Chatham Islands Research Articles

The importance of replicating genomic analyses to verify phylogenetic signal for recently evolved lineages.

Genomewide SNP data generated by nontargeted methods such as RAD and GBS are increasingly being used in phylogenetic and phylogeographic analyses. When these methods are used in the absence of a reference genome, however, little is known about the locations and evolution of the SNPs. In using such data to address phylogenetic questions, researchers risk drawing false conclusions, particularly if a representative number of SNPs is not obtained. Here, we empirically test the robustness of phylogenetic inference based on SNP data for closely related lineages. We conducted a genomewide analysis of 75712 SNPs, generated via GBS, of southern bull-kelp (Durvillaea). Durvillaea chathamensis co-occurs with D.antarctica on Chatham Island, but the two species have previously been found to be so genetically similar that the status of the former has been questioned. Our results show that D.chathamensis, which differs from D.antarctica ecologically as well as morphologically, is indeed a reproductively isolated species. Furthermore, our replicated analyses show that D.chathamensis cannot be reliably distinguished phylogenetically from closely related D.antarctica using subsets (ranging in size from 400 to 10 000 sites) of the 40 912 parsimony-informative SNPs in our data set and that bootstrap values alone can give misleading impressions of the strength of phylogenetic inferences. These results highlight the importance of independently replicating SNP analyses to verify that phylogenetic inferences based on nontargeted SNP data are robust. Our study also demonstrates that modern genomic approaches can be used to identify cases of recent or incipient speciation that traditional approaches (e.g. Sanger sequencing of a few loci) may be unable to detect or resolve.

Phylogeography of the Lessonia variegata species complex (Phaeophyceae, Laminariales) in New Zealand

A goal of phylogeography is to relate phylogenetic patterns to potential historic and contemporary geographic isolating events. Genetic breaks found in phylogeographic studies may denote boundaries between more generally applicable biogeographic regions. We investigated the distribution of Lessonia variegata, an important habitat forming alga, found on most rocky shores around New Zealand’s main islands, plus related species from surrounding waters. L. variegata has been shown to consist of four distinct cryptic species. Our aim was to compare the distribution of L. variegata with proposed bioregions; and to develop phylogeographic hypotheses to explain its present day distribution. Both a mitochondrial (atp8-sp) and plastid (RuBisCo spacer) marker, with different mutation rates, were used to gain information of the phylogenetic history of Lessonia. The data revealed high phylogeographic structuring and reciprocal endemism for all L. variegata cryptic species. One species (L. variegata / N) is confined to the northern part of the North Island of New Zealand; L. variegata / W is found at the southeast of the North Island and the northern South Island; L. variegata / K is endemic to the northeast South Island; and L. variegata / S is restricted to the southern part of the South Island. No overlapping areas of L. variegata species distribution were found. The data showed that genetic breaks in Lessonia do mostly correlate to bioregions, and highlight the importance of Cape Campbell at the northeast of the South Island and East Cape in the North Island, well known phylogeographic breaks, as a barrier between adjacent species. Key words: bioregions; Chatham Islands; Lessonia; mitochondrial marker; Phaeophyceae; plastid marker; Subantarctic islands

South polar greenhouse insects (Arthropoda: Insecta: Coleoptera) from the mid-Cretaceous Tupuangi Formation, Chatham Islands, eastern Zealandia

