turn has been suggested to be the ongoing development of a species pair. Here we study environmentally induced morphological differences in two age classes of Arctic char (Salvelinus alpinus) influencing char performance and diet in relation to resource availability. We found that structurally complex habitats with relatively lower zooplankton densities gave rise to individuals with a deeper body, and a downward positioned tip of the snout compared with individuals from structurally simple habitats with relatively higher zooplankton densities for both age classes. Environment also had an effect on foraging efficiency on zooplankton, with fish from structurally simple habitats had a higher foraging rate than fish from structurally complex habitats. Diet analyses showed that resource use in char mainly depends on the relative abundance of different resources. Therefore, to gain further understanding of resource polymorphism we suggest that future studies must include population dynamic feedbacks by the resources on the consumers.
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| 3. |
- Andersson, Stefan
(författare)
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Fitness consequences of floral variation in Senecio jacobaea (Asteraceae): evidence from a segregating hybrid population and a resource manipulation experiment
- 2001
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Ingår i: Biological Journal of the Linnean Society. - 0024-4066. ; 74:1, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- The present study examines some of the ecological factors that might exert selection on floral morphology in Senecio jacobaea, a self-sterile composite which exhibits geographic variation in the frequency of rayed and discoid individuals. Regression analyses of phenotypic data from a large, segregating hybrid population, established in a semi-natural (garden) environment and studied over a 2-year period, revealed a negative relationship between the size of the rays and the average germination rate of the maternal seed crop, a pattern that can be attributed to the reduced germination speed of achenes from ray florets. There was no effect of ray size on the amount of cross-pollination achieved, the proportion of heads infested by larvae of seed flies (Pegohylemyia) and the amount of resources retained for the next flowering season. The lack of resource costs was also apparent in a manipulation experiment with greenhouse-grown plants of the rayed phenotype: artificial removal of all rays at the early bud or flowering stage had no detectable effect on subsequent flower and fruit development, regardless of whether the plants experienced high or low water stress. Given these and other observations, I hypothesize that plant-animal interactions and resource costs sometimes play a minor role in exerting selection on flower morphology and that spatially varying selection on germination behaviour accounts for some of the morph frequency variation in S. jacobaea. (C) 2001 The Linnean Society of London.
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| 4. |
- Araújo, Priscila, et al.
(författare)
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Body size and the architecture of the visual system in crepuscular and diurnal bees
- 2023
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 138:3, s. 328-340
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Tidskriftsartikel (refereegranskat)abstract
- Crepuscular bees have larger compound eyes, ommatidia and ocelli than diurnal bees. These visual adaptations allow these bees to forage during twilight. While the sizes of visual organs are positively correlated with body size in diurnal bees, this relationship is as yet unclear in crepuscular bees. Here we measured the sizes of the ocellus; compound eyes; ommatidial density; and dorsal, frontal and ventral facets of 11 phylogenetically related bee species with different temporal patterns. We tested whether and how each of these visual attributes is correlated with body size and/or temporal pattern. Except for ommatidial density and size of the frontal ommatidia, which are similar in crepuscular bees of different sizes, we found that all other visual variables in diurnal and crepuscular bees are correlated with both body size and temporal pattern. The lower variability in ommatidial density among crepuscular bees suggests that their eyes operate on the threshold between light sensitivity and visual acuity. Furthermore, similar frontal ommatidial sizes in bees of different sizes indicate that this eye region is under higher evolutionary pressure in small than in large crepuscular bees to ensure light sensitivity. Finally, those crepuscular bees from different families convergently share the same visual characteristics.
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| 5. |
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| 6. |
- Bengtsson, Bengt Olle, et al.
(författare)
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Direct and indirect selection in moth pheromone evolution: population genetical simulations of asymmetric sexual interactions
- 2007
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 90:1, s. 117-123
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Tidskriftsartikel (refereegranskat)abstract
- Female moths generally use pheromones to attract males. Normally, all females in a population produce a specific chemical blend with only a limited variance, and the local males are highly attracted to this blend. To better understand the direct and indirect selective forces acting on this communication system, where, unusually, it is the reproductively limited sex that signals for matings, a population genetical model has been constructed and numerically analysed. Basic to the model is the assumption that the pheromone attraction system functions asymmetrically, leading to strong sexual selection between males but no direct sexual selection between females. Evolutionary simulations using the model show that sexual selection in males causes an indirect stabilizing selection on the pheromone blends produced by females. Thus, a more narrow range of pheromone variation is selected for, even in the absence of female sexual selection. The strength of the selection is analysed, and it is suggested that this indirect stabilizing selection becomes particularly important in situations where geographically adjacent populations have evolved different pheromone blends.
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| 7. |
- Bergek, Sara, 1979-, et al.
(författare)
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Genetic and morphological divergence reveals local subdivision of perch (Perca fluviatilis L.)
- 2009
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Ingår i: Biological Journal of the Linnean Society. - : Wiley-Blackwell. - 0024-4066 .- 1095-8312. ; 96:4, s. 746-758
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Tidskriftsartikel (refereegranskat)abstract
- The level of gene flow is an important factor influencing genetic differentiation between populations. Typically, geographic distance is considered to be the major factor limiting dispersal and should thus only influence the degree of genetic divergence at larger spatial scales. However, recent studies have revealed the possibility for small-scale genetic differentiation, suggesting that the spatial scale considered is pivotal for finding patterns of isolation by distance. To address this question, genetic and morphological differentiation were studied at two spatial scales (range 2–13 km and range 300 m to 2 km) in the perch (Perca fluviatilis L.) from the east coast archipelago of Sweden, using seven microsatellite loci and geometric morphometrics. We found highly significant genetic differentiation between sampled locations at both scales. At the larger spatial scale, the distance not affecting the level of divergence. At the small scale, however, we found subtle patterns of isolation by distance. In addition, we also found morphological divergence between locations, congruent with a spatial separation at a microgeographic scale, most likely due to phenotypic plasticity. The present study highlights the importance of geographical scale and indicates that there might be a disparity between the dispersal capacity of a species and the actual movement of genes. Thus, how we view the environment and possible barriers to dispersal might have great implications for our ability to fully understand the evolution of genetic differentiation, local adaptation, and, in the end, speciation.
