Massey Research Online - Browsing by Author "Trewick SA"

Browsing by Author "Trewick SA"

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A new species of large Hemiandrus ground wētā (Orthoptera: Anostostomatidae) from North Island, New Zealand
(Magnolia Press, 2021-03-12) Trewick SA
A new species of Hemiandrus ground wētā is described from North Island, New Zealand. Hemiandrus jacindasp. nov.is larger and more brightly coloured than other species in the region, but appears to be scarce and restricted to remnant native forest habitat.
Climate change and alpine-adapted insects: modelling environmental envelopes of a grasshopper radiation
(The Royal Society, 2022-03-02) Koot EM; Morgan-Richards M; Trewick SA
Mountains create steep environmental gradients that are sensitive barometers of climate change. We calibrated 10 statistical models to formulate ensemble ecological niche models for 12 predominantly alpine, flightless grasshopper species in Aotearoa New Zealand, using their current distributions and current conditions. Niche models were then projected for two future global climate scenarios: representative concentration pathway (RCP) 2.6 (1.0°C rise) and RCP8.5 (3.7°C rise). Results were species specific, with two-thirds of our models suggesting a reduction in potential range for nine species by 2070, but surprisingly, for six species, we predict an increase in potential suitable habitat under mild (+1.0°C) or severe global warming (+3.7°C). However, when the limited dispersal ability of these flightless grasshoppers is taken into account, all 12 species studied are predicted to suffer extreme reductions in range, with a quarter likely to go extinct due to a 96-100% reduction in suitable habitat. Habitat loss is associated with habitat fragmentation that is likely to escalate stochastic vulnerability of remaining populations. Here, we present the predicted outcomes for an endemic radiation of alpine taxa as an exemplar of the challenges that alpine species, both in New Zealand and internationally, are subject to by anthropogenic climate change.
Comparison of growth, relative abundance, and diet of three sympatric Hemiandrus ground wētā (Orthoptera, Anostostomatidae) in a New Zealand Forest
(Pensoft Publishers for the Orthopterists' Society, 2025-01) Chikwature N; Morgan-Richards M; Vereijssen J; Trewick SA
Ecology is an essential discipline for understanding the biology and behavior of organisms. This study increased knowledge of three sympatric species of ground wētā (Hemiandrus spp.). Hemiandrus ground wētā are nocturnal Ensifera that live in burrows during the day, and for these reasons, there is limited knowledge of their activity, development, and diet. We examined the diet of Hemiandrus electra, Hemiandrus ‘disparalis’, and Hemiandrus nox by examining the crop contents of specimens caught in malaise traps set in a native forest (St Arnaud) over seven months during two spring-summer-autumn seasons (2004/2005 and 2005/2006). The three species investigated varied in the plant and invertebrate fragment proportions in their diets. Hemiandrus electra and H. ‘disparalis’ were predominantly herbivores, while H. nox was primarily carnivorous, although plant matter constituted 20% of its diet. We identified the species and sex of 966 Hemiandrus wētā that were intercepted by the same malaise traps. Our results showed that H. electra was the most abundant species, with 701 individuals, while 157 and 109 were identified as H. ‘disparalis’ and H. nox, respectively. Surprisingly, the species with maternal care (H. electra) was the only one of the three sympatric Hemiandrus to have an even sex ratio; for the other two species, more males were caught in the traps. Using hind leg dimensions, we categorized each female H. electra specimen using naïve Gaussian mixture model clustering, which identified five size clusters (putatively corresponding to instars). Based on the month of collection and the growth category, we observed no seasonality in the development of this species of ground wētā, as almost all instars were found in each month of the sampling period. This study found no evidence that these nocturnal forest species synchronize their growth or reproduction with seasons.
De-novo assembly of four rail (Aves: Rallidae) genomes: A resource for comparative genomics.
