Study of COI sequences from endemic New Zealand aphids highlights high mitochondrial DNA diversity in Rhopalosiphina (Hemiptera: Aphididae)

Focussed searches were made across New Zealand between 2013 and 2016, for endemic aphids from the Schizaphis (Rhopalosiphina) genus, which is currently represented by two putative, undescribed species from the endemic host plants Aciphylla and Dracophyllum. Cytochrome c oxidase I (COI) gene sequences (48 in total) from the Schizaphis were analysed together with those from a broader collection of New Zealand endemic aphids that has been assembled since the year 2000. The bulk of the Schizaphis belonged to two clusters corresponding to the host plant genera. Two aphids from central North Island Dracophyllum represented a much diverged lineage without clear affiliations to other New Zealand Schizaphis. Inter-population variation in the New Zealand Schizaphis was high compared with that seen in international studies of Aphidinae and among populations of other endemic New Zealand Aphidina. Within Schizaphis from Dracophyllum, geography played an apparent role in genetic structuring, with populations from Taranaki (North Island) and especially Mt Lyford (South Island) being divergent from those on the South Island main divide. Two distinct lineages of Schizaphis, which co-occurred at some sites, were found on Aciphylla. Our sequence comparisons, including GMYC analyses, indicated up to five New Zealand Schizaphis lineages, and two newly discovered endemic Aphis species from the host plants Clematis and Hebe.     

Phylogeography and ecological niche modelling of the New Zealand stick insect Clitarchus hookeri (White) support survival in multiple coastal refugia

Aim Increasing our understanding of the effects of the Last Glacial Maximum (LGM) and determining the location of refugia requires studies on widely distributed species with dense sampling of populations. We have reconstructed the biogeographic history of Clitarchus hookeri (White), a widespread species of New Zealand stick insect that exhibits geographic parthenogenesis, using phylogeographic analysis and ecological niche modelling. Location New Zealand. Methods We used DNA sequence data from the mitochondrial cytochrome c oxidase subunit I gene to reconstruct phylogenetic relationships among haplotypes from C. hookeri and two undescribed Clitarchus species. We also used distribution data from our own field surveys and museum records to reconstruct the geographic distribution of C. hookeri during the present and the LGM, using ecological niche modelling. Results The ecological niche models showed that the geographic distribution of C. hookeri has expanded dramatically since the LGM. Our model predicted large areas of suitable LGM habitat in upper North Island, and small patches along the east coast of South Island. The phylogeographic analysis shows that populations in the northern half of North Island contain much higher levels of genetic variation than those from southern North Island and South Island, and is congruent with the ecological niche model. The distribution of bisexual populations is also non-random, with males completely absent from South Island and very rare in southern North Island. Main conclusions During the LGM C. hookeri was most likely restricted to several refugia in upper North Island and one or more smaller refugia along the east coast of South Island. The unisexual populations predominate in post-glacial landscapes and are clearly favoured in the recolonization of such areas. Our study exemplifies the utility of integrating ecological niche modelling and phylogeographic analysis.     

Description of Eucalyptodiplosis chionochloae sp. nov., a cecidomyiid feeding on inflorescences of Chionochloa (Poaceae) in New Zealand

Abstract

A cecidomyiid that feeds on developing seeds in the inflorescences of the New Zealand tussock grasses Chionochloa australis, C. conspicua, C. crassiuscula, C.flavescens, C. macra, C. oreophila, C. pallens, C. rigida, C. rubra, C. spiralis and C. teretifolia is formally described from C. pallens. The new species, named Eucalyptodiplosis chionochloae Kolesik, is the most ubiquitous of flower feeders of Chionochloa. Its larvae do not form galls but feed on the developing seeds in autumn, overwinter as diapausing larvae inside the floret, and pupate then rapidly eclose in summer, sometimes after extended diapause. Methods for rearing adults are described. Based on its morphological characters this species is most closely related to two described congeners that form galls on buds of Eucalyptus trees in Australia. Seed predation by Eucalyptodiplosis chionochloae larvae appears to be the primary driver of the extreme mast seeding (variation among years in flower crops) seen in the host Chionochloa species.     

