What are the dynamics and regularities underlying social contact, and how can contact with the people in one's social network be predicted? In order to characterize distributional and temporal patterns underlying contact probability, we asked 40 participants to keep a diary of their social contacts for 100 consecutive days. Using a memory framework previously used to study environmental regularities, we predicted that the probability of future contact would follow in systematic ways from the frequency,...
The parameters that drive population dynamics typically show a relationship with body size. By contrast, there is no theoretical or empirical support for a body-size dependence of mutual interference, which links foraging rates to consumer density. Here, I develop a model to predict that interference may be positively or negatively related to body size depending on how resource body size scales with consumer body size. Over a wide range of body sizes, however, the model...
From finding food to choosing mates, animals must make intertemporal choices that involve fitness benefits available at different times. Species vary dramatically in their willingness to wait for delayed rewards. Why does this variation across species exist? An adaptive approach to intertemporal choice suggests that time preferences should reflect the temporal problems faced in a species's environment. Here, I use phylogenetic regression to test whether allometric factors relating to body size, relative brain size and...
Migratory birds often form flocks on their wintering grounds, but important details of social structure such as the patterns of association between individuals are virtually unknown. We analysed networks of co-membership in short-term flocks for wintering golden-crowned sparrows (Zonotrichia atricapilla) across three years and discovered social complexity unsuspected for migratory songbirds. The population was consistently clustered into distinct social communities within a relatively small area (~ 7 ha). Birds returned to the same community across...
Data from: Population size-structure dependent fitness and ecosystem consequences in Trinidadian guppiesRonald D. Bassar, , Michael C. Marshall, Steven A. Thomas, Alexander S. Flecker, David N. Reznick & Thomas Heatherly
1. Decades of theory and recent empirical results have shown that evolutionary, population, community and ecosystem properties are the result of feedbacks between ecological and evolutionary processes. The vast majority of theory and empirical research on these eco-evolutionary feedbacks has focused on interactions among population size and mean traits of populations. 2. However, numbers and mean traits represent only a fraction of the possible feedback dimensions. Populations of many organisms consist of different size classes...
Hox genes regulate regionalization of the axial skeleton in vertebrates, and changes in their expression have been proposed to be a fundamental mechanism driving the evolution of new body forms. The origin of the snake-like body form, with its deregionalized pre-cloacal axial skeleton, has been explained as either homogenization of Hox gene expression domains9, or retention of standard vertebrate Hox domains with alteration of downstream expression that suppresses development of distinct regions. Both models assume...
Data from: Competition for hummingbird pollination shapes flower color variation in Andean SolanaceaeNathan Muchhala, Sönke Johnsen & Stacey Dewitt Smith
One classic explanation for the remarkable diversity of flower colors across angiosperms involves evolutionary shifts among different types of pollinators with different color preferences. However, the pollinator shift model fails to account for the many examples of color variation within clades that share the same pollination system. An alternate explanation is the competition model, which suggests that color divergence evolves in response to interspecific competition for pollinators, as a means to decrease interspecific pollinator movements....
University of Nebraska - Lincoln7
University of California System1
University of Georgia1
French National Centre for Scientific Research1
Max Planck Institute for Human Development1
University of Colorado Boulder1
University of Missouri1
University of California, Riverside1
University of California, Santa Cruz1