Structure and allometry of genitalia in males and females of a social African ground squirrel with high polygynandry

    Authors

    M. B. Manjerovic; A. A. Kinahan; J. M. Waterman; N. C. Bennett;P. W. Bateman

    Comments

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    Abbreviated Journal Title

    J. Zool.

    Keywords

    genitalia; sexual selection; allometry; polygynandry; SPERM COMPETITION GAMES; SEXUAL SELECTION; XERUS-INAURIS; PAGOPHILUS-GROENLANDICUS; FERTILIZATION SUCCESS; TESTIS SIZE; HARP SEAL; EVOLUTION; COEVOLUTION; MAMMALS; Zoology

    Abstract

    The few studies that have looked at genital allometry in mammals have typically shown a positively allometric relationship with body size and high coefficients of variation. Cryptic female choice, sexual conflict or sperm competition are mechanisms underlying genital evolution and as these are not mutually exclusive, they are often difficult to disentangle. In addition, these mechanisms are affected by both male and female social structure and/or mating strategies and, as such, pre- and post-copulatory behaviours have been shown to alter selection on genitalia. We examined genital traits and allometry in a polygynandrous and social ground squirrel Xerus inauris. We found that male testes are positively allometric and account for 1.5% of their body weight, one of the highest percentages known for sciurids. The penis, at 42.4% of head/body length, was isometric while the female reproductive tract, 22.4% head/body length, demonstrated no such relationship. Based on the allometric relationships of both males and females presented here, in conjunction with high levels of competition for females and lack of male aggression and territoriality, we suggest that sperm competition is the most likely mechanism for the evolution of the extremely large genitalia in this species.

    Journal Title

    Journal of Zoology

    Volume

    275

    Issue/Number

    4

    Publication Date

    1-1-2008

    Document Type

    Article

    Language

    English

    First Page

    375

    Last Page

    380

    WOS Identifier

    WOS:000257990700006

    ISSN

    0952-8369

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