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| 8. |
- Berglund, Anders, et al.
(författare)
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Armaments and ornaments : An evolutionary explanation of traits of dual utility
- 1996
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Ingår i: Biological Journal of the Linnean Society. - 0024-4066 .- 1095-8312. ; 58:4, s. 385-399
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Tidskriftsartikel (refereegranskat)abstract
- Secondary sexual characters in many species function both in male-male competition and as cues for female choice. Based on a literature compilation of existing knowledge of traits with this dual function, we propose that they commonly arise through intrasexual selection processes and serve as honest signals to other males regarding fighting ability or dominance. Faking these traits, here called armaments, (i.e. weapons and status badges) is difficult, as they are constantly put to trial in male-male contests. Females that subsequently utilize them as indicators of male phenotypic quality when selecting a partner will benefit by acquiring males of higher quality to father their offspring. Thus, evolution of armaments through male-male competition is seen as a usually initiating process, whereas female choice later may assume a role as an additional selective factor. The reverse, that males use information from traits evolved through female choice, is, however, also possible. The traditional view of independently evolved and temporarily unordered intra- and intersexual selection processes fails to explain dual trait functions. Moreover, our model may more satisfyingly than traditional ones explain how trait honesty and trait genetic variance are maintained: theoretical and empirical evidence suggests that such honesty and variation are more easily maintained under male-male competition than under female choice. (C) 1996 The Linnean Society of London
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| 9. |
- Bicknell, Russell D. C., et al.
(författare)
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Habitat and developmental constraints drove 330 million years of horseshoe crab evolution
- 2022
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 136:1, s. 155-172
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Tidskriftsartikel (refereegranskat)abstract
- Records of evolutionary stasis over time are central to uncovering large-scale evolutionary modes, whether by long-term gradual change or via enduring stability punctuated by rapid shifts. The key to this discussion is to identify and examine groups with long fossil records that, ideally, extend to the present day. One group often regarded as the quintessential example of stasis is Xiphosurida, the horseshoe crabs. However, when, how and, particularly, why stasis arose in xiphosurids remain fundamental, but complex, questions. Here, we explore the protracted history of fossil and living xiphosurids and demonstrate two levels of evolutionary stability: developmental stasis since at least the Pennsylvanian and shape stasis since the Late Jurassic. Furthermore, shape and diversity are punctuated by two high-disparity episodes during the Carboniferous and Triassic - transitions that coincide with forays into habitation of marginal environments. In an exception to these general patterns, body size increased gradually over this period and, thus, cannot be described under the same, often-touted, static models of evolution. Therefore, we demonstrate that evolutionary stasis can be modular and fixed within the same group at different periods and in different biological traits, while other traits experience altogether different evolutionary modes. This mosaic in the tempo and mode of evolution is not unique to Xiphosurida but likely reflects variable mechanisms acting on biological traits, for example transitions in life modes, niche occupation and major evolutionary radiations.
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| 10. |
- Bjorklund, M
(författare)
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Similarity of growth among Great tits (Parus major) and Blue tits (P-caeruleus)
- 1996
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Ingår i: BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS LTD. - 0024-4066. ; 58:3, s. 343-355
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Differences in morphology among species are proximately caused by changes in the ontogeny of individuals. It is therefore of importance to analyse possible differences in growth parameters among closely related species in order to understand what paramete
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| 11. |
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| 12. |
- Björklund, Mats, et al.
(författare)
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Genetic differentiation in the urban habitat : the great tits (Parus major) of the parks of Barcelona city
- 2010
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Ingår i: Biological Journal of the Linnean Society. - 0024-4066 .- 1095-8312. ; 99:1, s. 9-19
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Tidskriftsartikel (refereegranskat)abstract
- The increase of urban areas has led to a fragmentation of habitats for many forest-living species. Man-made parks might be a solution, but they can also act as sinks that are unable to maintain themselves without immigration from natural areas. Alternatively, parks might act as true metapopulations with extinctions and colonizations. In both cases, we can expect genetic variation to be reduced in the parks compared to the natural habitat. A third alternative is that the parks have sufficient reproduction to maintain themselves. To test these hypotheses, we analysed the pattern of genetic variation in the great tit (Parus major) in 12 parks in central Barcelona, and in an adjacent forest population using microsatellites. Genetic variation was not lower in the parks compared to the forest population, but larger, and gene flow was higher from the town to the forest compared to vice versa. We found a significant genetic differentiation among the parks, with a structure that only partly reflected the geographic position of the parks. Relatedness among individuals within parks was higher than expected by chance, although we found no evidence of kin groups. Assignment tests suggest that some parks are acting as net donors of individuals to other parks.
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| 13. |
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| 14. |
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| 15. |
- Björklund, Mats, et al.
