East meets west: biogeology of the Campbell Plateau

The New Zealand Subantarctic Islands, emergent remnants of the Campbell Plateau, were given World Heritage status in 1998 in recognition of their importance to global biodiversity. We describe the flora and fauna of these islands and discuss the results of recent phylogenetic analyses. Part of the New Zealand Subantarctic biota appears to be relictual and to be derived from west Gondwana. The relictual element is characterized by genera endemic to the Campbell Plateau that show relationships with taxa of the southern South Island, New Zealand, southern South America, and the north Pacific. In contrast, a younger, east Gondwanan element is composed of species that are either taxonomically identical to widespread mainland species, or endemic species with close New Zealand relatives. Area cladograms support the inclusion of the southern South Island, New Zealand and Macquarie Island (although this is separate geologically) as parts of the Campbell Plateau, but suggest the Chatham Rise and Torlesse terranes of the eastern South Island, New Zealand were originally parts of east Gondwana. East and west Antarctica acted as independent plates during the breakup of Gondwana, and were separated by oceanic crust until a compressive phase sutured them along the trace of the trans‐Antarctic mountains during the early Tertiary. The Campbell Plateau microcontinent was connected to west Antarctica until its separation at 80 Mya, contemporaneous with the separation of the southern portion of the Melanesian rift from east Gondwana. Presently the Campbell Plateau is joined to the Melanesian Rift along the Alpine Fault. Cenozoic plate tectonic reconstructions place the Campbell Plateau adjacent to the Melanesian Rift throughout the rift–drift phase, relative motion being confined to strike–slip movement over the last 20 Myr. Our synthesis of phylogenetic and plate tectonic evidence suggests that the Alpine Fault is the most recent development of a much older extensional rift/basin boundary originally separating west and east Gondwana. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 86 , 95–115.     

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.     

Historical biogeography of the New Zealand freshwater crayfishes (Parastacidae,Paranephrops spp.): Restoration of a refugial survivor?

Abstract

New Zealand's two species of freshwater parastacid crayfishes have allopatric distributions, with one species in the North Island and northwestern South Island and the other in the eastern and southern South Island and Stewart Island. This gives the appearance of a vicariance event driven by uplift of the Southern Alps beginning in the Pliocene, and of former land connections across both Cook Strait and Foveaux Strait. However, separation of the two species may date from before the Southern Alps were formed. A diverse series of historical geological events is invoked to explain details of the distributions of these two species. Absence of Paranephrops from intermontane valleys of eastern flanks of the Southern Alps is notably different from patterns seen in freshwater fish species.     

Phylogeography of two New Zealand lizards: McCann's skink (Oligosoma maccanni) and the brown skink (O. zelandicum)

The New Zealand skink fauna has proven to be an ideal taxonomic group in which to examine the impact of climatic and geological processes on the evolution of the New Zealand biota since the Pliocene. Here we examine the phylogeography of McCann's skink (Oligosoma maccanni) in order to gain insight into the relative contribution of Pliocene and Pleistocene processes on patterns of genetic structure in the South Island biota, and investigate the phylogeography of the brown skink (O. zelandicum) to examine whether Cook Strait landbridges facilitated geneflow between the North and South Islands in the late-Pleistocene. We obtained mitochondrial DNA sequence data (ND2 and ND4; 1282bp) from across the range of both species. We examined the phylogeographic patterns evident in each species using Neighbour-Joining, Maximum Likelihood and Bayesian methods. We found substantial phylogeographic structure within O. maccanni, with seven distinct clades identified. Divergences among clades are estimated to have occurred during the Pliocene. Populations in the Otago/Southland region (south of the Waitaki River valley) formed a well-supported lineage within O. maccanni. A substantial genetic break was evident between populations in east and west Otago, either side of the Nevis-Cardrona fault system, while north-south genetic breaks were evident within the Canterbury region. Within-clade divergences in O. maccanni appear to have occurred during the mid- to late-Pleistocene. Shimodaira-Hasegawa topology tests indicated that the 'Garston' skink is not genetically distinct from O. maccanni. There was only relatively minor phylogeographic structure within O. zelandicum, with divergences among populations occurring during the mid- to late-Pleistocene. Our genetic data supports a single colonisation of the North Island by O. zelandicum from the South Island, with the estimated timing of this event (0.46mya) consistent with the initial formation of Cook Strait.     

