Life-history evolution of an invasive tephritid

Abstract

Natural selection and genetic drift may cause divergence in several life-history and behavioural traits among populations of cosmopolitan insect species that have evolved in allopatry. The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae) represents a unique model to address questions on the evolution of life history because of its (1) wide geographical distribution, (2) known invasion history and well studied population genetics, and (3) significance as an important model in demographic research. We summarize recent data of common garden experiments studying demographic and behavioural traits of medfly biotypes obtained from Greece, Portugal, Kenya, Brazil, Guatemala and Hawaii. These results reveal differences among the above populations in major demographic traits, such as longevity and reproduction schedule, and behavioural ones, such as male sexual signalling. In all biotypes and under constant laboratory conditions males outlived females. However, the gender gap in longevity differed a great deal among biotypes. Considering female longevity medfly biotypes obtained from Guatemala, Kenya and Hawaii are classified as short lived, and those from Greece, Portugal and Brazil as long lived. Nevertheless, taking into consideration male longevity, Kenyan and Hawaiian flies are grouped with Greek, Brazilian and Portuguese (long lived) and only Guatemalan males are classified as short lived. We also reviewed biological and behavioural data derived from wild medfly populations, and combined them with existing information on the Mediterranean fruit fly population genetics and global invasion history aiming at understanding shifts in demographic and behavioural traits in this important pest.