(författare)
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The genetic structure of crossbills suggests rapid diversification with little niche conservatism
- 2013
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 109:4, s. 908-922
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Tidskriftsartikel (refereegranskat)abstract
- Conservatism of ecological niches can cause geographical ranges or the formation of new species to be constrained, and might be expected in situations where strong trade-offs result in ecological specialization. Here we address the flexibility of resource use in European crossbills by comparing the ecological and genetic similarities between four Mediterranean and three northern European crossbill populations, all specialized in feeding on a different resource. We used sequence data of one mitochondrial and two nuclear genes from between 211 and 256 individuals. The northern crossbills were genetically too similar to infer which population was more related to the southern ones. Crossbills from the island of Mallorca showed genetic signatures of a stable and isolated population, supporting their past treatment as a locally (co)evolving taxon, and seem to have evolved from an ecologically distinct ancestor. Previous studies in other populations also suggest that genetic similarity does not predict morphological and resource similarity. We estimate that the divergence of all western European crossbills has occurred within the last 11000 years. Overall, it appears that crossbills can diversify rapidly and with little niche conservatism, but that such potentially reproductively isolated specialists are evolutionarily short-lived.
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| 16. |
- Bohlin, Titti, et al.
(författare)
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The detectability of the colour pattern in the aposematic firebug, Pyrrhocoris apterus : an image-based experiment with human 'predators'
- 2012
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 105:4, s. 806-816
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Tidskriftsartikel (refereegranskat)abstract
- Crypsis and aposematism are often regarded as two opposite protective strategies. However, there is large variation in prey appearance within both strategies. In this article, we investigated the conspicuousness of the aposematic red-and-black firebug, Pyrrhocoris apterus, by presenting images of natural and digitally manipulated phenotypes in their natural habitat on a computer screen to human predators, and comparing the detection times. We asked whether the natural colour pattern can be made more or less conspicuous by rearranging the spatial distribution of colour elements. Hence, we created a phenotype in which the black colour elements were moved to the body outline to test for a possible disruptive effect. In the black and red manipulations, we removed one of the two colours, creating two uniform colour variants. We found that some of our manipulations increased, but none reduced, the detection time significantly; this indicates that the naturally coloured firebug is highly conspicuous. The detection time varied among backgrounds and there was a significant relationship between detection time and chromatic similarity between the bug and the background for the natural and black phenotypes. Although background colour composition has an important effect on the signal, we argue that the coloration of P. apterus has evolved for high conspicuousness.
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| 17. |
- Bommarco, Riccardo, et al.
(författare)
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Genetic and phenotypic differences between thistle populations in response to habitat and weed management practices
- 2010
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 99:4, s. 797-807
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Tidskriftsartikel (refereegranskat)abstract
- Rapid evolutionary change is increasingly being recognized as commonplace, but the evolutionary consequences for species and ecosystems under human-induced selection regimes have not been explored in detail, although many species occur in such environments. In a common garden experiment and with amplified fragment length polymorphism markers, we examined whether genetic differentiation has taken place between spatially intermixed populations of creeping thistles Cirsium arvense (Asteraceae) collected from a natural habitat (maritime shores), a semi-natural habitat (road verges) and arable fields under two management regimes: conventional and organic farming. Populations of C. arvense have altered genetically and locally adapted their growth patterns with changed land use. Although plants from different habitats showed similar total biomass production, shoot and root production was higher for maritime populations, suggesting selection for increased competitive ability. Competitive ability then declined in the order semi-natural, conventional farms and organic farms. Thistles in arable fields may be more selected for tolerance against disturbances from herbicides and mechanical weed control. In addition, early shoot sprouting and genetic analysis showed differentiation between plants originating from conventional farms and farms that were converted to organic 9–30 years ago, suggesting some adaptation to altered crop cultivation practices
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| 18. |
- Bosque, Renan Janke, et al.
(författare)
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Müllerian mimicry and the coloration patterns of sympatric coral snakes
- 2022
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 135:4, s. 645-651
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Tidskriftsartikel (refereegranskat)abstract
- Coral snakes in the genus Micrurus are venomous, aposematic organisms that signal danger to predators through vivid coloration. Previous studies found that they serve as models to several harmless species of Batesian mimics. However, the extent to which Micrurus species engage in Mullerian mimicry remains poorly understood. We integrate detailed morphological and geographical distribution data to investigate if coral snakes are Mullerian mimics. We found that coloration is spatially structured and that Micrurus species tend to be more similar where they co-occur. Though long supposed, we demonstrate for the first time that coral snakes might indeed be Mullerian mimics as they show some convergence in coloration patterns. Additionally, we found that the length of red-coloured rings in Micrurus is conserved, even at large geographic scales. This finding suggests that bright red rings may be under more substantial stabilizing selection than other aspects of coloration and probably function as a generalized signal for deterring predators.
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| 19. |
- Braga Gonçalves, Inês, et al.
(författare)
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Effects of female mating order and male size on embryo survival in a pipefish.
- 2015
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 114:3, s. 639-645
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Tidskriftsartikel (refereegranskat)abstract
- In species that provide parental care, individuals should invest adaptively in their offspring in relation to the preand post-zygotic care provided by their partners. In the broad-nosed pipefish, Syngnathus typhle L., females transfer large, nutrient-rich eggs into the male brood pouch during mating. The male broods and nourishes the embryos for several weeks before independent juveniles emerge at parturition. Given a choice, females clearly prefer large partners. Yet, females provide protein-richer eggs when the same individual mates with a smaller than a larger male. In the present study, we allowed each female to mate with one small and one large male, in alternated order. We found a strong effect of female mating order, with larger clutches and higher embryo mortality in first- than second-laid broods, which may suggest that eggs over-ripen in the ovaries or reflect the negative effects of high embryo density in the brood pouch. In either case, this effect should put constraints on the possibility of a female being selective in mate choice. We also found that small and large males produced embryos of similar size and survival, consistent with the reproductive compensation hypothesis, suggesting that, in this species, larger males provide better nourishment to the embryos than smaller males.
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| 20. |
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| 21. |
- Cheney, K. L., et al.