(John Wiley and Sons Ltd, 2024-07-18) Gaspar J; Trewick SA; Gibb GC
Rails are a phenotypically diverse family of birds that includes 130 species and displays a wide distribution around the world. Here we present annotated genome assemblies for four rails from Aotearoa New Zealand: two native volant species, pūkeko Porphyrio melanotus and mioweka Gallirallus philippensis, and two endemic flightless species takahē Porphyrio hochstetteri and weka Gallirallus australis. Using the sequence read data, heterozygosity was found to be lowest in the endemic flightless species and this probably reflects their relatively small populations. The quality checks and comparison with other rallid genomes showed that the new assemblies were of good quality. This study significantly increases the number of available rallid genomes and will enable future genomic studies on the evolution of this family.
De-novo genome assembly of four rails (Aves: Rallidae): a resource for comparative genomics
(2023-12-25) Gaspar J; Trewick SA; Gibb GC
Effects of population density on adult morphology and life-history traits of female Mediterranean flour moth, Ephestia kuehniella (Lepidoptera: Pyralidae)
(Institute of Entomology, Biology Centre, Czech Academy of Science, České Budějovice, 2022-05-24) Bhavanam S; Trewick SA
Intraspecific competition and food shortage due to high population density during early life can have a profound effect on adult fitness.Organisms often mitigate negative effects of high population density by adjusting resource allocation to adult morphological and life-history traits. In Lepidoptera with short-lived adults that do not feed, it is predicted that females developed from dense larval aggregations invest more in reproduction and traits linked to offspring survival. Here, we investigated the effects of larval population density on adult morphology and life-history traits in the female Mediterranean flour moth, Ephestia kuehniella by raising larvae at a range of population densities. Adults from high population density (16 larvae per g of food) had smaller head, thorax, and forewing compared to other densities. The allometric slope of forewing length with body mass did not differ among population densities, indicating no changes in adult wing morphology at high population density. However, we found that females emerged from larvae at high population density had bigger abdomens relative to body mass, indicating resource investment in reproduction, probably to mitigate the negative effects of crowding on egg production. Ovipositor length did not differ among population densities, indicating conservation of resources to structures with egg-laying function that affect offspring survival. Taken together, these results suggest that female E. kuehniella responding to high larval population density invest relatively more in reproduction, a life-history strategy that could alleviate negative effects of population density on fitness. This study also highlights the importance of a species’ reproductive strategy in its adaptive response to environmental conditions, which is relevant to many capital breeders dependent on larval resources for reproduction.
Food plant odor perception in three sympatric alpine grasshopper species (Orthoptera: Acrididae: Catantopinae) in Aotearoa New Zealand
(Springer Nature, 2024-06-07) Nakano M; Park KC; Trewick SA; Morgan-Richards M
The alpine grasshoppers Sigaus nivalis, Sigaus australis and Sigaus nitidus are sympatric in the central mountains of South Island, Aotearoa New Zealand. These grasshoppers feed on a range of alpine plants but show preference towards dicots over monocots. Because herbivorous insects often use smell and taste to locate and recognize food plants it was expected that these grasshoppers would show sensitivity to their favorite foods and potential sensitivity to nonhost plants. Here, we determined feeding preference in captivity allowing each of these three sympatric grasshoppers the same choice of six native alpine plant species. We analyzed the chemical compositions of the plants used in these experiments using gas-chromatograph coupled with mass-spectrometry (GC-MS) and then recorded olfactory responses in the grasshoppers to plant-derived smells (with synthetic compounds) using electroantennogram (EAG). The grasshoppers were able to distinguish between the potential food plants and ate the shrub Coriaria sarmentosa but not the grass Chionochloa pallens, however, the chemicals we detected in the six plant species were very similar. High sensitivity to fatty acid derived aldehydes (decanal, (E,Z)-2,6-nonadienal, hexanal) and a 6-carbon alcohol ((Z)-2-hexen-1-ol) compared to terpenoids (α-phellandrene, β-myrcene, β-ocimene, eucalyptol, (S)-(-)-limonene, (1S)-(-)-α-pinene) or an aromatic compound (2-phenylethanol) was recorded in the antennae of all three grasshopper species and no species- or sex-specific sensitivity to particular compounds was observed. As aldehydes and alcohols are emitted upon plant damage, it is possible that these generalist grasshoppers are sensitive to the smells of damaged plants rather than species-specific plant smells.
