Abstract
Data from a 12-year field study have allowed us to quantify 'costs of reproduction' in a natural population of water pythons (Liasis fuscus) in tropical Australia. Both sexes of pythons cease feeding during the reproductive season. For males, this involves fasting for a 6 week period. Adult males lose weight rapidly over this period (approximately 17% of their body mass) but regain condition in the following months, and do not experience reduced survival. In contrast, reproductive adult females cease feeding for 3 months, lose an average of 44% of their body mass over this period, and experience increased mortality. A causal link between reproductive output and reduced female survival is supported by (i) a decrease in survival rates at female maturation; (ii) a correlation between survival rates and frequency of reproduction, in a comparison among different size classes of adult pythons; and (iii) a lowered survival rate for females that allocated more energy to reproduction. Hence, both sexes experience substantial energy costs of reproduction, but a relatively higher energy cost translates into a survival cost only in females. Such non-linearities in the relationship between energy costs and survival costs may be widespread, and challenge the value of simple energy-based measures of 'reproductive effort'.
Original language | English |
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Pages (from-to) | 670-675 |
Number of pages | 6 |
Journal | Austral Ecology |
Volume | 25 |
Issue number | 6 |
DOIs | |
Publication status | Published - Dec 2000 |
Externally published | Yes |
Keywords
- Feeding
- Growth
- Liasis fuscus
- Life-history
- Reproductive effort
- Reptile
- Snake
- Survival