Evolution
Domesticated species frequently spread their genes into populations of wild relatives through interbreeding. The domestication process often involves artificial selection for economically desirable traits. This can lead to an indirect response in unknown correlated traits and a reduction in fitness of domesticated individuals in the wild. Previous models for the effect of gene flow from domesticated species to wild relatives have assumed that evolution occurs in one dimension. Here, I develop a quantitative genetic model for the balance between migration and multivariate stabilizing selection. Different forms of correlational selection consistent with a given observed ratio between average fitness of domesticated and wild individuals offsets the phenotypic means at migration–selection balance away from predictions based on simpler one‐dimensional models. For almost all parameter values, correlational selection leads to a reduction in the migration load. For ridge selection, this reduction arises because the distance the immigrants deviates from the local optimum in effect is reduced. For realistic parameter values, however, the effect of correlational selection on the load is small, suggesting that simpler one‐dimensional models may still be adequate in terms of predicting mean population fitness and viability....
A central problem in evolutionary biology is identifying factors that promote the evolution of reproductive isolation. Among mosses, biogeographic evidence indicates that the potential for migration is great, suggesting that biological factors other than geographic isolation may be critical for speciation in this group. The moss Physcomitrella patens (Funariaceae) has long been used as a model for...
The oligochaete Limnodrilus hoffmeisteri at Foundry Cove (FC), New York evolved genetic resistance to cadmium (Cd) and lost resistance after contaminated sediments were removed by dredging. Selection (on survival time in dissolved Cd) was used to generate tolerance to evaluate fitness cost, the commonplace expectation for evolutionary reversal. The hypothesis that gene flow from neighboring populations...
Investigating the mechanisms underlying female mate choice is important for sexual‐selection theory, but also for population‐genetic studies, because distinctive breeding strategies affect differently the dynamics of gene diversity within populations. Using field‐monitoring, genetic‐assignment, and laboratory‐rearing methods, we investigated chorus attendance, mating success and offspring fitness...
At a locus subject to genomic imprinting, the expression pattern of an allele depends on its parent of origin. Typically, one allele is expressed while the other is transcriptionally silent, and natural selection at the locus will be driven by the inclusive fitness of the active allele. For some aspects of phenotype, the relevant fitness function differs between maternally and paternally derived alleles,...
When species are in intermediate stages of divergence, complicated patterns of reproductive isolation can arise among males and females of the incipient species. The Chrysoperla carnea group of green lacewings (Neuroptera: Chrysopidae) has recently experienced rapid speciation. They possess sexually monomorphic mating signals that were assumed to be important in mate recognition. Our objective was...
Trade‐offs are widespread between life‐history traits, such as reproduction and survival. However, their underlying physiological and behavioral mechanisms are less clear. One proposed physiological factor involves the trade‐off between investment in male reproductive effort and immunity. Based on this hypothesis, we investigated differences in fitness between artificially selected immune response...
Speciation, the evolution of reproductive isolation between populations, serves as the driving force for generating biodiversity. Postzygotic barriers to gene flow, such as F1 hybrid sterility and inviability, play important roles in the establishment and maintenance of biological species. F1 hybrid incompatibilities in taxa that obey Haldane's rule, the observation that the heterogametic sex suffers...
Many insects and other arthropods harbor maternally inherited bacteria inducing “cytoplasmic incompatibility” (CI), reduced egg hatch when infected males mate with uninfected females. CI‐causing infections produce a frequency‐dependent reproductive advantage for infected females. However, many such infections impose fitness costs that lead to unstable equilibrium frequencies below which the infections...
Molecular studies have demonstrated a deep lineage split between the two gorilla species, as well as divisions within these taxa; estimates place this divergence in the mid‐Pleistocene, with gene flow continuing until approximately 80,000 years ago. Here, we present analyses of skeletal data indicating the presence of substantial recent gene flow among gorillas at all taxonomic levels: between populations,...
Under simple assumptions, the evolution of epistatic “Dobzhansky–Muller” incompatibilities between a pair of species should yield an accelerating decline of log overall reproductive compatibility—a “snowball” effect that might rapidly provide new species with “reality.” Possible alternatives include: (1) simple exponential failure, giving a linear rate of log compatibility loss, and (2) “slowdown,”...
Greenbeards are genes that can identify the presence of copies of themselves in other individuals, and cause their bearer to behave nepotistically toward those individuals. In recent years, a number of examples have been discovered, and it has been suggested that greenbeards represent one of the fundamental routes to social behaviors such as cooperation. However, despite their possible theoretical...
We investigated sex allocation in the Neotropical ant Allomerus octoarticulatus var. demerarae. Because Allomerus is a plant symbiont, we could make geographically extensive collections of complete colonies and of foundresses in saplings, allowing us to estimate not only population‐ and colony‐level sex allocation but also colony resource levels and the relatednesses of competing ant foundresses....
Population‐level comparative analyses can link microevolutionary processes within populations to macroevolutionary patterns of diversification. We used the comparative method to study the evolution of sexual size dimorphism (SSD) among populations of side‐blotched lizards (Uta stansburiana). Uta stansburiana is polymorphic for different male mating and female life‐history strategies in some populations,...
Re‐evolution of lost complex morphological characters has been proposed for several characters, including insect wings, limbs, eyes in snakes, and digits in lizards, among others. There has also been much interest in whether the transition from oviparity to viviparity is reversible, particularly in squamate reptiles where the transition to viviparity has occurred more times than in any other lineage...
A central problem in evolutionary biology is to understand how spatial and temporal variation in selection maintain genetic variation within and among populations. Brown anole lizards (Anolis sagrei) exhibit a dorsal pattern polymorphism that is expressed only in females, which occur in “diamond,”“bar,” and intermediate “diamond‐bar” morphs. To understand the inheritance of this polymorphism, we conducted...
Aposematic herbivores are under selection pressure from their host plants and predators. Although many aposematic herbivores exploit plant toxins in their own secondary defense, dealing with these harmful compounds might underlay costs. We studied whether the allocation of energy to detoxification and/or sequestration of host plant defense chemicals trades off with warning signal expression. We used...
Defensive coloration that reduces the risk of predation is considered to be widespread in animals. Many closely related species adopt differing coloration strategies during the life cycle, including crypsis, conspicuousness, and ontogenic change between the two coloration types. Here, we use a dynamic state‐dependent approach to use ecological and intrinsic factors to predict the proportion of the...
The independent evolution of the sexes may often be constrained if male and female homologous traits share a similar genetic architecture. Thus, cross‐sex genetic covariance is assumed to play a key role in the evolution of sexual dimorphism (SD) with consequent impacts on sexual selection, population dynamics, and speciation processes. We compiled cross‐sex genetic correlations (rMF) estimates from...