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  • Alho, Jussi S., et al. (författare)
  • Increasing melanism along a latitudinal gradient in a widespread amphibian : local adaptation, ontogenic or environmental plasticity?
  • 2010
  • Ingår i: BMC Evolutionary Biology. - 1471-2148 .- 1471-2148. ; 10, s. 317-
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundThe thermal benefits of melanism in ectothermic animals are widely recognized, but relatively little is known about population differentiation in the degree of melanism along thermal gradients, and the relative contributions of genetic vs. environmental components into the level of melanism expressed. We investigated variation in the degree of melanism in the common frog (Rana temporaria; an active heliotherm thermoregulator) by comparing the degree of melanism (i) among twelve populations spanning over 1500 km long latitudinal gradient across the Scandinavian Peninsula and (ii) between two populations from latitudinal extremes subjected to larval temperature treatments in a common garden experiment.ResultsWe found that the degree of melanism increased steeply in the wild as a function of latitude. Comparison of the degree of population differentiation in melanism (PST) and neutral marker loci (FST) revealed that the PST > FST, indicating that the differences cannot be explained by random genetic drift alone. However, the latitudinal trend observed in the wild was not present in the common garden data, suggesting that the cline in nature is not attributable to direct genetic differences.ConclusionsAs straightforward local adaptation can be ruled out, the observed trend is likely to result from environment-driven phenotypic plasticity or ontogenetic plasticity coupled with population differences in age structure. In general, our results provide an example how phenotypic plasticity or even plain ontogeny can drive latitudinal clines and result in patterns perfectly matching the genetic differences expected under adaptive hypotheses. 
  • Hettyey, A, et al. (författare)
  • Does testis weight decline towards the Subarctic? A case study on the common frog, Rana temporaria
  • 2005
  • Ingår i: Naturwissenschaften. - : Springer. - 1432-1904. ; 92, s. 188-192
  • Tidskriftsartikel (refereegranskat)abstract
    • Interpopulation comparisons of variation in resource availability and in allocation patterns along altitudinal and latitudinal gradients allow insights into the mechanisms shaping the life history of animals. Patterns of between-population differences in female life history traits have been studied intensively across a wide range of taxa, but similar investigations in males have remained scarce. To study if testis weight - ameasure of reproductive investment - varies on a geographical scale in anurans, we focussed on the variation in relative testis weight (RelTW) and asymmetry in 22 populations of the common frog Rana temporaria along a 1,600-km latitudinal transect across the Scandinavian peninsula. We found that RelTW decreased towards the north. Body mass and body length both had independent positive effects on testes mass. We found evidence for directional asymmetry (DA) in testis weight with the right testis being larger than the left. The level of DA in testis weight was not related to latitude, but both body mass and testes mass had independent positive effects on asymmetry. We discuss the northwards decrease in RelTW in terms of a decreased reproductive investment as a possible consequence of harsher environmental conditions, and perhaps also, weaker sexual selection in the north than in the south.
  • Alho, J. S., et al. (författare)
  • Allen's rule revisited : quantitative genetics of extremity length in the common frog along a latitudinal gradient
  • 2011
  • Ingår i: Journal of Evolutionary Biology. - : Wiley: 12 months. - 1010-061X .- 1420-9101. ; 24:1, s. 59-70
  • Tidskriftsartikel (refereegranskat)abstract
    • Ecogeographical rules linking climate to morphology have gained renewed interest because of climate change. Yet few studies have evaluated to what extent geographical trends ascribed to these rules have a genetic, rather than environmentally determined, basis. This applies especially to Allen's rule, which states that the relative extremity length decreases with increasing latitude. We studied leg length in the common frog (Rana temporaria) along a 1500 km latitudinal gradient utilizing wild and common garden data. In the wild, the body size-corrected femur and tibia lengths did not conform to Allen's rule but peaked at mid-latitudes. However, the ratio of femur to tibia length increased in the north, and the common garden data revealed a genetic cline consistent with Allen's rule in some trait and treatment combinations. While selection may have shortened the leg length in the north, the genetic trend seems to be partially masked by environmental effects.