Geographic biotype and host-associated local adaptation in a polyphagous species, Lambdina fiscellaria (Lepidoptera: Geometridae) feeding on balsam fir on Anticosti Island, Canada

The debate about mechanisms underlying the evolution of host specialization by herbivorous insects remains open. Natural selection may act locally and lead to different patterns of geographic variation in life history traits of polyphagous herbivores. The hypothesis of genetically-based trade-offs in offspring performance on different hosts has been proposed but this has rarely been demonstrated. Under laboratory conditions, the biological performance of two populations of the hemlock looper Lambdina fiscellaria (Guenée), a highly polyphagous lepidopteran, was compared when reared on three different tree host species: balsam fir, eastern hemlock and sugar maple. One population originated from Anticosti Island, Québec, Canada, where the insect has evolved without having access to two of the three tree species tested, the other being from the mainland where all tree species are present. When reared on balsam fir foliage, which was naturally available to each population, larvae from Anticosti Island underwent four instars compared with five for the mainland population, indicating the existence of geographic biotypes in L. fiscellaria. When reared on the foliage of non-naturally available host trees, larvae from Anticosti Island had a higher incidence of supernumerary instars. This is a unique example where local adaptation to environmental conditions of an insect herbivore is expressed through a differential number of larval instars. Moreover, the Anticosti Island population showed a higher growth related index on the host available to both populations indicating that a fitness trade-off was the evolutionary process underlying the local adaptation of this population on balsam fir.     

Identifying glacial refugia in a geographic parthenogen using palaeoclimate modelling and phylogeography: the New Zealand stick insect Argosarchus horridus (White)

We have used phylogeographic analysis of mitochondrial DNA (COI and COII genes) and ecological niche modelling (ENM) to reconstruct the population history of Argosarchus horridus (White), a widespread species of New Zealand stick insect. These data were used to address outstanding questions on the role of glacial refugia in determining the distribution and genetic structure of New Zealand species. Phylogeographic analysis shows a general pattern of high diversity in upper North Island and reduced diversity in lower North Island and South Island. The ENM indicates that during the last glacial maximum, A. horridus was largely restricted to refugia around coastal areas of North Island. The ENM also suggests refugia on the northeast coast of South Island and southeast coast of North Island and this prediction is verified by phylogeographic analysis, which shows a clade restricted to this region. Argosarchus horridus is also most likely a geographic parthenogen where males are much rarer at higher latitudes. The higher levels of genetic variation in northern, bisexual populations suggest southern and largely unisexual populations originated from southwardly expanding parthenogenetic lineages. Bayesian skyline analysis also provides support for a recent population size increase consistent with a large increase in geographic distribution in the late Pleistocene. These results exemplify the utility of integrating ENM and phylogeographic analysis in testing hypotheses on the origin of geographic parthenogenesis and effects of Pleistocene environmental change on biodiversity.     

Extensive genetic differentiation in Gobiomorphus breviceps from New Zealand

Partial mitochondrial DNA sequences for parts of the cytochrome b gene and control region were obtained for 89 upland bullies Gobiomorphus breviceps from 19 catchments in New Zealand. There were two highly distinctive mtDNA clades: a northern clade corresponding to the North Island, northern South Island and west coast South Island, and a south‐east clade, in the southern and eastern South Island. Within these major clades there were further distinct clades that correlated with geographic sub‐regions and catchments. The marked genetic differentiation has occurred in the absence of obvious morphological divergence. Based on cytochrome b sequence divergences and the molecular clock hypothesis, the northern and southeastern clades correspond with the uplift of the Southern Alps during the Pliocene, while populations in the North Island and northern South Island were estimated to have diverged during the Pleistocene. The widescale geographic divergences were similar to those observed in the galaxiids, Galaxias vulgaris and Galaxias divergens , but biogeographic management boundaries may not be the same, reflecting different evolutionary histories for non‐diadromous species occupying the same areas.     

