Spatial and Temporal Distribution of the Polymorphism for Tail-Tip Albinism in the Hispid Pocket Mouse, Chaetodipus hispidus (Rodentia: Heteromyidae)

Abstract

-A survey of almost 1000 study skins of Chaetodipus hispidus from Oklahoma and Texas indicates that ca. 7% of all individuals are marked by tail-tip albinism, and that the character is about equally distributed by sex and nominal subspecies. No significant frequency differences were noted among the eight major habitats represented in the study area, although the three pooled habitats which comprise the interior grasslands of the Southern Plains support a significandly higher incidence of the partial albinism than the peripheral, more sparsely populated regions (remaining pooled habitats). Data from a single Texas county, spanning four decades, indicate that local populations undergo repeated fluctuations, which account for the observed erratic microgeographic (by county) distribution of the character. As with previous studies which have used partial albinism data as genetic indicators for past events and current population structure, we propose that surveys of mammal collections for examples of partial albinism could prove useful in the design of population genetic studies. The possible roles of selection and stochastic events in producing and maintaining the observed distribution patterns are discussed.