Evolutionary Ecology Research最新文献

{"title":"Magic cues versus magic preferences in speciation","authors":"M. Maan, O. Seehausen","doi":"10.7892/BORIS.16589","DOIUrl":"https://doi.org/10.7892/BORIS.16589","url":null,"abstract":"Question: How does divergent natural selection lead to divergence in mating traits and the evolution of reproductive isolation? Background: Ecological speciation of non-allopatric taxa usually requires the evolution of an association between selective mating and the traits underlying ecological adaptation. 'Magic traits' affect both ecological fitness and assortative mating and may therefore mediate rapid evolution of reproductive isolation. Problem: When assortative mating is mediated by separate preferences and cues, as opposed to being based on trait similarity (e.g. assortment by body size or habitat), pre-mating reproductive isolation between non-allopatric populations often requires divergence in both mating preferences and mating cues. However, most proposed cases of magic trait speciation rely on observation of divergent mating cues alone, leaving the consequences for reproductive isolation uncertain. Solution: We propose that a distinction should be made between mating cues and mating preferences when documenting divergent natural selection on mating traits. We argue that immediate effects of ecological adaptation on mating preferences, through direct selection or through pleiotropy, will drive divergence in both preferences and traits much more predictably than ecological selection on mating cues. The distinction between 'magic cues' and 'magic preferences' is critical for evaluating the evolutionary consequences of divergent selection on mating traits, and implies a need for increased research effort into documenting variation in mating preferences in diverging taxa.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"14 1","pages":"779-785"},"PeriodicalIF":0.0,"publicationDate":"2012-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71357623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distributions of reproductive and somatic cell numbers in diverse <i>Volvox</i> (Chlorophyta) species.","authors":"Deborah E Shelton,&nbsp;Alexey G Desnitskiy,&nbsp;Richard E Michod","doi":"","DOIUrl":"","url":null,"abstract":"<p><strong>Background: </strong><i>Volvox</i> (Chlorophyta) asexual colonies consist of two kinds of cells: a large number of small somatic cells and a few large reproductive cells. The numbers of reproductive and somatic cells correspond directly to the major components of fitness - fecundity and viability, respectively. <i>Volvox</i> species display diverse patterns of development that give rise to the two cell types.</p><p><strong>Questions: </strong>For <i>Volvox</i> species under fixed conditions, do species differ with respect to the distribution of somatic and reproductive cell numbers in a population of asexual clones? Specifically, do they differ with respect to the dispersion of the distribution, i.e. with respect to their intrinsic variability? If so, are these differences related to major among-species developmental differences?</p><p><strong>Data description: </strong>For each of five <i>Volvox</i> species, we estimate the number of somatic and reproductive cells for 40 colonies and the number of reproductive cells for an additional 200 colonies. We sampled all colonies from growing, low-density, asexual populations under standard conditions.</p><p><strong>Search method: </strong>We compare the distribution of reproductive cell numbers to a Poisson distribution. We also compare the overall dispersion of reproductive cell number among species by calculating the coefficient of variation (CV). We compare the bivariate (reproductive and somatic cell) dataset to simulated datasets produced from a simple model of cell-type specification with intrinsic variability and colony size variation. This allows us to roughly estimate the level of intrinsic variability that is most consistent with our observed bivariate data (given an unknown level of size variation).</p><p><strong>Conclusions: </strong>The overall variability (CV) in reproductive cell number is high in <i>Volvox</i> compared with more complex organisms. <i>Volvox</i> species show differences in reproductive cell number CV that were not clearly related to development, as currently understood. If we used the bivariate data and tried to account for the effects of colony size variation, we found that the species that have fast embryonic divisions and asymmetric divisions have substantially higher intrinsic variability than the species that have slow divisions and no asymmetric divisions. Under our culture conditions, the Poisson distribution is a good description of intrinsic variability in reproductive cell number for some but not all <i>Volvox</i> species.</p>","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"14 ","pages":"707-727"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4244606/pdf/nihms598473.