| 1. |
- Abbott, Jessica, et al.
(författare)
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Morph-specific variation in intersexual genetic correlations in an intra-specific mimicry system
- 2010
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Ingår i: Evolutionary Ecology Research. - : Evolutionary Ecology. - 1522-0613 .- 1937-3791. ; 12:1, s. 105-118
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Tidskriftsartikel (refereegranskat)abstract
- Background: Positive intersexual genetic correlations are typically viewed as constraining the evolution of sexual dimorphism, when traits are subject to sexually antagonistic selection. Our study species, the damselfly Ischnura elegans, has a female-limited colour polymorphism with three female colour morphs (males are monomorphic), one of which is considered to be a male mimic. Questions: Are there morph-specific differences in the magnitude of intersexual genetic correlations in I. elegans? Specifically, do male-mimic (Androchrome) females have higher intersexual genetic correlations for morphological traits than non-mimic (Infuscans) females'? Methods: We collected copulating pairs in the field and raised offspring from these pairs in the laboratory. We measured five morphological traits in both parent and offspring generations and investigated their heritabilities and genetic correlations. Results: We found a negative overall relationship between the degree of sexual dimorphism for a trait and its intersexual genetic correlation. But the magnitude and direction of intersexual genetic correlations depended on the female morph. As expected, male mimic (Androchrome) females had higher intersexual genetic correlations. In addition, the genetic correlations between the morphs were in all cases significantly lower than unity. Male mimic (Androchrome) females had higher mother son covariances than the non-mimic (Infuscans) morph, and this difference is the proximate explanation for the difference in intersexual genetic correlations between the morphs.
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| 2. |
- Andersson, Jens, et al.
(författare)
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Behavioural and morphological responses to cannibalism in Arctic charr (Salvelinus alpinus)
- 2005
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Ingår i: Evolutionary Ecology Research. - Tucson : Evolutionary Ecology. - 1522-0613 .- 1937-3791. ; 7:5, s. 767-778
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Tidskriftsartikel (refereegranskat)abstract
- Question: Does cannibalism lead to resource polymorphism in young Arctic charr (Salvelinusalpinus, Pisces)? Hypothesis: Cannibals should evoke a low-activity morph that is well adapted to benthivorybut not planktivory, and which differs in morphology compared with a planktivorous morph. Methods: We reared young-of-the-year charr in laboratory aquaria with and without largercannibalistic charr present. Thereafter, we measured foraging efficiency on pelagic and benthicresources, swimming speed when foraging, and morphology of the young charr. Conclusions: Living among cannibals did not affect the morphology of the young charr. Italso did not affect the foraging efficiency of the young charr on the benthic resource. However,individuals from cannibal treatments swam closer and had lower foraging efficiency on thepelagic resource.
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| 3. |
- Arbuthnott, Devin, et al.
(författare)
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Rugged fitness landscapes and by-product adaptation in experimental populations of Drosophila melanogaster
- 2018
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Ingår i: Evolutionary Ecology Research. - : EVOLUTIONARY ECOLOGY LTD. - 1522-0613 .- 1937-3791. ; 19:1, s. 15-28
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Tidskriftsartikel (refereegranskat)abstract
- Background: While the concept of the fitness landscape is central to evolutionary theory, empirical characterizations of fitness landscapes have remained difficult. Recently, a number of laboratory experiments using microbes have suggested that fitness landscapes are often rugged, though there is some variation across environments and species. However, there have been very few characterizations of fitness landscapes in sexual organisms, making it unclear whether the conclusions from studies of microbes are applicable to other groups. Questions: Are fitness landscapes smooth or rugged in simplified laboratory environments for sexual organisms? How does landscape topography influence patterns of adaptation? Methods: We conducted a series of experiments using replicate populations of Drosophila melanogaster adapted to either cadmium-or ethanol-enriched food to characterize the fitness and phenotypes of these populations in a simplified laboratory environment (ethanol-enriched media). Results: We found that replicate populations adapted to different laboratory environments have diverged phenotypically in physiology, mating behaviour, and offspring production in alternate environments. However, both ethanol-and cadmium-adapted populations show high fitness in the ethanol-enriched environment relative to their founding population, and cadmium-adapted males actually outcompete ethanol-adapted males for mates in an ethanol environment. Conclusions: Our data indicate that the simplified ethanol-enriched medium represents a rugged fitness landscape, and that alternately adapted populations occupy different fitness peaks on this landscape. Because cadmium-adapted populations were never exposed to ethanol previously, it appears that these populations adapted to ethanol as a by-product of adaptation to their cadmium-enriched environment. Therefore, even in simplified laboratory environments, we find evidence for rugged fitness landscapes, and the overlap of fitness peaks on the phenotypic landscape allowed for by-product adaptation.
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| 4. |
- Aunapuu, Maano, et al.
