Males and females share most of their genomes and express many of the same traits, yet the sexes often have markedly different selective optima for these shared traits. This sexually antagonistic (SA) selection generates intralocus sexual conflict that is thought to be resolved through the evolution of sexual dimorphism. However, we currently know little about the prevalence of SA selection, the components of fitness that generate sexual antagonism, or the relationship between sexual dimorphism and current SA selection. We reviewed published studies to address these questions, using 424 selection estimates representing 89 traits from 34 species. Males and females often differed substantially in the direction and magnitude of selection on shared traits, although statistically significant SA selection was relatively uncommon. Sexual selection generated stronger sexual antagonism than fecundity or viability selection, and these individual components of fitness tended to reinforce one another to generate even stronger sexual antagonism for net fitness. Traits exhibiting strong sexual dimorphism exhibited greater SA selection than did weakly dimorphic traits, although this pattern was not significant after we controlled for the inclusion of multiple traits nested within species. Our results suggest that intralocus sexual conflict often may persist despite the evolution of sexual dimorphism.

The California Floristic Province harbours more endemic plant and animal taxa and more identifiable subspecies than any other area of comparable size in North America. We present evidence that physical historical processes have resulted in congruent patterns of genetic diversity over the past 2-10 million years. Using a molecular clock approach we show that diversification and establishment of spatial genetic structure across six taxonomic groups coincide with the putative age of California's mountain ranges and aridification in the region. Our results demonstrate the importance of geographical barriers and climatological events to species diversification and the overall geographical structure of biodiversity. These results should facilitate conservation efforts in this biodiversity hotspot for taxa whose population genetic structure is still unknown and may suggest the potential utility of this approach in regional conservation planning efforts.

Natural selection is an important driver of microevolution. Yet, despite significant theoretical debate, we still have a poor understanding of how selection operates on interacting traits (i.e., morphology, performance, habitat use). Locomotor performance is often assumed to impact survival because of its key role in foraging, predator escape, and social interactions, and shows strong links with morphology and habitat use within and among species. In particular, decades of study suggest, but have not yet demonstrated, that natural selection on locomotor performance has shaped the diversification of Anolis lizards in the Greater Antilles.Here, we estimate natural selection on sprinting speed and endurance in small replicate island populations of Anolis sagrei. Consistent with past correlational studies, long-limbed lizards ran faster on broad surfaces but also had increased sprint sensitivity on narrow surfaces. Moreover, performance differences were adaptive in the wild. Selection favored long-limbed lizards that were fast on broad surfaces, and preferred broad substrates in nature, and also short-limbed lizards that were less sprint sensitive on narrow surfaces, and preferred narrow perches in nature. This finding is unique in showing that selection does not act on performance alone, but rather on unique combinations of performance, morphology, and habitat use. Our results support the long-standing hypothesis that correlated selection on locomotor performance, morphology, and habitat use drives the evolution of ecomorphological correlations within Caribbean Anolis lizards, potentially providing a microevolutionary mechanism for their remarkable adaptive radiation.

Tropical ectotherms are thought to be especially vulnerable to climate change because they are adapted to relatively stable temperature regimes, such that even small increases in environmental temperature may lead to large decreases in physiological performance. One way in which tropical organisms may mitigate the detrimental effects of warming is through evolutionary change in thermal physiology. The speed and magnitude of this response depend, in part, on the strength of climate-driven selection. However, many ectotherms use behavioral adjustments to maintain preferred body temperatures in the face of environmental variation. These behaviors may shelter individuals from natural selection, preventing evolutionary adaptation to changing conditions. Here, we mimic the effects of climate change by experimentally transplanting a population of Anolis sagrei lizards to a novel thermal environment. Transplanted lizards experienced warmer and more thermally variable conditions, which resulted in strong directional selection on thermal performance traits. These same traits were not under selection in a reference population studied in a less thermally stressful environment. Our results indicate that climate change can exert strong natural selection on tropical ectotherms, despite their ability to thermoregulate behaviorally. To the extent that thermal performance traits are heritable, populations may be capable of rapid adaptation to anthropogenic warming. Bahamas | thermoregulationA nthropogenic climate change may be the single most dramatic physical change our planet has experienced during human history (1). In the tropics, where species are adapted to relatively stable climates, the impacts of climate change are predicted to be especially severe (2-5) (but see refs. 6, 7). Because many species maintain a body temperature (T b ) that is already close to their thermal limits, even small increases in environmental temperature (T e ) may produce large decreases in physiological performance that could push populations toward extinction (4).In tropical environments, evolutionary adaptation may be one of the most important mechanisms by which populations can avoid extinction (8). As climates shift, fitness for many species will become increasingly linked to variation in traits important for performance in a warmer and more thermally variable world (4). Numerous theoretical, laboratory, and field studies demonstrate a capacity for rapid evolution on time scales similar to those over which global warming is predicted to occur (9-11). Indeed, recent work on lizards (12) and butterflies (13) has revealed rapid shifts in thermal physiology that appear to be directly associated with changing thermal environments. Despite mounting evidence that the capacity for evolution may fundamentally alter extinction probabilities in the face of anthropogenic climate change, the potential for rapid evolution is usually not considered in models that attempt to predict the impact of climate change on biological populations (8).The rate at which ...

