Data from: Niche differentiation and colonization of a novel environment by an asexual parasitic wasp.

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. Diachasma muliebre is an asexual Hymenopteran wasp that is
geographically and genetically isolated from all sexual relatives. D.
muliebre attack larvae of the western cherry fruit fly (Rhagoletis
indifferens), which in turn feed inside bitter cherry fruit (Prunus
emarginata) in August and September. R. indifferens has recently colonized
a new host plant with an earlier fruiting phenology (June/July),
domesticated sweet cherries (P. avium), and D. muliebre has followed its
host into this temporally earlier niche. We tested three hypotheses: 1)
that all D. muliebre lineages originate from a single asexual ancestor; 2)
that different D. muliebre 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 D. muliebre, 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 D. muliebre
is one of two lineages that have colonized the P. avium habitat,
consistent with the preferential colonization hypothesis. These data
suggest that D. muliebre 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 D. muliebre
system may allow for in-depth study of adaptation and long-term
persistence of asexual taxa.