Differences in Variation in Egg Size for Several Species of 



Salamanders (Amphibia: Caudata) That Use 



Different Larval Environments 



Christopher King Beachy 1 



Department of Biology, Western Carolina University, 



Cullowhee, North Carolina 28723 



ABSTRACT — Comparative descriptive data are provided on 

 variation of egg size in five species of salamanders. The species 

 differ in their use of larval habitats. Ambystoma maculatum uses 

 temporary, rain-filled pools in the southern Appalachian 

 Mountains. Desmognathus aeneus is a direct developer and is not 

 constrained by risk of larval desiccation. The remaining three 

 species, Eurycea wilderae, D. ochrophaeus, and D. santeetlah, have 

 permanent streams as their larval environment. Using the 

 coefficient of variation (CV), I document both variation within 

 individual clutches and variation at the interclutch level. The degree 

 of variation differs among individual clutches and among 

 species. Variation at the intraclutch level does not agree with 

 that predicted. However, variation at the interclutch level 

 conforms to the prediction that A. maculatum (which utilizes 

 ephemeral larval environments) exhibits the highest degree of 

 variation in egg size. 



In many populations of biphasic amphibians, the key factor 

 underlying the timing of metamorphosis and larval survivorship is 

 the time for which the larval environment remains hospitable. In a 

 permanent larval habitat, where mortality from desiccation is unlikely, 

 the larval period of an amphibian can be long. For example, 

 paedomorphic species of salamanders inhabit permanent bodies of 

 water. However, many species of amphibians inhabit larval 

 environments that are temporary and unpredictable, and desiccation 

 is a threat to species that use those bodies of water. Because 

 environmental pressure to escape the larval environment can vary 

 from year to year, species that breed in temporary pools may exhibit 

 different reproductive strategies than species that use permanent 

 bodies of water. 



Parental investment, one facet of the study of reproductive 

 strategies, has been the subject of theoretical and/or empirical studies 

 in amphibians (e.g., Wilbur 1977; Kaplan 1980, 1985; Crump 1981, 

 1984; Kaplan and Cooper 1984). These studies have documented the 



'Present address: Department of Biology, The University of Southwestern Louisiana, 

 P.O. Box 42451, Lafayette, LA 70504-2451. 



Brimleyana 18:71-82, June 1993 71 



