Stochasticity and spatial coexistence of semelparity and iteroparity as life histories

Authors: Tesar D.¹; Kaitala V.²; Ranta E.³

Source: Evolutionary Ecology, Volume 15, Number 3, 2001 , pp. 193-204(12)

Publisher: Springer

Abstract:

We investigate conditions enabling long-term coexistence of semelparity (reproducing only once per lifetime) and iteroparity (repeated spells of reproduction in subsequent breeding seasons). Bulmer (1985, 1994) has transferred the study of the fitness merit of reproducing semelparously vs. iteroparously into a density-dependent system, using an invasion scenario with an abundant resident population of one reproductive strategy and a rare mutant invader population of another reproductive strategy. For stable population dynamics, Bulmer (1994) derived condition v + P_A < 1 (P_A is adult survival and v is the ratio of offspring number of the iteroparous type over that of the semelparous type) where a semelparous population cannot be invaded by an iteroparous strategy. In order to study the generalisation of Bulmer's results in spatial population dynamics, we generate a population system consisting of a linear string of habitable sub-units. The sub-units are semi-independent, obeying discrete-time Ricker dynamics in renewal, but they are close enough for dispersing individuals to couple them together. At each time step, a random fraction of individuals in each sub-unit disperses into neighbourhood. In this setting, we observe long-term persistence of semelparity and iteroparity when dispersal is stochastic and positively autocorrelated. Stochasticity in dispersal creates fluctuating local dynamics and thus permits long-term persisting coexistence of semelparity and iteroparity even in the parameter region where Ricker dynamics are stable and the Bulmer inequality is true. Positively autocorrelated, in contrast to negatively autocorrelated dispersal time-series, promoted coexistence between semelparity and iteroparity.

Keywords: autocorrelated noise; coexistence; iteroparity; semelparity; spatial model

Language: English

Document Type: Regular paper

Affiliations: 1: Integrative Ecology Unit, Division of Population Biology, Department of Ecology and Systematics, P.O. Box 17 (Arkadiankatu 7) FIN-00014, University of Helsinki, Finland; fax: +358-9-191-28701; e-mail: david.tesar@helsinki.fi 2: Integrative Ecology Unit, Division of Population Biology, Department of Ecology and Systematics, P.O. Box 17 (Arkadiankatu 7) FIN-00014, University of Helsinki, Finland; Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FIN-40351 Jyväskylä, Finland 3: Integrative Ecology Unit, Division of Population Biology, Department of Ecology and Systematics, P.O. Box 17 (Arkadiankatu 7) FIN-00014, University of Helsinki, Finland

Publication date: 2001-01-01

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• In this Subject: Biology ,  Ecology
• By this author: Tesar D. ;  Kaitala V. ;  Ranta E.

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