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32847075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Does water depth or diet divergence predict progress towards ecological speciation in whitefish radiations","authors":"T. Ingram, A. G. Hudson, P. Vonlanthen, O. Seehausen","doi":"10.7892/BORIS.16333","DOIUrl":"https://doi.org/10.7892/BORIS.16333","url":null,"abstract":"Question: Is the extent of genetic divergence between sympatric whitefish ecotypes – a proxy for progress towards speciation – related to the extent of ecological divergence in spawning depth or diet? Study system: Whitefish (Coregonus spp.) that have diversified into two or more sympatric ecotypes in subalpine Swiss lakes. Sympatric ecotypes vary in the extent of reproductive isolation. Analytical methods: We measured the degree of spawning depth differentiation based on the depth-at-capture of different ecotypes. We estimated diet differentiation between ecotypes as Mahalanobis distances from stable isotopes. We compared each of these to genetic differentiation measured from AFLP data, using modified correlation tests and phylogenetically independent contrasts to account for non-independence of comparisons in lakes with more than two ecotypes. Results: We found that the magnitude of divergence in spawning depth was generally – albeit only marginally significantly – associated with the extent of genetic divergence between sympatric ecotypes. This effect was clearly stronger than the effect of diet divergence, which was not associated with genetic differentiation. Furthermore, there was no evidence for an interactive effect of depth and diet divergence on progress towards speciation.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"14 1","pages":"487-502"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71357615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of competition on niche dynamics of syntopic grazing ungulates: contrasting the predictions of habitat selection models using stable isotope analysis","authors":"D. Codron, J. Hull, J. Brink, J. Codron, D. Ward, M. Clauss","doi":"10.5167/UZH-49216","DOIUrl":"https://doi.org/10.5167/UZH-49216","url":null,"abstract":"Background: Theories of density-dependent habitat selection provide two solutions for co-existence of competing species. The niche compression hypothesis predicts that species reduce their respective niche breadths in response to inter-specific competition. Alternatively, if the species have similar resource preferences, the subordinate species may be forced to expand its niche to incorporate secondary resources. Aim: Determine whether grazing ungulate species partition the resource by compression or expansion of dietary niches. Organisms: Black wildebeest (Connochaetes gnou) and blue wildebeest (C. taurinus). Methods: Stable carbon and nitrogen isotope analysis of faeces. Isotopic niche breadths are compared across allopatric and sympatric wildebeest populations in South African grasslands. Results: Stable carbon and nitrogen isotope niche breadths of the two wildebeest species were virtually identical. In sympatry, however, black wildebeest had a narrower δ13C niche breadth (indicating almost exclusive use of C4 grass), whereas blue wildebeest had a wider δ13C niche breadth (indicating significant contributions from C3 sources). Blue wildebeest also had a wider δ15N niche breadth than sympatric black wildebeest. Moreover, the δ13C niche breadths of sympatric black wildebeest and blue wildebeest were narrower and wider, respectively, than those of allopatric populations of either species. Conclusions: Isotope niche dynamics across allopatric and sympatric populations arise due to the combined effects of competition and habitat heterogeneity on resource use. Although results for black wildebeest resemble niche compression, this hypothesis cannot explain patterns observed in blue wildebeest. Expansion of the blue wildebeest niche, and restricted niche breadth of black wildebeest, is consistent with predictions of a shared preference model in which black wildebeest are the dominant competitor. When competition is operating, differences in the way species use secondary resources can have an important role in structuring grazer assemblages.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"13 1","pages":"217-235"},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70654209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impacts of starvation on male reproductive success in Tribolium castaneum","authors":"S. Sbilordo, Vera M. Grazer, Marco Demont, O. Martin","doi":"10.3929/ETHZ-A-009988013","DOIUrl":"https://doi.org/10.3929/ETHZ-A-009988013","url":null,"abstract":"Background: Starvation is known to decrease male reproductive success in Tribolium castaneum. Starved males transfer less sperm, but we do not know whether reduced reproductive success is caused by lower oviposition rates of females or more frequent deposition of unfertilized eggs. Study organism: The red flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae). Questions: Does the nutritional state of a male influence female oviposition rate and/or fertilization capability? Does sperm use by females at fertilization reflect reduced numbers of sperm transferred by starved males? Hypothesis: If the number of sperm released by females reflects the number of sperm stored, we would expect the number of sperm per egg to be inferior if mated with starved males. Methods: We assessed female oviposition rate and fertilization capability in females mated with fed versus starved males. We also quantified sperm use via microscopical counts of DAPI-stained sperm heads on freshly deposited eggs. Results: Females mated with starved males were less likely to deposit eggs and deposited fewer eggs. Furthermore, the eggs of females mated with starved males had fewer sperm, and those females laid a significantly higher proportion of unfertilized eggs. Based on our counts of sperm per egg, we estimate that for starved males, about a third less sperm come close to the site of fertilization.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"13 1","pages":"347-359"},"PeriodicalIF":0.0,"publicationDate":"2011-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70173813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methane production in relation to body mass of ruminants and equids","authors":"R. Franz, C. Soliva, M. Kreuzer, P. Steuer, J. Hummel, M. Clauss","doi":"10.5167/UZH-41217","DOIUrl":"https://doi.org/10.5167/UZH-41217","url":null,"abstract":"Background: Mammalian herbivores produce methane during digestion. Questions: Do ruminants (such as bovids) produce more methane during digestion than do equids (non-ruminants)? What are the effects of allometric scaling of methane production when different species feed on similar diets? Methods: From the literature, we collected a set of data on methane production (litres ·day−1) of ruminants (body mass 26–610 kg) and equids (208–850 kg) fed only roughage. To these data we added our own experimental results from three sheep (Ovis orientalis aries, 94 ± 4 kg) and three mini Shetland ponies (Equus ferus caballus, 97 ± 6 kg). We gave these six animals ad libitum access to the same batch of grass hay. We measured their food intake and methane production (using respiratory chambers), and calculated gut fill and food digestibility. Results: Daily dry matter intake and dry matter digestibility were 39 ± 10 g ·kg−0.75 day−1 and 48 ± 2% in sheep and 72 ± 16 g ·kg−0.75 day−1 and 41 ± 3% in ponies, respectively; the calculated dry matter gut fill was 2.0 ± 0.5% of body mass in sheep and 1.9 ± 0.4% in ponies. Methane production was higher in sheep (30.3 ± 3.0 litres ·day−1) than in ponies (13.4 ± 4.6 litres ·day−1), representing 6.7 ± 1.7% and 1.5 ± 0.2% of gross energy intake, respectively. The data set revealed a linear increase of methane production with body mass (i.e. M1.0) in equids and ruminants. However, a ruminant produces 3.6 times as much methane as does an equid of comparable body mass. Conclusions: Because energy and food intake scale allometrically with body mass (M0.75), our results mean that energetic losses due to methane production (as a proportion of overall energy intake) increase with increasing body mass. The magnitude of the losses is enough to limit the maximum size of a ruminant’s body, but not that of an equid.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"12 1","pages":"727-738"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70652875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ploidy composition in all-hybrid frog populations in relation to ecological conditions","authors":"C. Jakob, Martina Arioli, H. Reyer","doi":"10.5167/UZH-38402","DOIUrl":"https://doi.org/10.5167/UZH-38402","url":null,"abstract":"Question: What explains the differences in ratios of diploid (LR) and two types of triploid frogs (LLR, LRR) among all-hybrid frog populations? Hypothesis: Ecological conditions favouring one (LL) or the other (RR) parental species also favour those triploids that carry two copies of the respective genome (dosage effect), whereas diploids dominate under intermediate conditions. Organism: European water frog (Pelophylax esculentus). Field site: Thirty-four natural ponds in the province of Skane, southern Sweden. Methods: We caught more than 3000 frogs, determined their genotypes with microsatellites, and related the ploidy composition to several uncorrelated ecological parameters, including pond morphology, vegetation, and physical and chemical water parameters. Conclusions: We found a shift from predominantly LLR in small isolated ponds to more LRR in large wetland ponds. This parallels the preferences of the parental species LL and RR for small and large bodies of water, respectively. The effects that pond vegetation and physico-chemical water parameters exert on the parental species were not found in all-hybrid populations. This suggests that environmental parameters affect the genotype composition of all-hybrid populations less than populations containing the parental species. Pond-to-pond differences in LR, LLR, and LRR proportions seem to be better explained by differences in gamete production and thus inheritance patterns.