Seasonal reproduction in wild and captive male koala (Phascolarctos cinereus) populations in south-east Queensland

Allen, Camryn D.; Villiers, Deidré L. de; Manning, Brett D; Dique, David S.; Burridge, Michelle; Chafer, Mandy L.; Nicolson, V.; Jago, Sophia C.; McKinnon, A.; Booth, Rosemary; McKee, Jeff J.; Pyne, Michael; Zee, Yeng Peng; Lundie-Jenkins, Geoff; Theilemann, P.; Wilson, Richard; Carrick, F. N.; Johnston, Stephen D.

doi:10.1071/rd09113

Cited by 18 publications

(14 citation statements)

References 28 publications

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“…Therefore, the male‐specific ratio of collagen and elastin, testosterone exposure during development, and the dramatic increase in testosterone that is known to occur in male koalas just prior to the breeding season (Mitchell, ; Allen et al. ) will likely increase the stiffness of the VVFs. This could facilitate the particularly low frequency oscillation of the VVFs during call production in males, allowing them to produce their extremely low F0 bellow vocalisations.…”

Section: Discussionmentioning

confidence: 99%

The remarkable vocal anatomy of the koala (Phascolarctos cinereus): insights into low‐frequency sound production in a marsupial species

et al. 2018

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Koalas are characterised by a highly unusual vocal anatomy, with a descended larynx and velar vocal folds, allowing them to produce calls at disproportionately low frequencies. Here we use advanced imaging techniques, histological data, classical macroscopic dissection and behavioural observations to provide the first detailed description and interpretation of male and female koala vocal anatomy. We show that both males and females have an elongated pharynx and soft palate, resulting in a permanently descended larynx. In addition, the hyoid apparatus has a human-like configuration in which paired dorsal, resilient ligaments suspend the hyoid apparatus from the skull, while the ventral parts tightly connect to the descended larynx. We also show that koalas can retract the larynx down into the thoracic inlet, facilitated by a dramatic evolutionary transformation of the ventral neck muscles. First, the usual retractors of the larynx and the hyoid have their origins deep in the thorax. Secondly, three hyoid muscles have lost their connection to the hyoid skeleton. Thirdly, the genioglossus and geniohyoid muscles are greatly increased in length. Finally, the digastric, omohyoid and sternohyoid muscles, connected by a common tendinous intersection, form a guiding channel for the dynamic down-and-up movements of the ventral hyoid parts and the larynx. We suggest that these features evolved to accommodate the low resting position of the larynx and assist in its retraction during call production. We also confirm that the edges of the intra-pharyngeal ostium have specialised to form the novel, extra-laryngeal velar vocal folds, which are much larger than the true intra-laryngeal vocal folds in both sexes, but more developed and specialised for low frequency sound production in males than in females. Our findings illustrate that strong selection pressures on acoustic signalling not only lead to the specialisation of existing vocal organs but can also result in the evolution of novel vocal structures in both sexes.

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Section: Discussionmentioning

confidence: 99%

The remarkable vocal anatomy of the koala (Phascolarctos cinereus): insights into low‐frequency sound production in a marsupial species

et al. 2018

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“…Suitable animals were captured by flagging the animal to the ground in a manner similar to that described by Thompson (2001) and Radford et al (2006). Captured animals were placed in a cloth bag, measured, weighed, visually assessed for disease, given a body condition score (Allen et al 2010) and, if suitable, collared with a single-stage VHF radio-collar with automatic drop-off feature (Sirtrack, Havelock North, New Zealand) and then released at the site of capture. All collars were programmed to automatically fall off on 31 January 2010.…”

Section: Capture and Collaring Of Koalasmentioning

confidence: 99%

Ecology and movement of urban koalas adjacent to linear infrastructure in coastal south-east Queensland