Phylogeny, biogeography and adaptive radiation of Pachycladon (Brassicaceae) in the mountains of South Island, New Zealand

Aim To report analyses and propose hypotheses of adaptive radiation that explain distributional patterns of the alpine genus Pachycladon Hook.f. – a morphologically diverse genus from New Zealand closely related to Arabidopsis thaliana. Location South Island, New Zealand. Methods Morphological and nrDNA ITS sequence phylogenies were generated for Pachycladon. An analysis is presented of species distributional patterns and attributes. Results Phylogenetic analyses of morphological characters and nrDNA ITS sequence data were found to be congruent in supporting three New Zealand clades for Pachycladon. Monophyletic groups identified within the genus are geographically distinct and are associated with different geological parent materials. Distribution maps, latitude and altitude range, and data on geological parent material are presented for the nine named and one unnamed species of Pachycladon from New Zealand. Main conclusions (a) Panbiogeographic hypotheses accounting for the origin and present‐day distribution of Pachycladon in New Zealand are not supported.
(b) Species diversity and distributions of Pachycladon are explained by a Late Tertiary–Quaternary adaptive radiation associated with increasing specialization to geological substrates. Pachycladon cheesemanii Heenan & A.D.Mitch. is morphologically similar to the closest overseas relatives. It is a geological generalist and has wide latitudinal and altitudinal ranges, and we suggest it resembles the ancestral form of the genus in New Zealand. Pachycladon novae‐zelandiae (Hook.f.) Hook.f. and P. wallii (Carse) Heenan & A.D.Mitch. are a southern South Island group that predominantly occurs on Haast Schist, are polycarpic, have lobed leaves, and lateral inflorescences. Pachycladon enysii (Cheeseman) Heenan & A.D.Mitch., P. fastigiata (Hook.f.) Heenan & A.D.Mitch., and P. stellata (Allan) Heenan & A.D.Mitch. are restricted to greywacke in the eastern South Island, and are facultatively monocarpic, have serrate leaves, and stout terminal inflorescenes.
(c) Present distributions of Pachycladon species may relate to Pleistocene climate change. Pachycladon enysii reaches the highest altitude of New Zealand species of Pachycladon and is most common in the Southern Alps in Canterbury. We propose that this species survived on nunataks at the height of the last glaciation. In contrast, P. fastigiata grows at a lower altitude and is absent from the high mountains of the Southern Alps. We suggest it was extirpated from this area during the last glaciation.     

Hello New Zealand

Islands of the Pacific Ocean have long fascinated evolutionists. Oceanic islands, generally the products of volcanic activity, provide natural experiments as biological populations are well delimited and the age of islands can be determined using radiometric dating. 'Continental islands', including New Caledonia and New Zealand, provide equally valuable opportunities for evolutionary study. For students of New Zealand biogeography, the peculiar composition of the biota coupled with a limited interpretation of geology has resulted in the widespread acceptance that the flora and fauna is primarily ancient and of vicariant Gondwanan origin. There is increasing evidence from molecular data that much of this biodiversity is the product of evolution following relatively recent colonization. Such data have prompted biologists to consider geological information on New Zealand in more detail. At the heart of the issue is the question of whether modern New Zealand has a terrestrial link through time with the continent Zealandia that split from Gondwanaland some 80 Ma. Zealandia, which includes New Caledonia, Lord Howe Island and several of the subantarctic islands, is now largely submerged, and New Zealand's present terrestrial existence is the product of tectonic activity initiated around 26 Ma. We argue that for the purposes of biogeographical interpretation, New Zealand can be treated as an oceanic island.     