Forecasting Range Shifts in Terrestrial Alpine Insects Under Global Warming
(John Wiley and Sons Incorporated, Hoboken, New Jersey, 2025-01) Meza-Joya FL; Morgan-Richards M; Trewick SA
Anthropogenic planetary heating is disrupting global alpine systems, but our ability to empirically measure and predict responses in alpine species distributions is impaired by a lack of comprehensive data and technical limitations. We conducted a comprehensive, semi-quantitative review of empirical studies on contemporary range shifts in alpine insects driven by climate heating, drawing attention to methodological issues and potential biotic and abiotic factors influencing variation in responses. We highlight case studies showing how range dynamics may affect standing genetic variation and adaptive potential and discuss how data integration frameworks can improve forecasts. Although biotic and abiotic factors influence individual species responses, most alpine insects studied so far are shifting to higher elevations. Upslope shifts are often accompanied by range contractions that are expected to diminish species genetic variation and adaptive potential, increasing extinction risk. Endemic species on islands are predicted to be especially vulnerable. Inferences drawn from the responses of alpine insects, also have relevance to species in other montane habitats. Correlative niche modelling is a keystone tool to predict range responses to planetary heating, but its limited ability to consider biological processes underpinning species' responses complicates interpretation. Alpine insects exhibit some potential to respond to rising temperatures via genetic change or phenotypic plasticity. Thus, future efforts should incorporate biological processes by using flexible hybrid niche modelling approaches to enhance the biological realism of predictions. Boosting scientific capability to envisage the future of alpine environments and their associated biota is imperative given that the speed and intensity of heating on high-mountain ecosystems can surpass our ability to collect the empirical data required to guide effective conservation planning and management decisions.
Fossil-calibrated phylogenies of Southern cave wētā show dispersal and extinction confound biogeographic signal
(The Royal Society, 2024-02-14) Dowle EJ; Trewick SA; Morgan-Richards M
The biota of continents and islands are commonly considered to have a source-sink relationship, but small islands can harbour distinctive taxa. The distribution of four monotypic genera of Orthoptera on young subantarctic islands indicates a role for long-distance dispersal and extinction. Phylogenetic relationships were inferred from whole mtDNA genomes and nuclear sequences (45S cassette; four histones). We used a fossil and one palaeogeographic event to calibrate molecular clock analysis. We confirm that neither the Australian nor Aotearoa-New Zealand Rhaphidophoridae faunas are monophyletic. The radiation of Macropathinae may have begun in the late Jurassic, but trans-oceanic dispersal is required to explain the current distribution of some lineages within this subfamily. Dating the most recent common ancestor of seven island endemic species with their nearest mainland relative suggests that each existed long before their island home was available. Time estimates from our fossil-calibrated molecular clock analysis suggest several lineages have not been detected on mainland New Zealand, Australia, or elsewhere most probably due to their extinction, providing evidence that patterns of extinction, which are not consistently linked to range size or lineage age, confound biogeographic signal.
Genotypic detection of barriers to rat dispersal: Rattus rattus behind a peninsula predator-proof fence.
(Springer Nature, 2023-02-06) Yarita S; Morgan-Richards M; Trewick SA
Clear delimitation of management units is essential for effective management of invasive species. Analysis of population genetic structure of target species can improve identification and interpretation of natural and artificial barriers to dispersal. In Aotearoa New Zealand where the introduced ship rat (Rattus rattus) is a major threat to native biodiversity, effective suppression of pest numbers requires removal and limitation of reinvasion from outside the managed population. We contrasted population genetic structure in rat populations over a wide scale without known barriers, with structure over a fine scale with potential barriers to dispersal. MtDNA D-loop sequences and microsatellite genotypes resolved little genetic structure in southern North Island population samples of ship rat 100 km apart. In contrast, samples from major islands differed significantly for both mtDNA and nuclear markers. We also compared ship rats collected within a small peninsula reserve bounded by sea, suburbs and, more recently, a predator fence with rats in the surrounding forest. Here, mtDNA did not differ but genotypes from 14 nuclear loci were sufficient to distinguish the fenced population. This suggests that natural (sea) and artificial barriers (town, fence) are effectively limiting gene flow among ship rat populations over the short distance (~ 500 m) between the peninsula reserve and surrounding forest. The effectiveness of the fence alone is not clear given it is a recent feature and no historical samples exist; resampling population genetic diversity over time will improve understanding. Nonetheless, the current genetic isolation of the fenced rat population suggests that rat eradication is a sensible management option given that reinvasion appears to be limited and could probably be managed with a biosecurity programme.
