Geography and past climate changes have shaped the evolution of a widespread lizard from the Chilean hotspot

Shifts in the Distribution Range and Niche Dynamics of the Globally Threatened Western Tragopan (Tragopan melanocephalus) Due to Climate Change and Human Population Pressure

The impact of a changing climate, particularly global warming, often harms the distribution of pheasants, particularly those with limited endemic ranges. To effectively create plans of action aimed at conserving species facing threats such as the Western Tragopan, (Tragopan melanocephalus; Gray, 1829; Galliformes, found in the western Himalayas), it is crucial to understand how future distributions may be affected by anticipated climate change. This study utilized MaxEnt modeling to assess how suitable the habitat of the targeted species is likely to be under different climate scenarios. While similar studies have been conducted regionally, there has been no research on this particular endemic animal species found in the western Himalayas throughout the entire distribution range. The study utilized a total of 200 occurrence points; 19 bioclimatic, four anthropogenic, three topographic, and a vegetation variable were also used. To determine the most fitting model, species distribution modeling (SDM) was employed, and the MaxEnt calibration and optimization techniques were utilized. Data for projected climate scenarios of the 2050s and 2070s were obtained from SSPs 245 and SSPs 585. Among all the variables analyzed; aspect, precipitation of coldest quarter, mean diurnal range, enhanced vegetation index, precipitation of driest month, temperature seasonality, annual precipitation, human footprint, precipitation of driest quarter, and temperature annual range were recognized as the most influential drivers, in that order. The predicted scenarios had high accuracy values (AUC-ROC > 0.9). Based on the feedback provided by the inhabitants, it was observed that the livability of the selected species could potentially rise (between 3.7 to 13%) in all projected scenarios of climate change, because this species is relocating towards the northern regions of the elevation gradient, which is farther from the residential areas, and their habitats are shrinking. The suitable habitats of the Tragopan melanocephalus in the Himalayan region will move significantly by 725 m upwards, because of predicted climate change. However, the fact that the species is considered extinct in most areas and only found in small patches suggests that further research is required to avert a further population decline and delineate the reasons leading to the regional extinction of the species. The results of this study can serve as a foundation for devising conservation strategies for Tragopan melanocephalus under the changing climate and provide a framework for subsequent surveillance efforts aimed at protecting the species.

Atmospheric corrosion and impact toughness of steels: Case study in steels with and without galvanizing, exposed for 3 years in Rapa Nui Island

We studied atmospheric corrosion on Rapa Nui Island, using galvanized and non-galvanized SAE 1020 steel samples exposed on racks. We also added Charpy samples of both materials to directly determine the effect of corrosion rate on these materials' impact toughness. The results indicated a correlation between corrosion rate and toughness loss in the studied materials. In the corrosion study, we could also demonstrate the effect from increased insular population growth on contaminants which aid atmospheric corrosivity. Results showed that atmospheric SO₂ has tripled compared with similar corrosion studies done 20 years ago (Mapa Iberoamericano de Corrosión, MICAT), increasing corrosion rates. Our results show how human factors can influence changes in environmental variables that strengthen corrosion.

Climate Change and Human Activities, the Significant Dynamic Drivers of Himalayan Goral Distribution (Naemorhedus goral)

