Browsing by Author "Trewick SA"

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A new species of Celatoblatta cockroach that coincides with the distribution of kauri forests in New Zealand
(Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2025-07-16) Morgan-Richards M; Trewick SA
A new species of Blattidae cockroach is described from northern Aotearoa New Zealand. Celatoblatta kauri sp. nov. can be distinguished from similar conspecific species by its distinctive facial markings. The recorded distribution of Celatoblatta kauri sp. nov. matches that of the historic distribution of kauri forest (Agathis australis) in northern New Zealand. Zoobank LSID: urn:lsid:zoobank.org:pub:93794424-1A7B-4CCA-A7A1-A303BCE8EACA.
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.
Cretaceous Connections Among Camel Cricket Lineages in the Himalaya Revealed Through Fossil-Calibrated Mitogenomic Phylogenetics
(MDPI (Basel, Switzerland), 2025-07-01) Dorji C; Morgan-Richards M; Trewick SA; Heller K-G
The nocturnal, flightless camel crickets (Rhaphidophoridae) have a global distribution and are believed to have originated prior to the breakup of Pangea. We investigated the phylogeny and the timing of the radiation of East Asian species with mitogenomic data. Initially we analyzed a large taxon dataset (n = 117) using available partial mitochondrial and nuclear DNA sequences to confirm the monophyly of subfamilies and current taxonomy. Our findings support the monophyly of each genus within the subfamily Aemodogryllinae, with a minor inconsistency between taxonomy and phylogeny resolved by resurrection of the genus Gymnaeta Adelung. Fossil-calibrated molecular clock analysis used 11,124 bp alignment of 13 complete mitochondrial protein-coding genes for 20 species of Rhaphidophoridae, with a focus on the neglected Rhaphidophorinae and Aemodogryllinae lineages. Divergence time estimates suggest that the most recent common ancestor of the family lived during the Early Jurassic (189 Mya ± 23 Mya) before Pangea broke into the supercontinents or possibly during the early stage of breakup when Gondwana and Laurasia were still connected by land. The two subfamilies, Rhaphidophorinae and Aemodogryllinae, that overlap in Asia are estimated to have diverged 138 Mya ± 17 Mya, well before the Late Cretaceous northern connection between America and Asia (the Bering Land Bridge). Thus, our extended sampling of species from East Asia and Oceania refutes the importance of continental drift in the evolution of this wingless orthopteran family.
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.
Integrative taxonomic revision of the Australian cave cricket Speleotettix Chopard, 1944 (Orthoptera: Rhaphidophoridae): New species, distribution and conservation implications
(John Wiley and Sons Australia, Ltd on behalf of Australian Entomological Society, 2025-08-01) Beasley-Hall PG; Trewick SA; Hedges BA; Cooper SJB; Reed EH; Austin AD
Cave crickets, also called wētā, are an important component of subterranean realms globally, but the true diversity of the group is poorly known. Speleotettix Chopard, 1944 contains two species from southeast Australia, Speleotettix tindalei Chopard, 1944 and Speleotettix chopardi (Karny, 1935). However, the initial description of the genus was poorly characterised, and its taxonomy has remained unclear since. Here, we take an integrative molecular and morphological approach to redescribe Speleotettix and describe three new species: Speleotettix aolae Beasley-Hall, sp. nov. from Victoria and Speleotettix binoomea Beasley-Hall, sp. nov. from New South Wales, both found in limestone caves, and Speleotettix palaga Beasley-Hall, sp. nov. from mineshafts in Victoria. To provide consistency in future work on the group, we also redescribe S. tindalei and treat S. chopardi as a nomen dubium. Finally, we transfer the threatened species Cavernotettix craggiensis Richards, 1974, an island species from Tasmania's Bass Strait, into the genus as Speleotettix craggiensis (Richards, 1974) comb. nov. In so doing, we increase the number of described rhaphidophorid species in Australia to 27 and significantly expand the distribution of Speleotettix, making it the most widespread of the Australian genera currently known. As all members of Speleotettix are short-range endemics at risk of decline, these findings have implications for their future conservation management.
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.
Molecular phylogenetics illuminates the evolutionary history and hidden diversity of Australian cave crick ets (Orthoptera: Rhaphidophoridae)
(John Wiley and Sons Ltd on behalf of Royal Entomological Society., 2025-06-23) Beasley-Hall PG; Trewick SA; Eberhard SM; Zwick A; Reed EH; Cooper SJB; Austin AD; Blaimer B
Cave crickets (Orthoptera: Rhaphidophoridae) are a globally distributed group of insects found in dark, humid microhabitats including natural caves, alpine scree, and forest litter. Ten extant subfamilies are currently recognised, of which Macropathinae, which comprises the entirety of the fauna in South America, South Africa, Australia, and New Zealand, is thought to be the most ancient. New Zealand comprises high phylogenetic diversity of Rhaphidophoridae throughout its mesic zone, with most species occurring above ground. In contrast, the Australian fauna is poorly known and contains an apparently greater relative proportion of species utilising caves as refugia. A robust phylogenetic framework is needed to underpin future taxonomic work on the group and uncover potentially contrasting patterns of taxonomic diversity. Here, we performed fossil-calibrated phylogenetic analysis using whole mitochondrial genomes and nuclear markers to reconstruct the evolutionary history of Macropathinae with a focus on the Australian fauna. By dramatically increasing taxon sampling relative to past studies, we recovered the Australian fauna as rampantly polyphyletic, with the remaining Macropathinae nested among six distinct Australian lineages. Deep divergences between major clades imply additional Australian lineages remain undetected, either due to extinction or sampling bias, and have likely confounded past biogeographic signal. We inferred the radiation of Macropathinae began during the Lower Cretaceous prior to the fragmentation of Gondwana with a potential Pangaean origin for Rhaphidophoridae. Finally, we found evidence for several undescribed species and genera of Australian Macropathinae, all of which qualify as short-range endemics, and discuss the conservation implications of these restricted distributions.