Life history of the frog Crinia signifera in Tasmania, Australia
B. LauckSchool of Zoology, University of Tasmania, GPO Box 252-05, Hobart, Tas. 7001, Australia. Email: vlauck@postoffice.utas.edu.au
Australian Journal of Zoology 53(1) 21-27 https://doi.org/10.1071/ZO04028
Submitted: 13 April 2004 Accepted: 26 November 2004 Published: 24 February 2005
Abstract
A pitfall-trap study was used to investigate the importance of body size, age, body condition (males only), season and growth history as determinates of male and female life-history fitness traits in a population of the frog Crinia signifera. Specimens were dissected to determine physiological characteristics and skeletochronology was used to determine age. Females lived longer and attained a larger size than males by delaying sexual maturity. Most females and males attained sexual maturity after three and two years, respectively; although eggs were found in females as young as one year old. Body size (but not age) was the primary determinant of fecundity, total reproductive output (clutch mass) and oviduct mass for females. Season was the predominant influence on egg size, with smaller eggs produced in summer than in other seasons. Direct investment in male gonads (testes size) was determined by body size and also by age. This, and the fact that sexual size dimorphism in amphibians is commonly female biased, suggests that male size is not necessarily the primary determinant of male reproductive success in C. signifera. Whereas selection on reproductive traits in females is likely to act predominantly on body size, selection in males is also likely to act on survival.
Acknowledgments
I am especially grateful to the help given me by Dick Bashford from Forestry Tasmania, who provided the frog samples and without whom this study would not have been possible. Special acknowledgement must also go to Wayne Kelly at the School of Zoology for assistance with the skeletochronology. Thanks also to Roy Swain, Frank Lemckert and Dick Bashford who provided valuable comments on drafts of this manuscript. I was supported by an Australian Postgraduate Award.
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