Gull-billed Tern
Gull-billed Tern (Gelochelidon nilotica) Science Article 1
abstract
Fisher (1930) predicted that natural selectionshould favour equal parental investmentin male and female offspring, and that populationsex ratios at the end of the period ofparental care should be inversely related to thecost of producing individuals of each sex if fitnessreturns from investment in sons and daughtersare similar. However, when the relationshipbetween fitness return and environmentalconditions differs between sexes, natural selectionwould favour facultative adjustmentsof offspring sex ratio in response to varyingenvironmental conditions at the time of breeding
A. VILLEGAS, J. M. SANCHEZ-GUZMAN, R. MORAN and C. CORBACHO, Ardeola, 52(2), December 2005, 341-343