Population genetic subdivision in the New Zealand greenshell mussel (Perna canaliculus) inferred from single-strand conformation polymorphism analysis of mitochondrial DNA

Single-strand conformation polymorphism (SSCP) analysis of the NADH IV region of the mitochondrial DNA (mtDNA) molecule in greenshell mussels (Perna canaliculus) indicated strong population genetic structuring in this endemic New Zealand species. A northern and a southern group were differentiated by frequency shifts in common haplotypes and by the occurrence of a unique southern haplotype at approximately 20% frequency. This split occurred south of Cook Strait (the body of water between the North and the South Island) at approximately 42 degrees S latitude. Northern populations were less genetically diverse than southern populations and mussels from the west coast of the South Island were most distinct from northern mussels. We hypothesize that the unique haplotype VIII originated in the lower South Island, and that its spread northwards was obstructed by the opening of Cook Strait approximately 15 000-16 000 years ago and the subsequent establishment of present-day surface water circulation patterns in Greater Cook Strait. We suggest that present-day strong tidal flows and turbulent mixing of water masses in Cook Strait, and intense up-welling on the east and west coasts in this region, represent a barrier to gene flow between mussels located in the North Island and northern South Island vs. mussels in most of the South Island and Stewart Island.     

The vegetation of roadside verges with respect to environmental gradients in southern New Zealand

Abstract. A survey of the vegetation of roadside verges was made across the southern part of the South Island of New Zealand. Samples were taken at 10-km intervals along selected roads providing a climatic range from the suboceanic conditions of the east coast into semi-arid Central Otago, and from Central Otago through the Southern Alps to the hyper-oceanic areas of high rainfall on the west Coast. The variation in the floristic composition is associated mainly with variation in rainfall, continentality, altitude, soil acidity, soil organic matter, and presence of forest. Sites in the arable and pastoral regions on the eastern side of the Southern Alps support a herbaceous vegetation consisting mostly of exotic species of European origin, with a few native grasses scattered through the drier and less fertile sites. A greater proportion of native species is found at higher altitudes. Roadside vegetation in the area of high rainfall to the west is characterized by indigenous ferns and woody species, although vegetation adjacent to cleared areas is more similar to that on roadsides adjacent to farmland on the east coast. The pattern of distribution of both native and exotic species is strongly related to altitudinal and climatic gradients, and the environmental responses of the exotic species are similar to those recorded in Europe. This suggests a colonization of all available sites by the exotic species, despite the relatively short time since their introduction to New Zealand, rather than an incomplete invasion.     

Glacial refugia in a maritime temperate climate: Cicada (Kikihia subalpina) mtDNA phylogeography in New Zealand

Understanding the biological significance of Pleistocene glaciations requires knowledge of the nature and extent of habitat refugia during glacial maxima. An opportunity to examine evidence of glacial forest refugia in a maritime, Southern Hemisphere setting is found in New Zealand, where the extent of Pleistocene forests remains controversial. We used the mitochondrial phylogeography of a forest-edge cicada ( Kikihia subalpina ) to test the hypothesis that populations of this species survived throughout South Island during the Last Glacial Maximum. We also compared mitochondrial DNA phylogeographic patterns with male song patterns that suggest allopatric divergence across Cook Strait. Cytochrome oxidase I and II sequences were analyzed using network analysis, maximum-likelihood phylogenetic estimation, Bayesian dating and Bayesian skyline plots. K. subalpina haplotypes from North Island and South Island form monophyletic clades that are concordant with song patterns. Song divergence corresponds to approximately 2% genetic divergence, and Bayesian dating suggests that the North Island and South Island population-lineages became isolated around 761 000 years bp . Almost all South Island genetic variation is found in the north of the island, consistent with refugia in Marlborough Sounds, central Nelson and northwest Nelson. All central and southern South Island and Stewart Island haplotypes are extremely similar to northern South Island haplotypes, a 'northern richness/southern purity' pattern that mirrors genetic patterns observed in many Northern Hemisphere taxa. Proposed southern South Island forest habitat fragments may have been too small to sustain populations of K. subalpina , and/or they may have harboured ecological communities with no modern-day analogues.     