The distribution of large ungulates is more often negatively impacted by the changing climate, especially global warming and species with limited distributional zones. While developing conservation action plans for the threatened species such as the Himalayan goral (Naemorhedus goral Hardwicke 1825; a mountain goat that mostly inhabits rocky cliffs), it is imperative to comprehend how future distributions might vary based on predicted climate change. In this work, MaxEnt modeling was employed to assess the habitat suitability of the target species under varying climate scenarios. Such studies have provided highly useful information but to date no such research work has been conducted that considers this endemic animal species of the Himalayas. A total of 81 species presence points, 19 bioclimatic and 3 topographic variables were employed in the species distribution modeling (SDM), and MaxEnt calibration and optimization were performed to select the best candidate model. For predicted climate scenarios, the future data is drawn from SSPs 245 and SSPs 585 of the 2050s and 2070s. Out of total 20 variables, annual precipitation, elevation, precipitation of driest month, slope aspect, minimum temperature of coldest month, slope, precipitation of warmest quarter, and temperature annual range (in order) were detected as the most influential drivers. A high accuracy value (AUC-ROC > 0.9) was observed for all the predicted scenarios. The habitat suitability of the targeted species might expand (about 3.7 to 13%) under all the future climate change scenarios. The same is evident according to local residents as species which are locally considered extinct in most of the area, might be shifting northwards along the elevation gradient away from human settlements. This study recommends additional research is conducted to prevent potential population collapses, and to identify other possible causes of local extinction events. Our findings will aid in formulating conservation plans for the Himalayan goral in a changing climate and serve as a basis for future monitoring of the species.

A comprehensive overview of the genetic diversity in Thylamys elegans (Didelphimorphia: Didelphidae): establishing the phylogeographic determinants

Background

For the genus Thylamys, the rivers have been reported as barriers to dispersal, limiting current and historical distribution of its lineages. We hypothesized that the Maipo river has affected the genetic structure of northern and southern lineages of Thylamys elegans, recovering a phylogenetic relationships with reciprocally monophyletic sister groups on opposite river banks. We evaluated the role of other rivers in the Mediterranean zone of Chile as historical and recent modulators of the biogeographic processes of this species.

Methods

We applied a phylogeographic approach, using the cytochrome-b mitochondrial gene for 93 individuals of T. elegans, from 37 localities in a latitudinal gradient between 21°25’ and 35˚56’S, encompassing a geographic area between the Atacama Desert and most of the Mediterranean Chilean zone.

Results

The phylogenetics results recovered six lineages within T. elegans: Thylamys elegans elegans, Thylamys elegans coquimbensis, the Loa lineage and three other lineages not described previously (Aconcagua, South 1 and South 2). We suggest that following rivers play a role like primary barrier: the Maipo river in the genetic differentiation of northern and southern ancestral lineages, and the Mataquito river and its tributary Teno river for the South 1 and South 2 lineages. On the other hand, the Quilimarí river preserve the genetic divergence in T. e. coquimbensis and Aconcagua lineage and the Aconcagua river in Aconcagua lineage and T. e. elegans acting like secondary barriers.

Conclusions

We concluded that the genetic diversity and biogeographic history of T. elegans was shaped by mountain glaciers, changes in river water levels during the Pleistocene glaciations and hyperaridity, promoting the differentiation and persistance of the T. elegans lineages.

Large- and small-scale geographic structures affecting genetic patterns across populations of an Alpine butterfly

Understanding factors influencing patterns of genetic diversity and the population genetic structure of species is of particular importance in the current era of global climate change and habitat loss. These factors include the evolutionary history of a species as well as heterogeneity in the environment it occupies, which in turn can change across time. Most studies investigating spatio-temporal genetic patterns have focused on patterns across wide geographic areas rather than local variation, but the latter can nevertheless be important particularly in topographically complex areas. Here, we consider these issues in the Sooty Copper butterfly (Lycaena tityrus) from the European Alps, using genome-wide SNPs identified through RADseq. We found strong genetic differentiation within the Alps with four genetic clusters, indicating western, central, and eastern refuges, and a strong reduction of genetic diversity from west to east. This reduction in diversity may suggest that the southwestern refuge was the largest one in comparison to other refuges. Also, the high genetic diversity in the west may result from (a) admixture of different western refuges, (b) more recent demographic changes, or (c) introgression of lowland L. tityrus populations. At small spatial scales, populations were structured by several landscape features and especially by high mountain ridges and large river valleys. We detected 36 outlier loci likely under altitudinal selection, including several loci related to membranes and cellular processes. We suggest that efforts to preserve alpine L. tityrus should focus on the genetically diverse populations in the western Alps, and that the dolomite populations should be treated as genetically distinct management units, since they appear to be currently more threatened than others. This study demonstrates the usefulness of SNP-based approaches for understanding patterns of genetic diversity, gene flow, and selection in a region that is expected to be particularly vulnerable to climate change.

