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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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Fitness consequences of variation in social group size are not population‐specific but are associated with access to food in the communally breeding rodent, Octodon degus
Abstract Studies that concurrently investigate the functional benefits of group living in multiple populations of the same species are rare. Over a 3‐year period (2014–2016), we examined two ecologically contrasting populations to test multiple hypotheses for the adaptive significance of group living in the communally breeding rodentOctodon degus. We quantified the size of social units (number of adults, number of adult females), edible vegetation at burrow systems, and per capita offspring weaned (PCOW) in each population. Contrary to expectations, we did not observe population‐specific associations between group size and edible vegetation or PCOW nor universal benefits of group living. In one population, PCOW increased in mid‐sized groups with more edible vegetation. However, this trend was not consistent across years. Notably, we observed a complete reproductive failure in one population during the first year of study, one that was characterized by low rainfall and no detectable edible vegetation. This result is important because reproductive failure occurred regardless of group size, suggesting that communal living may not buffer degus against the harshest of environmental conditions. Examining how social organization shapes individual reproductive success under extreme variation in food availability is an important step towards understanding how populations will respond to a changing climate.
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- Award ID(s):
- 1854177
- PAR ID:
- 10530956
- Publisher / Repository:
- Ethology
- Date Published:
- Journal Name:
- Ethology
- Volume:
- 130
- Issue:
- 9
- ISSN:
- 0179-1613
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/eth.13491