Global warming leads to habitat loss and genetic erosion of alpine biodiversity
(John Wiley and Sons Ltd, 2023-03-11) Meza-Joya FL; Morgan-Richards M; Koot EM; Trewick SA; Parmakelis A
Aim Species living on steep environmental gradients are expected to be especially sensitive to global climate change, but little is known about the factors influencing their responses to contemporary warming. Here, we investigate the influence of climate on the biogeography of three alpine species with overlapping ranges. Location Te Waipounamu (South Island) Aotearoa–New Zealand. Taxon Endemic alpine adapted Catantopinae grasshoppers. Methods We used niche modelling to estimate and project the potential niche of three focal species under past and future climate scenarios. Vulnerability assessments were performed using niche factor analyses. Demographic trends and phylogeographic structure were investigated using samples from 15 mountain tops to generate mitochondrial DNA haplotype networks and population genetic statistics. Results Niche models and genetic data suggest suitable habitat for all three alpine species was more widespread and contiguous in the past than today. Demographic analyses indicate in situ survival rather than post-Pleistocene colonisation of current habitat. Population structuring and genetic divergence suggest that mountain uplift during the Pliocene and environmental barriers during Pleistocene glacial and interglacial stages shaped contemporary population structure of each species. Although geographically overlapping, niche analyses suggest these alpine species are not ecologically identical, each showing distinct responses to environmental change, but all will lose intraspecific diversity through population extinction. Main Conclusions Climatic, biological and geophysical factors controlled population structuring of three cold-adapted species during the Pleistocene with a legacy of spatially separate intraspecific lineages. Ecological niche models for each species emphasise distinct combinations of environmental proxies, but all are expected to experience severe habitat reduction during climate warming. Increased global temperatures drive available habitat to higher elevation resulting in population contractions, range shifts, habitat fragmentation, local extinctions and genetic impoverishment. Despite alpine species not being ecologically identical, we predict all mountain biota will lose significant genetic diversity due to global warming.
High alpine sorcerers: Revision of the cave wētā genus Pharmacus Pictet & de Saussure (Orthoptera: Rhaphidophoridae: Macropathinae), with the description of six new species and three new subspecies
(Consortium of European Natural History Museums, 2022-04-04) Hegg D; Morgan-Richards M; Trewick SA; Robillard T; Tan M-K; Fernández P
The New Zealand alpine cave wētā genus Pharmacus was first described by Pictet & de Saussure (1893) as a monotypic taxon. Three species were added to the genus by Richards in 1972. Here we clarify the status and appearance of all known species of Pharmacus. Based on morphology and mtDNA sequences we determine that the species Pharmacus brewsterensis Richards, 1972 is better placed within the genus Notoplectron Richards, 1964. We also resolve the species Isoplectron cochleatum Karny, 1935 and show that it belongs to the genus Pharmacus. Additionally, we describe six new species and three new subspecies from the southern regions of South Island, New Zealand. We provide key traits and known distributions for all known species and subspecies in this alpine genus. New combinations: Pharmacus brewsterensis Richards, 1972 becomes Notoplectron brewsterense (Richards, 1972) comb. nov.; Isoplectron cochleatum Karny, 1935 becomes Pharmacus cochleatus (Karny, 1935) comb. nov. New species and subspecies: Pharmacus cochleatus rawhiti subsp. nov., Pharmacus cochleatus fiordensis subsp. nov., Pharmacus cochleatus nauclerus subsp. nov., Pharmacus concinnus sp. nov., Pharmacus cristatus sp. nov., Pharmacus notabilis sp. nov., Pharmacus perfidus sp. nov., Pharmacus senex sp. nov. and Pharmacus vallestris sp. nov. New synonyms: Pharmacus dumbletoni Richards, 1972 = Pharmacus montanus Pictet & de Saussure, 1893 syn. nov.; Pharmacus chapmanae Richards, 1972 = Pharmacus cochleatus (Karny, 1935) syn. nov.
