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Evolution; International Journal of Organic Evolution

Yasuoki Takami, Tomohiko Fukuhara, Jun Yokoyama, Masakado Kawata
Sexual conflict is a strong driver of evolution. The evolutionary outcomes of sexual conflict can, in turn, influence ecological processes within populations, e.g., demography. However, evidence for the latter hypothesis is scarce, especially in the wild. Here, we show that sexual conflict is associated with demographic processes determining population size in the ground beetle Carabus insulicola with elaborate male and female genitalia, based on individual- and population-level analyses. We found that sexually antagonistic selection can operate on the genitalia: longer male genitalia can be beneficial in sperm competition but decrease female reproductive success with increased egg dumping, while longer female genitalia are resistant to this male harassment via decreased egg dumping and increased fertilization rate...
September 21, 2018: Evolution; International Journal of Organic Evolution
Howard D Rundle, Locke Rowe
Abundant evidence supports a role for sexual selection in the evolution of reproductive isolation, and it is thus unsurprising that much attention has been given, both conceptually and empirically, to understanding its role in speciation. In doing so, debate has arisen on how sexual selection fits within the much used ecological vs. mutation-order classification of speciation mechanisms, with sexual selection often presented as a distinct third alternative. We argue that models of speciation by sexual selection include a fundamental role of divergent selection between environments or mutation-order in initiating the process...
September 20, 2018: Evolution; International Journal of Organic Evolution
Elizabeth S C Scordato
Sexual selection operates via female choice and male competition, which can act independently, in concert, or in opposition. Female choice is typically considered the stronger selective force, but how these two processes interact to shape phenotypic divergence is poorly understood. I tested the hypothesis that variation in sexual selection in different habitats drives song divergence in the greenish warbler ring species. I evaluated the strength, direction, and targets of female choice and male competition in three populations spanning 2400 km of latitude...
September 19, 2018: Evolution; International Journal of Organic Evolution
Daniel S Caetano, Brian C O'Meara, Jeremy M Beaulieu
The state-dependent speciation and extinction models (SSE) have recently been criticized due to their high rates of "false positive" results. Many researchers have advocated avoiding SSE models in favor of other "non-parametric" or "semi-parametric" approaches. The hidden Markov modeling (HMM) approach provides a partial solution to the issues of model adequacy detected with SSE models. The inclusion of "hidden states" can account for rate heterogeneity observed in empirical phylogenies and allows for reliable detection of state-dependent diversification or diversification shifts independent of the trait of interest...
September 18, 2018: Evolution; International Journal of Organic Evolution
Samuel M Scheiner
Although the environment varies, adaptive trait plasticity is uncommon, which can be due to either costs or limitations. Currently there is little evidence for costs of plasticity; limitations are a more promising explanation, including information reliability. A possible cause for a decrease in information reliability is the channeling of environmental information through one trait that then affects the phenotype of a second trait, the information path. Using an individual-based simulation model, I explored the ways in which configurations of trait interactions and patterns of environmental variation in space and time affect the evolution of phenotypic plasticity...
September 17, 2018: Evolution; International Journal of Organic Evolution
Kazuo H Takahashi, Motoyuki Ishimori, Hiroyoshi Iwata
The molecular chaperone protein HSP90 has been proposed to modulate genotype-phenotype relationship in a broad range of organisms. We explore the proposed genetic modifier effect of HSP90 through a genomewide analysis. Here, we show that HSP90 functions as a genetic modifier of genital morphology in Drosophila melanogaster. We identified a large number of single-nucleotide polymorphisms (SNPs) with an HSP90-dependent effect by using genome wide association analysis. We classified the SNPs into the ones under capacitance effect (smaller allelic effect under HSP90 inhibition) or the ones under potentiation effect (larger allelic effect under HSP90 inhibition)...
