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Detecting contemporary evolution requires demonstrating that genetic change has occurred. Mixed effects models allow estimation of quantitative genetic parameters and are widely used to study evolution in wild populations. However, predictions of evolution based on these parameters frequently fail to match observations. Here, we applied three commonly used quantitative genetic approaches to predict the evolution of size at maturity in a wild population of Trinidadian guppies. Crucially, we tested our predictions against evolutionary change observed in common-garden experiments performed on samples from the same population. We show that standard quantitative genetic models underestimated or failed to detect the cryptic evolution of this trait as demonstrated by the common-garden experiments. The models failed because (1) size at maturity and fitness both decreased with increases in population density, (2) offspring experienced higher population densities than their parents, and (3) selection on size was strongest at high densities. When we accounted for environmental change, predictions better matched observations in the common-garden experiments, although substantial uncertainty remained. Our results demonstrate that predictions of evolution are unreliable if environmental change is not appropriately captured in models. [ABSTRACT FROM AUTHOR]

Organisms can change their environment and in doing so change the selection they experience and how they evolve. Population density is one potential mediator of such interactions because high population densities can impact the ecosystem and reduce resource availability. At present, such interactions are best known from theory and laboratory experiments. Here we quantify the importance of such interactions in nature by transplanting guppies from a stream where they co-occur with predators into tributaries that previously lacked both guppies and predators. If guppies evolve solely because of the immediate reduction in mortality rate, the strength of selection and rate of evolution should be greatest at the outset and then decline as the population adapts to its new environment. If indirect effects caused by the increase in guppy population density in the absence of predation prevail, then there should be a lag in guppy evolution because time is required for them to modify their environment. The duration of this lag is predicted to be associated with the environmental modification caused by guppies. We observed a lag in life-history evolution associated with increases in population density and altered ecology. How guppies evolved matched predictions derived from evolutionary theory that incorporates such density effects. [ABSTRACT FROM AUTHOR]

Theory predicts that the sex linkage of sexually selected traits can influence the direction and rate of evolution and should itself evolve in response to sex-specific selection. Some studies have found intraspecific differences in sex linkage associated with differences in selection pressures, but we know nothing about how fast these differences can evolve. Here we show that introduced guppy populations showing rapid evolution of male coloration also show rapid changes in sex-linkage patterns. A comparison, using hormonal manipulations in females, of introduced populations of different ages suggests a consistent increase of autosomal or X-linked coloration 2 years after introduction from high- to low-predation environments. Twenty years after introduction, populations already show the same pattern of coloration inheritance typical of natural low-predation populations in similar habitats. These results highlight that the contemporary evolution of sexually selected traits ought to be studied in concert with contemporary changes in linkage relationships. [ABSTRACT FROM AUTHOR]

Raia et al. propose that the evolution of the shape and complexity of animal ornaments (e.g., deer antlers) can be explained by interspecific variation in body size and is not influenced by sexual selection. They claim to show that ornament complexity is related to body size by an 0.25-power law and argue that this finding precludes a role for sexual selection in the evolution of ornament complexity. However, their study does not test alternative hypotheses and mismeasures antler shape allometry by omitting much of the published data. We show that an index of sexual selection (sexual size dimorphism) is positively correlated with size-corrected antler complexity and that the allometric slope of complexity is substantially greater than 0.25, contra Raia et al. We conclude that sexual selection and physical constraints both affect the evolution of antler shape. [ABSTRACT FROM AUTHOR]

Mate choice is a common feature of sexually reproducing species. In sessile or sedentary external fertilizers, however, direct interactions between reproductive partners are minimal, and instead mate recognition and choice must occur at the level of gametes. It is common for some sperm and egg combinations to have higher fertilization success than others, but it remains unclear whether differences in fertilization reflect gamete-level mate choice (GMC) for paternal quality or parental compatibility. Here, we examine the mechanisms underlying GMC in an externally fertilizing ascidian. A manipulative mate-choice assay confirmed that offspring viability was greater in clutches where we allowed GMC than in clutches where we precluded GMC. A complementary quantitative genetic experiment then revealed that paternal quality effects were generally weaker than parental compatibility effects, particularly for the trait combination underlying the benefits of GMC. Overall, our data suggest that gametes that are more compatible at fertilization produce more viable offspring than gametes that are less compatible at fertilization. Therefore, although the regalia we typically associate with sexual selection are absent in external fertilizers, mechanisms that allow females to bias fertilization in favor of some males over others produce significant fitness benefits in organisms reproducing via the ancestral strategy. [ABSTRACT FROM AUTHOR]

