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Darwinian fitness in Drosophila. II. Quantification of total fitness in Drosophila prosaltans*
Cláudia Márcia Aparecida Carareto; Celso Abbade Mourão+
Departamento de Biologia, Instituto de Biociências, Letras e Ciências Exatas, UNESP, 15055 São José do Rio Preto, SP, Brasil. Send correspondence to C.M.A.C
+Decased
ABSTRACT
An evaluation was made of Darwinian fitness and the relative importance, for total fitness, of 23 fitness components, covering almost the entire lifespan of Drosophila prosaltans females. Three strains, from Brazil, Costa Rica and Trinidad Tobago were used. Total fitness was divided into four fractions (sexual activity, inseminated and uninseminated females activity and progeny) which were combined into two indices, W' and W", proposed as representative of total Darwinian fitness. The inseminated female and progeny fraction values, involving almost all the components related to productivity and viability, gave the highest W' and w" values for the Brazil strain when compared to the others. A striking heterogeneity of the strains was disclosed by an analysis of the hierarchical order of the relative importance of the components, which implies different adaptive strategies. Mating frequency, duration of the pre-copula, time to first copula, longevity, number of eggs (total and daily), pupae and imagines, and duration of pupation and of imaginal emergence period had different degrees of importance in each strain, suggesting a prominent role of these components for the total fitness. The methods employed to study the complex problem of estimating Darwinian fitness (W' and w") and for the relative importance of its fractions or components were shown to be proper and sensible for these purposes and for detecting infra and interstrain variability.
Keywords: Darwinian fitness; Drosophila prosaltans.
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* Part of a thesis presented by C.M.A.C. to Instituto de Biociências, Letras e Ciências Exatas - UNESP.