![]() ![]() We found that body mass of all species remained stable over time and across space. Using temporal and spatial datasets of three rodent species distributed across different climatic zones in China, we investigated temporal and spatial trends of body size (length and mass), identified the critical drivers of these trends, and inferred the potential causes underlying the distinct body-size responses to the critical drivers. In mammals, body-size responses to warming climates are diverse, and the mechanisms underlying these different responses have been little investigated. simulans Living in different macrohabitats is a reflection of the degree of partitioning between sexes or nutritional quality of available food. Our results, therefore, did not provide strong evidence to substantiate the hypotheses that the magnitude of dimorphism among populations of D. Finally, only one of eight comparisons involving kangaroo rats Living in adjacent plant communities showed a significant two-way interaction between dimorphism and macrohabitat type. This pattern of variation was observed in all three-way comparisons and suggests the possibility of habitat mediated phenotypic responses. Smaller animals occupied Californian Grassland and Coastal-scrub, and Vizcaino vegetation communities. Both sexes were larger in Sierran Montane Conifer Forest and Californian Chaparral macrohabitats. External and cranial measures of size dimorphism were not correlated significantly with any major geographic factor and only cranial measures were associated significantly with variation in climate, At a local level, kangaroo rats living in different vegetation communities within the same latitudinal zone also exhibited significant sexual dimorphism in size however, macrohabitat heterogeneity appeared to affect males and females equally. This pattern was clearly counter to Bergmann's rule, but consistent with the hypothesis that temporal variation in availability of food may be an important factor leading to geographic variation in size. ![]() This morphologic gradient represented an increase in size with less seasonal variation in precipitation and temperature. Large kangaroo rats inhabited warm and arid southernmost latitudes, whereas small animals inhabited relatively cool and moist regions to the north. On a regional scale, our results indicated a significant shift in morphology of males and females along a north-south latitudinal gradient. We tested these hypotheses by quantifying between-sex differences in size in populations of the Dulzura kangaroo rat (Dipodomys simulans) from several macrohabitat types at regional and local geographic scales. The magnitude of sexual dimorphism in size among populations of some small mammals Living in different habitats may be a reflection of the degree of habitat partitioning between sexes or nutritional quality of available food. ![]()
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