September 17, 2018: Evolution; International Journal of Organic Evolution
Chang S Han, Cristina Tuni, Jakob Ulcik, Niels J Dingemanse
The expression of aggression depends not only on the direct genetic effects (DGEs) of an individual's genes on its own behaviour, but also on indirect genetic effects (IGEs) caused by heritable phenotypes expressed by social partners. IGEs can affect the amount of heritable variance on which selection can act. Despite the important roles of IGEs in the evolutionary process, it remains largely unknown whether the strength of IGEs varies across life stages or competitive regimes. Based on manipulations of nymphal densities and >3000 pair-wise aggression tests across multiple life stages, we experimentally demonstrate that IGEs on aggression are stronger in field crickets (Gryllus bimaculatus) that develop at lower densities than in those that develop at higher densities, and that these effects persist with age...
September 17, 2018: Evolution; International Journal of Organic Evolution
Kentaro M Tanaka, Yoshitaka Kamimura, Aya Takahashi
Mechanical incompatibility of male and female genitalia is common in animals with internal fertilization. However, our knowledge regarding the precise mechanisms is limited. One key question regards the susceptibility of the match between male and female genitalia to morphological modification. To address this issue, we generated six different second-chromosome introgression lines possessing partially Drosophila mauritiana-like genital morphology in multiple structures in D. simulans background. Three of the six introgression males showed elevated mobility at some stages during copulation with D...
September 10, 2018: Evolution; International Journal of Organic Evolution
Michael J Landis, William A Freyman, Bruce G Baldwin
The Hawaiian silversword alliance (Asteraceae) is an iconic adaptive radiation. However, like many island plant lineages, no fossils have been assigned to the clade. As a result, the clade's age and diversification rate are not known precisely, making it difficult to test biogeographic hypotheses about the radiation. In lieu of fossils, paleogeographically structured biogeographic processes may inform species divergence times; for example, an island must first exist for a clade to radiate upon it. We date the silversword clade and test biogeographic hypotheses about its radiation across the Hawaiian Archipelago by modeling interactions between species relationships, molecular evolution, biogeographic scenarios, divergence times, and island origination times using the Bayesian phylogenetic framework, RevBayes...
September 9, 2018: Evolution; International Journal of Organic Evolution
Jean Peccoud, David R J Pleydell, Nicolas Sauvion
Determining how reproductive barriers modulate gene flow between populations represents a major step towards understanding the factors shaping the course of speciation. Although many indices quantifying reproductive isolation (RI) have been proposed, they do not permit the quantification of cross direction-specific RI under varying species frequencies and over arbitrary sequences of barriers. Furthermore, techniques quantifying associated uncertainties are lacking, and statistical methods unrelated to biological process are still preferred for obtaining confidence intervals and p-values...
September 8, 2018: Evolution; International Journal of Organic Evolution
Matthew P Zuellig, Andrea L Sweigart
Reproductive isolation, which is essential for the maintenance of species in sympatry, is often incomplete between closely related species. In these taxa, reproductive barriers must evolve within species, without being degraded by ongoing gene flow. To better understand this dynamic, we investigated the frequency and geographic distribution of alleles underlying a two-locus, hybrid lethality system between naturally hybridizing species of monkeyflower (Mimulus guttatus and M. nasutus). We found that M. guttatus typically carries hybrid lethality alleles at one locus (hl13) and M...
September 8, 2018: Evolution; International Journal of Organic Evolution
Madeline A E Peters, Arthur E Weis
Co-expression of genes in plant sporophytes and gametophytes allows correlated gametic and sporophytic selection. Theory predicts that, under outcrossing, an allele conferring greater pollen competitive ability should fix within a population unless antagonistic pleiotropy with the sporophyte stage is strong. However, under strong selfing, pollen competitiveness is immaterial as superior and inferior competitors are deposited on opposite stigmas, producing assortative competition. Because many plant species have mixed-mating systems, selfing should be critical in the spread and maintenance of pollen-expressed genes affecting competitiveness...
September 8, 2018: Evolution; International Journal of Organic Evolution
Beata Matysioková, Vladimír Remeš
Incubation is an important component of parental care in birds, and species differ widely in their incubation rhythm. In this comparative study, we focused on factors responsible for those differences. As hypothesized by A. Skutch, increased parental activity at the nest increases the probability of nest depredation. High risk of nest predation should therefore lead to the evolution of lower frequency of parental activity at the nest. We thus expected to find a negative relationship between frequency of nest visits and the risk of nest depredation...