ONSET OF GLACIATION DROVE SIMULTANEOUS VICARIANT ISOLATION OF ALPINE INSECTS IN NEW ZEALAND

The origin of the New Zealand “beech gap,” a low‐diversity zone in the central South Island corresponding with a disjunction in the distribution of many taxa, has been the focus of biogeographical debate for many decades. Here, we use comparative phylogeographic analysis (COI; H3) of six alpine stonefly genera (116 individuals, 102 localities) to test a vicariant evolutionary hypothesis for the origin of this “biotic gap.” We find strikingly similar phylogeographic patterns in all six genera, with the deepest genetic divergences always found between samples north and south of the beech gap. The magnitude of north‐south genetic differentiation for COI is similar across all six genera (ranging from 0.074 to 0.091), with a test for simultaneous vicariance confirming that divergence is consistent with a single evolutionary event. The concordant cladogenesis detected across multiple taxa is consistent with vicariant isolation caused by the onset of glaciation in the late Pliocene. This study thus indicates an important cladogenetic role for glaciation, an abiotic evolutionary process that is more typically associated with loss of biodiversity.     

Phylogeography and ecological niche modelling implicate coastal refugia and trans‐alpine dispersal of a New Zealand fungus beetle

The Last Glacial Maximum (LGM) severely restricted forest ecosystems on New Zealand’s South Island, but the extent of LGM distribution for forest species is still poorly understood. We used mitochondrial DNA phylogeography (COI) and ecological niche modelling (ENM) to identify LGM refugia for the mycophagous beetle Agyrtodes labralis (Leiodidae), a forest edge species widely distributed in the South Island. Both the phylogenetic analyses and the ENM indicate that A. labralis refuged in Kaikoura, Nelson, and along much of the South Island’s west coast. Phylogeography of this species indicates that recolonization of the largely deforested east and southeast South Island occurred in a west–east direction, with populations moving through the Southern Alps, and that the northern refugia participated little in interglacial population expansion. This contradicts published studies of other New Zealand species, in which recolonization occurs in a north–south fashion from many of the same refugia.     

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 field voles (Microtus agrestis) in Eurasia inferred from mitochondrial DNA sequences

In a distribution-wide phylogeographic survey of the field vole (Microtus agrestis), 75 specimens from 56 localities across Eurasia were examined for DNA sequence variation along the whole 1140 base pair (bp) mitochondrial (mt) cytochrome b gene. The species is subdivided into three main mtDNA phylogeographic groups - western, eastern and southern - with largely allopatric distributions. The western phylogeographical group is found in west and central Europe and spread most probably from a glacial refugium in the Carpathians. The eastern group covers a large range from Lithuania to central Asia, and probably originated from a southeast European source (e.g. the southern Urals or the Caucasus). The southern group occupies an area from Portugal to Hungary, with division into two distinct mtDNA sublineages that presumably derive from separate glacial refugia in the Iberian Peninsula. Molecular clock estimates suggest that the western and eastern field vole populations separated during the last glaciation, whereas the southern population dates back 0.5-0.9 Myr. High levels of mtDNA variation indicate relatively large population sizes and subdivisions within phylogeographic groups during the last glaciation. We report a possible new suture zone in east Europe.     

Gondwanan radiation of the Southern Hemisphere crayfishes (Decapoda: Parastacidae): evidence from fossils and molecules

Aim The sequential break‐up of Gondwana is thought to be a dominant process in the establishment of shared biota across landmasses of the Southern Hemisphere. Yet similar distributions are shared by taxa whose radiations clearly post‐date the Gondwanan break‐up. Thus, determining the contribution of vicariance versus dispersal to seemingly Gondwanan biota is complex. The southern freshwater crayfishes (family Parastacidae) are distributed on Australia and New Guinea, South America, Madagascar and New Zealand and are unlikely to have dispersed via oceans, owing to strict freshwater limitations. We test the hypotheses that the break‐up of Gondwana has led to (1) a predominately east–west (((Australia, New Zealand: 80 Ma) Madagascar: 160–121 Ma) South America: 165–140 Ma), or (2) a southern (((Australia, South America: 52–35 Ma) New Zealand: 80 Ma) Madagascar: 160–121 Ma) pattern for parastacid crayfish. Further, we examine the evidence for a complete drowning of New Zealand and subsequent colonization by freshwater crayfish. Location Southern Hemisphere. Methods The evolutionary relationships among the 15 genera of Parastacidae were reconstructed using mitochondrial [16S, cytochrome c oxidase subunit I (COI)] and nuclear (18S, 28S) sequence data and maximum likelihood and Bayesian methods of phylogenetic reconstruction. A Bayesian (multidivtime ) molecular dating method using six fossil calibrations and phylogenetic inference was used to estimate divergence time among crayfish clades on Gondwanan landmasses. Results The South American crayfish are monophyletic and a sister group to all other southern crayfish. Australian crayfish are not monophyletic, with two Tasmanian genera, Spinastacoides and Ombrastacoides, forming a clade with New Zealand and Malagasy crayfish (both monophyletic). Divergence of crayfish among southern landmasses is estimated to have occurred around the Late Jurassic to Early Cretaceous (109–178 Ma). Main conclusions The estimated phylogenetic relationships and time of divergence among the Southern Hemisphere crayfishes were consistent with an east–west pattern of Gondwanan divergence. The divergence between Australia and New Zealand (109–160 Ma) pre‐dated the rifting at around 80 Ma, suggesting that these lineages were established prior to the break‐up. Owing to the age of the New Zealand crayfish, we reject the hypothesis that there was a complete drowning of New Zealand crayfish habitat.     