Environments that vary within a generation of an organism provide opportunities for adaptation if the level of variation is severe and predictable. We describe a model of evolution in such environments with genotypes that show trade-offs in viability and fecundity. One genotype develops rapidly and has superior viability but reduced fertility relative to the alternative genotype. Conditions that allow the evolution of the rapidly developing genotypes are explored. We show how the evolution of ovoviviparity and resource specialization in Drosophila sechellia shares many important features of this model. We suggest that our model may capture many of the evolutionary forces responsible for the evolution of niche specialization and ovoviviparity seen in D. sechellia. [ABSTRACT FROM AUTHOR]

Selection on naturally occurring hybrid individuals is a key component of speciation theory, but few studies examine the functional basis of hybrid performance. We examine the functional consequences of hybridization in nature, using the freshwater sunfishes (Centrarchidae), where natural hybrids have been studied for more than a century and a half. We examined bluegill (Lepomis macrochirus), green sunfish (Lepomis cyanellus), and their naturally occurring hybrid, using prey-capture kinematics and morphology to parameterize suction-feeding simulations on divergent parental resources. Hybrid individuals exhibited kinematics intermediate between those of the two parental species. However, performance assays indicated that hybrids display performance most similar to the worse-performing species for a given parental resource. Our results show that intermediate hybrid phenotypes can be impaired by a lessthan- intermediate performance and hence suffer a larger loss in fitness than could be inferred from morphology alone. [ABSTRACT FROM AUTHOR]

Luxuriant, bushy antlers, bizarre crests, and huge, twisting horns and tusks are conventionally understood as products of sexual selection. This view stems from both direct observation and from the empirical finding that the size of these structures grows faster than body size (i.e., ornament size shows positive allometry).We contend that the familiar evolutionary increase in the complexity of ornaments over time in many animal clades is decoupled from ornament size evolution. Increased body size comes with extended growth. Since growth scales to the quarter power of body size, we predicted that ornament complexity should scale according to the quarter power law as well, irrespective of the role of sexual selection in the evolution and function of the ornament. To test this hypothesis, we selected three clades (ammonites, deer, and ceratopsian dinosaurs) whose species bore ornaments that differ in terms of the importance of sexual selection to their evolution.We found that the exponent of the regression of ornament complexity to body size is the same for the three groups and is statistically indistinguishable from0.25.We suggest that the evolution of ornament complexity is a by-product of Cope's rule. We argue that although sexual selection may control size in most ornaments, it does not influence their shape. [ABSTRACT FROM AUTHOR]

The evolution of convergent phenotypes in lineages subject to similar selective pressures is a common feature of adaptive radiation. In geographically replicated radiations, repeated convergence occurs between clades occupying distinct regions or islands. Alternatively, a clade may repeatedly reach the same adaptive peaks in broadscale sympatry, resulting in extensive convergence within a region. Rockfish (Sebastes sp.) have radiated in both the northeast and northwest Pacific, allowing tests of the extent and geographic pattern of convergence in a marine environment. We used a suite of phylogenetically informed methods to test for morphological convergence in rockfish. We examined patterns of faunal similarity using nearest neighbor distances in morphospace and the frequency of morphologically similar yet distantly related species pairs. The extent of convergence both between regions and within the northeast Pacific exceeds the expectation under a Brownian motion null model, although constraints on trait space could account for the similarity. We then used a recently developed method (SURFACE) to identify adaptive peak shifts in Sebastes evolutionary history. We found that the majority of convergent peak shifts occur within the northeast Pacific rather than between regions and that the signal of peak shifts is strongest for traits related to trophic morphology. Pacific rockfish thus demonstrate a tendency toward morphological convergence within one of the two broad geographic regions in which they have diversified. [ABSTRACT FROM AUTHOR]

Traits that increase mating success in males may come at a cost, such as an increased risk of predation. However, predatormediated selection is challenging to document in natural populations, hampering our understanding of the trade-offs between sexual selection and predation. Here we report on a study of predator- mediated natural selection on wing traits in the damselfly Calopteryx splendens, the males of which possess conspicuous wing patches. Wagtails (genus Motacilla) are important avian predators of C. splendens, capturing them in flight and removing the wings prior to consumption. Using geometric morphometric techniques, we quantified the strength and mode of selection on wing traits by comparing wings from depredated individuals with the standing variation present in the population. Our results reveal that predator- mediated selection is stronger on secondary sexual characters than on size and shape, suggesting that traits related to flight performance are closer to their adaptive peaks. This could be a consequence of the long-term evolutionary association with avian predators, whereas stronger selection on conspicuous secondary sexual traits may reflect trade-offs between sexual and natural selection. Finally, even though C. splendens possesses nearly identical fore- and hindwings, we found evidence for divergent selection between them. [ABSTRACT FROM AUTHOR]