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"12 1","pages":"633-652"},"PeriodicalIF":0.0,"publicationDate":"2010-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70650889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Size-dependent energetics of metamorphosis in the yellow dung fly, Scathophaga stercoraria","authors":"C. Reim, C. Kaufmann, W. Blanckenhorn","doi":"10.5167/UZH-30455","DOIUrl":"https://doi.org/10.5167/UZH-30455","url":null,"abstract":"Competing hypotheses: (1) Large body size confers more efficient energy use (relative efficiency hypothesis). (2) Large body size requires more energy to be sustained, a disadvantage when food is limited (absolute energy demand hypothesis). Organism: Yellow dung flies, Scathophaga stercoraria (Diptera: Scathophagidae), artificially selected for large and small body size in the laboratory for 24 generations to augment the available phenotypic body sizes. Methods: Larvae were reared under limited and unlimited food (dung) conditions, and the energy content of pupae was measured at the beginning and the end of the pupal stage in different, size-matched individuals. Conclusions: Over the pupal period, lipids and glycogen decreased whereas sugar content increased. Net energy loss per unit body mass was higher at unlimited food. Contrary to expectation, males (the larger sex) lost less energy than females. Large selection line pupae showed the highest absolute and mass-specific energy loss during metamorphosis, indicating a correlated physiological response to body size selection because phenotypic body sizes do not differ between the lines at limited dung. We conclude that energetic costs due to greater absolute energy demand of larger individuals during the pupal phase outweigh the benefits due to greater metabolic efficiency.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"11 1","pages":"1111-1130"},"PeriodicalIF":0.0,"publicationDate":"2009-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70647776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The genetic correlation between flower size and water use efficiency in monkeyflowers.","authors":"John K Kelly,&nbsp;Liza M Holeski,&nbsp;H S Arathi","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>QUESTION: Does water loss during drought stress represent an important physiological constraint on the evolution of flower size? ORGANISM: A genetically diverse population of Mimulus guttatus (yellow monkeyflower) originally sampled from an alpine meadow in Oregon, USA. METHODS: We grew plants of three different genotypic classes (small, medium, and large flowered) under both well-watered and drought-stress conditions and measured water use efficiency using stable carbon isotopes. RESULTS: There was no difference in water use efficiency among flower size genotypes under well-watered conditions, but the water use efficiency of small-flowered plants was substantially lower than that of medium or large genotypes under drought stress. Whether this paradoxical result is a direct effect of flower size or an indirect (i.e. pleiotropic) effect, the presence of a genetic correlation between floral and physiological traits indicates that selection of one does impact the other.</p>","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"10 1","pages":"147-152"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2911802/pdf/nihms109634.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"29162654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Megaherbivores as pacemakers of carnivore diversity and biomass: distributing or sinking trophic energy?","authors":"J. Hummel, M. Clauss","doi":"10.5167/UZH-9009","DOIUrl":"https://doi.org/10.5167/UZH-9009","url":null,"abstract":"Question: What is the trophic role of megaherbivores? Hypothesis: Depending on their life histories, megaherbivores can either act as sinks or distributors of trophic energy. Methods: Comparative review of mammal and dinosaur faunas, and aspects of their reproductive biology. Conclusion: Extant (mammalian) megaherbivore populations represent trophic sinks that potentially limit carnivore diversity and productivity, because they are immune to predation and follow a reproductive strategy of very few, well-protected offspring. In contrast, in dinosaur faunas, particularities of reproductive biology such as a larger number of offspring and limited parental care made a major part of megaherbivore biomass available to carnivores. This increase in available trophic energy in consequence allowed for larger body masses and higher species diversity of dinosaur carnivores.","PeriodicalId":50469,"journal":{"name":"Evolutionary Ecology Research","volume":"10 1","pages":"925-930"},"PeriodicalIF":0.0,"publicationDate":"2008-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70663830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}