Indirect fitness benefits to philopatric juvenile prairie voles Microtus ochrogaster
Solomon, Nancy Gail
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Permalink
https://hdl.handle.net/2142/21161
Description
Title
Indirect fitness benefits to philopatric juvenile prairie voles Microtus ochrogaster
Author(s)
Solomon, Nancy Gail
Issue Date
1991
Doctoral Committee Chair(s)
Burley, Nancy
Department of Study
Biology
Discipline
Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Zoology
Language
eng
Abstract
Investigators disagree over the selection pressures responsible for helping behavior. Controversy stems from the relative importance of direct and indirect fitness benefits. In this study, I focused on possible indirect fitness benefits to begin to evaluate the relative importance of these selective forces.
Initially, I investigated potential current indirect benefits accruing to philopatric juvenile prairie voles. Fathers engaged in non-parental behavior more frequently in families with juveniles than those without juveniles. Mothers delivered subsequent litters sooner if juveniles were present during the rearing of the previous litter. Pups reared with juveniles grew, developed, and survived better prior to separation from parents. Growth, development, and survival may have been affected by the length of time pups were alone in the nest. Pups reared with juveniles were alone in the nest less frequently than those without juveniles. Survival shortly after separation from parents in juvenile-assisted young was enhanced through their larger separation weight.
Weight at separation from parents may affect subsequent size and/or reproduction. Weight at separation from parents was positively correlated with pairing weight in males and females. Pairs containing large males produced litters sooner than those with small males. Pups of large females showed increased growth prior to separation from parents. Both female and male voles showed a significant preference for large versus small mates.
Also, prairie vole pups were raised with or without older siblings to determine the relative importance of weight at separation from parents versus preseparation social experience on subsequent reproduction. Female weight at separation predicted pup growth and the interlitter interval. Reproduction of males was not affected by separation weight.
The results of these experiments suggest that parents and young benefit directly and juveniles indirectly from their presence at the natal nest. Presence of juveniles enhanced reproduction in parents and younger female sibs. Rapid pup growth may allow earlier termination of investment in the current litter and concomitant production of a subsequent litter sooner. The ability to produce litters quickly may be extremely important in species with high predation rates.
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