Browsing by Author "Meza-Joya FL"

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    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.
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    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.
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    Relationships among body size components of three flightless New Zealand grasshopper species (Orthoptera, Acrididae) and their ecological applications
    (Pensoft Publishers on behalf of the Orthopterists’ Society, 2022-06-16) Meza-Joya FL; Morgan-Richards M; Trewick SA; Cigliano M-M
    Body size is perhaps the most fundamental property of an organism and is central to ecology at multiple scales, yet obtaining accurate estimates of ecologically meaningful size metrics, such as body mass, is often impractical. Allometric scaling and mass-to-mass relationships have been used as alternative approaches to model the expected body mass of many species. However, models for predicting body size in key herbivorous insects, such as grasshoppers, exist only at the family level. To address this data gap, we collected empirical body size data (hind femur length and width, pronotum length, live fresh mass, ethanol-preserved mass, and dry mass) from 368 adult grasshoppers of three flightless species at Hamilton Peak, Southern Alps, New Zealand. We examined the relationships among body size components across all species using linear and non-linear regression models. Femur length and preserved mass were robust predictors of both fresh mass and dry mass across all species; however, regressions using preserved mass as a predictor always showed higher predictive power than those using femur length. Based on our results, we developed species-specific statistical linear mixed-effects models to estimate the fresh and dry masses of individual grasshoppers from their preserved mass and femur length. Including sex as an additional co-variate increased model fit in some cases but did not produce better estimates than traditional mass-to-mass and allometric scaling regressions. Overall, our results showed that two easy-to-measure, unambiguous, highly repeatable, and non-destructive size measures (i.e., preserved mass and femur length) can predict, to an informative level of accuracy, fresh and dry body mass across three flightless grasshopper species. Knowledge about the relationships between body dimensions and body mass estimates in these grasshoppers has several important ecological applications, which are discussed.