Intraspecific variation in mortality rates of the livebearing fish Poeciliopsis baenschi

Autor: Fernanda R. Rodríguez-Reyes, Jerald B. Johnson, Claudia Olivera-Tlahuel, R. Jonathan Maceda-Cruz, Claudia Molina-Zuluaga, J. Jaime Zúñiga-Vega
Rok vydání: 2012
Předmět:
Zdroj: Environmental Biology of Fishes. 95:259-273
ISSN: 1573-5133
0378-1909
DOI: 10.1007/s10641-012-9989-1
Popis: Identifying differences in mortality rates in wild fish populations can provide insight into ecolog- ical and evolutionary variation within species, includ- ing differences between sexes. In this study, we examined natural mortality patterns among four pop- ulations of a viviparous freshwater fish (Poeciliopsis baenschi) from western Mexico that shows sexual size dimorphism. Our purpose was to test for differences in mortality rates among populations and to determine if these differences are sex- or size-dependent. We fit mark-recapture data to several competing models to test for differences in mortality rates among collection localities and between sexes, as well as to evaluate a potential relationship between size and mortality. The best-fitting model included an interaction between size and source population without a sex effect, indicating a strong relationship between size and mortality that differed among populations. In three populations, adult individuals of medium sizes experienced in- creased mortality rates compared to smaller or larger adults. In one of these three populations, this pattern was more pronounced with medium-sized individuals suffering strikingly higher mortality. In the remaining population, we found the opposite pattern: adult indi- viduals of medium sizes experienced lower mortality rates compared to smaller or larger adults. In all cases, these effects were independent of sex. We consider explanations for this pattern based on ecological fac- tors, such as differences in predation intensity, and discuss our results in the context of intraspecific phe- notypic divergence. Our findings demonstrate the val- ue of comparing mortality rates among populations within a fish species.
Databáze: OpenAIRE
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