Reproduction and life history in the red-tailed phascogale, Phascogale calura (Marsupialia: Dasyuridae): the adaptive-stress senescence hypothesis



A population of the red-tailed phascogale (Phascogale calura), a marsupial with a restricted distribution, was studied during a three-year period at a small reserve in the South-Westem Wheatbelt of Western Australia. This species shows a life-history pattern which is typical of many Antechinus species and is characterized by a synchronized winter mating period followed by a complete male post-mating mortality. Mating occurs during a three-week period in July. In the field, males live only 11.5 months while females may live up to 36 months. Females are monoestrous and polyovular and have eight teats which are usually all occupied by pouch young. The production of supernumerary young is common. Pregnant females become aggressive toward the males.

To explain the semelparous life history in this species, an adaptive-stress-senescence hypothesis is proposed. As males enter the mating period they make major physiological adjustments which are beneficial to the success of mating. However, there may be a longer-term cost, that of hormonally accelerated ageing and senescence, which is finally expressed in impairment of feedback control of adrenocortical function.