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.     

Southern hemisphere biogeography inferred by event-based models: plant versus animal patterns

The Southern Hemisphere has traditionally been considered as having a fundamentally vicariant history. The common trans-Pacific disjunctions are usually explained by the sequential breakup of the supercontinent Gondwana during the last 165 million years, causing successive division of an ancestral biota. However, recent biogeographic studies, based on molecular estimates and more accurate paleogeographic reconstructions, indicate that dispersal may have been more important than traditionally assumed. We examined the relative roles played by vicariance and dispersal in shaping Southern Hemisphere biotas by analyzing a large data set of 54 animal and 19 plant phylogenies, including marsupials, ratites, and southern beeches (1,393 terminals). Parsimony-based tree fitting in conjunction with permutation tests was used to examine to what extent Southern Hemisphere biogeographic patterns fit the breakup sequence of Gondwana and to identify concordant dispersal patterns. Consistent with other studies, the animal data are congruent with the geological sequence of Gondwana breakup: (Africa(New Zealand(southern South America, Australia))). Trans-Antarctic dispersal (Australia <--> southern South America) is also significantly more frequent than any other dispersal event in animals, which may be explained by the long period of geological contact between Australia and South America via Antarctica. In contrast, the dominant pattern in plants, (southern South America(Australia, New Zealand)), is better explained by dispersal, particularly the prevalence of trans-Tasman dispersal between New Zealand and Australia. Our results also confirm the hybrid origin of the South American biota: there has been surprisingly little biotic exchange between the northern tropical and the southern temperate regions of South America, especially for animals.     

Vicars,tramps and assembly of the New Zealand avifauna: a review of molecular phylogenetic evidence

The avifauna of New Zealand is taxonomically and ecologically distinctive, as is typical of island biotas. However, the potential for an old geological age of New Zealand has encouraged a popular notion of a ‘Moa’s ark’ based on the idea that much of the fauna was isolated when Zealandia broke from Gondwana c. 83 million years ago. Molecular phylogenetics has proved useful for exploring the relative importance of different biogeographical processes, revealing for example that ‘tramp’ species (widely dispersing taxa) have arrived in New Zealand even in the last few hundred years, and that some avian taxa have close phylogenetic relatives overseas (predominantly Australian), indicating their recent ancestors were tramps, too. Distinctive taxa with deep phylogenetic ancestry might be ‘vicars’ that owe their presence to vicariance, but lack of close morphological, taxonomic and phylogenetic affinity provides only tenuous evidence for this. Disproving the alternative possibility that apparent vicars are descended from tramps that dispersed in earlier times remains challenging, but molecular analyses have yielded startling insights. Among New Zealand’s iconic taxa, the world’s largest eagle shared a Pleistocene ancestor with a small Australian eagle, and giant, flightless moa are phylogenetic sisters of the much smaller, flying tinamous of South America. The New Zealand avifauna is neither isolated nor stable, but demonstrative of prolonged and ongoing colonization, speciation and extinction.     