High-resolution stable isotope profiles from shells of the land snail Placostylus reveal contrasting patterns between snails originating from New Zealand and New Caledonia
(John Wiley and Sons Ltd, 2023-05-31) Quenu M; Judd EJ; Morgan-Richards M; Trewick SA; Holt K; Tyler J; Lorrey AM
The stable oxygen (δ18Oshell) and carbon (δ13Cshell) isotope ratios retrieved from the carbonate shell of terrestrial gastropods can be used as an environmental proxy and are thought to reflect dietary composition and ambient climatic conditions (e.g. precipitation amount, humidity, temperature). Here, we generate high-resolution isotopic profiles of nine modern land snails of the genus Placostylus, collected from two locations in New Caledonia and one location in New Zealand. We found that snails from New Zealand had, on average, higher δ18Oshell values than their counterparts in New Caledonia, which surprisingly runs counter to the expected relationship based on the isotopic composition of rainwater between these two regions. Specimens from New Caledonia exhibit ephemeral decreases in their δ18Oshell values, which could be linked to extreme precipitation events in this region, while snails from New Zealand have less variation in their δ18Oshell values. Snails from New Zealand had, on average, slightly higher δ13Cshell than their counterparts in New Caledonia, but a large difference in carbon isotopes was sometimes observed between snails collected at the same location. Most snails exhibit a temporal trend in their δ13Cshell values, indicating potential shifts in diet through to maturity.
Insect Freeze-Tolerance Downunder: The Microbial Connection
(MDPI (Basel, Switzerland), 2023-01-13) Morgan-Richards M; Marshall CJ; Biggs PJ; Trewick SA; Hoffmann KH
Insects that are freeze-tolerant start freezing at high sub-zero temperatures and produce small ice crystals. They do this using ice-nucleating agents that facilitate intercellular ice growth and prevent formation of large crystals where they can damage tissues. In Aotearoa/New Zealand the majority of cold adapted invertebrates studied survive freezing at any time of year, with ice formation beginning in the rich microbiome of the gut. Some freeze-tolerant insects are known to host symbiotic bacteria and/or fungi that produce ice-nucleating agents and we speculate that gut microbes of many New Zealand insects may provide ice-nucleating active compounds that moderate freezing. We consider too the possibility that evolutionary disparate freeze-tolerant insect species share gut microbes that are a source of ice-nucleating agents and so we describe potential transmission pathways of shared gut fauna. Despite more than 30 years of research into the freeze-tolerant mechanisms of Southern Hemisphere insects, the role of exogenous ice-nucleating agents has been neglected. Key traits of three New Zealand freeze-tolerant lineages are considered in light of the supercooling point (temperature of ice crystal formation) of microbial ice-nucleating particles, the initiation site of freezing, and the implications for invertebrate parasites. We outline approaches that could be used to investigate potential sources of ice-nucleating agents in freeze-tolerant insects and the tools employed to study insect microbiomes.
Introduced mammalian predators influence demography and trait variation of a New Zealand stag beetle
(Springer Nature, 2024-08-01) Grey L; Trewick SA; Johnson SL
Abstract: Most species co-evolve with their predators and develop strategies to avoid predation. This is not possible when a novel predator invades an environment. Native residents must quickly adapt to their new predator or face local extinction. Intense competition for mating opportunities exerts significant selective pressure that can drive the evolution of exaggerated structures across taxa. However, these elaborate traits can elevate the risk of predation for some organisms. In the present study, we observe the effect that rats have had on a population of endemic New Zealand stag beetles, Geodorcus helmsi. Rats in Rakiura | Stewart Island often prey on stag beetles, taking them to a sheltered area to eat them and discard any uneaten parts of the beetle, namely the head and mandibles. We compared the head size, mandible size and numbers of predated and non-predated male and female beetles in three sites in Rakiura | Stewart Island that differ in their abundance of mammalian predators. We found that the population demography and the size of the beetles differed significantly between sites. Additionally, we determined whether predated beetles were larger than non-predated beetles, across multiple years, regardless of site. We found that overall the predated specimens were larger than the non-predated beetles. The trends found here suggest that exaggeration of the male mandibles increases the predation risk of these iconic beetles, acting as a limit to mandible size. Implications for insect conservation: Our results show for the first time the effect that novel predators can have on a population of animals with exaggerated sexually selected traits. The presence of novel predators can cause a shift in both population demography and trait distribution.