Global biodiversity of Scorpionflies and Hangingflies (Mecoptera) in freshwater

Seven species and one sub-species of Mecoptera are aquatic as larvae and pupae. All aquatic species are classified in two genera of the family Nannochoristidae and have very restricted geographic ranges, with three species confined to extreme southern South America, three species and one sub-species confined to New South Wales or Tasmania in Australia, and one species confined to the South Island of New Zealand. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Contrasting patterns of population structure and demographic history in cryptic species of Bostrychia intricata (Rhodomelaceae,Rhodophyta) from New Zealand

Spatial patterns of genetic diversity provide insight into the demography and history of species. Morphologically similar but genetically distinct “cryptic” species are increasingly being recognized in marine organisms through molecular analyses. Such species are, on closer inspection, often discovered to display contrasting life histories or occasionally minor morphological differences; molecular tools can thus be useful indicators of diversity. Bostrychia intricata, a marine red alga, is widely distributed throughout the Southern Hemisphere and comprises many cryptic species. We used mitochondrial cytochrome c oxidase I gene sequences to assess the genetic variation, population genetic structure, and demographic history of B. intricata in New Zealand. Our results supported the existence of three cryptic species of B. intricata (N2, N4, and N5) in New Zealand. Cryptic species N4, which was found throughout New Zealand, showed a higher genetic diversity and wider distribution than the other two species, which were only found in the North Island and northern South Island. Our analyses showed low to moderate genetic differentiation among eastern North Island populations for cryptic species N2, but high differentiation among North and South Island populations for N4, suggesting different population structure between these cryptic species. Data also indicated that N2 has recently undergone population expansion, probably since the Last Glacial Maximum (LGM), while the higher genetic diversity in N4 populations suggests persistence in situ through the LGM. The contrasting population structures and inferred demographic histories of these species highlight that life history can vary greatly even among morphologically indistinguishable taxa.     

Molecular biogeography and host relations of a parasitoid fly

Successful geographic range expansion by parasites and parasitoids may also require host range expansion. Thus, the evolutionary advantages of host specialization may trade off against the ability to exploit new host species encountered in new geographic regions. Here, we use molecular techniques and confirmed host records to examine biogeography, population divergence, and host flexibility of the parasitoid fly, Ormia ochracea (Bigot). Gravid females of this fly find their cricket hosts acoustically by eavesdropping on male cricket calling songs; these songs vary greatly among the known host species of crickets. Using both nuclear and mitochondrial genetic markers, we (a) describe the geographical distribution and subdivision of genetic variation in O. ochracea from across the continental United States, the Mexican states of Sonora and Oaxaca, and populations introduced to Hawaii; (b) demonstrate that the distribution of genetic variation among fly populations is consistent with a single widespread species with regional host specialization, rather than locally differentiated cryptic species; (c) identify the more‐probable source populations for the flies introduced to the Hawaiian islands; (d) examine genetic variation and substructure within Hawaii; (e) show that among‐population geographic, genetic, and host song distances are all correlated; and (f) discuss specialization and lability in host‐finding behavior in light of the diversity of cricket songs serving as host cues in different geographically separate populations.     

Intraspecific Variation in the Epicuticular Wax Composition of Four Species of Chionochloa

Intraspecific variation in four New Zealand species of Chionochloa, C. flavescens, C. pallens, C. rigida; and C. rubra, was investigated by examining the major carbon chain lengths of fatty acids, alcohols, aldehydes, wax esters and alkanes of the epicuticular waxes. The major even-carbon chain lengths ranged generally from C₂₄ to C₃₂ in the acids, alcohols and aldehydes; C₂₉ to C₃₃ in the alkanes; and even-carbon chains between C₃₆ and C₅₂ in the wax esters. A computer program was used to calculate the degree of similarity between samples in terms of chain length distribution. In C. rigida eastern and western South Island localities were identified; in C. flavescens Canterbury and Nelson, western South Island and southern North Island regions were recognized; and C. pallens and C. rubra were divisible into four regions; Canterbury, Nelson, western South Island and southern North Island. The possible elongation-decarboxylation pathways and the specificity of the enzymes in the biosynthetic pathways of epicuticular wax synthesis suggest the possibility that the northwest Nelson region could be a biogenetic centre from which wax synthesis has diversified along three routes, one to the western South Island, another to eastern South Island and the third to southern North Island. Identification of each of the four species based on the distribution of the carbon chain lengths in the individual lipid fractions is impossible unless the locality of collection is known. Intraspecific variation in lipid composition is not coincident with patterns of variation already reported.     