Evolving in islands of mud: old and structured hidden diversity in an endemic freshwater crayfish from the Chilean hotspot

Parastacus is a genus of South American freshwater crayfishes disjunctively distributed in southern Chile, Northern Argentina, Uruguay and Southeastern Brazil. Parastacus pugnax is a Chilean endemic distributed along 700 km of latitude in central-southern Chile from the Pacific coast to the Andean piedmont, which is intensively captured for consumption for local communities. Considering the habitat (wet meadows) and natural history (primary burrower, non-migrant) of the species, we tested a hypothesis of highly structured genetic diversity using mtDNA of 465 specimens gathered at 56 localities across the species range. The crown age of P. pugnax was estimated at 38 Ma, predating the main Andean uplift. The genetic variation of P. pugnax is large and geographically structured. In some cases, genetic groups do not match basin limits, suggesting a previous to current dynamic of basin evolution. The uncovered intraspecific main lineages have different demographic histories. A latitudinal cline in past effective population size reduction suggests environmental singularities with a glacial effect in the southern populations. We suggest adding morphologic and more genetic data in order to assess species limits. Our results contribute to improve future conservation actions for this taxon, providing basic information to delimit conservation units.

Genetic Diversity and Demographic History of the Shaggy Soft-Haired Mouse Abrothrix hirta (Cricetidae; Abrotrichini)

Genetic information on species can inform decision making regarding conservation of biodiversity since the response of organisms to changing environments depend, in part, on their genetic makeup. Territories of central-southern Chile and Argentina have undergone a varying degree of impact during the Quaternary, where the response of local fauna and flora was rather species-specific. Here, we focus on the sigmodontine rodent Abrothrix hirta, distributed from 35° S in Chile and Argentina to northern Tierra del Fuego. Based on 119,226 transcriptome-derived SNP loci from 46 individuals of A. hirta, we described the geographic distribution of the genetic diversity of this species using a maximum likelihood tree, principal component and admixture analyses. We also addressed the demographic history of the main intraspecific lineages of A. hirta using GADMA. We found that A. hirta exhibited four allopatric intraspecific lineages. Three main genetic groups were identified by a Principal Component Analysis and by Ancestry analysis. The demographic history of A. hirta was characterized by recent population stability for populations at the northernmost part of the range, while southern populations experienced a recent population expansion.

Anthropogenic and natural barriers affect genetic connectivity in an Alpine butterfly

Dispersal is a key biological process serving several functions including connectivity among populations. Habitat fragmentation caused by natural or anthropogenic structures may hamper dispersal, thereby disrupting genetic connectivity. Investigating factors affecting dispersal and gene flow is important in the current era of anthropogenic global change, as dispersal comprises a vital part of a species' resilience to environmental change. Using finescale landscape genomics, we investigated gene flow and genetic structure of the Sooty Copper butterfly (Lycaena tityrus) in the Alpine Ötz valley system in Austria. We found surprisingly high levels of gene flow in L. tityrus across the region. Nevertheless, ravines, forests, and roads had effects on genetic structure, while rivers did not. The latter is surprising as roads and rivers have a similar width and run largely in parallel in our study area, pointing towards a higher impact of anthropogenic compared with natural linear structures. Additionally, we detected eleven loci potentially under thermal selection, including ones related to membranes, metabolism, and immune function. This study demonstrates the usefulness of molecular approaches in obtaining estimates of dispersal and population processes in the wild. Our results suggest that, despite high gene flow in the Alpine valley system investigated, L. tityrus nevertheless seems to be vulnerable to anthropogenically-driven habitat fragmentation. With anthropogenic rather than natural linear structures affecting gene flow, this may have important consequences for the persistence of species such as the butterfly studied here in altered landscapes.