(författare)
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Regulation, constraints and benefits of colour plasticity in a mimicry system
- 2017
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 122:2, s. 385-393
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Tidskriftsartikel (refereegranskat)abstract
- Rapid colour change is used in aggressive interactions, ontogenetic transitions, nuptial displays and to prevent detection and/or recognition from predators or prey. The underlying mechanisms, constraints and benefits of colour change are often unclear, but examining such factors offers insights into phenotypic plasticity. Here, we investigated the mechanisms behind how an aggressive reef fish mimic (bluestriped fangblenny Plagiotremus rhinorhynchos) changes colour rapidly (1-5 min) between mimetic and other colour forms. Black with one neon blue dorsal stripe (mimic), black with two neon blue stripes, brown, olive and orange forms differed in melanophore density. Fish skin biopsies were modulated in vitro by hormones, and smaller fangblennies changed coloration more rapidly than larger fish suggesting that the ability to change colour is diminished as fish get larger. Individuals may be limited by differences in pigment cell densities to change colour between extreme colour forms (black to orange); therefore, longer morphological changes may also occur or fangblennies may exhibit dimorphic populations. Behavioural observations suggest that small black and orange individuals were equally successful in attacking passing fish to feed on dermal tissue/scales, indicating that deceptive strategies used by each colour form may deliver equal fitness benefits. The present study demonstrates for the first time how fangblennies change colour and highlights that colour plasticity offers important adaptive advantage; however, physiological constraints should also be considered.
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| 22. |
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| 23. |
- Conde-Padin, P., et al.
(författare)
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Revealing the mechanisms of sexual isolation in a case of sympatric and parallel ecological divergence
- 2008
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 94:3, s. 513-526
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Tidskriftsartikel (refereegranskat)abstract
- Two ecotypes of a marine intertidal snail (Littorina saxatilis), living at different microhabitats and shore levels, have evolved in sympatry and in parallel across the Galician rocky shore. These ecotypes differ in many traits (including size) due to differential adaptation. They meet, mate assortatively, and partially hybridize at the mid shore where the two microhabitats overlap. The partial sexual isolation observed is claimed to be a side-effect of the size differences between ecotypes combined with a size assortative mating found in most populations of this species. We investigated this hypothesis using three complementary experimental approaches. First, we investigated which of the different shell variables contributed most to the variation in individual sexual isolation in the field by using two new statistics developed for that purpose: (1) pair sexual isolation and (2) r(i), which is based on the Pearson correlation coefficient. We found that size is the most important trait explaining the sexual isolation and, in particular, the males appear to be the key sex contributing to sexual isolation. Second, we compared the size assortative mating between regions: exposed rocky shore populations from north-westwern Spain (showing incomplete reproductive isolation due to size assortative mating) and protected Spanish and Swedish populations (showing size assortative mating but not reproductive isolation between ecomorphs). Most of the variation in size assortative mating between localities was significantly explained by the within-population level of variation on size. Third, we performed a laboratory male choice experiment, which further suggested that the choice is made predominantly on the basis of size. These results confirm the mechanism proposed to explain the sexual isolation in the Galician hybrid zone and thus support this case as a putative example of parallel incipient speciation. (C) 2008 The Linnean Society of London.
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| 24. |
- Cusminsky, Gabriela, et al.
(författare)
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Late quaternary environmental changes in Patagonia as inferred from lacustrine fossil and extant ostracods
- 2011
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 103:2, s. 397-408
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we compare modern and Quaternary ostracods from two lacustrine basins: Laguna Cari-Laufquen (41 degrees S) and Lago Cardiel (49 degrees S) in Patagonia. Taxonomic and quantitative analyses along with isotopic and chemical studies of the extant ostracod fauna indicate that distinct ostracod associations can be identified as a function of conductivity. Three ostracod associations can be distinguished: (1) springs, ponds and small creeks, characterized by low conductivity (e. g. 1015 ms cm(-1)); (2) lakes and permanent ponds, characterized by medium conductivity (e. g. 1625 ms cm(-1)) and (3) ephemeral lacustrine environments, generally characterized by higher conductivity (e. g. 16 480 ms cm(-1)) These modern ostracod associations were also identified in older sequences from sediments outcropping in the Laguna Cari-Laufquen current shoreline, as well as in sediment cores from Lago Cardiel. The predominance of Limnocythere rionegroensis Cusminsky & Whatley in the Cari-Laufquen sections suggests the development of a saline and turbid lake during the Late Pleistocene and Early Holocene, and thus higher precipitation at these latitudes. Changes in ostracod abundance and associations have been observed in Lago Cardiel during the last approximately 16 000 calibrated years BP. Conductivity is known to change as a function of the ratio of precipitation to evaporation and a decrease in conductivity from the Late Pleistocene to the Middle Holocene suggests substantial hydrological variations (i. e. increase of the precipitation/ evaporation ratio suggests minor conductivity). These two examples show that ostracods provide an excellent proxy for interpreting palaeoclimatic and palaeoenvironmental changes in Patagonia. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 397-408.
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| 25. |
- Dalén, Love, et al.
(författare)
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Population history and genetic structure of a circumpolar species : the arctic fox
- 2005
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 84:1, s. 79-89
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Tidskriftsartikel (refereegranskat)abstract
- The circumpolar arctic fox Alopex lagopus thrives in cold climates and has a high migration rate involving long-distance movements. Thus, it differs from many temperate taxa that were subjected to cyclical restriction in glacial refugia during the Ice Ages. We investigated population history and genetic structure through mitochondrial control region variation in 191 arctic foxes from throughout the arctic. Several haplotypes had a Holarctic distribution and no phylogeographical structure was found. Furthermore, there was no difference in haplotype diversity between populations inhabiting previously glaciated and unglaciated regions. This suggests current gene flow among the studied populations, with the exception of those in Iceland, which is surrounded by year-round open water. Arctic foxes have often been separated into two ecotypes: ‘lemming’ and ‘coastal’. An analysis of molecular variance suggested particularly high gene flow among populations of the ‘lemming’ ecotype. This could be explained by their higher migration rate and reduced fitness in migrants between ecotypes. A mismatch analysis indicated a sudden expansion in population size around 118 000 BP, which coincides with the last interglacial. We propose that glacial cycles affected the arctic fox in a way opposite to their effect on temperate species, with interglacials leading to short-term isolation in northern refugia.
