The role of historical factors and natural selection in the evolution of breeding systems of Oxalis alpina in the Sonoran desert 'Sky Islands'.

Pleistocene climatic oscillations are known to influence the patterns of genetic diversity and the distribution of traits that are the target of selection. Here, we combine phylogeographical and ecological niche modelling (ENM) approaches to explore the influence of historical factors (Pleistocene climatic shifts) and natural selection on the evolution of distyly (two floral morphs) from tristyly (three floral morphs) of Oxalis alpina in the Sky Islands of the Sonoran Desert. Molecular data and ENM indicate that historical factors have had a strong influence on the genetic structure and the geographical distribution of reproductive systems of O. alpina. Moreover, genetic results suggest the possibility that distylous populations do not represent a monophyletic group. We propose that the combined effects of natural selection and genetic drift have influenced the tristyly-distyly transition.

Dynamics of range margins for metapopulations under climate change.

We link spatially explicit climate change predictions to a dynamic metapopulation model. Predictions of species' responses to climate change, incorporating metapopulation dynamics and elements of dispersal, allow us to explore the range margin dynamics for two lagomorphs of conservation concern. Although the lagomorphs have very different distribution patterns, shifts at the edge of the range were more pronounced than shifts in the overall metapopulation. For Romerolagus diazi (volcano rabbit), the lower elevation range limit shifted upslope by approximately 700 m. This reduced the area occupied by the metapopulation, as the mountain peak currently lacks suitable vegetation. For Lepus timidus (European mountain hare), we modelled the British metapopulation. Increasing the dispersive estimate caused the metapopulation to shift faster on the northern range margin (leading edge). By contrast, it caused the metapopulation to respond to climate change slower, rather than faster, on the southern range margin (trailing edge). The differential responses of the leading and trailing range margins and the relative sensitivity of range limits to climate change compared with that of the metapopulation centroid have important implications for where conservation monitoring should be targeted. Our study demonstrates the importance and possibility of moving from simple bioclimatic envelope models to second-generation models that incorporate both dynamic climate change and metapopulation dynamics.

Museum specimen data predict crop damage by tropical rodents.

Museum collections constitute a massive store of information on biological diversity. We used museum specimen data to generate ecological niche models that provide predictions of geographic distributions of native rodent pest species and agricultural census data that summarize the geographic distribution of nine crops in the state of Veracruz, Mexico, as well as crop losses between planting and harvest. Herein, we show that crop damage is related significantly to the predicted presence of rodent species for seven of nine crops. Museum collections may thus provide important baseline information for designing land-use and agricultural pest-management programs.

Field immobilization of pygmy spotted skunks from Mexico.

We immobilized 21 pygmy spotted skunks (Spilogale pygmaea), in the tropical deciduous forest at the Chamela Biological Station (Mexico) from October 1994 to May 1997, with a mixture of ketamine (KH) and xylazine (XH). Skunks were immobilized with a mean (+/- SD) dosage of 15.7 +/- 8.3 mg/kg KH and 8.1 +/- 4.3 mg/kg XH. Mean induction and recovery time (n = 21) were 1.7 +/- 1.6 and 34.2 +/- 12.2 min, respectively. One individual was immobilized with XH, induction time was 1 min, and recovery time was 45 min. Foaming salivation was observed in this animal. No other adverse effects were observed for the other animals in this sample.