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The Influence of Male‐Defended Oviposition Sites on Early Embryo Mortality in Bullfrogs
Author(s) -
Howard Richard D.
Publication year - 1978
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938783
Subject(s) - biology , embryo , predation , ecology , rana , zoology , avian clutch size , reproduction , anatomy , fishery
Field studies were conducted on factor affecting embryo mortality in bullfrogs, Rana catesbeiana, in 1975 and 1976 at the E. S. George Reserve of the University of Michigan. Larger ♀ produced significantly larger clutches than smaller ♀ (6000 to >20,000). Older ♀ produced 2 clutches each year with 2nd clutches containing significantly fewer eggs than 1st clutches. Egg size appeared to be unrelated to ♀ size; however, 2nd clutches contained significantly smaller eggs than initial clutches for all ♀♀. Embryo mortality depended on ♀ choice of oviposition sites. Such sites were controlled by territorial ♂♂. Larger ♂ ♂ controlled oviposition sites that had significantly lower embryo mortality than the sites of smaller ♂ ♂. Sources of embryo mortality included developmental abnormalities and predation. Choice of oviposition sites included: (a) advance of areas with high water temperatures (>32 degrees C) that result in increased developmental abnormalities and (b) preference for areas that increase embryo survival by increasing developmental rate and/or decreasing efficiency of predation on embryos by the leech. Macrobdella decora.