Introduction
Population structure analyses using genetic data provide extensive
information about populations, including genetic distribution, genetic
diversity, gene flow, and selection. Furthermore, these analyses can be
used to evaluate relationships between secondary traits such as
phenotype, reproductive strategy, and symbiotic bacterial communities.
Among secondary traits, wing morph is the principal phenotype associated
with direct dispersal, distribution, and reproductive strategies in
insects (Roff, 1986). In ants, wings play a salient role in nuptial
flight, which determines dispersal and breeding success. However, the
wing is not a sine qua non in several species. Winglessness and
wing reduction in reproductive ants are widespread across all
subfamilies (Buschinger & Heinze, 1992; Heinze & Tsuji, 1995; Peeters,
1991; Peeters, 2012; Peeters & Ito, 2001; Tinaut & Heinze, 1992;
Villet, 1991).
Vollenhovia emeryi Wheeler (Hymenoptera: Myrmicinae) is a common
ant species endemic to East Asia; this species has invaded North America
(Kjar & Suman, 2007; Wetterer, Guenard, & Booher, 2015; Wright &
Kubik, 2011). It is polymorphic for normal long and aberrant short wing
length in queens. The two morphs are not thought to coexist in nature,
and colonies of the long-winged (L) morph are typically monogynous,
while short-winged (S) morph colonies are polygynous (Kinomura &
Yamauchi, 1994). Unlike other ant species and Hymenopteran insects in
general, queens and males are produced clonally, while sterile workers
arise sexually (Kobayashi, Hasegawa, & Ohkawara, 2008, 2011; Ohkawara,
Nakayama, Satoh, Trindl, & Heinze, 2006). This unusual clonal
reproduction system is very similar to the system first found in some
populations of the little fire ant Wasmannia auropunctata(Foucaud, Estoup, Loiseau, Rey, & Orivel, 2010; Foucaud et al., 2007;
Foucaud et al., 2006; Fournier et al., 2005) and in the highly invasive
longhorn crazy ant Paratrechina longicornis (Pearcy, Goodisman,
& Keller, 2011). Selfish clonal reproduction in both sexes might evolve
without allowing genetic contamination by the opposite sex, thereby
giving rise to genetically homogeneous clonal lineages. Such an unusual
reproductive system might be due to infection by a selfish reproductive
manipulator (Jeong & Stouthamer 2004).
The Wolbachia bacterium is a maternally-inherited endosymbiont
that infects a wide variety of invertebrates such as insects (including
ants) and other arthropods (Bourtzis, & Miller, 2008; Correa &
Ballard, 2016; Hilgenboecker, Hammerstein, Schlattmann, Telschow, &
Werren, 2008; Kautz, Rubin, Russell, & Moreau, 2013; Werren, 1997;
Zientz , Feldhaar, Stoll, & Gross, 2005; Zug, & Hammerstein, 2014).
Infection induces various types of reproductive alterations in the host,
including cytoplasmic incompatibility, feminization, male-killing, and
parthenogenesis (Fujii, Kubo, Ishikawa, & Sasaki, 2004; Jeong & Suh,
2008; Stouthamer, Breeuwer, & Hurst, 1999).
Despite the ecological and evolutionary importance of V. emeryiand Wolbachia , little is known about their distribution and
population biology. The specific aims of this study were to examine 1)
the population genetic structure of the mitochondrial genes of V.
emeryi ; 2) the phylogeographic relationships among the two winged
morphs from Korea and Japan; 3) the approximate divergence time of the
two winged morphs; 4) the ubiquity of Wolbachia infection in ant
species; and 5) potential relationships between host phenotype andWolbachia infection.