Stilwell, J.D., Vitacca, J. & Mays, C., April 2016. South polar greenhouse insects (Arthropoda: Insecta: Coleoptera) from the mid-Cretaceous Tupuangi Formation, Chatham Islands, eastern Zealandia. Alcheringa 40, xxx–xxx. ISSN 0311-5518 Rare insect body fossils have been discovered for the first time after 175 years of research on the Chatham Islands, eastern ‘Zealandia’. The coleopteran (beetle) insects, dated to ca 95 Ma and extracted from fine-grained, upper delta plain facies in the lower Upper Cretaceous (Cenomanian–lowermost Turonian) Tupuangi Formation at Waihere Bay on the remote Pitt Island, represent the most southern, polar-latitude (ca 70–80°S) faunal assemblage from the Cretaceous recorded to date. Three species are represented in the insect fauna: a portion of a segmented abdomen of a probable carabid? ground beetle and two distinct coleopteran elytra, one preserved with a brilliantly iridescent carapace upon discovery, comparable with Cretaceous taxa within the Buprestidae (metallic wood borers), but identification with the Chrysomelidae (leaf beetles) or Tenebrionidae (darkling beetles) can not be discounted entirely. Another specimen has more weakly preserved greenish iridescence and has a morphology consistent with Carabidae; given the preservational deficiencies and rarity of material, the specimens are attributed to Buprestidae? genus et species indeterminate and Carabidae? genus et species indeterminate A and B, respectively. These coleopteran fossils represent the only recorded iridescence in Mesozoic invertebrates from Zealandia. Importantly, these mid-Cretaceous insects existed in South Polar forests near the height of the ‘hothouse’ phase of relatively warm, alternating intervals of full daylight in the summer months and total darkness during the winter, before eastern Zealandia diverged at ca 83 Ma from the Marie Byrd Land region of West Antarctica, as part of the final break-up of Gondwana. Jeffrey D. Stilwell* [ jeffrey.stilwell@monash.edu ], Jesse V. Vitacca [ jesse.vitacca@gmail.com ] & Chris Mays [ chris.mays@monash.edu ], School of Earth, Atmosphere and Environment, Monash University, Clayton VIC 3800, Australia. *Also affiliated with the Australian Museum, 6 College Street, Sydney NSW 2000, Australia.

Genetic and morphological evidence for two species ofLeucocarboshag (Aves, Pelecaniformes, Phalacrocoracidae) from southern South Island of New Zealand

Leucocarbo shags are a species-rich seabird clade exhibiting a southern circumpolar distribution. New Zealand's endemic Stewart Island shag, Leucocarbo chalconotus (G. R. Gray, 1845), comprises two regional groups (Otago and Foveaux Strait) that show consistent differences in relative frequencies between pied (black and white) and bronze (wholly dark) plumages, the extent and colour of facial carunculation, body size (based on postcranial morphometrics), and breeding season. Moreover, previous genetic research on modern and historical specimens utilizing mitochondrial DNA control-region sequences has also shown that the Otago and Foveaux lineages may not be sister taxa; instead, in several analyses the Otago lineage is sister to the endemic Chatham Island shag, Leucocarbo onslowi (Forbes, 1893). We present new ancient DNA analyses of the type specimens for the Otago and Foveaux Strait lineages of L. chalconotus, including a phylogenetic reanalysis of the available ancient, historical, and modern control-region sequence data for these lineages (including L. onslowi), and additional statistical analyses incorporating new morphometric characters. These analyses indicate that under the diagnosable species concept the two lineages of Stewart Island shag represent two separate species, which we now recognize as the Otago shag, L. chalconotus (G. R. Gray, 1845), and the Foveaux shag, Leucocarbo stewarti (Ogilvie-Grant, 1898).

Geometric morphometrics and molecular systematics of Xanthocnemis sobrina (McLachlan, 1873) (Odonata: Coenagrionidae) and comparison to its congeners.

