Estimates of gene flow from rare alleles in natural populations of medfly Ceratitis capitata (Diptera: Tephritidae)

Abstract

Gene flow based on the spatial distribution of rare alleles at 25 gene loci was estimated in 15 populations of Ceratitis capitata (Wiedemann) from different parts of the world. Estimates of Nm, the number of migrants exchanged per generation among populations in different regions of the world, appeared to be quite similar, ranging from 3.36 in tropical Africa to 2.94 in the New World and 2.72 in Mediterranean basin populations. This suggests that gene flow among neighbouring populations of medfly is quite extensive. The genetic differentiation in American, Mediterranean and African populations was related to major climatic differences between North and South. These differences arise mainly from five loci that showed gene frequency patterns suggestive of latitudinal clines in allele frequencies. The clinal variation was such that tropical-subtropical populations were more heterozygous than temperate populations. It was concluded that gene flow, counteracting the forces of natural selection and genetic drift, determines the extent to which geographical populations of C. capitata are differentiated.

Unveiling biogeographical patterns in the worldwide distributed Ceratitis capitata (medfly) using population genomics and microbiome composition

“…The present study investigates the population history and microbiome of the Mediterranean fruit fly C. capitata on a global scale, using a reduced representation of the genome in combination with a microbial characterisation, of samples from key geographical locations. We find strong evidence for the existence of two genetic clusters corresponding to the South African individuals and the other localities in the introduced range respectively, in agreement with virtually all previous studies using allozymes (Gasperi et al, 1991, 2002; Kourti, 2004; Malacrida et al, 1992), mitochondrial DNA markers (Arias et al, 2018; Elfekih et al, 2010, 2013; Karsten et al, 2013; Ruiz‐Arce et al, 2020), and microsatellites (Bonizzoni et al, 2004; Bonizzoni et al, 2001; Deschepper et al, 2021; Karsten et al, 2015; Nikolouli et al, 2020). In addition, when we analysed the five sampling sites from the introduced range only (i.e., we removed the South African samples), populations from Brazil represented a unique genetic cluster that had not been recognized in previous studies.…”

Population Genetics of Ceratitis capitata in South Africa: Implications for Dispersal and Pest Management

“…However, recent studies have indicated that such methods may significantly under-estimate population size and migration (see e.g. [20], [21]). …”

“…Furthermore, an understanding of the population structure allows inferences about movement patterns and neighbourhood sizes (see e.g. [20], [26]–[31]). While it is clear that medfly can have population genetic structure on large geographic scales [3], [27], it is presently unknown at what spatial scale this pattern breaks down or in fact, whether the spatial patterns is dependent on climate or various environmental factors.…”

GENETIC DIVERSITY OF NATURAL POPULATIONS OF Bactrocera occipitalis (Bezzi) AND B. philippinensis Drew and Hancock (Diptera: Tephritidae) IN SELECTED MANGO PRODUCING AREAS IN THE PHILIPPINES USING MICROSATELLITES

“…The differences had been attributed to geographical isolation and barriers to gene flow (Li et al, 2007). Genetic diversity was also high at enzyme loci in populations of the Mediterranean fruit fly, Ceratitis capitata with average Fst values ranging from 0.108 to 0.283 (Kourti, 2004). The low Fst value (0.05) indicates considerable gene flow among the four populations.…”