A fundamental question in evolutionary biology asks whether organisms experiencing similar selective pressures will evolve solutions or historical contingencies dominate the process and yield disparate outcomes. It is perhaps most likely that both shared forces as well unique histories play key roles course of evolution. Consequently, when multiple species face a common environmental gradient, their patterns divergence might exhibit elements. Here we describe general framework for...

Abstract Predation is heterogeneously distributed across space and time, presumed to represent a major source of evolutionary diversification. In fishes, fast-starts–udden, high-energy swimmingbursts–are often importan tin avoiding capture during predator strike. Thus, in the presence predators, we might expect evolution morphological features that facilitate increased fast-start speed. We tested this hypothesis using populations western mosquitofish (Gambusia affinis) differed level...

Abstract Potential constraints on the evolution of phenotypic plasticity were tested using data from a previous study predator‐induced morphology and life history in freshwater snail Physa heterostropha . The benefit can be reduced if facultative development is associated with energetic costs, developmental instability, or an impaired range. I examined two traits for 29 families P. to see it was growth rate fecundity, within‐family variance, potential produce extreme phenotypes. Support...

We examined intraspecific morphological diversification between river channel and lagoon habitats for two Neotropical fish (Bryconops caudomaculatus, Characidae; Biotodoma wavrini, Cichlidae). hypothesized that differences (e.g. flow regime, foraging opportunities) might create selective pressures resulting in divergence conspecific populations. collected from four channel-lagoon habitat pairs the Río Cinaruco, Venezuela, compared body morphology using geometric morphometrics. There were...

Male genitalia may experience more rapid, divergent evolution than any other animal character, but why? Research during the past several decades has culminated in view that genital diversification primarily results from postmating sexual selection (e.g., sperm competition or cryptic female choice). However, potential roles of premating mate choice) and natural have received little attention. We examined possible importance these mechanisms by investigating divergence male among populations...

Divergent natural selection drives evolutionary diversification. It creates phenotypic diversity by favoring developmental plasticity within populations or genetic differentiation and local adaptation among populations. We investigated divergence in the livebearing fish Poecilia mexicana along two abiotic environmental gradients. These typically inhabit nonsulfidic surface rivers, but also colonized sulfidic cave habitats. assessed variation a factorial combination of habitat types using...

Variation in behavior, morphology and life history traits of larval anurans across predator gradients, consequences that variation, have been abundantly studied. Yet the functional link between burst‐swimming speed is largely unknown. We conducted experiments with two divergent species anurans, Scaphiopus holbrookii Rana sphenocephala , to examine how behavior influence vulnerability, whether tadpole shape related performance. a typically uses ephemeral pools, was more active, exhibited...

Abstract Environmental factors influence phenotypes directly, as well indirectly via trait correlations and interactions with other environmental variables. Using nine populations of the African cyprinid Barbus neumayeri , we employed path analysis to examine direct, indirect total effects two variables, water flow (WF) dissolved oxygen (DO), on several morphological traits. WF DO directly influenced relative gill size, body shape caudal fin in manners consistent a priori predictions....

Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors vibrotactile information from environment. Pinnipeds possess largest vibrissae among mammals their vibrissal hair shafts demonstrate a diversity shapes. The most phocid seals exhibit beaded morphology with repeating sequences crests troughs along length. However, there few detailed analyses pinniped morphology, these limited to species. Therefore, we comparatively...

Two hypotheses have been considered in the literature regarding how anuran morphology reduces predation risk: by (1) improving escape swimming performance, or (2) using tail as a lure to draw predator strikes away from body of tadpole. We investigated these modification morphology, and fitness path analysis Arnold (1983, Am. Zool. 23:347-361). Indirect effects on fitness, mediated burst speed, well direct paths survival with dragonfly larvae were included model. Tadpole did affect however,...

Since the announcement of species Australopithecus sediba, questions have been raised over whether Malapa fossils represent a valid taxon or inadequate allowance was made for intraspecific variation, in particular with reference to temporally and geographically proximate Au. africanus. The morphology mandibular remains including newly recovered material discussed here, shows that it is not merely late-surviving morph Rather-as seen elsewhere cranium, dentition, postcranial skeleton-these...

Variation in terrestrial mammalian skull morphology is known to constrain feeding performance, which turn influences dietary habits and ultimately fitness. Among mustelids, otters have evolved two specializations: underwater raptorial capture of prey (mouth-oriented) by hand (hand-oriented), both likely associations with bite performance. However, biomechanics performance data for are sparse. The first goal this study was investigate the relationships between among mouth-oriented piscivores...

Compared to the striking diversification and levels of endemism observed in many terrestrial groups within Hawaiian Archipelago, marine invertebrates exhibit remarkably lower rates diversification. Supralittoral restricted specific coastal patchy habitats, however, have potential for high allopatric This is case Ligia isopods endemic which most likely arose from a rocky supralittoral ancestor that colonized archipelago via rafting, diversified into inland lineages. A previous study on...