Reproductive sharing and proximate factors mediating cooperative breeding in the African wild dog (Lycaon pictus) |
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Authors: | Penny A Spiering Michael J Somers Jesús E Maldonado David E Wildt Micaela Szykman Gunther |
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Institution: | (1) Center for Species Survival, Conservation and Research Center, National Zoological Park, Smithsonian Institution, Front Royal, VA 22630, USA;(2) Center for Conservation and Evolutionary Genetics, National Zoological Park, Smithsonian Institution, Washington, DC 20008, USA;(3) Centre for Wildlife Management, University of Pretoria, Pretoria, 0002, South Africa;(4) Centre for Invasion Biology, University of Pretoria, Pretoria, 0002, South Africa;(5) Department of Wildlife, Humboldt State University, Arcata, CA 95521, USA |
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Abstract: | Although dominant African wild dogs (Lycaon pictus) are generally believed to be the sole breeders within a pack, earlier behavioral and endocrine data suggest that reproduction
could be shared with subordinates. We performed an extensive behavioral, demographic, and genetic evaluation of a wild dog
population in South Africa to examine the level of such sharing and the proximate mechanisms influencing reproductive contributions
of each sex. While a majority of pups were born to dominants because of a lack of subordinate potential breeders, we discovered
a substantial portion of reproductive sharing between dominants and subordinates. Compared with alpha females that mated annually,
subordinate beta females bred in 54.5% of years whereas thetas never bred. The three top-ranking males all sired pups (56.0%,
32.0%, and 12.0%, respectively) when three or more adult males were present. With only two pack males, alpha and beta individuals
shared reproduction nearly equally (55.2% and 44.8%, respectively), and litters of mixed paternity were discovered on eight
of 15 (53.3%) occasions. A skewed adult sex-ratio and frequent alpha mortalities for females and behavioral aggression in
males allowed most individuals to attain dominant status in their lifetime, creating a constantly shifting social hierarchy.
Genetic parentage results corresponded to reported hormone profiles, suggesting physiological suppression in some lower-ranked
individuals of both sexes. Thus, a combination of demographic, behavioral, and hormonal proximate factors mediates reproductive
partitioning in wild dogs. We conclude that reproductive sharing can be significant in this species, especially for males
that have less robust suppressive mechanisms than females. |
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