Population dynamics of meta-population and ineraction among local population

点击翻译按钮获取中文摘要

The concepts of extinction-(re) colonization dynamics applies to naturally or artificially fragmented populations. We investigated the effects of habitat size and isolation (distance to nearest occupied habitat) on the patterns of presence or absence (occurrence) of patchily distributed stream-dwelling Dolly Varden in individual tributaries. We predicted that the probability of occurrence would 1) increase with habitat size because of low extinction rates in large habitats and 2) decrease with increasing distance among habitats because of low recolonization rates in isolated habitats. Our first prediction was supported by a logistic regression of Dolly Varden occurrence on habitat size, indicating that small populations may be especially prone to extinction. Oppositely, distance to nearest population did not affect Dolly Varden occurrence. This suggests that colonization of unoccupied habitats was rare and independent of geographic distance, and that extinction rates may exceed recolonization rates. However, a previous genetic study revealed isolation by distance, a pattern inconsistent with the present results. This discrepancy may result from the limited available information on temporal fluctuations of occurrence and deserves further attention.