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| 26. |
- Dinca, Vlad, et al.
(författare)
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Dispersal, fragmentation, and isolation shape the phylogeography of the European lineages of Polyommatus (Agrodiaetus) ripartii (Lepidoptera: Lycaenidae) :
- 2013
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 109:4, s. 817-829
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Tidskriftsartikel (refereegranskat)abstract
- Polyommatus ripartii is a biogeographically and taxonomically poorly understood species of butterfly with a scattered distribution in Europe. Recently, it has been shown that this species includes several European endemic and localized taxa (galloi, exuberans, agenjoi) that were previously considered species and even protected, a result that poses further questions about the processes that led to its current distribution. We analysed mitochondrial DNA and the morphology of P.ripartii specimens to study the phylogeography of European populations. Three genetically differentiated but apparently synmorphic lineages occur in Europe that could be considered evolutionarily significant units for conservation. Their strongly fragmented and counterintuitive distribution seems to be the result of multiple range expansions and contractions along Pleistocene climatic oscillations. Remarkably, based on the 79 specimens studied, these genetic lineages do not seem to extensively coexist in the distributional mosaic, a phenomenon most evident in the Iberian Peninsula. One of the important gaps in the European distribution of P.ripartii is reduced by the discovery of new Croatian populations, which also facilitate a better understanding of the biogeography of the species.
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| 27. |
- Ekendahl, Anette, et al.
(författare)
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Shell colour variation in Littorina saxatilis Olivi (Prosobranchia : Littorinidae): a multi-factor approach
- 1997
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Ingår i: Biological Journal of the Linnean Society. - 0024-4066. ; 62:3, s. 401-419
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Tidskriftsartikel (refereegranskat)abstract
- The marine snail Littorina saxatilis is highly polymorphic for shell colour. It lives in the heterogeneous intertidal zone, where there are sharp transitions in a number of abiotic factors that may influence the relative fitness of morphs. We investigated the hypothesis of selected variation by relating the colour distribution to five factors (wave exposure, substratum, shore level, sex, snail age), and to interactions between them. We compared patterns from geographical areas in Sweden, Iceland and Russia. Cryptic morphs (tessellated and different dark colours) generally dominated (80-98%) while conspicuous morphs (white, yellow, red and banded) were less common (2-20%). The colour frequencies were often related to wave exposure, substratum and shore level. Frequencies rarely varied with age and never with sex. In order to test the assumption that the different colours are genetically determined we cross-bred snails from Iceland in the laboratory. Both the presence of bands and the ground colours of the shell were inherited, and we have tentative support for a one-locus two-allele model for banding. Our results support a model of selected inherited colour variation, involving a number of different selective agents, the importance of which may vary between populations on local and geographical scales. (C) 1997 The Linnean Society of London.
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| 28. |
- EVANS, MR, et al.
(författare)
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VARIABLE SEXUAL ORNAMENTS IN SCARLET-TUFTED MALACHITE SUNBIRDS (NECTARINIA-JOHNSTONI) ON MOUNT KENYA
- 1995
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Ingår i: BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS (LONDON) LTD. - 0024-4066. ; 54:4, s. 371-381
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- order to be elaborated by sexual selection, sexual ornaments must vary perceptibly and genetically among individuals in natural populations. Rather little is known about ornament Variation in monogamous species, in which sexual selection should act more w
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| 29. |
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| 30. |
- Faulks, Leanne, et al.
(författare)
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Genetic and morphological divergence along the littoral–pelagic axis in two common and sympatric fishes : perch, Perca fluviatilis (Percidae) and roach, Rutilus rutilus (Cyprinidae)
- 2015
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 114:4, s. 929-940
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Tidskriftsartikel (refereegranskat)abstract
- Individuals are constantly in competition with one another and, on both ecological and evolutionary timescales, processes act to reduce this competition and promote the gain of fitness advantages via diversification. Here we have investigated the genetic (AFLP) and morphological (geometric morphometrics) aspects of the littoral–pelagic axis, a commonly observed resource polymorphism in freshwater fishes of postglacial lakes. We found a large degree of variation in the genetic and morphological divergence between littoral and pelagic perch and roach across Swedish lakes. Although there was evidence of assortative mating (elevated kinship values) in both species, we could not find any significant coupling of morphology and genetic divergence. Instead, there was evidence that the extent of resource polymorphism may be largely caused by phenotypic plasticity. These results suggest that assortative mating, which can lead to genetically determined adaptive divergence, does occur in these species, particularly perch, but not according to genetically fixed morphological traits. The behavioural mechanisms facilitating associative mating need to be investigated to explore the interaction between phenotypic plasticity and adaptive genetic divergence and their roles in diversification.
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| 31. |
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| 32. |
- Fitzpatrick, Susan, et al.
