Publications [#140638] of V. Louise Roth
search PubMed.Papers Accepted
- Davis, C.M. & V.L. Roth, The evolution of sexual size dimorphism in cottontail rabbits (Sylvilagus, Leporidae),
Biological Journal of the Linnean Society
(publication expected 2008),
pp. 40 [text & tables] + 4 Figs. .
(last updated on 2007/12/21)Abstract:
In mammals, "female-biased" sexual size dimorphism (SSD), in which females are larger than males, is uncommon. Here we examine Sylvilagus, a purported case of female-biased SSD, for evolutionary correlations among species between SSD, body-size, and life-history variables. We find that (1) although most species are female-biased, the degree and direction of SSD vary more than was previously recognized; (2) the degree of SSD decreases with increasing body size. Hence, Sylvilagus provides a new example, unusual for a female-biased taxon, in which allometry for SSD is consistent with "Rensch's Rule". As a corollary to Rensch's Rule, we observe that changes in SSD in Sylvilagus are typically associated with larger, more significant changes in males than females. Female-biased SSD could be produced by selection for larger females, smaller males or both. Although larger female size may be related to high fecundity and the extremely rapid fetal and neonatal growth in Sylvilagus, we find little evidence for a correlation between SSD and various fecundity-related traits in among-species comparisons. Smaller male size may confer greater reproductive success through greater mobility and reduced energetic requirements. We propose that a suite of traits -- female dispersion, large male home ranges, reduced aggression, and a promiscuous mating system -- has favored smaller males and thus influenced the evolution of SSD in cottontails.
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