Reconciling phylogeography and ecological niche models for New Zealand beetles: Looking beyond glacial refugia

Northern Richness, Southern Dead End-Origin and Dispersal Events of Pseudolycoriella (Sciaridae, Diptera) between New Zealand's Main Islands

Sciaridae (Diptera) is a widespread insect family of which some species can reach high abundances in arboreal habitats. This trait, together with their (passive) mobility, enables them to quickly colonise suitable habitats. To reveal the biogeographic history of the New Zealand members of the sciarid genus Pseudolycoriella, we analysed three molecular markers of selected species and populations in a Bayesian approach. At the intra- and interspecific levels, we detected a pattern of northern richness vs. southern purity, which has probably developed as a result of Pleistocene glacial cycles. Since the late Miocene, we identified 13 dispersal events across the sea strait separating New Zealand's main islands. As nine of these dispersal events were south-directed, North Island can be considered the centre of radiation for this genus. An unequivocal re-colonisation of North Island was only observed once. Based on the inclusion of three undescribed species from Tasmania and on previously published data, three colonisations of New Zealand are likely, all of them assumed to be of Australian origin. One of these most probably took place during the late Miocene, and the other two during the late Pliocene or at the Pliocene-Pleistocene boundary.

Ancient relicts or recent immigrants? Different dating strategies alter diversification scenarios of New Zealand aquatic beetles (Coleoptera: Hydrophilidae: Berosus)

Dated species-level phylogenies are crucial for understanding the origin and evolutionary history of modern faunas, yet difficult to obtain due to the frequent absence of suitable age calibrations at species level. Substitution rates of related or more inclusive clades are often used to overcome this limitation but the accuracy of this approach remains untested. We compared tree dating based on substitution rates with analyses implementing fossil data by direct node-dating and indirect root-age constraints for the New Zealand endemic Berosus water beetles (Coleoptera: Hydrophilidae). The analysis based solely on substitution rates indicated a Miocene colonization of New Zealand and Pleistocene origin of species. By contrast, all analyses that implemented fossil data resulted in significantly older age estimates, indicating an ancient early Cenozoic origin of the New Zealand clade, diversification of species during or after the Oligocene transgression and Miocene-Pliocene origin of within-species population structure. Rate-calibrated time trees were incongruent with recently published Coleoptera time trees, the fossil record of Berosus and the distribution of outgroup species. Strong variation of substitution rates among Coleoptera lineages, as well as among lineages within the family Hydrophilidae, was identified as the principal reason for low accuracy of rate-calibrated analyses, resulting in underestimated node ages in Berosus. We provide evidence that Oligocene to Pliocene events, rather than the Pleistocene Glacial cycles, played an essential role in the formation of the modern New Zealand insect fauna.

Genetic divergence between isolated populations of the North Island New Zealand Rifleman (Acanthisitta chloris granti) implicates ancient biogeographic impacts rather than recent habitat fragmentation

This research investigates the extent and causal mechanisms of genetic population divergence in a poorly flighted passerine, the North Island Rifleman or Titipounamu (Acanthisitta chloris granti). While this species has a historically widespread distribution, anthropogenic forest clearance has resulted in a highly fragmented current distribution. We conducted analyses of mitochondrial DNA (COI and Control Region) and 12 nuclear DNA microsatellites to test for population divergence and estimate times of divergence. diyabc and biogeobears were then used to assess likely past dispersal scenarios based on both mtDNA and nDNA. The results reveal several significantly divergent lineages across the North Island of New Zealand and indicate that some populations have been isolated for extensive periods of time (0.7-4.9 mya). Modeling indicated a dynamic history of population connectivity, with a drastic restriction in gene flow between three geographic regions, followed by a more recent re-establishment of connectivity. Our analyses indicate the dynamic influence of key geological and climatological events on the distribution of genetic diversity in this species, including support for the genetic impact of old biogeographic boundaries such as the Taupo Line and Cockayne's Line, rather than recent anthropogenic habitat fragmentation. These findings present a rare example of an avian species with a genetic history more like that of flightless taxa and so provide new general insights into vicariant processes affecting populations of passerines with limited dispersal.

