Population stability and extinction in a social spider Stegodyphus mimosarum (Araneae : Eresidae)

Citation
T. Crouch et Y. Lubin, Population stability and extinction in a social spider Stegodyphus mimosarum (Araneae : Eresidae), BIOL J LINN, 72(3), 2001, pp. 409-417
Citations number
25
Categorie Soggetti
Biology
Journal title
BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY
ISSN journal
00244066 → ACNP
Volume
72
Issue
3
Year of publication
2001
Pages
409 - 417
Database
ISI
SICI code
0024-4066(200103)72:3<409:PSAEIA>2.0.ZU;2-C
Abstract
Nests of social spiders in their natural habitat are clustered and colony c lusters may be short-lived. Rapid growth and subsequent extinction of colon ies and colony clusters are predicted for social spider populations; howeve r, little quantitative data exist on the longevity of colonies. Furthermore , processes that influence the growth and decline of social spider populati ons are poorly understood. In this study we followed a population of over 5 50 nests of S. mimosarum from September 1994 to December 1999 and analysed the changes in relation to abiotic (temperature and rainfall) and biotic (p arasitism) factors. We observed two years of apparent population stability (1994-1995), during which nest numbers remained high and constant. This was followed in 1996 by a c. 12% decrease in the numbers of active nests. At t he end of 1996 there was a mass dispersal event which was followed in 1997 by a steady decline of the population with no further recovery. Thus, the d ecline was preceded by dispersal and nest failure, indicating that conditio ns in the population were unfavourable. The population-wide synchrony of th ese events reflects the seasonally synchronized development in S. mimosarum . However, extrinsic factors related to climate did not explain the extreme events of dispersal and population decline. The potential importance of pa rasitism, on the one hand, and unknown intrinsic factors on the other, shou ld be considered as alternative explanations that remain to be tested.(C) 2 001 The Linnean Society of London.