September 7, 2018: Evolution; International Journal of Organic Evolution
Julienne Ng, Loreta B Freitas, Stacey D Smith
Developmental pathways play a major role in influencing the distribution of naturally occurring phenotypes. For example, pathway structure and regulation could make some phenotypes inaccessible or restrict the routes through which phenotypes evolve. In this study, we examine floral anthocyanin pigments across the Solanaceae family and test whether patterns of phenotypic variation are consistent with predicted constraints based on the structure of the flavonoid biosynthetic pathway. We find that anthocyanin evolution occurs in a stepwise manner whereby transitions between the production of red mono hydroxylated pelargonidin pigments and blue trihydroxylated delphinidin pigments first passes through an intermediate step of producing purple dihydroxylated cyanidin pigments...
September 5, 2018: Evolution; International Journal of Organic Evolution
Natalia Ershova
Environmental conditions during birds' nonbreeding season can affect the manifestation of secondary sexual traits and therefore sexual selection. In pied flycatchers, the size of the wing patch is a secondary sexual trait that signals mate value and is influenced by the previous winter's conditions. Female preference changes accordingly with the conditions of the previous nonbreeding season.
September 5, 2018: Evolution; International Journal of Organic Evolution
Rohan Maddamsetti, Daniel T Johnson, Stephanie J Spielman, Katherine L Petrie, Debora S Marks, Justin R Meyer
Viral gain-of-function mutations frequently evolve during laboratory experiments. Whether the specific mutations that evolve in the lab also evolve in nature and whether they have the same impact on evolution in the real world is unknown. We studied a model virus, bacteriophage λ, that repeatedly evolves to exploit a new host receptor under typical laboratory conditions. Here, we demonstrate that two residues of λ's J protein are required for the new function. In natural λ variants, these amino acid sites are highly diverse and evolve at high rates...
August 28, 2018: Evolution; International Journal of Organic Evolution
Ben H Warren, Oskar Hagen, Florian Gerber, Christophe Thébaud, Emmanuel Paradis, Elena Conti
Studies in insular environments have often documented a positive association of extinction risk and evolutionary uniqueness (i.e. how distant a species is from its closest living relative). However, the cause of this association is unclear. One explanation is that species threatened with extinction are evolutionarily unique because they are old, implying that extinction risk increases with time since speciation (age-dependent extinction). An alternative explanation is that such threatened species are last survivors of clades that have undergone an elevated extinction rate, and that their uniqueness results from the extinction of their close relatives...
August 27, 2018: Evolution; International Journal of Organic Evolution
Nathan C Layman, Jeremiah W Busch
Inbreeding depression is dependent on the ploidy of populations and can inhibit the evolution of selfing. While polyploids should generally harbor less inbreeding depression than diploids at equilibrium, it has been unclear whether this pattern holds in non-equilibrium conditions following bottlenecks. We use stochastic individual based simulations to determine the effects of population bottlenecks on inbreeding depression in diploids and autotetraploids, in addition to cases where neo-autotetraploids form from the union of unreduced gametes...
August 23, 2018: Evolution; International Journal of Organic Evolution
Julie N Taylor, William M Ternes, Matthew S Lattanzio
The ecological success of widespread species is attributed to an ability to generalize across diverse habitats, a so-called "jack of all trades" scenario. However, this assumption ignores the potential for local specialization, an alternative scenario whereby spatial variation in natural selection generates habitat-specific fitness surfaces. Despite a growing recognition of spatial variation in selection in nature, and the inevitable exploitation of distinct habitat types across an extensive geographic range, attention to this hypothesis has been lacking for widespread taxa...
August 22, 2018: Evolution; International Journal of Organic Evolution
Judy A Stamps, Peter A Biro, David J Mitchell, Julia B Saltz
Interactions between genotypes and environments are central to evolutionary genetics, but such interactions are typically described, rather than predicted from theory. Recent Bayesian models of development generate specific predictions about genotypic differences in developmental plasticity (changes in the value of a given trait as a result of a given experience) based on genotypic differences in the value of the trait that is expressed by naïve subjects. We used these models to make a priori predictions about the effects of an aversive olfactory conditioning regime on the response of Drosophila melanogaster larvae to the odor of ethyl acetate...
August 22, 2018: Evolution; International Journal of Organic Evolution
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