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Accueil du site → Doctorat → Australie → 1995 → Female reproductive success and maternal investment in the euro (Macropus robustus erubescens) in the arid zone

University of New South Wales (1995)

Female reproductive success and maternal investment in the euro (Macropus robustus erubescens) in the arid zone

Ashworth, Deborah Lynne

Titre : Female reproductive success and maternal investment in the euro (Macropus robustus erubescens) in the arid zone

Auteur : Ashworth, Deborah Lynne.

Université de soutenance : University of New South Wales

Grade : Doctor of Philosophy (Ph. D.) 1995.

Résumé
Female reproductive success and maternal investment were investigated in free-ranging euros (Macropus robustus erubescens) in arid New South Wales. Female reproductive success was profoundly affected by temporal changes in grass abundance, which affected survival to reproductive age, fecundity, offspring survival and reproductive life span. The life history strategy of female euros in this environment appears to emphasize adult survival to bridge poor environmental conditions and increase the number of opportunities to breed in good environmental conditions. During good environmental conditions females commenced breeding when under 2.5 years old, then bred continuously. Offspring mortality was high even in good conditions, with most young lost around permanent pouch emergence. Spatial differences in habitat quality contributed to variability in female reproductive success with greater reproductive success associated with steeper, more rugged home ranges with more grasses and forbs. Sociality was correlated with habitat and did not explain an independent proportion of the variability in female reproductive success. The lifetime reproductive success (number of young reared to weaning) of females who survived to breed was estimated to range from 3.4-17 with a mean of 11.7. These values were considered to be unrealistically high as they did not account for drought episodes or maternal age. An empirical model is presented to predict long-term female euro lifetime reproductive success accounting for these factors. Females appeared to be investing in young in an adaptive manner according to their age, their ability to expend resources on their young, and the sex of the young. Overall investment in male and female offspring is likely to be equivalent in the long-term as population pouch young sex ratios were mostly close to parity. However, females appeared to invest more heavily in male young prior to weaning, and to produce male young preferentially when they were in better than avenge physical condition and at the end of their lives. Most male young dispersed before 2.5 years of age whereas most female young were philopatric, continuing to associate with their mothers after they were mature. No evidence was found that female young may incur long-term costs as a result of local resource competition.

Présentation (National Library of Australia)

Accès au document : Proquest Dissertations & Theses

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