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GENETIC AND ENVIRONMENTAL BASIS OF VARIABLE SEX RATIOS IN LABORATORY STRAINS OF POECILIOPSIS LUCIDA
Author(s) -
Sullivan Judy A.,
Schultz R. Jack
Publication year - 1986
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.1986.tb05726.x
Subject(s) - biology , sex ratio , offspring , strain (injury) , zoology , ecology , genetics , demography , pregnancy , population , anatomy , sociology
Skewed sex ratios are common among several species of Poeciliopsis , a viviparous fish from northwestern Mexico. Since previous, unrelated studies from this laboratory (Angus and Schultz, 1983) suggested that deviation from a 1:1 sex ratio might be influenced by temperature, two inbred strains of P. lucida were tested for temperature‐dependent sex determination by comparing sex ratios of offspring from pregnant females held at different water temperatures. Different sex ratios were produced by the two strains at the same temperature: one strain produced almost all‐male offspring at 30°C and female‐biased sex ratios at 24°C, while the other strain produced a 1:1 sex ratio at both temperatures. At intermediate temperatures, the labile strain produced sequentially fewer males with decreasing temperatures. The other strain produced a consistent sex ratio regardless of temperature. Poeciliopsis lucida apparently has a genetic polymorphism for temperature‐influenced sex determination. An hypothesis is offered for the evolutionary origin of environmental sex determination.