The taxonomy of the damselfly genus Xanthocnemis is revised, with particular focus on populations inhabiting the North Island of New Zealand. Earlier studies revealed two species: X. sobrina, restricted to cool, shaded streams in kauri forests and other forested areas, and X. zealandica, a common species throughout New Zealand except the Chatham and subantarctic islands. A field study encompassing aquatic habitats throughout the whole North Island was carried out to establish the relationship between morphological variation (body size and various morphological traits over the entire body) observed by previous researchers with ecological conditions and/or geographical location. The main aim was to propose reliable diagnostic features that could be used in future studies. Morphological and molecular variation was assessed. Morphological examination included assigning landmarks for all body parts corresponding to the external morphological features that are usually used in Odonata taxonomy. Molecular analysis targeted fragments of the 28S and 16S rRNA genes. Congruence was sought between both types of data, statistical support for two morphological types previously described as different species and a maximum likelihood phylogenetic tree in conjunction with a pairwise genetic distance matrix constructed from the DNA sequences obtained from the sampled specimens. Geometric morphometrics revealed statistically significant differentiation between specimens identified as X. zealandica and X. sobrina for four traits: (1) dorsal view of the head for both sexes as well as male appendages from (2) dorsal, (3) ventral and (4) lateral views. Wings appeared different when analysed for males only. Molecular analysis, however, grouped all specimens into a single undifferentiated cluster with very low mean pairwise distance (<0.01) between them showing almost no variation at the molecular level among the sampled populations on the North Island. Therefore, an additional analysis of the mitochondrial cytochrome c-oxidase I gene was carried out comparing randomly selected North Island specimens to Xanthocnemis specimens targeted in other molecular studies (Nolan et al. 2007, Amaya-Perilla et al. 2014). The analysis of the COI gene confirmed that all North and South Island isolates of Xanthocnemis cluster together in a well-supported clade with pairwise identity >96% and ~93% pairwise identity with X. tuanuii sequences obtained from the Chatham Island specimens. A careful investigation of the thin plate spline deformations generated for the geometric morphometric landmarks showed that the significant variations in the appendages of the Xanthocnemis specimens appeared to be the result of size, rather than shape, differences. Therefore, X. sobrina is proposed as a synonym of X. zealandica. Recently Amaya-Perilla et al. (2014) synonymised X. sinclairi with X. zealandica and confirmed the status of the Chatham Island X. tuanuii as a distinct species. It is therefore proposed that the genus Xanthocnemis consists of two species only: zealandica occurring all over the North, South and Stewart Islands, and tuanuii, endemic to Chatham and Pitt islands. Considering several statistical tests involving body measurements and ecological variables recorded during the field study, as well as various discussion points from similar studies of other species of Odonata, two alternative hypotheses are proposed for future testing. The first hypothesis synonymises X. sobrina with X. zealandica and suggests a possible explanation for the evolution of the two morphological traits that have previously been considered diagnostic for these species. The second hypothesis suggests that as typical X. sobrina were not sampled during this study this could represent a species that is now extinct, unless future studies prove it otherwise.

Zealandia’s oldest volutes (Mollusca: Gastropoda: Volutidae) from the early Paleogene of South Island and Chatham Islands: post Gondwana break-up and evolutionary divergence

AbstractThe isolation of Zealandia in the latest Cretaceous and early Paleogene following the final break-up of Gondwana fostered significant provincialism in molluscan faunas, concomitant with the segmentation of oceanic circulation patterns and changing climate nearing the end of the greenhouse phase in the Southwest Pacific. The earliest volutes (Gastropoda: Volutidae) from the Zealandian region reflect this isolation after separation from the Marie Byrd Land region of West Antarctica with several endemic groups being recognized for the first time since collecting first started in the Wangaloa Formation at Mitchells Rocks (Wangaloa), South Island, New Zealand in 1869. Five taxa attributed to the Volutidae are described herein from South Island (Wangaloa Formation and Steel Greensand) and also the Chatham Islands (Red Bluff Tuff) from the early (mid-Danian) to late Paleocene (Thanetian?). These comprise a new mid-Danian fulgorariine? genus and species,Wangaluta henaconstrictan. gen. n. sp.; a new combination also from the Wangaloa Formation,Wangaluta? neozelanica(Finlay and Marwick, 1937); two new zidonine volutes, the mid-DanianAlcithoe. s.l.wangaloaensisn. sp. from the Wangaloa Formation, and alsoTeremelon onouan. sp. from the late Paleocene-early Eocene of the Red Bluff Tuff; and a probable volute, Fulgorariine? gen. indet. sp. indet. from the mid-Danian of the Steel Greensand. All of these taxa are endemic in the early Paleogene of New Zealand and represent a significant boost in our knowledge of post-K-Pg boundary diversification of volutid gastropods in the shrinking Weddellian Biotic Province in the southern rim of the Pacific.

