Niche differentiation and colonization of a novel environment by an asexual parasitic wasp. (20th March 2013)

• Record Type: Journal Article
• Authors: Forbes, A. A.; Rice, L. A.; Stewart, N. B.; Yee, W. L.; Neiman, M.
• Is Part Of: Journal of evolutionary biology. Volume 26:Number 6(2013:Jun.)
• Page Start: 1330
• Page End: 1340
• Publication Date: 2013-03-20
• Subjects: Evolution (Biology) -- Periodicals; Biology -- Periodicals; 576.8
• DOI: 10.1111/jeb.12135
• Languages: English
• ISSNs: 1010-061X

Abstract

<abstract abstract-type="main" xml:lang="en" id="jeb12135-abs-0001"> <title>Abstract</title> <p>How do asexual taxa become adapted to a diversity of environments, and how do they persist despite changing environmental conditions? These questions are linked by their mutual focus on the relationship between genetic variation, which is often limited in asexuals, and the ability to respond to environmental variation. Asexual taxa originating from a single ancestor present a unique opportunity to assess rates of phenotypic and genetic change when access to new genetic variation is limited to mutation. <italic>Diachasma muliebre</italic> is an asexual Hymenopteran wasp that is geographically and genetically isolated from all sexual relatives. <italic>D. muliebre</italic> attack larvae of the western cherry fruit fly (<italic>Rhagoletis indifferens</italic>), which in turn feed inside bitter cherry fruit (<italic>Prunus emarginata</italic>) in August and September. <italic>R. indifferens</italic> has recently colonized a new host plant with an earlier fruiting phenology (June/July), domesticated sweet cherries (<italic>P. avium</italic>), and <italic>D. muliebre</italic> has followed its host into this temporally earlier niche. We tested three hypotheses: 1) that all <italic>D. muliebre</italic> lineages originate from a single asexual ancestor; 2) that different <italic>D. muliebre</italic> lineages (as defined by unique mtDNA haplotypes) have differentiated on their ancestral host in an important life‐history trait, eclosion timing; and 3) that early‐eclosing lineages have preferentially colonized the new sweet cherry niche. We find that mitochondrial COI and microsatellite data provide strong support for a single ancestral origin for all lineages. Furthermore, COI sequencing revealed five mitochondrial haplotypes among <italic>D. muliebre</italic>, and individual wasps possessing one distinctive mitochondrial haplotype (haplotype II) eclosed as reproductive adults significantly earlier than wasps with all other haplotypes. In addition, this early‐eclosing lineage of <italic>D. muliebre</italic> is one of two lineages that have colonized the <italic>P. avium</italic> habitat, consistent with the preferential colonization hypothesis. These data suggest that <italic>D. muliebre</italic> has evolved adaptive phenotypic variation despite limited genetic variation, and that this variation has subsequently allowed an expansion of some wasps into a novel habitat. The <italic>D. muliebre</italic> system may allow for in‐depth study of adaptation and long‐term persistence of asexual taxa.</p> </abstract>