Density‐Dependent Variation in Lifetime Breeding Success and Natural and Sexual Selection in Soay Rams

Coltman, David W.; Smith, Judith A.; Bancroft, David; Pilkington, Jill G.; MacColl, Andrew D. C.; Clutton‐Brock, Tim; Pemberton, Josephine M.

doi:10.1086/303274

Cited by 145 publications

(153 citation statements)

References 51 publications

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“…This value is much lower than the one typically observed in species with female defense systems in which a few males monopolize the access to females. For example, in the highly polygynous and sexually dimorphic northern elephant seal (Mirounga angustirostris), Soay sheep (Ovis aries), and bighorn sheep (Ovis canadensis), the average Is value for males were 21.8, 3.5, and 4.5, respectively (Le Boeuf and Reiter 1988;Coltman et al 1999Coltman et al , 2002. The Is values that we observed are in the order of those reported for other squirrel species.…”

Section: Discussionsupporting

confidence: 63%

Factors affecting male and female reproductive success in a chipmunk (Tamias sibiricus) with a scramble competition mating system

Marmet

Pisanu

Chapuis

et al. 2012

Behav Ecol Sociobiol

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While sexual selection in mammals with female defense systems has historically received considerable attention, much less is known about the factors affecting reproductive success in mammalian species with scramble competition mating systems. Using mark-recapture techniques and DNA microsatellite loci to assign parentage, we examined the mating system and factors affecting the variation of the annual reproductive success in an introduced population of the Siberian chipmunk, Tamias sibiricus, a small, monomorphic, solitary squirrel. Our analyses showed that breeding females were spatially dispersed, setting the stage for a scramble competition mating system. Male reproductive success was positively associated with the size of the home range. The strength of sexual selection on this behavioral trait was very strong, equaling previous estimates for morphological traits in female defense mating systems. These findings suggest that a behavioral trait, space use, strongly influences the annual reproductive success in males, which is consistent with expectations in a scramble competition mating system. In both sexes, reproductive success was influenced by habitat, with twice as many juveniles produced in semiopen than in closed habitat, possibly due to differences in food availability between the two habitats.

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Section: Discussionsupporting

confidence: 63%

Factors affecting male and female reproductive success in a chipmunk (Tamias sibiricus) with a scramble competition mating system

Marmet

Pisanu

Chapuis

et al. 2012

Behav Ecol Sociobiol

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“…However, this project opens the way to the more challenging task of detecting QTL affecting a variety of morphological and physiological traits. The Soay sheep has been the subject of a number of studies aimed at estimating quantitative genetic parameters for traits like birth weight and body size (Coltman et al 1999;Milner et al 2000Milner et al , 2004. It has been found that the additive genetic variance of these traits is low but not null, despite the pressure of selection acting on them (Milner et al 2000).…”

Section: Mapping Ofmentioning

confidence: 99%

Development of a Linkage Map and Mapping of Phenotypic Polymorphisms in a Free-Living Population of Soay Sheep (Ovis aries)

et al. 2006

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An understanding of the determinants of trait variation and the selective forces acting on it in natural populations would give insights into the process of evolution. The combination of long-term studies of individuals living in the wild and better genomic resources for nonmodel organisms makes achieving this goal feasible. This article reports the development of a complete linkage map in a pedigree of free-living Soay sheep on St. Kilda and its application to mapping the loci responsible for three morphological polymorphisms for which the maintenance of variation demands explanation. The map was derived from 251 microsatellite and four allozyme markers and covers 3350 cM ($90% of the sheep genome) at $15-cM intervals. Marker order was consistent with the published sheep map with the exception of one region on chromosome 1 and one on chromosome 12. Coat color maps to chromosome 2 where a strong candidate gene, tyrosinase-related protein 1 (TYRP1), has also been mapped. Coat pattern maps to chromosome 13, close to the candidate locus Agouti. Horn type maps to chromosome 10, a location similar to that previously identified in domestic sheep. These findings represent an advance in the dissection of the genetic diversity in the wild and provide the foundation for QTL analyses in the study population.

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“…Although Nunney's (1993) model accounts for the potential disparity between seasonal and lifetime variance in reproductive success (provided that sex ratio is estimated in an appropriate manner), the use of cross-sectional data may be biased if there is substantial interannual variation in mating patterns. For example, long-term studies of free-ranging red deer (Cervus elaphus) and Soay sheep (Ovis aries) have demonstrated cohort-specific effects on male reproductive success as a result of environmental and demographic variation in the year of birth (Pemberton et al 1996(Pemberton et al , 1999Clutton-Brock et al 1997;Rose et al 1998;Coltman et al 1999b).…”

Section: /Nmentioning

confidence: 99%

Genetic Consequences of Polygyny and Social Structure in an Indian Fruit Bat, Cynopterus Sphinx. Ii. Variance in Male Mating Success and Effective Population Size

2001

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Abstract. Variance in reproductive success is a primary determinant of genetically effective population size (N e ), and thus has important implications for the role of genetic drift in the evolutionary dynamics of animal taxa characterized by polygynous mating systems. Here we report the results of a study designed to test the hypothesis that polygynous mating results in significantly reduced N e in an age-structured population. This hypothesis was tested in a natural population of a harem-forming fruit bat, Cynopterus sphinx (Chiroptera: Pteropodidae), in western India. The influence of the mating system on the ratio of variance N e to adult census number (N) was assessed using a mathematical model designed for age-structured populations that incorporated demographic and genetic data. Male mating success was assessed by means of direct and indirect paternity analysis using 10-locus microsatellite genotypes of adults and progeny from two consecutive breeding periods (n ϭ 431 individually marked bats). Combined results from both analyses were used to infer the effective number of male parents in each breeding period. The relative proportion of successfully reproducing males and the size distribution of paternal sibships comprising each offspring cohort revealed an extremely high within-season variance in male mating success (up to 9.2 times higher than Poisson expectation). The resultant estimate of N e /N for the C. sphinx study population was 0.42. As a result of polygynous mating, the predicted rate of drift (1/2N e per generation) was 17.6% higher than expected from a Poisson distribution of male mating success. However, the estimated N e /N was well within the 0.25-0.75 range expected for age-structured populations under normal demographic conditions. The life-history schedule of C. sphinx is characterized by a disproportionately short sexual maturation period scaled to adult life span. Consequently, the influence of polygynous mating on N e /N is mitigated by the extensive overlap of generations. In C. sphinx, turnover of breeding males between seasons ensures a broader sampling of the adult male gamete pool than expected from the variance in mating success within a single breeding period.

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Density‐Dependent Variation in Lifetime Breeding Success and Natural and Sexual Selection in Soay Rams

Cited by 145 publications

References 51 publications

Factors affecting male and female reproductive success in a chipmunk (Tamias sibiricus) with a scramble competition mating system

Factors affecting male and female reproductive success in a chipmunk (Tamias sibiricus) with a scramble competition mating system

Development of a Linkage Map and Mapping of Phenotypic Polymorphisms in a Free-Living Population of Soay Sheep (Ovis aries)

Genetic Consequences of Polygyny and Social Structure in an Indian Fruit Bat, Cynopterus Sphinx. Ii. Variance in Male Mating Success and Effective Population Size

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