Dispersal barriers and opportunities drive multiple levels of phylogeographic concordance in the Southern Alps of New Zealand

Phylogeographic concordance, or the sharing of phylogeographic patterns among codistributed species, suggests similar responses to topography or climatic history. While the orientation and timing of breaks between lineages are routinely compared, spatial dynamics within regions occupied by individual lineages provide a second opportunity for comparing responses to past events. In environments with complex topography and glacial history, such as New Zealand's South Island, geographically nested comparisons can identify the processes leading to phylogeographic concordance between and within regional genomic clusters. Here, we used single nucleotide polymorphisms (obtained via ddRADseq) for two codistributed forest beetle species, Agyrtodes labralis (Leiodidae) and Brachynopus scutellaris (Staphylinidae), to evaluate the role of climate change and topography in shaping phylogeographic concordance at two, nested spatial scales: do species diverge over the same geographic barriers, with similar divergence times? And within regions delimited by these breaks, do species share similar spatial dynamics of directional expansion or isolation-by-distance? We found greater congruence of phylogeographic breaks between regions divided by the strongest dispersal barriers (i.e., the Southern Alps). However, these shared breaks were not indicative of shared spatial dynamics within the regions they delimit, and the most similar spatial dynamics between species occurred within regions with the strongest gradients in historical climatic stability. Our results indicate that lack of concordance as traditionally detected by lineage turnover does not rule out the possibility of shared histories, and variation in the presence and type of concordance may provide insights into the different processes shaping phylogeographic patterns across geologically dynamic regions.

Evolutionary History of a Desert Shrub Ephedra przewalskii (Ephedraceae): Allopatric Divergence and Range Shifts in Northwestern China

Based on two chloroplast DNA sequences, psbA-trnH and trnT-trnF, phylogeographical patterns of a desert shrub, Ephedra przewalskii, were examined across most of its geographic range in northwestern China. A total of sixteen haplotypes were detected. There was a common haplotype in each basin, that was haplotype A in Tarim Basin, haplotype G in Junggar Basin, and haplotype M in Qaidam Basin. Genetic variance mainly occurred among populations, geographic regions, and eleven geographic groups subdivided by SAMOVA analysis. E. przewalskii likely had a smaller and more fragmented geographic range during the Last Glacial Maximum, which was determined based on ecological niche modelling. Three groups of E. przewalskii populations were detected to have experience range expansion, and this was based on significant values of Fu’s F_S, Tajima’s D, and unimodel mismatch distributions. The cold and dry climate during the glacial period of the Quaternary is postulated to have been a driver for significant genetic isolation and divergence among populations or groups in E. przewalskii, whereas the warmer and wetter climate during the interglacial period is speculated to have provided favourable conditions for range expansion of the species.

Integrating phylogeography and species distribution models: cryptic distributional responses to past climate change in an endemic rodent from the central Chile hotspot

AIM

Biodiversity losses under the species level may have been severely underestimated in future global climate change scenarios. Therefore, it is important to characterize the diversity units at this level, as well as to understand their ecological responses to climatic forcings. We have chosen an endemic rodent from a highly endangered ecogeographic area as a model to look for distributional responses below the species level: Phyllotis darwini.

LOCATION

The central Chile biodiversity hotspot: This area harbours a high number of endemic species, and it is known to have experienced vegetational displacements between two mountain systems during and after the Last Glacial Maximum.

METHODS

We have characterized cryptic lineages inside P. darwini in a classic phylogeographic approach; those intraspecific lineages were considered as relevant units to construct distribution models at Last Glacial Maximum and at present, as border climatic conditions. Differences in distribution between border conditions for each lineage were interpreted as distributional responses to post-glacial climate change.

RESULTS

The species is composed of two major phylogroups: one of them has a broad distribution mainly across the valley but also in mountain ranges, whereas the other displays a disjunct distribution across both mountain ranges and always above 1500 m. The lineage distribution model under LGM climatic conditions suggests that both lineages were co-distributed in the southern portion of P. darwini's current geographic range, mainly at the valley and at the coast.