Phylogeography reveals a North Island range extension for New Zealand's only sexually wing-dimorphic stonefly (Stenoperla helsoni)

Stenoperla helsoni is an endemic New Zealand stonefly characterised by distinctive sexually dimorphic wing loss. Previous distribution records indicated that this species was restricted to the South Island's Southern Alps, although our recent collections of wing-reduced specimens from a site in the Tararua Ranges suggest that this species may extend into the lower North Island. We amplified the mitochondrial COI gene to confirm the identity of North Island specimens, and to assess phylogeographic structuring within the species and genus. North Island specimens were confirmed as S. helsoni, indicating that this species has a much wider geographic range than previously thought. This broad distribution, combined with low levels of intraspecific divergence, suggests that female S. helsoni may be strong fliers, despite males being flightless. Distinct North Island and South Island populations were identified, with a 1.5% divergence between the two populations.     

Phylogeography of the New Zealand blue duck (<Emphasis Type="Italic">Hymenolaimus malacorhynchos</Emphasis>): implications for translocation and species recovery

Translocation of individuals among extant populations is an important tool in species conservation that allows managers to supplement dwindling populations and potentially alleviate the deleterious effects of inbreeding. Ideal translocation strategy should consider historical relationships among existing populations to avoid potential disruption of population subdivision and local adaptation. Here, we examine mitochondrial sequence variation in the endangered blue duck Hymenolaimus malacorhynchos, a New Zealand endemic riverine specialist, to facilitate informed decision making in future translocations. Behavioural observations suggest that blue duck dispersal is limited and may result in genetic structure within and between regional populations. We analysed 894 base pairs of mitochondrial control region in 78 adult blue ducks sampled from 11 river catchments across the species’ range (representing four regions in the North Island and three regions in the South Island) and found strong and significant genetic structure both within and among islands. These results, combined with a 2.0% sequence divergence between islands, indicates that North Island and South Island blue ducks should be treated as separate management units. The relationship between genetic differentiation and geographic distance for blue ducks on the South Island conformed to an “isolation by distance” pattern. Overall, we recommend that translocations of blue ducks should not be made between the North and the South Islands and those within each island should be restricted to neighbouring catchments.     

Oviposition by introduced Ophelimus eucalypti (Hymenoptera: Eulophidae) and morphogenesis of female-induced galls on Eucalyptus saligna(Myrtaceae) in New Zealand

An Australian gall-inducing eulophid, Ophelimus eucalypti (Gahan) was first recorded on the foliage of Eucalyptus botryoides after it invaded New Zealand in 1987. It has spread throughout the eucalypt plantations in the North Island and in the northern parts of the South Island affecting several species of Eucalyptus in the section Transversaria (subgenus Symphyomyrtus). Because gall-inducing insects usually have extremely narrow host ranges, O. eucalypti that induces galls on E. saligna and E. botryoides is currently recognized as a biotype, O. eucalypti(Transversaria). Heavily galled leaves abscise from the plant. Repeated defoliation led to widespread die-back of susceptible eucalypt species in the 1990s. Female larvae of O. eucalypti induce circular, protruding galls on the leaves of E. botryoides and E. saligna, whereas the males induce pit galls on the same species. The biology of O. eucalypti females and the development of their galls are described. Adult female O. eucalypti antennate the leaf surface before inserting the ovipositor (otherwise concealed within the metasomal apex) into the young host leaf. The egg is inserted at approximately 45 degrees and discharged between differentiating palisade cells. Callus-type cells surround the egg chamber, but cytologically specialized nutritive cells appear once the egg hatches and the larva begins to feed. The gall also differentiates a multi-layered sclerenchymatous tissue around the nutritive tissue. After feeding for many months, the larva pupates and the active nutritive tissue degenerates. The adult wasp emerges after cutting an exit hole through to the outside of the gall. Abscission of heavily galled leaves results in widespread defoliation and loss of growth and vigour in susceptible trees in New Zealand.     