Ploughmarks and pits on the Chatham Rise: a record of deep-keeled Antarctic icebergs at 43° 20′ S

Icebergs calved from the Antarctic Ice Sheet have drifted eastwards and northwards into the southern Pacific Ocean carried by the Antarctic Circumpolar Current (ACC). Grounding of these icebergs on the seafloor of Chatham Rise, 500 km east of New Zealand, has produced distinctive linear ploughmarks and circular pits similar to those observed in other parts of the world (e.g. Kudrass & Von Rad 1984; Woodworth-Lynas et al. 1991). The 1000 km long Chatham Rise trends east–west (174° E–176° W), with a width of 250 km, from the east coast of the South Island. A crest water depth of c. 400 m is observed on a significant bathymetric high on Chatham Rise; several shallow banks and the Chatham Islands are also prominent highs. Modern shipborne and Remotely Operated Vehicle (ROV) derived multibeam bathymetric and sidescan sonar data were collected over the Chatham Rise crest, showing iceberg ploughmarks and circular pits. Linear iceberg ploughmarks and circular pits are observed within the area bounded by 43° 20′ – 43° 39′ S latitude and 179° 45′–179° 03′ E longitude …

Unexpected positive and negative effects of continuing inbreeding in one of the world's most inbred wild animals.

Inbreeding depression, the reduced fitness of offspring of related individuals, is a central theme in evolutionary biology. Inbreeding effects are influenced by the genetic makeup of a population, which is driven by any history of genetic bottlenecks and genetic drift. The Chatham Island black robin represents a case of extreme inbreeding following two severe population bottlenecks. We tested whether inbreeding measured by a 20-year pedigree predicted variation in fitness among individuals, despite the high mean level of inbreeding and low genetic diversity in this species. We found that paternal and maternal inbreeding reduced fledgling survival and individual inbreeding reduced juvenile survival, indicating that inbreeding depression affects even this highly inbred population. Close inbreeding also reduced survival for fledglings with less-inbred mothers, but unexpectedly improved survival for fledglings with highly inbred mothers. This counterintuitive interaction could not be explained by various potentially confounding variables. We propose a genetic mechanism, whereby a highly inbred chick with a highly inbred parent inherits a "proven" genotype and thus experiences a fitness advantage, which could explain the interaction. The positive and negative effects we found emphasize that continuing inbreeding can have important effects on individual fitness, even in populations that are already highly inbred.

Revision of Southern Hemisphere taxa referred to Fosterella (Crustacea: Cirripedia), and their extinction in response to Pleistocene cooling.

Extensive barnacle coquinas (barnamols) formed around New Zealand's North and Chatham Islands during the late Pliocene to early Pleistocene. The inner-shelf megabalanine Fosterella is the primary constituent of these lithofacies, which also include epifaunal bivalves, bryozoans and less modified balanids like Notobalanus and Notomegabalanus. The status of genus Fosterella is reviewed, 3 species are retained and a new genus, Porobalanus, is proposed for Fosterella hennigi, a species restricted to the Early Pliocene of Cockburn Island, Antarctica. Significantly, Fosterella did not survive the New Zealand Pleistocene, although Notobalanus and Notomegabalanus, which have fossil records extending back to the Early Miocene, remain important components of present day cool-temperate Southern Hemisphere faunas. Extinction of Fosterella, in shelf waters off Argentina, is explained through a combination of changing circulatory and sedimentary regimes, competition for food and space, predation and physiological constraints. The driver of these factors was rapid regional cooling. Zoobank registration: urn:lsid:zoobank.org:pub:DBB1CB34-83E4-48BA-AA10-81823017F37A.

Checklist and type designations of New Zealand Aleocharinae (Coleoptera: Staphylinidae).