MAIN CONCLUSIONS

Present distribution of lineages in P. darwini is the consequence of a cryptic distributional response to climate change after LGM: postglacial northward colonization, with strict altitudinal segregation of both phylogroups.

Phylogeographical structure inferred from cpDNA sequence variation of Zygophyllum xanthoxylon across north-west China

Zygophyllum xanthoxylon, a desert species, displaying a broad east-west continuous distribution pattern in arid Northwestern China, can be considered as a model species to investigate the biogeographical history of this region. We sequenced two chloroplast DNA spacers (psbK-psbI and rpl32-trnL) in 226 individuals from 31 populations to explore the phylogeographical structure. Median-joining network was constructed and analysis of AMOVA, SMOVA, neutrality tests and distribution analysis were used to examine genetic structure and potential range expansion. Using species distribution modeling, the geographical distribution of Z. xanthoxylon was modeled during the present and at the Last Glacial Maximum (LGM). Among 26 haplotypes, one was widely distributed, but most was restricted to either the eastern or western region. The populations with the highest levels of haplotype diversity were found in the Tianshan Mountains and its surroundings in the west, and the Helan Mountains and Alxa Plateau in the east. AMOVA and SAMOVA showed that over all populations, the species lacks phylogeographical structure, which is speculated to be the result of its specific biology. Neutrality tests and mismatch distribution analysis support past range expansions of the species. Comparing the current distribution to those cold and dry conditions in LGM, Z. xanthoxylon had a shrunken and more fragmented range during LGM. Based on the evidences from phylogeographical patterns, distribution of genetic variability, and paleodistribution modeling, Z. xanthoxylon is speculated most likely to have originated from the east and migrated westward via the Hexi Corridor.

Impact of past climatic changes and resource availability on the population demography of three food-specialist bees

Past climate change is known to have strongly impacted current patterns of genetic variation of animals and plants in Europe. However, ecological factors also have the potential to influence demographic history and thus patterns of genetic variation. In this study, we investigated the impact of past climate, and also the potential impact of host plant species abundance, on intraspecific genetic variation in three codistributed and related specialized solitary bees of the genus Melitta with very similar life history traits and dispersal capacities. We sequenced five independent loci in samples collected from the three species. Our analyses revealed that the species associated with the most abundant host plant species (Melitta leporina) displays unusually high genetic variation, to an extent that is seldom reported in phylogeographic studies of animals and plants. This suggests a potential role of food resource abundance in determining current patterns of genetic variation in specialized herbivorous insects. Patterns of genetic variation in the two other species indicated lower overall levels of diversity, and that M. nigricans could have experienced a recent range expansion. Ecological niche modelling of the three Melitta species and their main host plant species suggested a strong reduction in range size during the last glacial maximum. Comparing observed sequence data with data simulated using spatially explicit models of coalescence suggests that M. leporina recovered a range and population size close to their current levels at the end of the last glaciation, and confirms recent range expansion as the most likely scenario for M. nigricans. Overall, this study illustrates that both demographic history and ecological factors may have contributed to shape current phylogeographic patterns.

Climate refugia: joint inference from fossil records, species distribution models and phylogeography

Climate refugia, locations where taxa survive periods of regionally adverse climate, are thought to be critical for maintaining biodiversity through the glacial-interglacial climate changes of the Quaternary. A critical research need is to better integrate and reconcile the three major lines of evidence used to infer the existence of past refugia - fossil records, species distribution models and phylogeographic surveys - in order to characterize the complex spatiotemporal trajectories of species and populations in and out of refugia. Here we review the complementary strengths, limitations and new advances for these three approaches. We provide case studies to illustrate their combined application, and point the way towards new opportunities for synthesizing these disparate lines of evidence. Case studies with European beech, Qinghai spruce and Douglas-fir illustrate how the combination of these three approaches successfully resolves complex species histories not attainable from any one approach. Promising new statistical techniques can capitalize on the strengths of each method and provide a robust quantitative reconstruction of species history. Studying past refugia can help identify contemporary refugia and clarify their conservation significance, in particular by elucidating the fine-scale processes and the particular geographic locations that buffer species against rapidly changing climate.

