| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Halpin, Christina G., et al.
(författare)
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The effect of distastefulness and conspicuous coloration on the post-attack rejection behaviour of predators and survival of prey
- 2017
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press. - 0024-4066 .- 1095-8312. ; 120:1, s. 236-244
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Tidskriftsartikel (refereegranskat)abstract
- Aposematic insects use bright colours and/or distinct markings to advertise their toxins to potential predators. When toxins are bitter-tasting and detectable upon attack, birds are able to use taste when making decisions about whether or not to eat defended prey. Taste-rejection behaviour, when birds taste but do not ingest a prey item, is often assumed to increase the survival of defended prey, yet few empirical studies have investigated the post-attack survival rates of live defended insects. We used naïve domestic chicks (Gallus gallus domesticus) foraging on live waxmoth larvae (Galleria mellonella) in a laboratory setting, where conspicuousness and distastefulness could be controlled and manipulated to investigate the effects of taste-rejection behaviour, as well as the associated handling behaviour, on post-attack survival of prey. We found that being distasteful increased the probability of being rejected by naïve chicks, and taste-rejection behaviour tended to be more frequent when distasteful prey were conspicuous compared with when they were cryptic. Conspicuous coloration also appeared to affect predators’ assessment of prey distastefulness, with past experience strongly influencing the probability that conspicuous (but not cryptic) prey were rejected. However, in contrast to previous findings, there was no evidence that either distastefulness or conspicuousness altered how predators handled the prey before making a decision about whether or not to eat it, in any way that enhanced prey survival post-attack. Therefore, taste-rejection behaviour appears to be a useful measure of prey survival. Our results provide novel insights into the potential importance of signal conspicuousness for prey populations with variable defences, and highlight the need to consider the role of taste-rejection behaviour in mimicry dynamics.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Jia, Shu-Wen, et al.
(författare)
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Evolutionary history of Gymnocarpos (Caryophyllaceae) in the arid regions from North Africa to Central Asia
- 2016
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 119:2, s. 511-522
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Tidskriftsartikel (refereegranskat)abstract
- Gymnocarpos has only about ten species distributed in the arid regions of Asia and Africa, but it exhibits a geographical disjunction between eastern Central Asia and western North Africa and Minor Asia. We sampled eight species of the genus and sequenced two chloroplast regions (rps16 and psbB-psbH), and the nuclear rDNA (ITS) to study the phylogeny and biogeography. The results of the phylogenetic analyses corroborated that Gymnocarpos is monophyletic, in the phylogenetic tree two well supported clades are recognized: clade 1 includes Gymnocarpos sclerocephalus and G. decandrus, mainly the North African group, whereas clade 2 comprises the remaining species, mainly in the Southern Arabian Peninsula. Molecular dating analysis revealed that the divergence age of Gymnocarpos was c. 31.33 Mya near the Eocene and Oligocene transition boundary, the initial diversification within Gymnocarpos dated to c. 6.69 Mya in the late Miocene, and the intraspecific diversification mostly occurred during the Quaternary climate oscillations. Ancestral area reconstruction suggested that the Southern Arabian Peninsula was the ancestral area for Gymnocarpos. Our conclusions revealed that the aridification since mid-late Miocene significantly affected the diversification of the genus in these areas.
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| 10. |
- Johansson, Frank, et al.
(författare)
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Genetic differentiation in the boreal dragonfly Leucorrhinia dubia in the Palearctic region
- 2017
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Ingår i: Biological Journal of the Linnean Society. - : OXFORD UNIV PRESS. - 0024-4066 .- 1095-8312. ; 121:2, s. 294-304
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Tidskriftsartikel (refereegranskat)abstract
- The last glacial period had a strong influence on the population genetic structure of boreal species in southern and central Europe. In addition, recent and current human impact on the boreal environment has led to habitat loss, which also has a large influence on population genetic structure of species. Here we present the spatial genetic structure of the boreal dragonfly Leucorrhinia dubia using ddRAD sequencing. We sampled individuals from nine locations in Europe, three in Asia (Russia and Japan) and one location of L. intermedia in Japan. Results showed three distinct genetic clusters in Europe. One genetic cluster consisted of individuals sampled from the locations in the Swiss Alps, a second consisted of individuals sampled in the United Kingdom, and a third cluster consisted of individuals from the rest of the seven sampled locations in Europe covering a latitudinal gradient from the French Pyrenees to the north of Finland. There was also a week support that the French Pyrenees and Austrian Alps samples differentiated from the cluster of the five samples from central and north Europe. We suggest that these clusters reflect historical recolonization patterns since the last glaciation. The L. dubia individuals sampled from locations in Asia formed one cluster referring to L. dubia orientalis separated from the individuals sampled in European and from the L. intermedia locality sampled. Our result suggests that aquatic insects in the fragmented boreal landscape in south central Europe and United Kingdom need conservation consideration.
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