(författare)
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Ornaments or offspring : costs to reproductive success restrict sexual selection processes
- 1995
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Ingår i: Biological Journal of the Linnean Society. - 0024-4066 .- 1095-8312. ; 55:3, s. 251-260
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Tidskriftsartikel (refereegranskat)abstract
- If, in their partner choice, males seek direct benefits (fecund females), the result will be selection for traits indicating female quality rather than for arbitrary (Fisherian) traits. However, the costs of developing and maintaining the sexually selected traits (ornaments) may reduce the resources available to the female for allocation to reproduction and hence result in lower reproductive success per brood. This hitherto unrecognized fecundity cost of sexually selected traits will constrain both the potency of sexual selection mechanisms and the degree of elaboration of sexually selected traits in females, and can also apply to males which invest in their offspring: sexual selection becomes self-limiting. The fitness implications of these costs are examined for both sexes in a variety of mating and parental care patterns. Sexual selection acting on both sexes may lead to either dimorphism or monomorphism, the latter being the case when the quality indicators chosen by both sexes coincide. Ways of evasion or reduction of these reproductive costs of allocations to sexually selected traits include using different resource components for the ornament and for reproduction, or partitioning the two allocations in time. (C) 1995 The Linnean Society of London
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| 33. |
- FITZPATRICK, S, et al.
(författare)
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ORNAMENTS OR OFFSPRING - COSTS TO REPRODUCTIVE SUCCESS RESTRICT SEXUAL SELECTION PROCESSES
- 1995
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Ingår i: BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS (LONDON) LTD. - 0024-4066. ; 55:3, s. 251-260
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- If, in their partner choice, males seek direct benefits (fecund females), the result will be selection for traits indicating female quality rather than for arbitrary (Fisherian) traits. However, the costs of developing and maintaining the sexually selecte
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| 34. |
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| 35. |
- Fredga, K, et al.
(författare)
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The complex hybrid zone between the Abisko and Sidensjo chromosome races of Sorex araneus in Sweden
- 2000
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Ingår i: BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS LTD. - 0024-4066. ; 70:2, s. 285-307
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Tidskriftsartikel (refereegranskat)abstract
- Six chromosome races of the common shrew occur in Sweden, each with its characteristic arm combination of metacentric chromosomes. G-banded karyotypes were analysed from 201 common shrews in 14 localities of the northern hybrid zone in Sweden. Analyses fr
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| 36. |
- Fumi, Michele, et al.
(författare)
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Consistent seasonal polyphenism in male genitalia of three Leptidea butterfly species (Lepidoptera : Pieridae)
- 2019
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 126:1, s. 80-94
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Tidskriftsartikel (refereegranskat)abstract
- Insect genitalia are important for species identification and taxonomy and are key traits for the evolution of reproductive isolation through their 'lock-And-key mechanism'. Nevertheless, few studies have evaluated intraspecific variation and the impact of seasonal environmental variation on genital morphology. We used geometric morphometric analysis to quantify male genital morphology within and among the three taxa in the Leptidea sinapis cryptic species complex (Lepidoptera: Pieridae). We focused on the potential presence of seasonal polyphenism, i.e. consistent differences among temporally separated generations. As predicted, our analysis revealed that male genitalia differed in size, shape and form (the joint effect of size and shape) among species. More surprisingly, all species harboured consistent genital variation between the spring and summer generations. The interspecific variation in genital structures could function as a mechanical reproductive barrier, although contemporary populations of these butterflies do not engage in heterospecific matings. We suggest that the smaller, but significant, genital differences among conspecific generations provide an opportunity to test empirically whether a seasonal polyphenism in genital morphology could generate raw material for the build-up of reproductive isolation at an early stage of speciation. Collectively, our results provide evidence demonstrating that insect genitalia can indeed harbour ample intraspecific variation.
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| 37. |
- Förschler, Marc I., et al.
(författare)
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Gene flow and range expansion in a mountain-dwelling passerine with a fragmented distribution
- 2011
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 103:3, s. 707-721
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Tidskriftsartikel (refereegranskat)abstract
- We studied gene flow and bottleneck events in the population history of locally isolated citril finches endemic to European mountains. For the present study, we used two genetic markers with different rates of evolution: a fast evolving mitochondrial marker (ATPase6/8) and a more slowly evolving nuclear marker (02401). Populations north of the Pyrenees showed in general fewer haplotypes and a considerable lower nucleotide and gene diversity than the Iberian populations. Unexpectedly, we found very little genetic variability in the fast evolving mitochondrial marker, arguing for a strong and relatively recent bottleneck event in the species population history. This pattern potentially reflects a sudden decrease of crucial resources during Mid-Holocene (mountain pine, Scots pine, and black pine) and a subsequent breakdown of the population. The bottleneck could also have been caused or coincide with a selective sweep in the mitochondrion. By contrast, the slowly evolving nuclear marker showed a much higher variability. This marker probably reflects major gene flow along a potential expansion pathway from the Eastern Pyrenees, northwards to the populations of Central Europe, and southwards to the more fragmented populations of central and southern Spain. The population of the Western Pyrenees (Navarra) appears to be cut-off from this major gene flow and our data indicate a certain degree of partial isolation, probably reflecting more ancient events (e.g. the separation in distinct refuge sites during the last glacial maximum).
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| 38. |
- Gamero, Anna, et al.
(författare)
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Population differences in the structure and coloration of great tit contour feathers
- 2015
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 114:1, s. 82-91
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Tidskriftsartikel (refereegranskat)abstract
- Contour feathers cover most of the avian body and play critical roles in insulation, social communication, aerodynamics, and water repellency. Feather production is costly and the development of the optimum characteristics for each function may be constrained by limited resources or time, and possibly also lead to trade-offs among the different characteristics. Populations exposed to different environmental conditions may face different selective pressures, resulting in differences in feather structure and coloration, particularly in species with large geographical distributions. Three resident populations of great tit Parus major L. from different latitudes differed in feather structure and coloration. Individuals from the central population exhibited less dense and longer contour feathers, with a higher proportion of plumulaceous barbs than either northern or southern birds, which did not differ in their feather structure. Ultraviolet reflectance and brightness of the yellow of the contour feathers of the breast was higher for the southern than for the northern population. Birds with greener plumage (higher hue) had less dense but longer feathers, independently of the population of origin. Differences in feather structure across populations appear to be unrelated to the contour feather colour characteristics except for hue. Nutritional and time constraints during molt might explain the pattern of feather structure, whereas varying sexual selection pressure might underlie the coloration patterns observed. Our results suggest that different selective pressures or constraints shape contour feather traits in populations exposed to varying environmental conditions.(c) 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114, 82-91.