Insights into the origin and distribution of biodiversity in the Brazilian Atlantic forest hot spot: a statistical phylogeographic study using a low-dispersal organism

The relative importance of the processes that generate and maintain biodiversity is a major and controversial topic in evolutionary biology with large implications for conservation management. The Atlantic Forest of Brazil, one of the world's richest biodiversity hot spots, is severely damaged by human activities. To formulate an efficient conservation policy, a good understanding of spatial and temporal biodiversity patterns and their underlying evolutionary mechanisms is required. With this aim, we performed a comprehensive phylogeographic study using a low-dispersal organism, the land planarian species Cephaloflexa bergi (Platyhelminthes, Tricladida). Analysing multi-locus DNA sequence variation under the Approximate Bayesian Computation framework, we evaluated two scenarios proposed to explain the diversity of Southern Atlantic Forest (SAF) region. We found that most sampled localities harbour high levels of genetic diversity, with lineages sharing common ancestors that predate the Pleistocene. Remarkably, we detected the molecular hallmark of the isolation-by-distance effect and little evidence of a recent colonization of SAF localities; nevertheless, some populations might result from very recent secondary contacts. We conclude that extant SAF biodiversity originated and has been shaped by complex interactions between ancient geological events and more recent evolutionary processes, whereas Pleistocene climate changes had a minor influence in generating present-day diversity. We also demonstrate that land planarians are an advantageous biological model for making phylogeographic and, particularly, fine-scale evolutionary inferences, and propose appropriate conservation policies.

Unique rostrate larvae and basidiomycophagy in the beetle family Corylophidae

The head morphology of larvae of two undescribed species of the corylophid genus Holopsis were examined. Both are associated with the same basidiomycete host Ganoderma cf applanatum. Whereas the round and convex adults are very similar, one of the disc-shaped larvae is characterized by an elongate weevil-like snout, which is a unique feature in larval beetles. The posterior head region, the mouthparts and the general configuration of the musculature are similar in the larvae of both species. However, in the rostrate Holopsis sp. 1 most muscles are either widened along the longitudinal axis or elongated. Moreover, an additional bundle of M. frontobuccalis posterior is present, which strengthens the pharyngeal pumping apparatus. Both species share an unusual connection between the prepharynx and pharynx. This is a potential autapomorphy of the genus. The larval cephalic morphology of Holopsis sp. 2 and the corylophine genus Sericoderus is quite similar. However, they differ in some muscular features and in the configuration of the foregut. Holopsis species are associated with Basidiomycetes. Whether this is an ancestral condition in Corylophidae remains ambiguous due to conflicting phylogenetic hypotheses and the largely unknown biology of the Australian subfamily Periptyctinae. Several features of Holopsis are likely plesiomorphic and possibly related with the association with basidiomycetes. However, the larval rostrum of sp. 1 is doubtlessly derived, and could have a performance advantage over other species feeding on the spores of Ganoderma cf applanatum including Holopsis sp. 2.

Present, past and future of the European rock fern Asplenium fontanum: combining distribution modelling and population genetics to study the effect of climate change on geographic range and genetic diversity

BACKGROUND AND AIMS

Climate change is expected to alter the geographic range of many plant species dramatically. Predicting this response will be critical to managing the conservation of plant resources and the effects of invasive species. The aim of this study was to predict the response of temperate homosporous ferns to climate change.

METHODS

Genetic diversity and changes in distribution range were inferred for the diploid rock fern Asplenium fontanum along a South-North transect, extending from its putative last glacial maximum (LGM) refugia in southern France towards southern Germany and eastern-central France. This study reconciles observations from distribution models and phylogeographic analyses derived from plastid and nuclear diversity.

