Female preferences, paternity and fitness: A combined morphometric/molecular genetic study on Poecilia latipinna and Poecilia formosa
Mate preferences represent an adaptive choice when costs associated with reproduction can be alleviated through gaining direct or indirect benefits from choosing the better mate. Female poeciliid fishes do show clear mate preferences for certain males although males in this highly promiscuous taxon only contribute sperm to reproduction. Thus, females do not receive any direct benefits post-mating. Here, I investigated the assumption that female preferences of Poecilia latipinna (sailfin molly) and P. formosa (Amazon molly) increase their reproductive success (quality or quantity of offspring) through indirect or direct benefits associated with the sperm. Since the male's genome is not incorporated in the reproduction of the gynogenetic P. formosa (AVISE ET AL. 1991; SCHARTL ET AL. 1995), they do not receive any indirect (genetic) benefits. Therefore, they represent an ideal model organism to test for direct benefits associated with sperm. Poecilia latipinna females (N = 27) were mated with both a preferred as well as with a non-preferred male, paternity was assigned via microsatellite analysis. Poecilia formosa females (N = 34) were mated with either a preferred or a non-preferred male. I found evidence that female preferences in both species did not depend on male size (a measure for male quality). But in P. latipinna, the number of offspring significantly increased with male size (N = 6 successful broods, 110 analyzed embryos). However, neither offspring quantity nor offspring quality (embryo dry weight) was influenced by female preferences. With 4 successful matings in P. formosa no significant relations could be found. Nonetheless the study fulfilled its objective of being a pilot study. This comparative and integrative study is the first of its kind to methodically combine life history measures (embryo dry weight) and genetic analyses (paternity analysis) of poeciliid fish embryos. DNA could be preserved through gentle desiccation at a low temperature. Besides, tissues were preserved in ethanol instead of commonly used formaldehyde, allowing life history measures on poeciliid fish embryos without destroying the DNA for further genetic analyses.
sexual selection, mate choice, life history, microsatellite analysis, live-bearing fish, sexuelle Selektion, Partnerwahl, Mikrosatelliten-Analyse, lebendgebärende Fische
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