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| 39. |
- Gosden, Thomas, et al.
(författare)
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Range limits, large-scale biogeographic variation, and localized evolutionary dynamics in a polymorphic damselfly
- 2011
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 102:4, s. 775-785
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Tidskriftsartikel (refereegranskat)abstract
- Studies of heritable colour polymorphisms allow investigators to track the genetic dynamics of natural populations. By comparing polymorphic populations over large geographic areas and across generations, issues about both morph stability and evolutionary dynamics can be addressed, increasing our understanding of the potential mechanisms maintaining genetic polymorphisms. In the present study, we investigated population morph frequencies in a sex-limited heritable colour polymorphic damselfly (Ischnura elegans, Vander Linden), with three discrete female morphs. We compared the frequencies of these three female morphs in 120 different populations from ten European countries at differing latitudes and longitudes. There were pronounced differences in morph frequencies both across the entire European biogeographic range, as well as at a smaller scale within regions. We also found considerable between-population variation at the local scale within regions, particularly at the edges of the range of this species. We discuss these findings in the context of recent models of adaptive population divergence along the range of a species. This polymorphism is thus highly dynamic, with stable morph frequencies at the core of the species range but fluctuating morph dynamics at the range limits. We finish with a discussion of how local interactions and climatic factors can be expected to have a strong influence on the biogeographic patterns in this species and other sexually selected polymorphisms. (c) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 775-785.
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| 40. |
- Gotthard, Karl, et al.
(författare)
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The evolution of alternative morphs: density-dependent determination of larval colour dimorphism in a butterfly
- 2009
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 98:2, s. 256-266
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the ultimate causes for the presence of polymorphisms within populations requires knowledge of how the expression of discrete morphs is regulated. In the present study, we explored the determination mechanism of a colour dimorphism in larvae of the butterfly Pararge xiphia (Satyrinae: Nymphalidae) with the ultimate aim of understanding its potential adaptive value. Last-instar larvae of P. xiphia develop into either a green or a brown morph, although all individuals are invariably green during the preceding three instars. A series of laboratory experiments reveal that morph development is strongly environmentally dependent and not the result of alternative alleles at one locus. Photoperiod, temperature, and in particular larval density, all influenced morph determination. The strong effect of a high larval density in inducing the brown morph parallels other known cases of density-dependent melanization in Lepidopteran larvae. Because melanization is often correlated with increased immune function, this type of determination mechanism is expected to be adaptive. However, the ecology and behaviour of P. xiphia larvae suggests that increased camouflage under high-density conditions may be an additional adaptive explanation. We conclude that the colour dimorphism of P. xiphia larvae is determined by a developmental threshold that is influenced both by heredity and by environmental conditions, and that selection for increased immune function and camouflage under high-density conditions may be responsible for maintaining the dimorphism. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 256–266.
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| 41. |
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| 42. |
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| 43. |
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| 44. |
- Gunnarsson, Bengt, 1954, et al.
(författare)
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Foraging mode of spiders affects risk of predation by birds
- 2015
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 115:1, s. 58-68
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Tidskriftsartikel (refereegranskat)abstract
- Avian insectivores are top predators of arboreal arthropods in different forest ecosystems. The selective effects of bird predation in relation to foraging behaviour in canopy-living spiders were studied in a 2-year field experiment using exclosures in a spruce forest in southern Sweden. Three different hunting strategies – free-hunting, two-dimensional web, three-dimensional web – were included in the analysis. Comparisons of bird predation rate (ratio ln (abundance net-enclosed branch/abundance control)) showed considerable variation between spider groups. Free-hunting spiders suffered most from avian insectivores and predation rate was significantly higher than in spiders with two-dimensional webs. Spiders with three-dimensional webs were exposed to a predation rate in between those of the two other hunting strategies. Generally, the experimental effect was significantly higher in spring samples than in autumn, suggesting a stronger predation pressure in winter. The high variation in susceptibility to predation by insectivores implies that selection on behaviour of spider individuals is strong. Web building in itself is probably part of the protective mechanism, suggesting that webs have dual functions. We conclude that the risk of bird predation is a selective force on foraging behaviour of spiders in a forest canopy system.
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| 45. |
- Hedberg, O
(författare)
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The genus Koenigia L. emend. Hedberg (Polygonaceae)
- 1997
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Ingår i: BOTANICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS LTD. - 0024-4066. ; 124:4, s. 295-330
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Pollen morphological studies revealed the occurrence of the characteristic spinulose pollen type of Koenigia not only in the three species earlier recognized in the genus (K. islandica, K. nepalensis and K. pilosa) but also in three additional species ear
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| 46. |
- Hedren, M, et al.
(författare)
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Allozyme variation and racial differentiation in Swedish Carex lepidocarpa sl (Cyperaceae)
- 1996
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Ingår i: BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS LTD. - 0024-4066. ; 59:2, s. 179-200
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Two morphological races have previously been recognized within the sedge, Carex lepidocarpa, in Sweden. These largely allopatric races are accorded specific status, as C. lepidocarpa s.s. and C. jemtlandica, in Scandinavian floras. A study of allozyme var
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| 47. |
- Hedrén, Mikael, et al.