KEY RESULTS

Genetic diversity distribution and niche modelling propose that genetic diversity accumulates in the LGM climate refugium in southern France with the formation of a diversity gradient reflecting a slow, post-LGM range expansion towards the current distribution range. Evidence supports the fern's preference for outcrossing, contradicting the expectation that homosporous ferns would populate new sites by single-spore colonization. Prediction of climate and distribution range change suggests that a dramatic loss of range and genetic diversity in this fern is possible. The observed migration is best described by the phalanx expansion model.

CONCLUSIONS

The results suggest that homosporous ferns reproducing preferentially by outcrossing accumulate genetic diversity primarily in LGM climate refugia and may be threatened if these areas disappear due to global climate change.

Species radiation of carabid beetles (broscini: mecodema) in new zealand

New Zealand biodiversity has often been viewed as Gondwanan in origin and age, but it is increasingly apparent from molecular studies that diversification, and in many cases origination of lineages, postdate the break-up of Gondwanaland. Relatively few studies of New Zealand animal species radiations have as yet been reported, and here we consider the species-rich genus of carabid beetles, Mecodema. Constrained stratigraphic information (emergence of the Chatham Islands) and a substitution rate for Coleoptera were separately used to calibrate Bayesian relaxed molecular clock date estimates for diversification of Mecodema. The inferred timings indicate radiation of these beetles no earlier than the mid-Miocene with most divergences being younger, dating to the Plio-Pleistocene. A shallow age for the radiation along with a complex spatial distribution of these taxa involving many instances of sympatry implicates recent ecological speciation rather than a simplistic allopatric model. This emphasises the youthful and dynamic nature of New Zealand evolution that will be further elucidated with detailed ecological and population genetic analyses.

More than just records: analysing natural history collections for biodiversity planning

Natural History Collections (NHCs) play a central role as sources of data for biodiversity and conservation. Yet, few NHCs have examined whether the data they contain is adequately representative of local biodiversity. I examined over 15,000 databased records of Hymenoptera from 1435 locations across New Zealand collected over the past 90 years. These records are assessed in terms of their geographical, temporal, and environmental coverage across New Zealand. Results showed that the spatial coverage of records was significantly biased, with the top four areas contributing over 51% of all records. Temporal biases were also evident, with a large proportion (40%) of records collected within a short time period. The lack of repeat visits to specific locations indicated that the current set of NHC records would be of limited use for long-term ecological research. Consequently, analyses and interpretation of historical data, for example, shifts in community composition, would be limited. However, in general, NHC records provided good coverage of the diversity of New Zealand habitats and climatic environments, although fewer NHC records were represented at cooler temperatures (<5°C) and the highest rainfalls (>5000 mm/yr). Analyses of NHCs can be greatly enhanced by using simple techniques that examine collection records in terms of environmental and geographical space. NHCs that initiate a systematic sampling strategy will provide higher quality data for biodiversity research than ad hoc or point samples, as is currently the norm. Although NHCs provide a rich source of information they could be far better utilised in a range of large-scale ecological and conservation studies.

Molecular data and ecological niche modelling reveal a highly dynamic evolutionary history of the East Asian Tertiary relict Cercidiphyllum (Cercidiphyllaceae)

East Asia's temperate deciduous forests served as sanctuary for Tertiary relict trees, but their ages and response to past climate change remain largely unknown. To address this issue, we elucidated the evolutionary and population demographic history of Cercdiphyllum, comprising species in China/Japan (Cercdiphyllum japonicum) and central Japan (Cercdiphyllum magnificum). Fifty-three populations were genotyped using chloroplast and ribosomal DNA sequences and microsatellite loci to assess molecular structure and diversity in relation to past (Last Glacial Maximum) and present distributions based on ecological niche modelling. Late Tertiary climate cooling was reflected in a relatively recent speciation event, dated at the Mio-/Pliocene boundary. During glacials, the warm-temperate C. japonicum experienced massive habitat losses in some areas (north-central China/north Japan) but increases in others (southwest/-east China, East China Sea landbridge, south Japan). In China, the Sichuan Basin and/or the middle-Yangtze were source areas of postglacial northward recolonization; in Japan, this may have been facilitated through introgressive hybridization with the cool-temperate C. magnificum. Our findings challenge the notion of relative evolutionary and demographic stability of Tertiary relict trees, and may serve as a guideline for assessing the impact of Neogene climate change on the evolution and distribution of East Asian temperate plants.