Geographic variation in sterilizing parasite species and the Red Queen

The Red Queen hypothesis predicts that sexual reproduction should be favoured in locations where the risk of infection by virulent parasites is consistently high. When hosts are exposed to multiple parasites over their geographic range, the coevolving parasite species may vary among host populations. We surveyed 26 streams on the South Island of New Zealand to determine whether the frequency of snails ( Potamopyrgus antipodarum ) infected by various sterilizing trematode parasite species was correlated with the frequency of sexual individuals. We compared the results with a survey conducted over 20 years ago to determine whether the associations were consistent. We also evaluated different measures of parasite-mediated selection among populations, including prevalence of the most common local parasite (MCLP) species and parasite diversity to assess the best predictor of sexual reproduction among stream populations. The results showed that the relationship between male frequency and parasite infection is more geographically widespread than previously recorded. Additionally, we found that the prevalence of the MCLP was the best predictor of sex in habitats where hosts populations are infected with multiple parasites (approximately 15 trematode species). This study provides evidence that sexual snails occur more often in environments with high infection levels, and that the pattern of parasite-imposed selection is geographically variable. Support for the Red Queen may be strengthened by focussing on the MCLP, which may vary among host populations.     

Genetic divergence of three freshwater isopod species from southern New Zealand

Aim We examined the biogeography of three freshwater isopod species (Austridotea annectens, A. lacustris, A. benhami), and tested the hypotheses that genetic differences would: (1) exist between geographic locations; and (2) correspond to known geological events (e.g. appearance of islands leading to the availability of habitat). Location Southern New Zealand, including South Island, Stewart Island, Campbell Island and Chatham Islands. Methods We examined specimens throughout the known species range from 12 populations of A. lacustris, five populations of A. annectens, and three populations of A. benhami, using mitochondrial DNA (cytochrome c oxidase I) sequence analyses. Results We resolved three main clades corresponding to the three species, with 16% sequence divergence between A. annectens and A. benhami, and 31% divergence between these species and A. lacustris. Divergence within A. benhami was < 2.0%. However, divergence within A. lacustris reached up to 10% with four main groupings: (1) Chatham Islands; (2) Campbell Island; (3) Fiordland; and (4) east coast South Island and Stewart Island. Divergence within A. annectens reached up to 4.4%, with two main groupings: (1) Chatham Islands and (2) east coast South Island and Stewart Island. Patterns of genetic divergence were most likely the result of geographical isolation among A. lacustris and A. annectens populations. In particular, the divergence of A. lacustris and A. annectens on Chatham Islands may correspond to the availability of this habitat c. 4 Ma, whereas the divergence of A. lacustris on the much older Campbell Island and in Fiordland may indicate either a rare founder event or a change in ocean circulation that resulted in their isolation from a once more widespread gene pool. Main conclusions The three New Zealand species of Austridotea are genetically distinct, with up to 31% divergence between species. Genetic variability was highest between populations of the two most widely distributed species, and divergence was greatest on islands distant from mainland New Zealand and in the discrete Fiordland region. The magnitude of genetic divergence of isopods on the Auckland and Chatham Islands is consistent with these populations having been founded in the Pliocene via oceanic dispersal from mainland New Zealand.     

Crossing the Tasman Sea: Inferring the introduction history of Litoria aurea and Litoria raniformis (Anura: Hylidae) from Australia into New Zealand

Abstract The amphibian fauna of New Zealand consists of three native species (Leiopelma spp.), and three Litoria species introduced from Australia in the last 140 years. We conducted a molecular phylogeographical study that aimed to identify the Australian origins of two species, Litoria aurea and Litoria raniformis. We used partial sequences of the mitochondrial cytochrome oxidase I (cox1) gene from 59 specimens sampled from across the range of both species to identify the probable source populations for the New Zealand introductions, and to describe the current genetic diversity among New Zealand Litoria populations. Our genetic data suggest that L. aurea was introduced into the North Island of New Zealand from two regions in Australia, once from the northern part of coastal New South Wales and once from the southern part of coastal New South Wales. Our data indicate that L. raniformis introductions originated from the Melbourne region of southern Victoria and once established in the South Island of New Zealand, the species subsequently spread throughout both islands. In addition, we found a distinct haplotype in L. raniformis from Tasmania that strongly suggests, contrary to earlier reports, that this species was not introduced into New Zealand from Tasmania. Finally, we identified two very distinctive mitochondrial lineages of L. raniformis within the mainland Australia distribution, which may be previously unrecognized species.     

