Geographic variation and thermal adaptation in Bicyclus anynana

This thesis investigates mechanisms of adaptation to climate, and in particular temperature, in the African butterfly Bicyclus anynana. The work takes an integrated approach and brings together studies at the phenotypic, physiological and genetic level. By examining geographical variation among wild populations, the thesis investigates how B. anynana is adapted to geographically varying thermal conditions. The first half of the thesis is focused on phenotypic plasticity, which is a major component of adaptation to climate in B. anynana. Chapter 2 compares the plasticity response to temperature of two populations, and reveals a population-specific response for wing pattern but very small to no differences in the response of life history traits. Chapter 3 shows that a discontinuous regulatory hormone signal during development underlies the seasonal plasticity in B. anynana. In the second half of the thesis, I take a molecular genetic approach by studying geographic patterns of neutral and adaptive evolution in wild populations. Chapter 4 indicates that the B. anynana species area expanded southwards after the last ice age from glacial equatorial habitat refugia. Chapter 5 identifies clinal variation in genes coding for metabolic enzymes, indicating a putative role of these genes in thermal adaptation.UBL - phd migration 201