Shape and sound reveal genetic cohesion not speciation in the New Zealand orthopteran, Hemiandrus pallitarsis, despite high mitochondrial DNA divergence

Abstract

Levels of neutral mitochondrial (mt)DNA sequence diversity play a prominent role in alpha taxonomy, with divergence thresholds of approximately 3% widely being accepted as indicative of species differences. However, a number of studies of New Zealand invertebrates conclude that intraspecific mtDNA divergences are commonly much higher. We investigated the diversity and distribution of mitochondrial cytochrome oxidase I DNA sequences from populations of the New Zealand ground weta Hemiandrus pallitarsis with respect to variation among ten morphological characters and analysis of acoustic signalling associated with mate recognition. We looked for correlation between neutral mtDNA sequence variation and potential indicators of species differences. Despite high genetic distances (> 8.0% uncorrected) among mtDNA haplotypes in this species, morphological and male precopulation signals refute a hypothesis that multiple species exist. Other possible explanations for high genetic diversity, including accidental sampling of nuclear paralogues and elevated substitution rate, are not supported, whereas there is evidence for stable population size through time. We conclude that generalizations about genetic diversity and species status are overly simplistic. In some circumstances, notably southern hemisphere invertebrate taxa, species cohesion appears to have been retained throughout the Pleistocene, indicating the persistence of a relatively high population size.

A preliminary survey of altitudinal variation in two ground wētā species,Hemiandrus maculifrons(Walker) andHemiandrus pallitarsis(Walker) (Orthoptera: Anostostomatidae)

“…Male H. pallitarsis were the larger of the two taxa according to metafemur length (t = −2.48, P < 0.05). The sample size was too small to test sexual size dimorphism for H. maculifrons, but adult males are generally smaller than adult females in both species (Chappell et al 2012(Chappell et al , 2014. However, as a result of the difficulty of accurate identification in the field, the smaller H. maculifrons individuals measured may be late instars rather than adults.…”

“…The two species of interest in this study are both common and widespread: Hemiandrus pallitarsis (Walker, 1869) which occurs across most of the North Island, and Hemiandrus maculifrons (Walker, 1869) which is found in both the North and South Islands (Pratt et al 2008;Chappell et al 2012; although it is probably a species complex; B Taylor Smith, pers. comm.…”

Mitochondrial divergence suggests unexpected high species diversity in the opsariichthine fishes (Teleostei: Cyprinidae) and the revalidation of Opsariichthys macrolepis

“…Our phylogenetic relationships within the opsariichthine group were mostly concordant with previous studies (Huang, Wang, & Wang, ), and three main groups were found: the Candidia ‐ Parazacco ‐ Nipponocypris group with one longitudinal stripe on the flanks, the Zacco group with an indistinct vertical stripe or band on the side of the body, and the Opsariichthys group with several distinct vertical stripes or bands along its body. Earlier studies proposed that the levels of mitochondrial DNA sequence diversity play a prominent role in taxonomy, with divergence thresholds of approximately 3% widely being accepted as indicative of species differences (Chappell et al, ; Hebert et al, ; Johnston et al, ). The present results showed that, when a 3% genetic distance was used as a threshold for species delimitation, there were 35 haplogroups in the opsariichthine mitochondrial phylogeny, nine haplogroups in Candidia ‐ Parazacco ‐ Nipponocypris group, six haplogroups in the Zacco group, and 20 haplogroups in the Opsariichthys group, respectively.…”

New Zealand ground wētā (Anostostomatidae:Hemiandrus): descriptions of two species with notes on their biology

“…obs.). Some ecological research has been undertaken on Hemiandrus maculifrons (Walker, 1869) (Cary 1983), Hemiandrus subantarcticus (Salmon, 1950) (Butts 1983), Hemiandrus 'peninsularis'/'horomaka' (Wahid 1978) and Hemiandrus pallitarsis (Walker, 1869) (Gwynne 2002(Gwynne , 2004(Gwynne , 2005Chappell et al 2012).…”

“…Reduction in ovipositor length has therefore been inferred as having occurred at least three times in the New Zealand Hemiandrus (Pratt et al 2008). Of the seven putative species with extremely short ovipositors (Johns 2001), six are narrow endemics (Chappell et al 2012). Two species, Hemiandrus maia sp.…”