Interaction Between Fitness and Genetic Diversity May Lead to the Relatively High Diversification of Active Foragers

Dylan J Padilla Perez, Martha M. Muñoz, David K Skelly

Differences in the diversification of species across the Tree of Life may emerge from the ecological and evolutionary consequences of organismal traits. Foraging behavior may influence species diversification through its effects on fitness and genetic diversity.  Different foraging strategies can be expected to alter patterns of movement, gene flow, and adaptation in different ways.  Active foragers travel widely in search of food, potentially increasing genetic divergence through local adaptation to different environments.  By contrast, limited movement of sit-and-wait foragers may reduce gene flow among populations, prompting genetic divergence through isolation.  Behavioral plasticity in foraging may provide a third pathway by exposing previously hidden genetic variation to selection.   To test these predictions, we conducted a comparative analysis of 997 reptile species that vary in their locomotor behavior while foraging.  We found that the net diversification of reptiles depends on an interaction between foraging behavior and unobserved factors.  Specifically, active foragers appear to have the highest species diversification.  This observation may be the result of the positive association between lifetime reproductive output and genetic diversity in active foragers, which may confer them more potential variation for selection to act upon.  By contrast, fitness of plastic and sit-and-wait foragers appears to decrease with genetic diversity.  In this context, genetic costs associated with plastic and sit-and-wait foraging might have a constraining effect on species diversification.  We used genomic data and macroevolutionary observations supported by microevolutionary processes to provide key insights into mechanisms of diversification.