Nonparallel evolution, where independent populations occupy similar environments but show phenotypic differences, can uncover previously ignored selective factors. We investigated a nonparallelism in the life-history strategy of a Trinidadian guppy population, a system famous for parallel adaptation to differences in predation risk. We tested the hypothesis that high mortality drives an observed fast life-history pattern (i.e., earlier maturation and more frequent reproductive events) that is atypical for a low-predation environment. Using mark-recapture techniques, we compared neighboring low-predation populations, finding significantly higher mortality rates in the population with atypical life-history traits. Mortality was elevated during the wet season, when flooding was common. Moreover, individuals from the anomalous population were more likely to transition from healthy to infected disease states. Our results stand out against previous patterns observed in this system, indicating that higher mortality caused by disease and flooding may have selected for a faster life history. Thus, we highlight that even in systems famous for parallel adaptation, variation in selective pressures can result in nonparallel phenotypic evolution [ABSTRACT FROM AUTHOR]

Our knowledge about how the environment influences sexual selection regimes and how ecology and sexual selection interact is still limited. We performed an integrative study of wing pigmentation in calopterygid damselflies, combining phylogenetic comparative analyses, field observations and experiments. We investigated the evolutionary consequences of wing pigmentation for sexual dimorphism, speciation, and extinction and addressed the possible thermoregulatory benefits of pigmentation. First, we reconstructed ancestral states of male and female phenotypes and traced the evolutionary change of wing pigmentation. Clear wings are the ancestral state and that pigmentation dimorphism is derived, suggesting that sexual selection results in sexual dimorphism. We further demonstrate that pigmentation elevates speciation and extinction rates. We also document a significant biogeographic association with pigmented species primarily occupying northern temperate regions with cooler climates. Field observations and experiments on two temperate sympatric species suggest a link between pigmentation, thermoregulation, and sexual selection, although body temperature is also affected by other phenotypic traits such as body mass, microhabitat selection, and thermoregulatory behaviors. Taken together, our results suggest an important role for wing pigmentation in sexual selection in males and in speciation. Wing pigmentation might not increase ecological adaptation and species longevity, and its primary function is in sexual signaling and species recognition. [ABSTRACT FROM AUTHOR]

An eco-evolutionary feedback loop is defined as the reciprocal impacts of ecology on evolutionary dynamics and evolution on ecological dynamics on contemporary timescales. We experimentally tested for an eco-evolutionary feedback loop in the green peach aphid, Myzus persicac, by manipulating initial densities and evolution. We found strong evidence that initial aphid density alters the rate and direction of evolution, as measured by changes in genotype frequencies through time. We also found that evolution of aphids within only 16 days, or approximately three generations, alters the rate of population growth and predicts density compared to nonevolving controls. The impact of evolution on population dynamics also depended on density. In one evolution treatment, evolution accelerated population growth by up to 10.3% at high initial density or reduced it by up to 6.4% at low initial density. The impact of evolution on population growth was as strong as or stronger than that caused by a threefold change in intraspecific density. We found that, taken together, ecological condition, here intraspecific density, alters evolutionary dynamics, which in turn alter concurrent population growth rate (ecological dynamics) in an eco-evolutionary feedback loop. Our results suggest that ignoring evolution in studies predicting population dynamics might lead us to overor underestimate population density and that we cannot predict the evolutionary c.utcome within aphid populations without considering population size. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the author discusses various reports within the issue on topics including the interaction between evolution and ecology, evolution changes ecology, and conceptual unification of the life sciences.