A checklist of all identified species of the staphylinid subfamily Aleocharinae known to occur in New Zealand and associated outer islands (including the Kermadec, Chatham and Auckland Islands) is presented. Included for each species, and for synonyms known from New Zealand, is a reference to the original description, type locality and type depository, and for each species the known distribution within and outside New Zealand. Type material was sought and is summarized for all indigenous New Zealand species, with lectotypes designated for 55 names and confirmation of holotypes and prior designation of lectotypes when necessary. One nomenclatural change is implemented: the preoccupied generic name Gyronotus Cameron is replaced by Marecon Blackwelder. Other taxonomic changes are not made, pending further study and revision that is badly needed. Of the 169 currently known species of Aleocharinae reported from New Zealand, at least 26 are believed to be adventive from elsewhere, two may occur naturally elsewhere, and 141 (83%) are evidently endemic to this region. Of the 65 genera represented by these described species, 27 (42%) are also endemic to the New Zealand region; an additional five genera represented in New Zealand only by unidentified or undescribed species are also noted. Ten genera are adventive. However, the actual aleocharine fauna of New Zealand will undoubtedly be much larger, and the generic composition highly modified, when the fauna is fully explored and studied in a world context.

Assessment of hybridisation between the endangered Chatham Island black robin (Petroica traversi) and the Chatham Island tomtit (Petroica macrocephala chathamensis)

Hybridisation between an endangered species and a more common species can facilitate population decline and extinction of the endangered species due to wasted reproductive effort, outbreeding depression and/or swamping of alleles due to widespread or complete admixture. The Chatham Island black robin (Petroica traversi) is an endangered songbird species, which was reduced to only five individuals in 1980. Intensive cross-fostering, whereby black robin offspring were placed into nests of the closely related Chatham Island tomtit (Petroica macrocephala chathamensis) to increase reproductive output, contributed to the rapid recovery of the species within 10 years. Several hybridisation events occurred and although those hybrids were successfully eliminated from the population, concerns remained for the possibility of introgression between the two species that may have gone unnoticed. In this study, we genotyped seven microsatellite loci in both species from the two islands where they coexist, to assess the level of hybridisation and the extent of introgression between the two species. The two species shared no alleles at five of the seven loci genotyped, and cluster analysis, AMOVA and admixture analysis of a total of 174 black robins and 78 Chatham Island tomtits showed no evidence of hybridisation or introgression on either of the two islands where they co-exist. As a result, there is no evidence that black robins are currently in any danger of population decline or extinction through hybridisation with tomtits, although small population size and skewed sex ratio, particularly in the smaller of the two populations, may facilitate future hybridisation events.

Climatic implications of Ginkgoites waarrensis Douglas emend. from the south polar Tupuangi flora, Late Cretaceous (Cenomanian), Chatham Islands

Abstract The flora of the Cenomanian–Turonian (ca. 96–90 Ma) Tupuangi Formation, Chatham Islands, New Zealand, was inhabiting a region well within the south polar circle (~ 70–80° S) during the early Late Cretaceous, an interval characterised by extreme global greenhouse conditions. The Tupuangi flora offers a unique perspective into an ecological and environmental setting which has no extant analogue, whilst providing proxies of polar palaeoclimatic conditions during a phase of extreme global warming. Ginkgoites waarrensis Douglas, 1965 (emended herein), a species known previously from a single occurrence in Australia, is an abundant element of the Tupuangi flora. Forty-five leaf samples from three localities are reported, and a systematic treatment of this species revealed a wide morphological range. In contrast to the exclusively riparian niche of more recent members of Ginkgoales, associated sedimentological and palaeoecological data suggest that this species had an ecological preference for regularly disturbed, coastal deltaic settings. Herein, we review the geographic and stratigraphic distributions of Cretaceous Gondwanan ginkgoalean leaf taxa. An increasing diversity of this group from the Early Cretaceous to the early Late Cretaceous supports a broader trend of floral provincialisation throughout this interval, most likely driven by concurrent global transgression and active tectonic extension across southern Gondwana. Carbon dioxide has been inferred as a primary proximate cause of the mid-Cretaceous global greenhouse. The leaf cuticles of Ginkgoites waarrensis were utilised to approximate atmospheric carbon dioxide (pCO2) during the Cenomanian. Stomatal index (SI) data were collected from ten specimens, and the stomatal ratio method yielded a semi-quantitative pCO2 estimate of 1150–1350 ppmv, which is consistent with modelled and proxy estimates of the Cenomanian. The present study explores the inherent limitations of the transfer function method for estimating CO2 when applied to taxa with very low SI values, such as G. waarrensis. In addition to pCO2, temperature and irradiance are identified as environmental variables which may have systematically promoted the low SI of G. waarrensis, but their combined influence is likely mitigated by the relatively high temperature of this region during the mid-Cretaceous and the high summer insolation at polar latitudes.

