Hinckley: Egg size variation of Theragrs chalcogramma 



481 



ators, however, small changes (10-20%) in egg diam- 

 eter may affect their ability to handle or consume eggs. 

 Also, if the abundance of egg predators increases, or 

 they co-occur more frequently with eggs, then smaller 

 but more numerous eggs (assuming a tradeoff between 

 egg size and fecundity; Svardson 1949, Bagenal 1978) 

 may be an adaptation to offset higher rates of preda- 

 tion later in the season. 



Miller et al. (1988) have shown that predation rates 

 are negatively correlated with larval size, possibly due 

 to differences in predator mouth size, encounter rates 

 of larvae and their predators, or the ability of larvae 

 to escape predators. Trends in egg size and the result- 

 ing differences in larval size at hatch may, therefore, 

 also be an adaptation to relieve predation on larvae, 

 if the size, species composition, and co-occurrence of 

 predators and larvae changes seasonally. 



Acknowledgments 



I wish to thank Annette Brown for her assistance in 

 the laboratory, Susan Picquelle for her advice on 

 statistical analysis and on the manuscript, and Drs. 

 Kevin Bailey and Arthur Kendall for their advice on 

 the manuscript and for general support. 



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