The biomass of living organisms hosts oniy a small portion of the elemental abundance at the surface of the Earth, yet biology plays a defining role in the composition and stability of the biosphere by acting on sensitive geochemical feedbacks controlling global element cycles. This type of influence is evident in a class of evolutionary innovations that have a profoundly disproportionate effect on the biosphere, referred to here as evolutionary innovation biospheric feedbacks (EIBFs). A particular biological innovation need not be complex, rather its influence is amplified by its effect on geochemical feedbacks controlling elemental cycling. The lead-up to the metazoan radiation (~585 million years ago) provides an example of such an EIBF. While commonly attributed to an increase in free oxygen concentration, the reason for this step increase in O2 almost 2 billion years after the advent of oxygenic photosynthesis is traced to a seemingly unrelated evolutionary innovation resulting in a critical by-product of the first soils: secondary clay minerals. Detrital clay minerals deposited in continental margin sediments sequester organic carbon compounds and thus prevent consumption ofatmospheric oxygen produced during photosynthesis. The transition from the abiotic to biotic land surface at the end of the Precambrian shifted biogeochemical cycling to this terrestrial-dominated modern mode that enabled sufficient oxygenation of the biosphere to trigger the metazoan radiation. [ABSTRACT FROM AUTHOR]

Density-dependent selection is one of earliest topics of joint interest to both ecologists and evolutionary biologists and thus occupies an important position in the histories of these disciplines. This joint interest is driven by the fact that density-dependent selection is the simplest form of feedback between an ecological effect of an organism's own making (crowding due to sustained population growth) and the selective response to the resulting conditions. This makes density-dependent selection perhaps the simplest process through which we see the full reciprocity between ecology and evolution. In this article, we begin by tracing the history of studying the reciprocity between ecology and evolution, which we see as combining the questions of evolutionary ecology with the assumptions and approaches of ecological genetics. In particular, density-dependent fitness and density-dependent selection were critical concepts underlying ideas about adaptation to biotic selection pressures and the coadaptation of interacting species. However, theory points to a critical distinction between density-dependent fitness and densitydependent selection in their influences on complex evolutionary and ecological interactions among coexisting species. Although densitydependent fitness is manifestly evident in empirical studies, evidence of density-dependent selection is much less common. This leads to the larger question of how prevalent and important density-dependent selection might really be. Life-history variation in the least kulifish Heterandria formosa appears to reflect the action of densitydependent selection, and yet compelling evidence is elusive, even in this well-studied system, which suggests some important challenges for understanding density-driven feedbacks between ecology and evolution. [ABSTRACT FROM AUTHOR]

Living nature Can be thought of as a tapestry, defined not only by its constituent parts but also by bow these parts are woven together. The weaving of this tapestry is a metaphor for species interactions, which can be divided into three broad classes: competitive, mutualistic, and consumptive. Direct interactions link together as more complex networks, for example, the joining of consumptive interactions into food webs. Food web dynamics are driven, in turn, by changes in the abundances of seeb members, whose numbers or biomass respond to bottom-up (resource limitation) and topdown (consumer limitation) forcing. The relative strengths of topdosen and bottom-up forcing on the abundance of a given web member depend on its ecological context, including its topological position ieithin the food web. Top-down effects by diverse consumers are nearly ubiquitous, in many cases influencing the structure and operation of ecosystems. While the ecological effects of such interactions are seell known, far less is knosen of their evolutionary consequences. In this essay, we describe sundry consequences of these interaction chains on species and ecosystem processes, explain several knosvn or suspected evolutionary effects of consumer-induced interaction chains, and identified areas where reciprocity between ecology and evolution involving the indirect effects of consumer-prey interaction chains might be further explored. [ABSTRACT FROM AUTHOR]

The extent to which evolutionary change occurs in a predictable manner under field conditions and how evolutionary changes feed back to influence ecological dynamics are fundamental, yet unresolved, questions. To address these issues, we established eight replicate populations of native common evening primrose (Oenothera biennis). Each population was planted with 18 genotypes in identical frequency. By tracking genotype frequencies with microsatellite DNA markers over the subsequent three years (up to three generations, ≈5,000 genotyped plants), we show rapid and consistent evolution of two heritable plant life-history traits (shorter life span and later flowering time). This rapid evolution was only partially the result of differential seed production; genotypic variation in seed germination also contributed to the observed evolutionary response. Since evening primrose genotypes exhibited heritable variation for resistance to insect herbivores, which was related to flowering time, we predicted that evolutionary changes in genotype frequencies would feed back to influence populations of a seed predator moth that specializes on 0. biennis. By the conclusion of the experiment, variation in the genotypic composition among our eight replicate field populations was highly predictive of moth abundance. These results demonstrate how rapid evolution in field populations of a native plant can influence ecological interactions. [ABSTRACT FROM AUTHOR]