Oliveira

Murray

Villiers³

et al. 2014

Aust. Mammalogy

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Abstract. In Redland City, koalas (Phascolarctos cinereus) are in rapid decline as they are exposed to anthropogenic threats such as habitat clearing, dog attacks, vehicle collisions and disease. This study investigated the influence of linear infrastructure on the movement and habitat use of urban koalas. Seven koalas were tracked for up to 28 weeks during the breeding season. Home ranges were calculated for 95% Minimum Convex Polygon (MCP95%) and 95% fixed Kernel Density (FK95%). Koalas responded to the landscape in different ways. Linear infrastructure did not restrict the movements of most koalas. Home ranges varied from 1.1 to 31.5 ha MCP95% and from 5 to 55 ha for FK95%. Koalas mainly used Eucalyptus tereticornis throughout the study site. A variety of non-regionally endemic and regionally endemic trees in urban and remnant vegetation areas were used, suggesting that all trees are potentially koala habitat. At the completion of the study, four koalas remained alive, two were killed by trains and one died from a dog attack. Despite the small sample size and short duration, our results suggest that koalas are able to navigate linear infrastructure; however, the high rates of mortality associated with these movements puts the long-term viability of urban koala populations in doubt.

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“…It is therefore interesting that koala also possesses a large sternal gland, the size and secretion of which appears to be under androgen control (Allen et al. ). In the domestic boar and the stallion, large amounts of oestrogen are also apparently secreted by the Leydig cells (Fawcett et al.…”

Section: Discussionmentioning

confidence: 99%

The seminiferous epithelial cycle and microanatomy of the koala (Phascolarctos cinereus) and southern hairy‐nosed wombat (Lasiorhinus latifrons) testis

et al. 2013

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The koala (Phascolarctos cinereus) and southern hairy-nosed wombat (Lasiorhinus latifrons) are iconic Australian fauna that share a close phylogenetic relationship but there are currently no comparative studies of the seminiferous epithelial cell or testicular microanatomy of either species. Koala and wombat spermatozoa are unusual for marsupials as they possess a curved stream-lined head and lateral neck insertion that superficially is similar to murid spermatozoa; the koala also contains Sertoli cells with crystalloid inclusions that closely resemble the Charcot-Bottcher crystalloids described in human Sertoli cells. Eighteen sexually mature koalas and four sexually mature southern hairy-nosed (SHN) wombats were examined to establish base-line data on quantitative testicular histology. Dynamics of the seminiferous epithelial cycle in the both species consisted of eight stages of cellular association similar to that described in other marsupials. Both species possessed a high proportion of the pre-meiotic (stages VIII, I -III; koala -62.2 AE 1.7% and SHN wombat -66.6 AE 2.4%) when compared with post-meiotic stages of the seminiferous cycle. The mean diameters of the seminiferous tubules found in the koalas and the SHN wombats were 227.8 AE 6.1 and 243.5 AE 3.9 lm, respectively. There were differences in testicular histology between the species including the koala possessing (i) a greater proportion of Leydig cells, (ii) larger Sertoli cell nuclei, (iii) crystalloids in the Sertoli cell cytoplasm, (iv) a distinctive acrosomal granule during spermiogenesis and (v) a highly eosinophilic acrosome. An understanding of the seminiferous epithelial cycle and microanatomy of testis is fundamental for documenting normal spermatogenesis and testicular architecture; recent evidence of orchitis and epididymitis associated with natural chlamydial infection in the koala suggest that this species might be useful as an experimental model for understanding Chlamydia induced testicular pathology in humans. Comparative spermatogenic data of closely related species can also potentially reflect evolutionary divergence and differences in reproductive strategies.

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Seasonal reproduction in wild and captive male koala (Phascolarctos cinereus) populations in south-east Queensland

Cited by 18 publications

References 28 publications

The remarkable vocal anatomy of the koala (Phascolarctos cinereus): insights into low‐frequency sound production in a marsupial species

The remarkable vocal anatomy of the koala (Phascolarctos cinereus): insights into low‐frequency sound production in a marsupial species

Ecology and movement of urban koalas adjacent to linear infrastructure in coastal south-east Queensland

The seminiferous epithelial cycle and microanatomy of the koala (Phascolarctos cinereus) and southern hairy‐nosed wombat (Lasiorhinus latifrons) testis

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