Dynamics of extinction in coupled populations of the flour beetle Tribolium castaneum

W A C Godoy,M I S Costa

doi:10.1590/s1519-69842005000200010

Abstract

In this study we analyzed the effect of migration on the persistence time of coupled local populations of Tribolium in different environments. Four treatments were set up to compare different levels of environmental heterogeneity. We established high, low, moderate, and no heterogeneity. These levels were estimated by the different amounts of food offered to each population. To investigate how risk spreading works, a stochastic model for two subpopulations was employed. The high heterogeneity treatment resulted in the longest persistence, even though survival analysis revealed no significant difference among treatments. The magnitude of differences in growth rates among subpopulations is probably associated with persistence.

Highlights

The forces that affect population size, age structure, and genetic composition include birth and death rates, behavioral interactions among individuals, environmental fluctuations, natural selection, and interactions with other species (Case, 2000)
The survival curves were very similar and the statistical analysis revealed no significant difference among treatments (χ2 = 4.85; p > 0.18), suggesting that Tribolium populations exhibit similar persistence dynamics in spite of the migration between source and sink populations
With high environmental heterogeneity (5 and 35 g of food), six populations of Tribolium became extinct within three generations

Summary

Introduction

The forces that affect population size, age structure, and genetic composition include birth and death rates, behavioral interactions among individuals, environmental fluctuations, natural selection, and interactions with other species (Case, 2000). Understanding temporal fluctuations in population abundance is essential in analyzing population dynamics. Individuals comprising a population are distributed in space (Goodwin & Fahrig, 1998; Turchin, 1998). An approach considering both time and space is useful in detecting two potentially important factors in population dynamics: spatial population structure, GODOY, W.

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Conclusion