Lack of assortative mating might explain reduced phenotypic differentiation where two grasshopper species meet
(John Wiley and Sons Ltd on behalf of European Society for Evolutionary Biology, 2022-04-12) Morgan-Richards M; Vilcot M; Trewick SA
Hybridization is an evolutionary process with wide-ranging potential outcomes, from providing populations with important genetic variation for adaptation to being a substantial fitness cost leading to extinction. Here, we focussed on putative hybridization between two morphologically distinct species of New Zealand grasshopper. We collected Phaulacridium marginale and Phaulacridium otagoense specimens from a region where mitochondrial introgression had been detected and where their habitat has been modified by introduced mammals eating the natural vegetation and by the colonization of many non-native plant species. In contrast to observations in the 1970s, our sampling of wild pairs of grasshoppers in copula provided no evidence of assortative mating with respect to species. Geometric morphometrics on pronotum shape of individuals from areas of sympatry detected phenotypically intermediate specimens (putative hybrids), and the distribution of phenotypes in most areas of sympatry was found to be unimodal. These results suggest that hybridization associated with anthropogenic habitat changes has led to these closely related species forming a hybrid swarm, with random mating. Without evidence of hybrid disadvantage, we suggest a novel hybrid lineage might eventually result from the merging of these two species.
Mwhitiwhiti Aotearoa: Phylogeny and synonymy of the silent alpine grasshopper radiation of New Zealand (Orthoptera: Acrididae)
(Magnolia Press, 2023-12-11) Trewick SA; Koot EM; Morgan-Richards M
Aotearoa New Zealand has a fauna of endemic alpine grasshoppers, consisting of thirteen species distributed among four genera. The many re-classifications of species within this group and the presence of species complexes highlight the uncertainty that surrounds relationships within and between these genera. High-throughput Next Generation Sequencing was used to assemble the complete mitochondrial genomes, 45S ribosomal cassettes and histone sequences of New Zealands four endemic alpine genera: Alpinacris, Brachaspis, Paprides and Sigaus. Phylogenetic analysis of these molecular datasets, as individual genes, partitions and combinations returned a consistent topology that is incompatible with the current classification. The genera Sigaus, Alpinacris, and Paprides all exhibit paraphyly. A consideration of the pronotum, epiphallus and terminalia of adult specimens reveals species-specific differences, but fails to provide compelling evidence for species groups justifying distinct genera. In combination with phylogenetic, morphological and spatial evidence we propose a simplified taxonomy consisting of a single genus for the mwhitiwhiti Aotearoa species radiation.
New Caledonian rovers and the historical biogeography of a hyper-diverse endemic lineage of South Pacific leaf beetles
(John Wiley & Sons Ltd on behalf of Royal Entomological Society, 2024-10-01) Platania L; Cardoso A; Anderson M; Fikáček M; Gauthier J; Hendrich L; Mille C; Morii Y; Reid CAM; Seidel M; Morgan-Richards M; Trewick SA; Toussaint EFA; Gómez-Zurita J
South Pacific archipelagos are central in the biogeographic debate on the relative importance of vicariance and dispersal in shaping the distribution of species. However, each taxonomic group was subject to different processes and histories, and here, we reveal the historical biogeography of the diverse Eumolpinae leaf beetles, widely distributed in the region. Extensive taxon sampling focusing on South Pacific Eumolpinae was used to infer the first molecular phylogeny of the group using three single-copy protein-coding nuclear and two mitochondrial markers. Upon assessing the clade of interest for lineage-specific variation in substitution rates, the age of the most recent common ancestors was estimated using out-group calibration and multi-gamma site models (MGSMs). Biogeographic analyses used standard event-based inferences also incorporating phylogenetic uncertainty. Zealandian Eumolpinae are monophyletic and appear to have split from their global relatives in the transition from the Cretaceous to the Paleogene. Variation in the rates of molecular evolution affected the in-group stem branch, with a significant drop in the substitution rate, and the MGSM correction recovered the crown age of Zealandian Eumolpinae during the Late Eocene–Oligocene transition. Biogeographic inference resolved the origin of the radiation in New Caledonia, favouring a null model without island age constraints, and repeated dispersal events to the other islands, including three independent but synchronous colonisations of New Zealand during the Miocene. New Caledonia, with a highly diverse Eumolpinae fauna of uncertain origin, acted as a hub and pump of biodiversity of these beetles in the entire South Pacific region, sending migrants to other islands through long-distance dispersal with lineages establishing when land became available.
