Abstract
An unprecedented global transfer of agricultural resources followed the discovery of the New World; one consequence of this process was that staple food plants of Neotropical origin, such as the common bean (Phaseolus vulgaris), soon expanded their ranges overseas. Yet many pests and diseases were also transported. Acanthoscelides obtectus is a cosmopolitan seed predator associated with P. vulgaris. Codispersal within the host seed seems to be an important determinant of the ability of A. obtectus to expand its range over long distances. We examined the phylogeographic structure of A. obtectus by (a) sampling three mitochondrial gene sequences (12s rRNA, 16s rRNA, and the gene that encodes cytochrome c oxidase subunit I (COI)) throughout most of the species’ range and (b) exploring its late evolutionary history. Our findings indicate a Mesoamerican origin for the current genealogical lineages of A. obtectus. Each of the two major centers of genetic diversity of P. vulgaris (the Andes and Mesoamerica) contains a highly differentiated lineage of the bean beetle. Brazil has two additional, closely related lineages, both of which predate the Andean lineage and have the Mesoamerican lineage as their ancestor. The cosmopolitan distribution of A. obtectus has resulted from recent expansions of the two Brazilian lineages. We present additional evidence for both pre-Columbian and post-Columbian range expansions as likely events that shaped the current distribution of A. obtectus worldwide.
Highlights
A significant global transfer of agriculturally valuable germplasm resources, referred to as the Columbian Exchange, occurred after the discovery of the New World [1]
Seven sequences from Mesoamerica (MAL_2, SJS_1, SJS_3, SPT_2, SPT_3, TLA_2, and YAU_1) were highly divergent. These seven sequences displayed several synonymous and several non-synonymous substitutions, ranging from five to 19. Five out of these seven sequences were obtained from bruchids that had been sampled from wild populations of P. vulgaris in Mesoamerica [10,11]
Given that none of the seven sequences contained either indels or in-frame stop codons and were obtained mostly from A. obtectus captured on wild P. vulgaris, we did not declare them as numts; rather, we considered them to be naturally occurring polymorphisms of the cytochrome oxidase subunit I (COI) gene of A. obtectus
Summary
A significant global transfer of agriculturally valuable germplasm resources, referred to as the Columbian Exchange, occurred after the discovery of the New World [1]. One staple food plant of Neotropical origin that was included in the Columbian Exchange was the common bean (Phaseolus vulgaris L.), which left the Americas and reached Europe in 1506 [2]. Two major gene pools are recognized: one in Mesoamerica and the other in the Andes [3,4]. A number of contrasting morphological, biochemical, and genetic traits, including partial reproductive isolation, set the Mesoamerican lineage apart from the Andean lineage of P. vulgaris [4,5] and suggest that, to a certain degree, these two major genealogical lineages evolved allopatrically under genetic isolation [6]. It has been proposed that either the Andes [7] or Mesoamerica [6] alone were the likely site of the origin of P. vulgaris
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