A reassessment of settlement patterns and subsistence at Point Durham, Chatham Island

AbstractOrthodox reconstructions of subsistence and settlement patterns on Chatham Island proposed that throughout the pre‐contact period, Moriori lived within small home ranges and relied for food predominantly on fur seals, with plant foods being of little importance. Reassessment of the Point Durham sites on which these reconstructions were based demonstrates that they were not contemporary, which undermines the orthodox model. Chronological evidence indicates two phases of pre‐contact occupation and that the largest fur seal midden probably derives from the early historical period. During both pre‐contact phases, settlement patterns involved residential mobility between sites of different function along with the transporting of resources over wider territories than the orthodox model allowed. Subsistence evidence shows a shift from initial reliance on fur seals to a broader spectrum of smaller marine animals. Furthermore, new palaeobotanical data indicate that plants, in particular kōpi (Corynocarpus laevigatus), were an important component of diet.

Broad-scale genetic patterns of New Zealand abalone, Haliotis iris, across a distribution spanning 13° latitude and major oceanic water masses.

The New Zealand black-foot abalone, Haliotis iris, or pāua, is endemic to the rocky reefs surrounding New Zealand, whose main land mass spans 13° of latitude and separates the Tasman Sea from the Pacific Ocean. In this study, we examined the population genetic structure of this important commercial, cultural and recreational species by genotyping nine microsatellite loci in 485 pāua from 27 locations distributed across mainland New Zealand and the Chatham Islands. We found low, but significant, levels of genetic differentiation. Key genetic breaks were identified among the Chatham Islands and mainland samples; patterns that are strongly corroborated by prior work employing mtDNA sequences. AMOVAs indicated that samples from the south of the North Island were more similar to the South Island samples than to other North Island samples, however multivariate analysis and Bayesian clustering could not identify a significant pattern. Differentiation between the Chatham Islands and the mainland is most likely due to isolation by distance, while differentiation of North Island samples corresponds with major components of New Zealand's oceanography, Cook Strait and the East Cape. Despite intense fishing pressure, we detected no signature of genetic bottlenecks in any region suggesting that population sizes have remained relatively stable over recent time or that the census size of this species is much larger than its effective population size.

Demographic rates of northern royal albatross at Taiaroa Head, New Zealand.

Demographic rates, such as annual survival rate, are generally difficult to estimate for long-lived seabirds, because of the length of time required for this kind of study and the remoteness of colonies. However, a small colony of northern royal albatross (Diomedea sanfordi) established itself on the mainland of New Zealand at Taiaroa Head, making possible regular banding and monitoring of its individuals since the first chick fledged, in 1938. Data on the presence/absence of birds, as well as on breeding outcomes, were available for the period from 1989–90 to 2011–12, and included 2128 annual resightings of 355 banded individuals of known age. The main goal of the present study was to estimate the annual survival rate of juveniles, pre-breeders, and adults at Taiaroa Head. These rates were estimated simultaneously in a single Bayesian multi-state capture-recapture model. Several models were fitted to the data, with different levels of complexity. From the most parsimonious model, the overall annual adult survival rate was estimated as 0.950 (95% CI [0.941–0.959]). In this model, adult survival declined with age, from 0.976 (95% CI [0.963–0.988]) at 6 years, the minimum age at first breeding, to 0.915 (95% CI [0.879–0.946]) at 40 years. Mean annual survival of pre-breeders was 0.966 (95% CI [0.950–0.980]), and 0.933 (95% CI [0.908–0.966]) for juveniles. There was no discernible difference in survival between males and females, and there was no apparent trend in survival over time. Estimates of other demographic rates were also obtained during the estimation process. The mean age at first return of juveniles to the colony was estimated as 4.8 years (95% CI [4.6–5.1]), and the mean age at first breeding as 8.9 years (95% CI [8.5–9.3]). Because all the birds of the colony were banded, it was possible to estimate the total population size. The number of northern royal albatross present annually at the Taiaroa Head colony has doubled since 1989–90, and the current total population size was estimated to be over 200 individuals. The ratio of the total population size to the number of annual breeding pairs varied from 5 to 12 among years, with an overall mean of 7.65 (95% CI [7.56–7.78]), and this high variability highlights the need for a sufficient number of surveys of seabird breeding populations before reliable conclusions on population trends can be made. Although long-term data allowed estimates of demographic rates of northern royal albatross at Taiaroa Head, the location of the colony and the ongoing management by staff mean that the population dynamics may differ from those of the main population on the Chatham Islands.

