Abstract
Movement of individuals influences individual reproductive success, fitness, genetic diversity and relationships among individuals within populations and gene exchange among populations. Competition between males or females for mating opportunities and/or local resources predicts a female bias in taxa with monogamous mating systems and a male-biased dispersal in polygynous species. In birds and mammals, the patterns of dispersal between sexes are well explored, while dispersal patterns in protandrous hermaphroditic fish species have not been studied. We collected 549 adult individuals of Asian seabass (Lates calcarifer) from four locations in the South China Sea. To assess the difference in patterns of dispersal between sexes, we genotyped all individuals with 18 microsatellites. Significant genetic differentiation was detected among and within sampling locations. The parameters of population structure (F ST), relatedness (r) and the mean assignment index (mAIC), in combination with data on tagging-recapture, supplied strong evidences for female-biased dispersal in the Asian seabass. This result contradicts our initial hypothesis of no sex difference in dispersal. We suggest that inbreeding avoidance of females, female mate choice under the condition of low mate competition among males, and male resource competition create a female-biased dispersal. The bigger body size of females may be a cause of the female-biased movement. Studies of dispersal using data from DNA markers and tagging-recapture in hermaphroditic fish species could enhance our understanding of patterns of dispersal in fish.
Highlights
Dispersal is an important life history trait
When males make no parental investment or the male contribution to parental care is minor, the competition for local resource among relatives for limited breeding resources may be greater among females [14,15]
Ethics Statement All handling of fishes was conducted in accordance with the guidelines on the care and use of animals for scientific purposes set up by the Institutional Animal Care and Use Committee (IACUC)
Summary
Dispersal is an important life history trait. It influences individual fitness, reproductive success, genetic variation and relationships among individuals within populations, gene flow among populations and the potential to colonize in new habitats [1]. Competition for mates and breeding resources, and inbreeding avoidance can result in sex-biased dispersal [3,5]. Competition among kin and inbreeding avoidance can produce sex-biased dispersal in mammals (Handley & Perrin 2007), birds [6,10] and some fish species [11,12], because competition among kin diminishes the inclusive fitness. Whether avoidance of kin competition can result in sex-biased dispersal is associated with the possibility that the two sexes compete for the same resources [13]. When the breeding resources limit the female reproductive success in polygynous or promiscuous systems, or when the effect of local competition among males and females is the same in monogamous systems, dispersal is not sex-biased [19]
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