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Although much is known about the biology of monotremes, many important aspectsof their reproduction remain unclear. Studies over the last century haveprovided valuable information on various aspects of monotreme reproductionincluding the structure and function of their reproductive system, breedingbehaviour, sex determination and seasonality. All three living genera ofmonotremes have been successfully maintained in captivity, often for longperiods, yet breeding has been rare and unpredictable. When breeding hasoccurred, however, significant gains in knowledge have ensued; for example amore accurate estimate of the gestation period of the platypus and theincubation period for the Tachyglossus egg. One of thegreat challenges for zoos has been to understand why breeding of monotremes isdifficult to achieve. Analysis of breeding successes of platypuses andshort-beaked echidnas provides some insights. The evidence suggests thatalthough annual breeding seasons are regionally predictable, individual adultfemales breed unpredictably, with some showing breeding intervals of manyyears. The reason for this variation in individual breeding intervals may beresource-dependant, influenced by social factors or may even be geneticallyinduced. Better knowledge of factors that influence breeding intervals mayimprove the success of monotreme captive breeding programmes. More certaintyin captive breeding is also an important issue for enterprises wishing totrade in Australian wildlife since current legislation limits export ofAustralian fauna for display to at least second-generation captive-bredindividuals. Given their unique evolutionary position, knowledge ofreproduction in monotremes needs to be gained in advance of any futurepopulation declines so that appropriate strategies can be developed to ensuretheir survival.Extra keywords: breeding seasonality, comparativeanatomy, echidnas, platypus. |
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