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

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.

A review of extinction in experimental populations

“…Consistent with theoretical predictions, they found that mean population sizes were larger in autocorrelated than in randomly variable habitats. In a study with Tribolium castaneum, Godoy & Costa (2005) established populations that each dispersed between two habitats. Pairs of habitats had a constant total amount of food, but differed in the extent to which food was evenly distributed or concentrated within one of the two habitats.…”

“…The lack of quantitative knowledge hampers the application of theory to natural populations. For example, we know that increasing variation in food abundance can increase extinction risk (Drake & Lodge 2004;Godoy & Costa 2005), but not how sensitive populations are to increasing variation or if there are thresholds. Partly this may result from system-specific idiosyncrasies.…”

“…Spatial variation in environmental quality should decouple dynamics of subpopulations and thereby decrease the risk of population extinction (Allen et al 1993;Earn et al 2000). (Gonzalez & Holt 2002) (Godoy & Costa 2005) In addition, factors within these broad categories are predicted to interact. For example, inbreeding is predicted to increase the influence of environmental stress.…”

Investigating Climate Change and Reproduction: Experimental Tools from Evolutionary Biology

“…The classic experimental evolution set-up with allopatric selection lines could be extended to a meta-population scenario by using multiple replicates of different population sizes. Migration could then be quite simply performed by exchanging individuals among populations at a given rate [165,166,167]. In particular, with regard to adaptation and speciation, gene flow and incoming migrants are expected to play important roles (see section 4).…”

Padrões Ecológicos E Tamanhos Populacionais Críticos: Sensores Importantes Em Modelagem E Controle

“…Modelos matemáticos são assim simplificações de sistemas (Godoy & Costa 2005), possibilitando reduzir complexidades a priori, visando a produção de protótipos compatíveis com os níveis de interpretação adequados para o conhecimento do sistema, no momento em que é analisado (Kot 2001). A variedade de comportamentos dinâmicos encontrada em diversas espécies de animais, sobretudo em insetos (Nicholson 1957, Turchin 1991, Dennis et al 1995, Godoy et al 1997), tem aumentado o interesse de ecólogos, tanto pelo desenvolvimento de experimentos biológicos com delineamentos focados nestas questões, como de modelos matemáticos com maior grau de especialização e adequação (Kot 2001).…”