  • Bachmann, Judith C., et al. (författare)
  • Gene Flow Limits Adaptation along Steep Environmental Gradients
  • 2020
  • Ingår i: American Naturalist. - : UNIV CHICAGO PRESS. - 0003-0147 .- 1537-5323. ; 195:3, s. E67-E86
  • Tidskriftsartikel (refereegranskat)abstract
    • When environmental variation is spatially continuous, dispersing individuals move among nearby sites with similar habitat conditions. But as an environmental gradient becomes steeper, gene flow may connect more divergent habitats, and this is predicted to reduce the slope of the adaptive dine that evolves. We compared quantitative genetic divergence of Rana temporaria frog populations along a 2,000-m elevational gradient in eastern Switzerland (new experimental results) with divergence along a 1,550-km latitudinal gradient in Fennoscandia (previously published results). Both studies found significant countergradient variation in larval development rate (i.e., animals from cold climates developed more rapidly). The dine was weaker with elevation than with latitude. Animals collected on both gradients were genotyped at similar to 2,000 singlenucleotide polymorphism markers, revealing that dispersal distance was 30% farther on the latitudinal gradient but 3.9 times greater with respect to environmental conditions on the elevational gradient. A meta-analysis of 19 experimental studies of anuran populations spanning temperature gradients revealed that countergradient variation in larval development, while significant overal I, was weaker when measured on steeper gradients. These findings support the prediction that adaptive population divergence is less pronounced, and maladaptation more pervasive, on steep environmental gradients.
  • Barnaby, Jonathan, 1965- (författare)
  • Cooperative Breeding in the Southern Anteater-Chat : Sexual Disparity, Survival and Dispersal
  • 2012
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Group-living sets the scene for complex social behaviours such as cooperative breeding, and exploring the factors that shape group-living is crucial in understanding these behaviours. This thesis explores the ecology of a population of the facultative cooperative breeding southern anteater-chat (Myrmecocichla formicivora), a group-living bird species endemic to southern Africa. It reveals a breeding system based around a breeding pair and up to three auxiliary males. Despite equal numbers of males and females produced as fledglings there was a surplus of adult males, which remained philopatric. Dispersal was strongly female biased. Females dispersed within their first year, they dispersed further than males, and they lost the benefits of the natal site. The sex skew in the population suggested that these factors drive differential mortality, with juvenile females having much lower annual survival than juvenile males. Adult survival was higher, with female survival only slightly lower than male survival. Dispersal distances suggested that males selected the breeding location, nearer to their natal site. There was no evidence of surplus non-breeding females. On the loss of a breeding female there was no replacement until new females entered the population, yet if a breeding male disappeared the female promptly re-paired with a male from another group. There was no indication of birds floating in the population, and if males were orphaned or widowed they joined other groups as unrelated helpers in preference to floating. There was no sign of inter-group or individual aggression among chats, and unrelated helpers were peacefully accepted into groups, suggesting mutual benefits. In fact all birds in a group helped raise offspring of the breeding pair, and groups with more helpers fledged more offspring, which implies that both direct and indirect fitness benefits can be gained through joining a group and helping. There was surprisingly little inheritance of breeding position by auxiliaries, and strikingly low levels of extra-pair paternity. This study suggests that the Southern anteater-chat group structure arises through male philopatry due to a shortage of breeding females, the benefits of remaining on the natal site and helping, and the potentially high costs of living alone.
  • Burraco, Pablo, et al. (författare)
  • Limits to compensatory responses to altered phenology in amphibian larvae
  • 2021
  • Ingår i: Oikos. - : WILEY. - 0030-1299 .- 1600-0706. ; 130:2, s. 231-239
  • Tidskriftsartikel (refereegranskat)abstract
    • Changes in phenology are among the most pervasive effects of current climate change. Modifications in the timing of life-cycle events can affect the behavior, physiology and life-history of wildlife. However, organisms can develop compensatory strategies in order to reduce the costs of phenological alterations. Here, we examine the extent and limits of compensatory developmental responses in amphibian larvae exposed to variation in hatching timing. Using a common-garden experiment, we analyze how changes in temperature and food conditions alter compensatory responses to hatching delay, paying particular attention at how adverse environmental conditions can constrain these responses. We found that under benign conditions (warm temperature, unrestricted food) larvae fully compensate for the hatching delay, without cost in mass. However, under detrimental conditions (cold temperature and restricted food) these responses were prevented, and the combination of adverse conditions with long hatching delay completely disrupt compensatory responses. This study highlights the need of examining ecological responses to climate variation across a broad spectrum of environmental conditions in order to accurately predict the putative effect that climatic alterations can have on the life-histories and survival of wildlife.