(författare)
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Intraguild predation and interspecific co-existence between predatory endotherms
- 2010
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Ingår i: Evolutionary Ecology Research. - Tucson : Evolutionary Ecology. - 1522-0613 .- 1937-3791. ; 12:2, s. 151-168
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Tidskriftsartikel (refereegranskat)abstract
- Background: According to the current predominant view, intraguild predation leads to the replacement of intermediate predators from highly productive habitats, whereas top predators and intermediate predators can co-exist in habitats with intermediate primary productivity. These predictions are contradicted by the observed abundance of intermediate predators in productive environments. But the predictions are derived by modelling interactions in food chains where the top predator is primarily adapted to exploit intermediate predators but also has some capacity to exploit the resources of the intermediate predators. We call this 'food chain omnivory'. In contrast, 'genuine intraguild predation' is the case where the two predators have shared tactics of resource acquisition, resulting in broadly overlapping prey preferences that is, the interacting predators belong to the same guild as defined by Root (1967). Questions: What are the effects of productivity on genuine intraguild predation? Do the predictions for food chain omnivory apply also to genuine intraguild predation'? Methods: We modelled genuine intraguild predation by using parameter values such that the intermediate predator and the basal prey were equally valuable to the top predator. We assumed that the basal prey was a herbivore, with a carrying capacity directly proportional to primary productivity and a habitat-specific intrinsic rate of population growth that increases asymptotically in response to increasing primary productivity. Results: With the above premises, intermediate predators can prevail even in highly productive habitat. Also, a priority effect is possible. Predictable replacement of intermediate predators by top predators requires that intermediate predators are much easier to find than basal prey. Stable co-existence requires biologically implausible parameter values. Conclusions: Genuine intraguild predation is a destabilizing force in food webs. The dynamics of genuine intraguild predation systems differ from those in food chain omnivory systems where the intermediate and top predators have different feeding tactics and, therefore, different prey preferences.
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| 5. |
- Bergek, Sara, 1979-, et al.
(författare)
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Spatiotemporal analysis shows stable genetic differentiation and barriers to dispersal in the Eurasian perch (Perca fluviatilis L.)
- 2009
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Ingår i: Evolutionary Ecology Research. - Tucson : Evolutionary Ecology Ltd.. - 1522-0613 .- 1937-3791. ; 11:5, s. 827-840
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recently, unexpected or cryptic barriers to gene flow causing genetic discontinuities have been found in a number of animal taxa, even in apparently highly connected areas such as aquatic environments. Goal: Investigate the temporal stability of previously documented microgeographic genetic structure in a fish. Organism: Eurasian perch (Perca fluviatilis L.) Method: We sampled four locations over a period of 2 years. We used six microsatellites to investigate population differentiation. We compared within-year to between-year differentiation. Results: The significant genetic differentiation found between locations in 2004 was still present in 2006. The strongest barriers to gene flow in the lake were consistent over both sampling periods. Furthermore, temporal differentiation existed within each site between the years. Populations of perch appear to cluster in different patches in the lake that harbour genetically differentiated groups of fish. Hence, limited migration and barriers to dispersal can persist over time, even at a very small geographical scale and in an open aquatic environment.
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| 6. |
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| 7. |
- Brännström, Åke, et al.
(författare)
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Modelling the ecology and evolution of communities : a review of past achievements, current efforts, and future promises
- 2012
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Ingår i: Evolutionary Ecology Research. - 1522-0613 .- 1937-3791. ; 14:5, s. 601-625
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Tidskriftsartikel (refereegranskat)abstract
- Background: The complexity and dynamical nature of community interactions make modelling a useful tool for understanding how communities develop over time and how they respond to external perturbations. Large community-evolution models (LCEMs) are particularly promising, since they can address both ecological and evolutionary questions, and can give rise to richly structured and diverse model communities.Questions: Which types of models have been used to study community structure and what are their key features and limitations? How do adaptations and/or invasions affect community formation? Which mechanisms promote diverse and stable communities? What are the implications of LCEMs for management and conservation? What are the key challenges for future research?Models considered: Static models of community structure, demographic community models, and small and large community-evolution models.Conclusions: Large community-evolution models encompass a variety of modelled traits and interactions, demographic dynamics, and evolutionary dynamics. They are able to reproduce empirical community structures. They have already generated new insights, such as the dual role of competition, which limits diversity through competitive exclusion yet facilitates diversity through speciation. Other critical factors determining eventual community structure are the shape of trade-off functions, inclusion of adaptive foraging, and energy availability. A particularly interesting feature of LCEMs is that these models not only help to contrast outcomes of community formation via species assembly with those of community formation via gradual evolution and speciation, but that they can furthermore unify the underlying invasion processes and evolutionary processes into a single framework.
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| 8. |
- Crispo, Erika, et al.