Disentangling causes of disjunction on the South Island of New Zealand: the Alpine fault hypothesis of vicariance revisited

Many elements of the flora and fauna of New Zealand's South Island show disjunct distributions with conspecific populations or closely-related species that occur in the north-west and south separated by a central gap. Three events have been implicated to account for this pattern: Pleistocene glaciations, Pliocene mountain building, or displacement along the Alpine fault, the border of the Pacific and Australian plates stretching diagonally across the South Island from south-west to north-east that formed during the Miocene. Disjunct distributions of species level taxa are probably too young to be due to Alpine fault vicariance. It has therefore been suggested that the biogeographical impact of the Alpine fault, if any, should be apparent on deeper phylogenetic levels. We tested this hypothesis by reconstructing the phylogenetic relationships of the hydrobiid gastropods of New Zealand based on mitochondrial DNA fragments of cytochrome oxidase subunit I (CO I ) and 16S rDNA. The creno- and stygobiont species of this family are typically poor dispersers. Therefore, ancient patterns of distribution may be conserved. The phylogenetic reconstructions were in accordance with the Alpine fault hypothesis uniting genera occurring on either side of the fault. Divergence estimates based on a molecular clock of CO I indicated splits predating the Pliocene uplift of the Alps.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 361–374.     

Comparative phylogeography reveals pre‐decline population structure of New Zealand Cyclodina (Reptilia: Scincidae) species

We examined the comparative phylogeography of all species within the endemic New Zealand skink genus Cyclodina to gain insight into the influence of historical processes on the biogeography of the North Island fauna. Until 1–2 kya, six Cyclodina species occurred sympatrically across the North Island of New Zealand. However, most species have undergone dramatic distributional declines subsequent to the introduction of mammals and the arrival of humans. We compare the phylogeographic patterns evident in Cyclodina species in three biogeographic categories: widespread species (Cyclodina aenea, Cyclodina ornata), North Island disjunct relics (Cyclodina macgregori, Cyclodina whitakeri), and northeastern island relics (Cyclodina alani, Cyclodina oliveri, Cyclodina townsi). Mitochondrial DNA (ND2) sequence data was obtained from across the entire range of each Cyclodina species. We used Neighbour‐joining, maximum likelihood and Bayesian methods to examine the phylogeographic patterns present in each species. Phylogeographic patterns varied among species in different biogeographic categories. Substantial phylogeographic structure was evident in the two widespread species (C. aenea, C. ornata), with Pliocene and Pleistocene divergences between clades evident. Divergences among island groups in the three northeastern island relic species (C. alani, C. oliveri, C. townsi) occurred during the late Pliocene–Pleistocene. By contrast, relatively shallow structure, indicative of late Pleistocene divergences, was present in the two North Island disjunct species (C. macgregori, C. whitakeri). The results strongly suggest that the Poor Knights Islands population of C. ornata represents a new species. We suggest that the contrasting phylogeographic patterns exhibited by Cyclodina species in different biogeographic categories might be related to body size, ecology, and habitat preferences. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 388–408.     

Phylogeography of the snakeskin chiton Sypharochiton pelliserpentis (Mollusca: Polyplacophora) around New Zealand: are seasonal near‐shore upwelling events a dynamic barrier to gene flow?

We present a phylogeographic study of the New Zealand and Australian intertidal chiton Sypharochiton pelliserpentis that was conducted to ascertain levels of population connectivity and to investigate the effect of previously hypothesized general phylogeographic boundaries. The analysis incorporated both cytochrome oxidase subunit 1 sequence data (approximately 700 bp) and RFLP data from 29 populations around New Zealand, and from one Australian population, for a total of N = 472. The major population structure observed was a strong disjunction between northern and southern populations (Φ_ST = 0.47), with the genetic breaks located at Cloudy/Clifford Bay and Farewell Spit, at the northern tip of the South Island. This finding corresponds with a common phylogeographic barrier observed in a number of other marine invertebrates, highlighting its significance and ubiquity. A third barrier to gene flow was identified between Spirits Bay and Ahipara, around the northern tip of the North Island. All three of these areas that exhibit significant population disjunctions have strong near‐shore upwelling along with water current movement offshore, and these features are prevalent during the time of year when S. pelliserpentis spawns. That these seasonal hydrographic patterns contribute to the population structuring of S. pelliserpentis is supported by comparison with other phylogeographic studies of marine invertebrates, where the strength of this barrier seems to correlate with spawning season. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 552–563.