Summary 1.A central tenet of life-history theory is that investment in reproduction compromises survival. However, the underlying physiological mechanisms that link reproduction to survival are poorly understood, particularly in wild populations. 2. Previous experiments in the brown anole lizard (Anolis sagrei) show that the elimination of reproduction via surgical ovariectomy results in a dramatic increase in the survival of wild females. We hypothesized that this trade-off reflects underlying differences in energy allocation between reproduction and physiological processes that influence survival. 3. To test this hypothesis, we compared ovariectomized (OVX) females to reproductive controls (SHAM) with respect to four physiological parameters that are thought to influence survival: energy storage, haematocrit, immune function and parasitemia. 4. Consistent with previous studies, we found that OVX females exhibited increased survival and growth relative to reproductive SHAM females. At the end of the breeding season, OVX also exceeded SHAM with respect to energy storage, haematocrit and immune response to phytohemagglutinin challenge. 5. Contrary to our predictions, OVX were more likely than SHAM to exhibit high levels of parasitemia. However, growth and parasite load were positively correlated in OVX and negatively correlated in SHAM, suggesting that reproductive investment may compromise parasite tolerance rather than parasite resistance. 6. Collectively, our results provide direct experimental evidence that reproductive investment affects several key physiological traits that likely interact to influence survival in wild populations.

We outline roles of frequency-dependent selection (FDS) in coadaptation and coevolutionary change. Coadaptation and coevolution occur because correlational selection (CS) and correlated evolution couple many traits. CS arises from causal interactions between traits expressed in two or more interactors, which invariably involve different traits (signalers-receivers). Thus, the causes of CS are due to FDS acting on trait interactions. Negative FDS, a rare advantage, is often coupled to positive FDS generating complex dynamics and FD cycles. Neural mechanisms of learning and perception create analogous routes by which traits are reinforced in cognitive and perceptual systems of interactors, substituting for positive FDS. FDS across all levels of biological organization is thus best understood as proximate causes that link interactors and shape genetic correlations within and among interactors on long timescales, or cognitive trait correlations within interactors on short timescales. We find rock-paper-scissors dynamics are common in nature.

Altruism presents a challenge to evolutionary theory because selection should favor selfish over caring strategies. Greenbeard altruism resolves this paradox by allowing cooperators to identify individuals carrying similar alleles producing a form of genic selection. In sideblotched lizards, genetically similar but unrelated blue male morphs settle on adjacent territories and cooperate. Here we show that payoffs of cooperation depend on asymmetric costs of orange neighbors. One blue male experiences low fitness and buffers his unrelated partner from aggressive orange males despite the potential benefits of defection. We show that recognition behavior is highly heritable in nature, and we map genetic factors underlying color and self-recognition behavior of genetic similarity in both sexes. Recognition and cooperation arise from genome-wide factors based on our mapping study of the location of genes responsible for self-recognition behavior, recognition of blue color, and the color locus. Our results provide an example of greenbeard interactions in a vertebrate that are typified by cycles of greenbeard mutualism interspersed with phases of transient true altruism. Such cycles provide a mechanism encouraging the origin and stability of true altruism.alternative strategies ͉ linkage map ͉ frequency-dependent selection ͉ evolutionarily stable strategy ͉ cooperation T he evolutionary stability of cooperative and altruistic behaviors requires that interindividual benefits be protected from competition, cheating, and defection (1-4). Without such safeguards, selfish strategies will eliminate altruistic strategies (5, 6). Hamilton (5) theorized that true altruism might evolve if a supergene simultaneously affected a signal and recognition of the signal and that signal recognition elicited social acts costly to donors but beneficial to recipients. Dawkins (6) coined Hamilton's social supergene a greenbeard in a hypothetical example of altruists that sported a green beard distinct in color from other beards sported by nonaltruists. Despite studies consistent with greenbeard altruism (7-12), few provide definitive evidence for greenbeard altruism.The annual side-blotched lizard, Uta stansburiana, exhibits six color genotypes (13, 14) (oo, bo, yo, bb, by, and yy), which serve as markers for three male strategies (15). Orange males (oo, bo, and yo) usurp territory. Blue males (bb) mate-guard. Yellow males (by and yy) are sneakers. Male competition drives rock-paper-scissors (RPS) cycles of three strategies: sneakers beat usurpers, mate guarders defeat sneakers, and usurpers prevail over mate guarders (13,(15)(16)(17)(18)(19). Previously, we showed that males with b alleles prefer to settle near non-kin but genetically similar bb males and cooperate in territory defense (15). Hereafter, we refer to bb males with genetically similar neighbors (based on allele sharing at nine microsatellite loci) as ''dyadic bb pairs'' (15). We contrast dyadic bb males with ''loner bb males'' that may have bb neighbors, but none are genetically...

Models of speciation in African rain forests have stressed either the role of isolation or ecological gradients. Here we contrast patterns of morphological and genetic divergence in parapatric and allopatric populations of the Little Greenbul, Andropadus virens, within different and similar habitats. We sampled 263 individuals from 18 sites and four different habitat types in Upper and Lower Guinea. We show that despite relatively high rates of gene flow among populations, A. virens has undergone significant morphological divergence across the savanna–forest ecotone and mountain–forest boundaries. These data support a central component of the divergence‐with‐gene‐flow model of speciation by suggesting that despite large amounts of gene flow, selection is sufficiently intense to cause morphological divergence. Despite evidence of isolation based on neutral genetic markers, we find little evidence of morphological divergence in fitness‐related traits between hypothesized refugial areas. Although genetic evidence suggests populations in Upper and Lower Guinea have been isolated for over 2 million years, morphological divergence appears to be driven more by habitat differences than geographic isolation and suggests that selection in parapatry may be more important than geographic isolation in causing adaptive divergence in morphology.