Herbivores are credited with driving the evolutionary diversification of plant defensive strategies over macroevolutionary time. For this to be true, herbivores must also cause short-term evolution within plant populations, but few studies have experimentally tested this prediction. We addressed this gap using a longterm manipulative field experiment where exclosures protected 22 plant populations from natural rabbit herbivory for <1 to 26 years. We collected seeds of Rumex acetosa L. (Polygonaceae) from our plots and grew them in a common greenhouse environment to quantify evolved differences among populations in individual plant growth rate, tolerance to herbivory, competitive ability, and the concentration of secondary metabolites (tanninS and oxalate) implicated in defense against herbivores. In 26 years without rabbit herbivory, plant growth rate decreased linearly by 30%. We argue that plant growth rate has evolved as a defense against intense rabbit herbivory. In contrast, we found no change in tolerance to herbivory or concentrations of secondary metabolites. We also found no change in competitive ability, suggesting that contemporary evolution may not feed back to alter ecological interactions within this plant community. Our results combined with those of other studies show that the evolution of gross morphological traits such as growth rate in response to herbivory may be common, which calls into question assumptions about some of the most popular theories of plant defense. [ABSTRACT FROM AUTHOR]

In proposing his genetic feedback mechanism, David Pimentel was one of the first biologists to argue that the reciprocal interplay of ecological and evolutionary dynamics is an important process regulating population dynamics and ultimately affecting community composition. Although the past decade has seen an increase in research activity on these so-called eco-evolutionary dynamics, there remains a conspicuous lack of compelling natural examples of such feedback. Here we argue that this lack may be due to an inherent difficulty in detecting eco-evolutionary dynamics in nature. By examining models of virulence evolution, host resistance evolution, and antigenic evolution, we show that the influence of evolution on ecological dynamics can often be obscured by other ecological processes that yield similar dynamics. We then show, however, that mechanistic models can be used to navigate this, in Pimentel's words, "devious" course of evolution when effectively combined with empirical data. We argue that these models, improving upon Pimentel's original mathematical models, svill therefore play an increasingly important role in identifying more subtle, but possibly ubiquitous, eco-evolutionary dynamics in nature. To highlight the importance of identifying these potentially subtle dynamics in nature, we end by considering our ability to anticipate the effect of population control strategies in the presence of these eco-evolutionary feedbacks. [ABSTRACT FROM AUTHOR]

Recent study of feedbacks between ecological and evolutionary processes has renewed interest in population regulation and density-dependent selection because they represent black-box descriptions of these feedbacks. The roles of population regulation and density-dependent selection in life-history evolution have received a significant amount of theoretical attention, but there are few empirical examples demonstrating their importance. We address this challenge in natural populations of the Trinidadian guppy (Poecilia reticulata) that differ in their predation regimes. First, we tested whether natural populations of guppies are regulated by density dependence and quantified in which phases of the life cycle the effects of density are important. We found that guppies from low-predation (LP) environments are tightly regulated and that the density-dependent responses disproportionately affected some size classes. Second, we tested whether there are differences in density-dependent selection between guppies from LP or high-predation (HP) environments. We found that the fitness of HP guppies is more sensitive to the depressant effects of density than the fitness of LP guppies. Finally, we used an evolutionary invasion analysis to show that, depending on the effect of density on survival of the HP phenotype, this greater sensitivity of the HP phenotype to density can partially explain the evolution of the LP phenotype. We discuss the relevance of these findings to the study of feedbacks between ecology and evolution. [ABSTRACT FROM AUTHOR]

Ecological and evolutionary processes may interact on the same timescale, but we are just beginning to understand how. Several studies have examined the net effects of adaptive evolution on ecosystem properties. However, we do not know whether these effects are confined to direct interactions or whether they propagate further through indirect ecological pathways. Even less well understood is how the combination of direct and indirect ecological effects of the phenotype promotes or inhibits evolutionary change.We coupled mesocosm experiments and ecosystem modeling to evaluate the ecological effects of local adaptation in Trinidadian guppies (Poecilia reticulata). The experiments show that guppies adapted to life with and without predators alter the ecosystem directly through differences in diet. The ecosystem model reveals that the small total indirect effect of the phenotype observed in the experiments is likely a combination of several large indirect effects that act in opposing directions. The model further suggests that these indirect effects can reverse the direction of selection that direct effects alone exert back on phenotypic variation. We conclude that phenotypic divergence can have major effects deep in the web of indirect ecological interactions and that even small total indirect effects can radically change the dynamics of adaptation. [ABSTRACT FROM AUTHOR]

