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We present the most extensive examination to date of proposed correlates of spe-cies richness.We use rigorous phylogenetic comparative techniques, data for 1,692 mammal species in four clades, and multivariate statistics to test four hypotheses about species richness and compare the evidence for each. Overall, we find strong support for the life-history model of diversification. Species richness is significantly correlated with shorter gestation period in the carnivores and large litter size in mar-supials. These traits and short interbirth intervals are also associated with species richness in a pooled analysis of all four clades. Additionally, we find some support for the abundance hypotheses in different clades of mammals: abundance correlates positively with species richness in primates but negatively in microchiropterans. Our analyses provide no evidence that mammalian species richness is associated with body size or degree of sexual dimorphism. [ABSTRACT FROM AUTHOR]

Day range (daily distance traveled) is an important measure for understanding relationships between animal distributions and food resources. However, our understanding of variation in day range across species is limited. Here we present a day range model and compare predictions against a comprehensive analysis of mammalian day range. As found in previous studies, day range scales near the power of body mass. Also, consistent with model predictions, 1/4 taxonomic groups differ in the way day range scales with mass, associated with the most common diet types and foraging habitats. Faunivores have the longest day ranges and steepest body mass scaling. Frugivores and herbivores show intermediate and low scaling exponents, respectively. Day range in primates did not scale with mass, which may be consistent with the prediction that three dimensional foraging habitats lead to lower exponents. Day ranges increase with group size in carnivores but not in other taxonomic groups. [ABSTRACT FROM AUTHOR]

Explaining variation in life histories remains a major challenge because they are multidimensional and there are many competing explanatory theories and paradigms. An influential concept in life-history theory is the fast-slow continuum, exemplified by mammals. Determining the utility of such concepts across taxonomic groups requires comparison of the groups' life histories in multidimensional space. Insects display enormous species richness and phenotypic diversity, but testing hypotheses like the fast-slow continuum has been inhibited by incomplete trait data. We use phylogenetic imputation to generate complete data sets of seven life-history traits in orthopterans (grasshoppers and crickets) and examine the robustness of these imputations for our findings. Three phylogenetic principal components explain 83%–96% of variation in these data. We find consistent evidence of an axis mostly following expectations of a fast-slow continuum, except that "slow" species produce larger, not smaller, clutches of eggs. We show that the principal axes of variation in orthopterans and reptiles are mutually explanatory, as are those of mammals and birds. Essentially, trait covariation in Orthoptera, with "slow" species producing larger clutches, is more reptilelike than mammal-like or birdlike. We conclude that the fast-slow continuum is less pronounced in Orthoptera than it is in birds and mammals, reducing the universal relevance of this pattern and the theories that predict it. [ABSTRACT FROM AUTHOR]

The negative scaling of plant and animal abundance with body mass is one of the most fundamental relationships in ecology. However, theoretical approaches to explain this phenomenon make the unrealistic assumption that species share a homogeneous resource. Here we present a simple model linking mass and metabolism with density that includes the effects of consumer size on resource characteristics (particle size, density, and distribution). We predict patterns consistent with the energy equivalence rule (EER) under some scenarios. However, deviations from EER occur as a result of variation in resource distribution and productivity (e.g., due to the clumping of prey or variation in food particle size selection). We also predict that abundance scaling exponents change with the dimensionality of the foraging habitat. Our model predictions explain several inconsistencies in the observed scaling of vertebrate abundance among ecological and taxonomic groups and provide a broad framework for understanding variation in abundance. [ABSTRACT FROM AUTHOR]