‘The miserable remnant of this ill-used people’: colonial genocide and the Moriori of New Zealand's Chatham Islands

Genocide scholars have not engaged with the killing of the Moriori people of New Zealand's Chatham Islands by two Māori iwi (tribes). New Zealand historians who have discussed Moriori have not used the paradigms and language of genocide studies. This article argues that Moriori were victims of genocide, and that their experience both challenges and deepens how colonial genocide is understood. Narratives of colonial genocides that assume the destruction of an indigenous people by a colonizing power are inadequate for understanding events on the Chathams, as are genocidal frameworks that assume perpetrators must be state actors. The colonial role was important but indirect: the encounter of Māori with Britain and Australia provided the physical and ideological tools that made the Moriori genocide possible. Māori behaviour on the Chathams diverged from tradition, with the racial tropes, destructive behaviours and justification for invading the Chathams all acquired through the colonial spread of British people into Polynesia. More recently, the use of imported imagery and politicization of the Moriori experience has revealed the consequences of successive generations’ failure to properly remember or even identify the genocide.

Three new species of the genus Notophthiracarus (Acari: Oribatida: Phthiracaridae), with an updated key to its known species in New Zealand

In this study, three new species of Notophthiracarus (Oribatida: Phthiracaridae) from New Zealand are described: Notophthiracarus sensifus sp. nov. from the Great Barrier Island, Broken Island and Rangiahua Island, Notophthiracarus sigifurcatus sp. nov. from the Bethells Matuku Reserve, Auckland, and Notophthiracarus chatham sp. nov. from the Mid Sisters Islands, Chatham Islands. An updated key to all known species of Notophthiracarus in New Zealand is provided.http://zoobank.org/urn:lsid:zoobank.org:pub:4D823C4A-9165-46CC-BCEF-DF4F6467F9E1