Distribution and forage use of exotic bumblebees in South Island, New Zealand

The rapid decline in bumblebee populations within Europe has been linked to habitat loss through agricultural intensification, and a consequential reduction in the availability of preferred forage plants. The successful introduction of four European Bombus species to the South Island of New Zealand from England (in 1885 and 1906) provides an opportunity to determine how important different forage plants (also introduced from the U.K.) are to two severely threatened European bumblebee species (Bombus ruderatus and B. subterraneus). In January 2003 we conducted a survey of bumblebee populations across 70 sites in the central and southern South Island, recording which plant species were being used as pollen and nectar sources for each Bombus species. All four bumblebee species showed a clear preference for plants of European origin. Only B. terrestris, the most polylectic species, was recorded feeding on native plant species. The longer-tongued bumblebees, B. hortorum, B. ruderatus, and B. subterraneus, foraged predominantly on just two plant species; Trifolium pratense for both nectar and pollen, and Echium vulgare for nectar. These plant species are now declining in abundance in the U.K. Our results provide support for the hypothesis that the loss of flower-rich meadows, particularly those containing populations of Fabaceae species with long corollae, is responsible for the decline of bumblebee species across Europe. Comparison with earlier bumblebee surveys suggests that long-tongued bumblebees may also be in decline in New Zealand, particularly B. subterraneus which is now very localised and scarce.     

Lack of pre-dispersal seed predators in introduced Asteraceae in New Zealand

The idea that naturalised invading plants have fewer phytophagous insects associated with them in their new environment relative to their native range is often assumed, but quantitative data are few and mostly refer to pests on crop species. In this study, the incidence of seed-eating insect larvae in flowerheads of naturalised Asteraceae in New Zealand is compared with that in Britain where the species are native. Similar surveys were carried out in both countries by sampling 200 flowerheads of three populations of the same thirteen species. In the New Zealand populations only one seed-eating insect larva was found in 7800 flowerheads (0.013% infected flowerheads, all species combined) in contrast with the British populations which had 487 (6.24%) flowerheads infested. Possible reasons for the low colonization level of the introduced Asteraceae by native insects in New Zealand are 1) the relatively recent introduction of the plants (100-200 years), 2) their phylogenetic distance from the native flora, and 3) the specialised nature of the bud-infesting habit of the insects.     

DECOUPLING OF SHORT‐ AND LONG‐DISTANCE DISPERSAL PATHWAYS IN THE ENDEMIC NEW ZEALAND SEAWEED CARPOPHYLLUM MASCHALOCARPUM (PHAEOPHYCEAE,FUCALES)1

The processes that produce and maintain genetic structure in organisms operate at different timescales and on different life‐history stages. In marine macroalgae, gene flow occurs through gamete/zygote dispersal and rafting by adult thalli. Population genetic patterns arise from this contemporary gene flow interacting with historical processes. We analyzed spatial patterns of mitochondrial DNA variation to investigate contemporary and historical dispersal patterns in the New Zealand endemic fucalean brown alga Carpophyllum maschalocarpum (Turner) Grev. Populations bounded by habitat discontinuities were often strongly differentiated from adjoining populations over scales of tens of kilometers and intrapopulation diversity was generally low, except for one region of northeast New Zealand (the Bay of Plenty). There was evidence of strong connectivity between the northern and eastern regions of New Zealand’s North Island and between the North and South Islands of New Zealand and the Chatham Islands (separated by 650 km of open ocean). Moderate haplotypic diversity was found in Chatham Islands populations, while other southern populations showed low diversity consistent with Last Glacial Maximum (LGM) retreat and subsequent recolonization. We suggest that ocean current patterns and prevailing westerly winds facilitate long‐distance dispersal by floating adult thalli, decoupling genetic differentiation of Chatham Island populations from dispersal potential at the gamete/zygote stage. This study highlights the importance of encompassing the entire range of a species when inferring dispersal patterns from genetic differentiation, as realized dispersal distances can be contingent on local or regional oceanographic and historical processes.