Genetic variation of the Chilean endemic long-haired mouse Abrothrix longipilis (Rodentia, Supramyomorpha, Cricetidae) in a geographical and environmental context

Quaternary climate and associated vegetational changes affected the fauna of the Chilean Mediterranean ecosystem. Here we studied the genetic variation of the long-haired mouse, Abrothrix longipilis, a sigmodontine rodent endemic to this area. Within an environmentally explicit context, we examined the geographic distribution of the genetic diversity and demographic history of the species based on sequences of the mitochondrial Cytochrome-b gene of 50 individuals from 13 localities and a large panel of single nucleotide polymorphisms of 17 individuals from 6 localities. The gene genealogy of A. longipilis revealed three intraspecific lineages that are allopatric and latitudinally segregated (northern, central, and southern lineages) with an estimated crown age for the whole species clade of 552.3 kyr B.P. A principal component analysis based on 336,596 SNP loci is in line with the information given by the the mitochondrial gene genealogy. Along its complete distributional range, A. longipilis showed patterns of isolation by distance and also isolation by environment. The general pattern of historical demography showed stability for most intraspecific lineages of A. longipilis. Northern and central lineages showed signals of historical demographic stability, while the southern lineage showed contrasting signals. In agreement with this, the niche models performed showed that in the northern range of A. longipilis, areas of high suitability for this species increased towards the present time; areas of central range would have remained relatively stable, while southern areas would have experienced more change through time. In summary, our study shows three distinct allopatric lineages of A. longipilis, each showing slightly different demographic history.

Mountains as Islands: Species Delimitation and Evolutionary History of the Ant-Loving Beetle Genus Panabachia (Coleoptera, Staphylinidae) from the Northern Andes

The ant-loving beetle genus Panabachia Park 1942 is a poorly studied beetle lineage from the new world tropics. We recently collected Panabachia from several previously unrecorded locations in the páramo biome of the high Ecuadorian Andes, with males exhibiting great morphological variation in the distribution of the foveae and depressions in the pronotum, as well as aspects of the male genitalia. Here, we employ phylogenetic and species delimitation methods with mitochondrial (COI) and nuclear protein-coding (wingless) gene sequences to examine the concordance of morphological characters and geography with hypothesized species boundaries. Three methods of species delimitation (bPTP, GMYC and Stacey) were used to estimate the number of species, and divergence times between putative species using molecular clock calibration. Phylogenetic analysis revealed two parallel radiations, and species delimitation analyses suggest there are between 17 and 22 putative species. Based on clade support and concordance across species delimitation methods we hypothesize 17 distinct clusters, with allopatric speciation consistent with most geographic patterns. Additionally, a widespread species appears to be present in northern páramo sites, and some sister species sympatry may indicate other diversification processes have operated on certain lineages of Panabachia. Divergence time estimates suggest that Panabachia originated in the Miocene, but most species analyzed diverged during the Pliocene and Pleistocene (5.3-0.11 Mya), contemporaneous with the evolution of páramo plant species.

Local persistence of Mann's soft-haired mouse Abrothrix manni (Rodentia, Sigmodontinae) during Quaternary glaciations in southern Chile

Quaternary climatic oscillations have impacted Patagonian sigmodontine fauna, leaving traceable genetic footprints. In southern Chile, changes in the landscape included transitions to different vegetation formations as well as the extension of ice sheets. In this study, we focus on the Valdivian forest endemic and recently described sigmodontine species Abrothrix manni. We aim to assess the genetic structure of this species, testing for the existence of intraspecific lineages, and inferring the recent demographic history of the species. Analyses were based on the first 801 bp of the mitochondrial gene Cytocrhome-b from 49 individuals of A. manni collected at 10 localities that covers most part of its geographic distribution. Genealogical analyses recovered two main intraspecific lineages that are geographically segregated and present an intermediate site of secondary contact. Historical demography shows signal of recent population decrease. Based on these results, we proposed that current genetic diversity of A. manni differentiated in at least two distinct refugial areas in southern Chile. This scenario, in addition to be unique among those uncovered for the so far studied Valdivian forest rodents, is noteworthy because of the reduced geographic scale inhabited by the species.