Bryozoa of the Early Eocene Tumaio Limestone, Chatham Island, New Zealand

The rich bryozoan fauna living in the sea around New Zealand at the present day is among the best known globally. However, despite the abundance of bryozoans in Cenozoic deposits onshore, little is known about these faunas and therefore the origin of the modern fauna. Here we describe a previously unstudied bryozoan fauna from the Tumaio Limestone of Early Eocene age on Chatham Island, totalling 77 species (22 Cyclostomata, two Ctenostomata and 53 Cheilostomata). The following new taxa are introduced: Plagioecia zatoni sp. nov., Mesenteripora jamesi sp. nov., Platonea dilatata sp. nov., Zagorsekia gen. nov., Heteropora scholzi sp. nov., Conopeum stamenocelloides sp. nov., Tumaiella dieffenbachi gen. et sp. nov., Marssonopora connexa sp. nov., Amphiblestrum paleogenicum sp. nov., Dactylostega spiralis sp. nov., Pyrisinella primazelandiae sp. nov., Chaperiopsis cookae sp. nov., Pseudothyracella campbelli sp. nov., Cladobryopastor philipi gen. et sp. nov., Floridina elegans sp. nov., Onychocella subtriangulata sp. nov., Melychocella bilamellata sp. nov., Melychocella obliqua sp. nov., Aspidostoma clava sp. nov., A. gelasinus sp. nov., A. twinn sp. nov., A. lamellatum nom. nov., Micropora chathamica sp. nov., Andreella dubia sp. nov., Cellaria bicuspidata sp. nov., C. gigas sp. nov., C. inarticulata sp. nov., C. palatum sp. nov., Quasitrilaminopora curiosa gen. et sp. nov., Moyanopora hugoi gen. et sp. nov., Arachnopusia dimorpha sp. nov., Exechonella chathamensis sp. nov., Diedroporidae fam. nov., Diedropora gravabilis gen. et sp. nov., Adeonellopsis incompta sp. nov., Multescharellina pisiformis sp. nov., Chataimulosia revelator sp. nov., Porella tiorioriensis sp. nov., Hemicyclopora dissidens sp. nov., Hemicyclopora ventricosa sp. nov., Exochella abigailae sp. nov., E. reidae sp. nov., E. woodae sp. nov., E. linearis sp. nov., Illusiopora bifax gen. et sp. nov., I. recta gen. et sp. nov., Gigantopora modesta sp. nov., G. grandis sp. nov., Porina turrita sp. nov., Lacerna ordinaria sp. nov., Phonicosia sinuosa sp. nov., Macrocamera obesa sp. nov., Siphonicytara primitiva sp. nov., S. litotes sp. nov., Osthimosia aurora sp. nov., O. curiosa sp. nov. and Reteporella mediocris sp. nov. Keys are given for New Zealand Cenozoic species of Aspidostoma and Cellaria. The Tumaio bryozoan fauna shows a high degree of endemicity, contains the earliest known records of several cheilostome families, and small colonies of encrusting species that may represent the oldest example of an ‘interstitial’ bryozoan fauna.http://zoobank.org/urn:lsid:zoobank.org:pub:2865FDB5-D812-4102-B5E2-638549D16C95

Sexual size dimorphism in island plants: the niche variation hypothesis and insular size changes

The niche variation hypothesis predicts insular populations exhibit increased sexual size dimorphism (SSD), to minimize intraspecific competition. Although many animal taxa conform to this prediction, insular patterns of SSD have yet to be investigated in plants. Here, we tested for differences in SSD of dioecious plants that colonised four island groups (Kermadec, Three Kings, Chatham and Auckland Islands) from New Zealand. Using herbarium collections, we quantified leaf and stem sizes of 263 individuals from 28 dioecious taxa. We developed a novel analytical technique to explore changes in the direction of SSD on islands. Lastly, we tested for evolutionary size changes of male and female plants on islands. The degree of SSD did not vary predictably between insular and mainland taxa, contrary to predictions of the niche variation hypothesis. Furthermore, the direction of SSD was not predictable on islands, while it was consistently female biased on the mainland. Our results suggest that selection favours increased size of both sexes on islands and that SSD is unpredictable for insular plants.

Herbivory and the evolution of divaricate plants: Structural defences lost on an offshore island

AbstractMany island plants are characterized by unique morphology. For example, the high branching angles and small leaves of divaricate plants are a common feature of the New Zealand flora. The divaricate growth form may be an adaptation to deter browsing by extinct avian herbivores (moa); alternatively aspects of the insular climate may be responsible. However, our understanding of the selective pressures responsible for the high branching angles and small leaves of divaricate plants is incomplete. Here, I tested for differences in traits associated with the divaricate growth form between plants from Chatham Island and the New Zealand mainland. Moa never reached the Chatham Islands and its flora is derived from plants on mainland New Zealand. Therefore, I predicted Chatham Island plants to have lost morphological adaptations that may have deterred moa herbivory. Traits were quantified on 316 individuals in the field, allowing for 12 island‐mainland taxonomic comparisons. Chatham Island plants consistently produced smaller branching angles, larger leaves, shorter internodes and larger stems than related mainland plants. Results are therefore consistent with the hypothesis that selection for small leaves and high angled branching may be relaxed on the Chatham Islands due to an absence of moa. Smaller branching angles and larger leaves may offer a competitive advantage to Chatham Island plants.