(författare)
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The evolution of phenotypic plasticity in response to anthropogenic disturbance
- 2010
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Ingår i: Evolutionary Ecology Research. - Tucson, AZ, USA : Evolutionary Ecology Ltd. - 1522-0613 .- 1937-3791. ; 12:1, s. 47-66
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Tidskriftsartikel (refereegranskat)abstract
- Questions: Do evolutionary changes in phenotypic plasticity occur after anthropogenic disturbance? Do these changes tend to be increases or decreases in plasticity? How do these evolutionary patterns differ among taxa and trait types? Does evolution of plasticity change with time since the disturbance?Data incorporated: Evolutionary rates for plasticity estimated from 20 studies that have compared a plastic response in two or more populations, at least one of which had experienced an anthropogenic disturbance in nature and at least one of which had not.Method of analysis: We estimate evolutionary rates (darwins and haldanes) for plasticity for each study, which represent the amount of evolutionary change in plasticity. We then perform analyses of covariance, with the evolutionary rate numerator (amount of evolutionary change) as a response variable, taxa and trait type as predictor variables, and the amount of evolutionary time as a covariate.Conclusions:We find that plasticity has evolved in several cases, including both increases and decreases in the levels of plasticity following anthropogenic disturbances. The typical direction of this evolutionary response depends on an interaction between taxon and trait type. For instance, invertebrates sometimes show the evolution of increased plasticity for life-history traits, but the evolution of decreased plasticity for morphological traits. Plants, on the other hand, show no trends in the direction of plasticity evolution.
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| 9. |
- Dahlgren, Jonas, et al.
(författare)
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Plant defences to no avail? : Responses of plants of varying edibility to food web manipulations in a low arctic scrubland
- 2009
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Ingår i: Evolutionary Ecology Research. - : Evolutionary ecology. - 1522-0613 .- 1937-3791. ; 11:8, s. 1189-1203
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Tidskriftsartikel (refereegranskat)abstract
- Background: According to the Green World Hypothesis of Hairston, Smith, and Slobodkin, all plants are edible for some herbivores. Hence, the copious abundance of plant biomass, typical for terrestrial ecosystems, depends on the collective regulatory action of predators on the herbivore guild. According to the counterarguments of Polis and Strong, the defensive traits of terrestrial plants attenuate terrestrial trophic cascades to species-specific trickles, so elimination of predators might lead to increased abundance of inedible plants but will not influence community-level plant biomass. Question: Does the elimination of predators from a low arctic scrubland, with high-quality forage plants and poorly edible evergreen ericoids, lead to a reduction of community-level plant biomass or to an increased abundance of well-defended evergreen ericoids? Methods: In 1991, we introduced grey-sided voles (Myodes rufocanus) to islands, initially harbouring dense scrubland vegetation, and established permanent plots there. In 2000, we transplanted vegetation blocks from a large three-trophic-level island with voles and predators, to two-trophic-level islands with introduced voles but without resident predators, and also to vole-free one-trophic-level islands, and back to the three-trophic-level island. Vole densities were monitored by semi-annual live trapping. Vegetation was monitored by the point-frequency method. Results: In the absence of predators, vole densities increased 3.7-fold and the community-level plant biomass was decimated. The least palatable plant group, evergreen ericoids, suffered especially heavily, whereas palatable herbaceous plants increased in abundance. However, all three functional plant groups responded positively to the elimination of grey-sided voles. Conclusions: Our results corroborate the Green World Hypothesis, indicating that in the absence of predators, plant defences do not prevent runaway consumption of the vegetation. The fate of plants in predator-free systems with browsing vertebrates depends primarily on the accessibility of each plant during the limiting season. Evergreen ericoids then form the most sensitive functional group.
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| 10. |
- Dahlgren, Jonas, et al.
(författare)
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Plant defense at no cost? : The recovery of tundra scrubland following heavy grazing by grey-sided voles (Myodes rufocanus)
- 2009
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Ingår i: Evolutionary Ecology Research. - : Evolutionary Ecology. - 1522-0613 .- 1937-3791. ; 11, s. 1205-1216
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Tidskriftsartikel (refereegranskat)abstract
- Background: Evergreen ericaceous dwarf shrubs form a dominating component of low arctic and low alpine vegetation. They typically produce high contents of secondary chemicals such as phenolics. The primary function of these chemicals may be to defend the shrubs by making them less palatable to herbivores. Question: Does the production of secondary chemicals carry a fitness cost in terms of low growth rate and, therefore, low capacity to recover from past herbivory? Methods: In 2000, we constructed vole-proof exclosures on low arctic islands where vegetation had, since 1991, been heavily impacted by grey-sided voles. In 2000 and 2003,we surveyed the vegetation of the exclosures, of unfenced plots on the same islands, and of control plots on a vole-free island. We used the point-frequency method for vegetation surveys. Results: In the exclosures, the biomasses of most plant species increased, by and large, at the same pace. The two woody species, which increased most rapidly, were the maximally palatable bilberry (Vaccinium myrtillus) and the phenolics-laden, maximally unpalatable northern crowberry (Empetrum nigrum ssp. hermaprhoditum). The recovery rates of these species were similar. Conclusions: The high concentrations of phenolics typical for evergreen arctic dwarf shrubs do not carry any obvious cost in the form of reduced capacity for compensatory growth. The principle of trade-offs does not help to explain the variation in plant palatability.
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