  • Cano, J. M., et al. (författare)
  • First-generation linkage map for the common frog Rana temporaria reveals sex-linkage group
  • 2011
  • Ingår i: Heredity. - 0018-067X .- 1365-2540. ; 107:6, s. 530-536
  • Tidskriftsartikel (refereegranskat)abstract
    • The common frog (Rana temporaria) has become a model species in the fields of ecology and evolutionary biology. However, lack of genomic resources has been limiting utility of this species for detailed evolutionary genetic studies. Using a set of 107 informative microsatellite markers genotyped in a large full-sib family (800 F1 offspring), we created the first linkage map for this species. This partial map-distributed over 15 linkage groups-has a total length of 1698.8 cM. In line with the fact that males are the heterogametic sex in this species and a reduction of recombination is expected, we observed a lower recombination rate in the males (map length: 1371.5 cM) as compared with females (2089.8 cM). Furthermore, three loci previously documented to be sex-linked (that is, carrying male-specific alleles) in adults from the wild mapped to the same linkage group. The linkage map described in this study is one of the densest ones available for amphibians. The discovery of a sex linkage group in Rana temporaria, as well as other regions with strongly reduced male recombination rates, should help to uncover the genetic underpinnings of the sex-determination system in this species. As the number of linkage groups found (n = 15) is quite close to the actual number of chromosomes (n = 13), the map should provide a useful resource for further evolutionary, ecological and conservation genetic work in this and other closely related species.
  • Carreira, Bruno M., et al. (författare)
  • Can heat waves change the trophic role of the world's most invasive crayfish? : Diet shifts in Procambarus clarkii
  • 2017
  • Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 12:9
  • Tidskriftsartikel (refereegranskat)abstract
    • In the Mediterranean basin, the globally increasing temperatures are expected to be accompanied by longer heat waves. Commonly assumed to benefit cold-limited invasive alien species, these climatic changes may also change their feeding preferences, especially in the case of omnivorous ectotherms. We investigated heat wave effects on diet choice, growth and energy reserves in the invasive red swamp crayfish, Procambarus clarkii. In laboratory experiments, we fed juvenile and adult crayfish on animal, plant or mixed diets and exposed them to a short or a long heat wave. We then measured crayfish survival, growth, body reserves and Fulton's condition index. Diet choices of the crayfish maintained on the mixed diet were estimated using stable isotopes (C-13 and N-15). The results suggest a decreased efficiency of carnivorous diets at higher temperatures, as juveniles fed on the animal diet were unable to maintain high growth rates in the long heat wave; and a decreased efficiency of herbivorous diets at lower temperatures, as juveniles in the cold accumulated less body reserves when fed on the plant diet. Heat wave treatments increased the assimilation of plant material, especially in juveniles, allowing them to sustain high growth rates in the long heat wave. Contrary to our expectations, crayfish performance decreased in the long heat wave, suggesting that Mediterranean summer heat waves may have negative effects on P. clarkii and that they are unlikely to boost its populations in this region. Although uncertain, it is possible that the greater assimilation of the plant diet resulted from changes in crayfish feeding preferences, raising the hypotheses that i) heat waves may change the predominant impacts of this keystone species and ii) that by altering species' trophic niches, climate change may alter the main impacts of invasive alien species.
  • Carreira, Bruno M., et al. (författare)
  • Heat waves trigger swift changes in the diet and life-history of a freshwater snail
  • 2020
  • Ingår i: Hydrobiologia. - 0018-8158 .- 1573-5117. ; 847:4, s. 999-1011
  • Tidskriftsartikel (refereegranskat)abstract
    • Extreme climatic events, such as heat waves, may induce changes in nutrient acquisition by omnivorous ectotherms. Likely modulated by the intensity, frequency and duration of these events, dietary shifts during heat waves may threaten the stability of freshwaters. We investigated the effects of heat wave duration on diet assimilation and life-history traits of the freshwater gastropod Radix balthica. We compared the magnitude of the effects of a short (1 week) and a long heat wave (7 weeks) on the assimilation of animal- and plant-based diets, measuring performance in terms of growth rate and reproduction. We hypothesized that heat waves should increase the proportion of plant material assimilated on the mixed diet and change the performance of snails on the animal and plant-based diets. Both heat waves increased the assimilation of plant material on the mixed diet and growth rate, with minor negative effects on reproduction. However, responses were disproportional to heat wave duration, as the short heat wave elicited swift and relatively stronger responses. Our findings showcase the role of phenotypic plasticity in aiding ectotherms to cope with increased thermal stress and acclimate. Temporarily changing the strength of trophic interactions, heat waves may alter community dynamics in freshwater habitats.
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