Genome-wide analyses of the Bemisia tabaci species complex reveal contrasting patterns of admixture and complex demographic histories

Abstract

Once considered a single species, the whitefly, Bemisia tabaci, is a complex of numerous morphologically indistinguishable species. Within the last three decades, two of its members (MED and MEAM1) have become some of the world's most damaging agricultural pests invading countries across Europe, Africa, Asia and the Americas and affecting a vast range of agriculturally important food and fiber crops through both feeding-related damage and the transmission of numerous plant viruses. For some time now, researchers have relied on a single mitochondrial gene and/or a handful of nuclear markers to study this species complex. Here, we move beyond this by using 38,041 genome-wide Single Nucleotide Polymorphisms, and show that the two invasive members of the complex are closely related species with signatures of introgression with a third species (IO). Gene flow patterns were traced between contemporary invasive populations within MED and MEAM1 species and these were best explained by recent international trade. These findings have profound implications for delineating the B. tabaci species status and will impact quarantine measures and future management strategies of this global pest.

Minimum sample sizes for invasion genomics: Empirical investigation in an invasive whitefly

“…Genome‐wide high‐throughput techniques based on RADseq have been widely used in ascertaining the population genomics of invasive species (Elfekih et al, ; Resh et al, ; Yi et al, ). Nevertheless, the choice of the sample sizes for such studies is generally ad hoc, and related studies are still scarce (Hoban, Gaggiotti, & Bertorelle, ).…”

“…The population genetics of B. tabaci has been studied using multiple molecular marker methods such as microsatellite loci (Chu et al, , ) or RAD sequencing (Elfekih et al, ). For example, the population genetics of B. tabaci using the RAD sequencing method by Elfekih et al () did not attempt to evaluate the minimum sample size, in which the sample sizes ranged from two to nine individuals. Since B. tabaci is a species complex which includes numerous cryptic species (De Barro, ), the potential effects that the different cryptic taxa may have on the sample size should be explored further.…”

“…The population genetics of B. tabaci has been studied using multiple molecular marker methods such as microsatellite loci (Chu et al, 2011(Chu et al, , 2013 or RAD sequencing (Elfekih et al, 2018). TA B L E 2 The optimal sample sizes required for different genetic parameters limited to a small number of SNPs (3,000) and limited sampling space.…”

“…Genome-wide high-throughput techniques based on RADseq have been widely used in ascertaining the population genomics of invasive species (Elfekih et al, 2018;Resh et al, 2018;Yi et al, 2018).…”

Mitochondrial DNA genomes of five majorHelicoverpapest species from the Old and New Worlds (Lepidoptera: Noctuidae)

“…Confusion in the scientific literature, especially relating to visually similar organisms, can lead to substantial difficulty in formulating and developing management, trade, and economic policies. Furthermore, the availability of high‐throughput sequencing data is revealing that hybridization between so‐called species, is perhaps more common than was previously thought (Anderson et al, ; Anderson, Tay, McGaughran, Gordon, & Walsh, ; Elfekih et al, ).…”