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By measuring the direct and indirect fitness costs and benefits of sexual interactions, the feasibility of alternate explanations for polyandry can be experimentally assessed. This approach becomes more complicated when the relative magnitude of the costs and/or benefits associated with multiple mating (i.e., remating with different males) vary with female condition, as this may influence the strength...
Populations of organisms separated by latitude provide striking examples of local adaptation, by virtue of ecological gradients that correlate with latitudinal position on the globe. Ambient temperature forms one key ecological variable that varies with latitude, and here we investigate its effects on the fecundity of self‐fertilizing nematodes of the species Caenorhabditis briggsae that exhibits...
Many ectotherms show crossing growth trajectories as a plastic response to rearing temperature. As a result, individuals growing up in cool conditions grow slower, mature later, but are larger at maturation than those growing up in warm conditions. To date, no entirely satisfactory explanation has been found for why this pattern, often called the temperature‐size rule, should exist. Previous theoretical...
In general, heterozygosity is considered to be advantageous, primarily because it masks the effects of deleterious recessive alleles. However, there is usually a reduction in fitness in individuals that are heterozygous due to the pairing of two species (heterospecific). Because the parental alleles arose along separate evolutionary paths, they may not function properly when brought together within...
Rapid cold‐hardening (RCH) is a unique form of phenotypic plasticity which confers survival advantages at low temperature. The fitness costs of RCH are generally poorly elucidated and are important to understanding the evolution of plastic physiology. This study examined whether RCH responses, induced by ecologically relevant diel temperature fluctuations, carry metabolic, survival, or fecundity costs...
We present a formulation of branching and aging processes that allows age distributions along lineages to be studied within populations, and provides a new interpretation of classical results in the theory of aging. We establish a variational principle for the stable age distribution along lineages. Using this optimal lineage principle, we show that the response of a population’s growth rate to age‐specific...
The process of speciation is key to the origins of biodiversity, and yet the Caenorhabditis nematode model system has contributed little to this topic. Genetic studies of speciation in the genus are now feasible, owing to crosses between the recently discovered Caenorhabditis sp. 9 and the well‐known C. briggsae producing fertile F1 hybrid females. We dissected patterns of postzygotic reproductive...
Natural diversity in aging and other life‐history patterns is a hallmark of organismal variation. Related species, populations, and individuals within populations show genetically based variation in life span and other aspects of age‐related performance. Population differences are especially informative because these differences can be large relative to within‐population variation and because they...
Modernization has increased longevity and decreased fertility in many human populations, but it is not well understood how or to what extent these demographic transitions have altered patterns of natural selection. I integrate individual‐based multivariate phenotypic selection approaches with evolutionary demographic methods to demonstrate how a demographic transition in 19th century female populations...
The major goal of evolutionary thermal biology is to understand how variation in temperature shapes phenotypic evolution. Comparing thermal reaction norms among populations from different thermal environments allows us to gain insights into the evolutionary mechanisms underlying thermal adaptation. Here, we have examined thermal adaptation in six wild populations of the fruit fly (Drosophila melanogaster...
Conflicts between family members are expected to influence the duration and intensity of parental care. In mammals, the majority of this care occurs as resource transfer from mothers to offspring during gestation and lactation. Mating systems can have a strong influence on the severity of familial conflict—where female promiscuity is prevalent, conflict is expected to be higher between family members,...
Inbreeding depression, the reduced fitness of offspring of related individuals, is a central theme in evolutionary biology. Inbreeding effects are influenced by the genetic makeup of a population, which is driven by any history of genetic bottlenecks and genetic drift. The Chatham Island black robin represents a case of extreme inbreeding following two severe population bottlenecks. We tested whether...
Late‐life plateaus in age‐specific mortality have been an evolutionary and biodemographic puzzle for decades. Although classic theory on the evolution of senescence predicts late‐life walls of death, observations in experimental organisms document the opposite trend: a slowing in the rate of increase of mortality at advanced ages. Here, I analyze published life‐history data on individual Drosophila melanogaster...
Understanding how some species may be able to evolve quickly enough to deal with anthropogenic pressure is of prime interest in evolutionary biology, conservation, and management. Wild boar (Sus scrofa scrofa) populations keep growing all over Europe despite increasing hunting pressure. In wild boar populations subject to male‐selective harvesting, the initially described polygynous mating system...
Cardinium and Wolbachia are common maternally inherited reproductive parasites that can coinfect arthropods, yet interactions between both bacterial endosymbionts are rarely studied. For the first time, we report their independent expression of complete cytoplasmic incompatibility (CI) in a coinfected host, and CI in a species of the haplodiploid insect order Thysanoptera. In Pezothrips kellyanus,...
Phenotypic plasticity is an important concept in life‐history evolution, and most organisms, including Drosophila melanogaster, show a plastic life‐history response to diet. However, little is known about how these life‐history responses are mediated. In this study, we compared adult female flies fed an alternating diet (yoyo flies) with flies fed a constant low (CL) or high (CH) diet and tested how...
Selection for secondary sexual trait (SST) elaboration may increase intralocus sexual conflict over the optimal values of traits expressed from shared genomes. This conflict can reduce female fitness, and the resulting gender load can be exacerbated by environmental stress, with consequences for a population's ability to adapt to novel environments. However, how the evolution of SSTs interacts with...
Dispersal is one of the strategies for organisms to deal with climate change and habitat degradation. Therefore, investigating the effects of dispersal evolution on natural populations is of considerable interest to ecologists and conservation biologists. Although it is known that dispersal itself can evolve due to selection, the behavioral, life‐history and metabolic consequences of dispersal evolution...
Male choosiness of prospective female mating partners provides an increasingly recognized pathway through which males can increase their fitness. For example, males may increase their number of offspring by targeting more fecund females as mating partners. If fecundity is heritable, males that mate with more fecund females can also receive the indirect benefit of more fecund daughters. In species...
Why do females of socially monogamous species engage in extra‐pair copulations? This long‐standing question remains a puzzle, because the benefits of female promiscuous behavior often do not seem to outweigh the costs. Genetic constraint models offer an answer by proposing that female promiscuity emerges through selection favoring alleles that are either beneficial for male reproductive success (intersexual...
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