Body size and sexual selection in the koala

@article{Ellis2010BodySA,
  title={Body size and sexual selection in the koala},
  author={William A. H. Ellis and Fred B. Bercovitch},
  journal={Behavioral Ecology and Sociobiology},
  year={2010},
  volume={65},
  pages={1229-1235}
}
Sexual selection is often characterized by polygynous breeding systems, size dimorphism, and skewed operational sex ratios. Koalas are sexually dimorphic in multiple domains, yet are absent from the literature on sexual selection and the structure of their mating system is unclear. We provide the first documentation of the strength of sexual selection in koalas by using microsatellite markers to identify sires. We combine the genetic data with morphological data in order to assess the role of… 
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31 Citations

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It is predicted that utilizing a variety of behavioral and MHC-dependent mate choice mechanisms improves female fitness through increased reproductive success and highlights the complexity ofmate choice mechanisms in a species.
Inbreeding and disease avoidance in a free‐ranging koala population
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No evidence that female koalas can avoid mating with relatively more related available mates is found, which is concerning from a conservation perspective, as small, isolated populations may be at even higher risk of inbreeding depression than expected.
Movement of Free-Ranging Koalas in Response to Male Vocalisation Playbacks
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Female koalas prefer bellows in which lower formants indicate larger males
Cues to body size in the formant spacing of male koala (Phascolarctos cinereus) bellows: honesty in an exaggerated trait
TLDR
The findings show that the formant spacing of male koala bellows has the potential to provide receivers with reliable information on the caller's body size, and reveal that vocal adaptations allowing callers to exaggerate (or maximise) the acoustic impression of their size have evolved independently in marsupials and placental mammals.
Free-Ranging Male Koalas Use Size-Related Variation in Formant Frequencies to Assess Rival Males
TLDR
The results indicate that male koalas invest more effort into their vocal responses when they are presented with bellows that have lower formants indicative of larger rivals, but also show that males are slower to engage in vocal exchanges with larger males that represent more dangerous rivals.
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