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MATERNAL AND ENVIRONMENTAL GRADIENTS IN THE EGG SIZE OF AN ITEROPAROUS FISH
Author(s) -
Johnston Thomas A.,
Leggett W. C.
Publication year - 2002
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2002)083[1777:maegit]2.0.co;2
Subject(s) - fecundity , biology , semelparity and iteroparity , offspring , juvenile , population , ecology , maternal effect , population size , latitude , zoology , reproduction , demography , geography , pregnancy , genetics , geodesy , sociology
Life history theory predicts that organisms inhabiting environments with relatively poor conditions for the growth and survival of their offspring should produce fewer and larger offspring. We examined egg size (an index of offspring size) of an iteroparous, broadcast‐spawning, freshwater fish—the walleye ( Stizostedion vitreum )—from 34 populations across 26° of latitude in order to determine whether egg size varied with respect to environmental indices of juvenile habitat quality. Variation among populations (among environments) was compared to variation within populations (among females). Within populations, egg size generally increased with maternal size and age. Slopes of these relationships were much more variable among populations ( cv > 100%) than interannually within populations ( cv < 50%). Egg size vs. female size/age correlations were stronger in populations closer to the northern and southern limits of the walleye range. Egg size was also related to maternal growth history, but the effects of recent growth (previous year) were inconsistent. Egg size varied much less than fecundity among females of the same population. For a standard size/age of female, predicted egg size was more variable among populations ( cv > 10%) than interannually within populations ( cv < 5%), but only slightly more variable than among females within populations (mean cv = 8.5%). Nevertheless, among‐population variability in egg size was related to environmental conditions. Mean egg size decreased with increasing latitude/decreasing mean annual temperature, contrary to our predictions. However, as predicted, egg size decreased with increasing lake productivity following adjustment for the latitudinal/temperature effect. These results suggest that egg size in fishes may be influenced by multiple environmental factors across populations, as well as by maternal effects within populations.