(författare)
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Plastid and nuclear DNA marker data support the recognition of four tetraploid marsh orchids (Dactylorhiza majalis s.l., Orchidaceae) in Britain and Ireland, but require their recircumscription
- 2011
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Ingår i: Biological Journal of the Linnean Society. - 0024-4066. ; 104:1, s. 107-128
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Tidskriftsartikel (refereegranskat)abstract
- Relationships among allotetraploid marsh orchids collectively assignable to Dactylorhiza majalis s.l. are exceptionally complex because of multiple origins, secondary hybridization with each other, and with their parental lineages, local adaptation, and genomic reorganization processes, all extending through time and space. We sampled 34 populations from Britain and Ireland in an attempt to simultaneously interpret patterns of genetic differentiation within and between populations. The material analysed consisted of 250 individuals that were examined for variation at five nuclear microsatellite loci, internal transcribed spacer (ITS), and plastid DNA. Once integrated, patterns of differentiation in the three molecular data sets show that the British and Irish members of the D. majalis s.l. complex should be assigned to a minimum of four genetically differentiated subgroups of equal status (either species or subspecies), broadly corresponding to the traditional D. majalis ssp. praetermissa, ssp. purpurella, ssp. occidentalis, and ssp. traunsteinerioides. UK plants previously attributed to 'Dactylorhiza lapponica' and given high conservation status have been shown to be genetically identical to ssp. traunsteinerioides. The endemic Hebridean marsh orchid, D. majalis ssp. ebudensis, genetically resembles ssp. traunsteinerioides. Dactylorhiza majalis 'ssp. cambrensis' could readily be accommodated within ssp. purpurella. Together, these observations reinforce a recent assertion that anthocyanin content has been over-weighted in previous morphologically based classifications of Dactylorhiza. Several study populations showed signs of hybridization and introgression with other allotetraploids, or their parental lineages, especially with D. incarnata s.l. However, ssp. praetermissa and ssp. traunsteinerioides were better separated than anticipated: southern populations widely regarded as mixed populations of the two taxa are arguably better treated as containing an unusually narrow-leaved, ecologically specialized form of ssp. praetermissa. Accepting this recircumscription means that the southern margins of the distributions of ssp. purpurella and ssp. traunsteinerioides now coincide, stretching from mid-Wales to the Humber Estuary of Yorkshire, and together indicating a significant genetic transition zone. Plastid haplotype data confirm that ssp. traunsteinerioides and ssp. praetermissa are relatively old polyploids derived from the Continental D. majalis s.l. complex, whereas ssp. purpurella and ssp. occidentalis may have more recent (most likely postglacial) origins within their current distributions. (C) 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 107-128.
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| 48. |
- Herman, Jeremy S., et al.
(författare)
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Genetic variation in field voles (Microtus agrestis) from the British Isles: selective sweeps or population bottlenecks?
- 2019
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Ingår i: Biological Journal of the Linnean Society. - : OXFORD UNIV PRESS. - 0024-4066 .- 1095-8312. ; 126:4, s. 852-865
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Tidskriftsartikel (refereegranskat)abstract
- The Eurasian field vole (Microtus agrestis) comprises three evolutionarily significant units (ESUs). The northern ESU is found at higher latitudes across the western Palaearctic region and includes six, largely allopatric, mitochondrial DNA lineages that were derived from population bottlenecks. One of these lineages is found in southern Britain and nearby areas of continental Europe. A prominent sub-lineage is nested within, and therefore derived from, the part of this lineage occupying southern Britain. The sub-lineage consists of an abundant central haplotype together with a series of closely related haplotypes, a distribution that would result from either a recent population bottleneck or a selective sweep. To distinguish between these, we sequenced a Y-chromosome marker in 167 field voles from Britain and Europe, and analysed a panel of 13 autosomal microsatellite loci in 144 field voles from eight populations in Britain. The Y-chromosome marker showed a continental-scale pattern of variation that was not aligned with that of the mitochondrial marker, while microsatellite variation did not show any evidence for a bottleneck, tentatively favouring selection instead. This implies a role for both stochastic and selective processes in generating phylogeographical patterns at different scales in the field vole.
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| 49. |
- Hjertson, ML
(författare)
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Taxonomy, phylogeny and biogeography of Lindenbergia (Scrophulariaceae)
- 1995
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Ingår i: BOTANICAL JOURNAL OF THE LINNEAN SOCIETY. - : ACADEMIC PRESS LTD. - 0024-4066. ; 119:4, s. 265-321
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Afro-Asiatic genus Lindenbergia Lehm. (Scrophulariaceae) is revised and 12 species are recognized. The position of the genus within the Scrophulariaceae is analysed, and it is concluded that Lindenbergia belongs in the tribe Gratioleae. Morphological
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| 50. |
- Hollander, Johan, et al.
(författare)
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Rates of gene flow in a freshwater snail and the evolution of phenotypic plasticity
- 2017
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 121:4, s. 764-770
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of phenotypic plasticity requires a number of conditions. Selection of plasticity is favoured when the organism experience environmental change, costs are low and cues are reliable about the environmental heterogeneity. However, organisms living in stable environments, not showing constitutive traits but a large amount of plasticity, are predicted to demonstrate high rates of gene flow in order for selection to favour the evolution of phenotypic plasticity, which accordingly should provide weak genetic structures across populations. We used the pulmonate freshwater gastropod Radix balthica, a species with known and considerable shell shape variation due to predator-induced plasticity, and used amplified fragment length polymorphism markers to test if the rate of gene flow can explain the evolution of phenotypic plasticity. Since R. balthica inhabit water bodies with different but consistent predator regimes, we envisaged a large dispersal rate. However, we found a contradictory result with clear population structures, even among adjacent ponds in southern Sweden. We discuss this apparent paradox in contrast to the evolution of ecotype formation, colonization mechanisms that have the potential to reduce gene flow and, in the context of costs of plasticity, we consider new perspectives about relaxed and variable selection that may drive the evolution of phenotypic plasticity.
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