Change of niche in guanaco (Lama guanicoe): the effects of climate change on habitat suitability and lineage conservatism in Chile

Background

The main goal of this contribution was to define the ecological niche of the guanaco (Lama guanicoe), to describe potential distributional changes, and to assess the relative importance of niche conservatism and divergence processes between the two lineages described for the species (L.g. cacsilensis and L.g. guanicoe).

Methods

We used maximum entropy to model lineage’s climate niche from 3,321 locations throughout continental Chile, and developed future niche models under climate change for two extreme greenhouse gas emission scenarios (RCP2.6 and RCP8.5). We evaluated changes of the environmental niche and future distribution of the largest mammal in the Southern Cone of South America. Evaluation of niche conservatism and divergence were based on identity and background similarity tests.

Results

We show that: (a) the current geographic distribution of lineages is associated with different climatic requirements that are related to the geographic areas where these lineages are located; (b) future distribution models predict a decrease in the distribution surface under both scenarios; (c) a 3% decrease of areal protection is expected if the current distribution of protected areas is maintained, and this is expected to occur at the expense of a large reduction of high quality habitats under the best scenario; (d) current and future distribution ranges of guanaco mostly adhere to phylogenetic niche divergence hypotheses between lineages.

Discussion

Associating environmental variables with species ecological niche seems to be an important aspect of unveiling the particularities of, both evolutionary patterns and ecological features that species face in a changing environment. We report specific descriptions of how these patterns may play out under the most extreme climate change predictions and provide a grim outlook of the future potential distribution of guanaco in Chile. From an ecological perspective, while a slightly smaller distribution area is expected, this may come with an important reduction of available quality habitats. From the evolutionary perspective, we describe the limitations of this taxon as it experiences forces imposed by climate change dynamics.

Phylogenomic analysis of the Chilean clade of Liolaemus lizards (Squamata: Liolaemidae) based on sequence capture data

The genus Liolaemus is one of the most ecologically diverse and species-rich genera of lizards worldwide. It currently includes more than 250 recognized species, which have been subject to many ecological and evolutionary studies. Nevertheless, Liolaemus lizards have a complex taxonomic history, mainly due to the incongruence between morphological and genetic data, incomplete taxon sampling, incomplete lineage sorting and hybridization. In addition, as many species have restricted and remote distributions, this has hampered their examination and inclusion in molecular systematic studies. The aims of this study are to infer a robust phylogeny for a subsample of lizards representing the Chilean clade (subgenus Liolaemus sensu stricto), and to test the monophyly of several of the major species groups. We use a phylogenomic approach, targeting 541 ultra-conserved elements (UCEs) and 44 protein-coding genes for 16 taxa. We conduct a comparison of phylogenetic analyses using maximum-likelihood and several species tree inference methods. The UCEs provide stronger support for phylogenetic relationships compared to the protein-coding genes; however, the UCEs outnumber the protein-coding genes by 10-fold. On average, the protein-coding genes contain over twice the number of informative sites. Based on our phylogenomic analyses, all the groups sampled are polyphyletic. Liolaemus tenuis tenuis is difficult to place in the phylogeny, because only a few loci (nine) were recovered for this species. Topologies or support values did not change dramatically upon exclusion of L. t. tenuis from analyses, suggesting that missing data did not had a significant impact on phylogenetic inference in this data set. The phylogenomic analyses provide strong support for sister group relationships between L. fuscus, L. monticola, L. nigroviridis and L. nitidus, and L. platei and L. velosoi. Despite our limited taxon sampling, we have provided a reliable starting hypothesis for the relationships among many major groups of the Chilean clade of Liolaemus that will help future work aimed at resolving the Liolaemus phylogeny.