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The frequency of polyandry has important implications for effective population size, genetic variation, and reproductive output. Compared to terrestrial organisms with complex social behaviors, the patterns and consequences of polyandry in marine populations are relatively less clear. Here we quantified polyandry in the Florida crown conchMelongena coronain the field under natural settings. We assessed the extent to which additional mates increase genetic diversity within broods, how polyandry relates to female reproductive output, and how consistent patterns are across their 5 mo reproductive season in 2 separate years. We found large variation in polyandry (2 to 19 sires per brood) and reproductive output among females. However, the number of sires per brood was unrelated to reproductive output. The number of sires increased genetic diversity within broods regardless of year or time of season. The number of sires per brood and reproductive output did not vary over the season or among years. Overall, our results show natural variation in polyandry upon which selection could act, but increased polyandry did not lead to females producing more hatchlings, and neither polyandry nor reproductive output increased over time when females could accumulate and store sperm. Any benefits of polyandry in terms of genetic diversity are expected to occur after hatching, if at all, rather than inside the egg capsule. Variation in polyandry could arise because males control mating and polyandry is less costly for females than trying to prevent superfluous matings.
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Is MHC diversity a better marker for conservation than neutral genetic diversity? A case study of two contrasting dolphin populations
Abstract Genetic diversity is essential for populations to adapt to changing environments. Measures of genetic diversity are often based on selectively neutral markers, such as microsatellites. Genetic diversity to guide conservation management, however, is better reflected by adaptive markers, including genes of the major histocompatibility complex (MHC). Our aim was to assess MHC and neutral genetic diversity in two contrasting bottlenose dolphin (Tursiops aduncus) populations in Western Australia—one apparently viable population with high reproductive output (Shark Bay) and one with lower reproductive output that was forecast to decline (Bunbury). We assessed genetic variation in the two populations by sequencing the MHC class II DQB, which encompasses the functionally important peptide binding regions (PBR). Neutral genetic diversity was assessed by genotyping twenty‐three microsatellite loci. We confirmed that MHC is an adaptive marker in both populations. Overall, the Shark Bay population exhibited greater MHC diversity than the Bunbury population—for example, it displayed greater MHC nucleotide diversity. In contrast, the difference in microsatellite diversity between the two populations was comparatively low. Our findings are consistent with the hypothesis that viable populations typically display greater genetic diversity than less viable populations. The results also suggest that MHC variation is more closely associated with population viability than neutral genetic variation. Although the inferences from our findings are limited, because we only compared two populations, our results add to a growing number of studies that highlight the usefulness of MHC as a potentially suitable genetic marker for animal conservation. The Shark Bay population, which carries greater adaptive genetic diversity than the Bunbury population, is thus likely more robust to natural or human‐induced changes to the coastal ecosystem it inhabits.
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- PAR ID:
- 10363975
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 9
- Issue:
- 12
- ISSN:
- 2045-7758
- Page Range / eLocation ID:
- p. 6986-6998
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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