Since Smith and Fretwell's seminal article in 1974 on the optimal offspring size, most theory has assumed a trade-off between offspring number and offspring fitness, where larger offspring have better survival or fitness, but with diminishing returns. In this article, we use two ubiquitous biological mechanisms to derive the shape of this trade-off: the offspring's growth rate combined with its size-dependent mortality (predation). For a large parameter region, we obtain the same sigmoid relationship between offspring size and offspring survival as Smith and Fretwell, but we also identify parameter regions where the optimal offspring size is as small or as large as possible. With increasing growth rate, the optimal offspring size is smaller. We then integrate our model with strategies of parental care. Egg guarding that reduces egg mortality favors smaller or larger offspring, depending on how mortality scales with size. For livebearers, the survival of offspring to birth is a function of maternal survival; if the mother's survival increases with her size, then the model predicts that larger mothers should produce larger offspring. When using parameters for Trinidadian guppies Poecilia reticulata, differences in both growth and size-dependent predation are required to predict observed differences in offspring size between wild populations from high- and low-predation environments. [ABSTRACT FROM AUTHOR]

Numerous studies of wild populations have shown that phenotypic traits can change adaptively on short timescales, but very few studies have considered coincident changes in major fitness components. We here examine adaptive changes in life-history traits and survival rates for wild guppies introduced into new environments. Female life-history traits in the derived (Damier River) populations diverged from the ancestral (Yarra River) population, as a result of adaptation to predation regime (high vs. low) and other aspects of the local river. Moreover, some components of the derived Damier populations, particularly juveniles, now show higher survival in the Damier than do contemporary representatives from the ancestral Yarra population. These results suggest that adaptive change can improve survival rates after fewer than 10 years (fewer than 30 guppy generations) in a new environment. [ABSTRACT FROM AUTHOR]

The empirical study of natural selection reveals that adaptations often involve trade-offs between competing functions. Because natural selection acts on whole organisms rather than isolated traits, adaptive evolution may be constrained by the interaction between traits that are functionally integrated. Yet, few attempts have been made to characterize how and when such constraints are manifested or whether they limit the adaptive divergence of populations. Here we examine the consequences of adaptive life-history evolution on locomotor performance in the live-bearing guppy. In response to increased predation from piscivorous fish, Trinidadian guppies evolve an increased allocation of resources toward reproduction. These populations are also under strong selection for rapid fast-start swimming performance to evade predators. Because embryo development increases a female's wet mass as she approaches parturition, an increased investment in reproductive allocation should impede fast-start performance. We find evidence for adaptive but constrained evolution of fast-start swimming performance in laboratory trials conducted on second-generation lab-reared fish. Female guppies from high-predation localities attain a faster acceleration and velocity and travel a greater distance during fast-start swimming trials. However, velocity and distance traveled decline more rapidly over the course of pregnancy in these same females, thus reducing the magnitude of divergence in swimming performance between high- and low-predation populations. This functional trade-off between reproduction and swimming performance reveals how different aspects of the phenotype are integrated and highlights the complexity of adaptation at the whole-organism level. [ABSTRACT FROM AUTHOR]

Documents a genetic basis for convergent life-history evolution in guppies from high and low predation sites on the north slope of the Northern Range Mountains of Trinidad. Controlled food availability; Estimation of reproductive efforts; Predator effects; Reasons for convergence.

Compares guppies from high-predation sites (Crenichichla localities) with those from low-predation sites (Rivulus localities) found on the south slope of the Northern Range Mountains of Trinidad. Characterization of the life-history of phenotype; Multivariate comparison of female life-history traits.

Conventional wisdom holds that the complex shapes of deer antlers are produced under the sole influence of sexual selection. We questioned this view by demonstrating that trends for increased body size evolution passively yield more-complex ornaments, even in organisms where no effect of sexual selection is possible, with similar allometric slopes. Recent investigations suggest that sexual selection on antlers of larger deer species is stronger than that in smaller species; hence, the use of conspicuous antlers for display in large male deer is a secondary function driven by especially intense sexual selection on these large-bodied species. Since ancestral deer were small and had very simple antlers, such an intense selection on antlers shape was probably absent in early deer. Therefore, the evolution of complex ornaments is coupled with body size evolution, even in deer. [ABSTRACT FROM AUTHOR]