Limited, episodic diversification and contrasting phylogeography in a New Zealand cicada radiation

BACKGROUND

The New Zealand (NZ) cicada fauna contains two co-distributed lineages that independently colonized the isolated continental fragment in the Miocene. One extensively studied lineage includes 90% of the extant species (Kikihia + Maoricicada + Rhodopsalta; ca 51 spp.), while the other contains just four extant species (Amphipsalta - 3 spp. + Notopsalta - 1 sp.) and has been little studied. We examined mitochondrial and nuclear-gene phylogenies and phylogeography, Bayesian relaxed-clock divergence timing (incorporating literature-based uncertainty of molecular clock estimates) and ecological niche models of the species from the smaller radiation.

RESULTS

Mitochondrial and nuclear-gene trees supported the monophyly of Amphipsalta. Most interspecific diversification within Amphipsalta-Notopsalta occurred from the mid-Miocene to the Pliocene. However, interspecific divergence time estimates had large confidence intervals and were highly dependent on the assumed tree prior, and comparisons of uncorrected and patristic distances suggested difficulty in estimation of branch lengths. In contrast, intraspecific divergence times varied little across analyses, and all appear to have occurred during the Pleistocene. Two large-bodied forest taxa (A. cingulata, A. zelandica) showed minimal phylogeographic structure, with intraspecific diversification dating to ca. 0.16 and 0.37 Ma, respectively. Mid-Pleistocene-age phylogeographic structure was found within two smaller-bodied species (A. strepitans - 1.16 Ma, N. sericea - 1.36 Ma] inhabiting dry open habitats. Branches separating independently evolving species were long compared to intraspecific branches. Ecological niche models hindcast to the Last Glacial Maximum (LGM) matched expectations from the genetic datasets for A. zelandica and A. strepitans, suggesting that the range of A. zelandica was greatly reduced while A. strepitans refugia were more extensive. However, no LGM habitat could be reconstructed for A. cingulata and N. sericea, suggesting survival in microhabitats not detectable with our downscaled climate data.

CONCLUSIONS

Unlike the large and continuous diversification exhibited by the Kikihia-Maoricicada-Rhodopsalta clade, the contemporaneous Amphipsalta-Notopsalta lineage contains four comparatively old (early branching) species that show only recent diversification. This indicates either a long period of stasis with no speciation, or one or more bouts of extinction that have pruned the radiation. Within Amphipsalta-Notopsalta, greater population structure is found in dry-open-habitat species versus forest specialists. We attribute this difference to the fact that NZ lowland forests were repeatedly reduced in extent during glacial periods, while steep, open habitats likely became more available during late Pleistocene uplift.

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.

The Invertebrate Life of New Zealand: A Phylogeographic Approach

Phylogeography contributes to our knowledge of regional biotas by integrating spatial and genetic information. In New Zealand, comprising two main islands and hundreds of smaller ones, phylogeography has transformed the way we view our biology and allowed comparison with other parts of the world. Here we review studies on New Zealand terrestrial and freshwater invertebrates. We find little evidence of congruence among studies of different taxa; instead there are signatures of partitioning in many different regions and expansion in different directions. A number of studies have revealed unusually high genetic distances within putative species, and in those where other data confirm this taxonomy, the revealed phylogeographic structure contrasts with northern hemisphere continental systems. Some taxa show a signature indicative of Pliocene tectonic events encompassing land extension and mountain building, whereas others are consistent with range expansion following the last glacial maximum (LGM) of the Pleistocene. There is some indication that montane taxa are more partitioned than lowland ones, but this observation is obscured by a broad range of patterns within the sample of lowland/forest taxa. We note that several geophysical processes make similar phylogeographic predictions for the same landscape, rendering confirmation of the drivers of partitioning difficult. Future multi-gene analyses where applied to testable alternative hypotheses may help resolve further the rich evolutionary history of New Zealand's invertebrates.