Ngāokeoke Aotearoa: The Peripatoides Onychophora of New Zealand
(MDPI (Basel, Switzerland), 2024-04-04) Trewick SA; Koot EM; Morgan-Richards M; Allegrucci G
(1) Background: Originally described as a single taxon, Peripatoides novaezealandiae (Hutton, 1876) are distributed across both main islands of New Zealand; the existence of multiple distinct lineages of live-bearing Onychophora across this spatial range has gradually emerged. Morphological conservatism obscured the true endemic diversity, and the inclusion of molecular tools has been instrumental in revealing these cryptic taxa. (2) Methods: Here, we review the diversity of the ovoviviparous Onychophora of New Zealand through a re-analysis of allozyme genotype data, mitochondrial DNA cytochrome oxidase subunit I sequences, geographic information and morphology. (3) Results: New analysis of the multilocus biallelic nuclear data using methods that do not require a priori assumptions of population assignment support at least six lineages of ovoviviparous Peripatoides in northern New Zealand, and mtDNA sequence variation is consistent with these divisions. Expansion of mitochondrial DNA sequence data, including representation of all existing taxa and additional populations extends our knowledge of the scale of sympatry among taxa and shows that three other lineages from southern South Island can be added to the Peripatoides list, and names are proposed here. In total, 10 species of Peripatoides can be recognised with current data.
Phenotypic and genetic divergence in a cold-adapted grasshopper may lead to lineage-specific responses to rapid climate change
(John Wiley and Sons Ltd, 2024-04-12) Meza-Joya FL; Morgan-Richards M; Trewick SA; Briski E
Aim: Species responses to global warming will depend on intraspecific diversity, yet studies of factors governing biogeographic patterns of variability are scarce. Here, we investigate the evolutionary processes underlying genetic and phenotypic diversity in the flightless and cold-adapted grasshopper Sigaus piliferus, and project its suitable space in time. Location: Te Ika-a-Māui Aotearoa—North Island of New Zealand. Methods: We used mitochondrial sequences to investigate population connectivity and demographic trends using phylogeographic tools and neutrality statistics. Metric data were used to document phenotypic variation using naïve clustering. We used niche metrics to assess intraspecific niche variation, and niche modelling to investigate suitability under past and future scenarios. Multiple matrix regressions with randomization explored the processes contributing to phenotypic differentiation among grasshopper populations. Results: Niche models and demographic analyses suggest suitable space for this grasshopper was more restricted during glacial than interglacial stages. Genealogical relationships among ND2 haplotypes revealed a deep north–south split partly concordant with phenotypic and niche variation, suggesting two ecotypes that have mixed during recolonisation of the central volcanic region. Multiple matrix regressions with randomization indicate a link between climate and phenotypic differentiation inferred from leg and pronotum dimensions but not pronotum shape. Niche projections predict severe habitat reduction due to climate warming. Main conclusions: The current distribution and intraspecific diversity of S. piliferus reflect complex biogeographical scenarios consistent with Quaternary climates and volcanism. Phenotypic divergence appears adaptive. Current levels of genetic and phenotypic variation suggest adaptive potential, yet the pace of anthropogenic warming over the next 50 years could result in small populations that may collapse before adapting. Differences in niche features between diverging intraspecific lineages suggest distinct responses to climate change, and this has implications for prioritising conservation actions and management strategies.

Browsing by Author "Trewick SA"

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