期刊
ANTARCTIC SCIENCE
卷 24, 期 1, 页码 15-22出版社
CAMBRIDGE UNIV PRESS
DOI: 10.1017/S0954102011000629
关键词
Araneae; Bergman body size cline; Marion Island; Myro kerguelenensis; resource limitation
资金
- USAID
- South African Department of Environmental Affairs and Tourism
Although spiders are a diverse and ecologically important group of predators across the sub-Antarctic islands, relatively little is known about their biology. Here we provide data on the abundance, body size variation and sex ratio of an indigenous spider, Myro kerguelenensis, across an altitudinal gradient on Marion Island. In so doing we test explicitly the hypotheses that density will decline with declining resource availability at higher elevations, and that a converse Bergmann body size cline will be found in this species. Density of M. kerguelenensis decreased with altitude and ranged from a mean density of 5.3 (SD 3.42) individuals per m(2) at 50 m a.s.l. to a mean density of 0.83 (SD 1.15) individuals per m(2) at 600 m a.s.l. Mean female sternum width was 1.39 mm (SD 0.44) and mean male sternum width was 1.40 mm (SD 0.22). No evidence for Bergmann or converse Bergmann clines was found. At increasing altitudes, sex ratios became increasingly female-biased with populations at 600 m a.s.l. comprising 0.87 (SD 0.28) females, on a proportional basis, possibly as a result of resource limitation and an increase in the prevalence of sexual cannibalism. The food web implications of this study are highlighted.
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