Extinction dynamics and the regional persistence of a tree frog metapopulation.
The concept of a metapopulation acknowledges local extinctions as a natural part of the dynamics of a patchily distributed population. However, if extinctions are not balanced by recolonizations or if there is a high degree of spatial synchrony of local extinctions, this poses a threat to and will reduce the metapopulation persistence time. Here we show that, in a metapopulation network of 378 pond patches used by the tree frog (Hyla arborea), even though extinctions are frequent (mean extinction probability p(e) = 0.24) they pose no threat to the metapopulation as they are balanced by recolonizations (p(c) = 0.33). In any one year there was a pattern of large populations tending to persist while small populations became extinct. The total number of individuals belonging to populations that went extinct was small (< 5%) compared with those populations that persisted. A spatial autocorrelation analysis indicated no clustering of local extinctions. The tree frog metapopulation studied consisted of a set of larger, persistent populations mixed with smaller populations characterized by high turnover dynamics.
Carlson
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Department of Conservation Biology, Swedish University of Agricultural Sciences, Uppsala. allan.carlson@nvb.slu.se
Edenhamn
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D000818:Animals; D001001:Anura / Q000254:growth & development / Q000502:physiology*; D017753:Ecosystem; D008297:Male; D011157:Population Dynamics; D013548:Sweden; D013997:Time Factors