Historical Distribution Research Articles

Conservation Priorities and Demographic History of Saussurea involucrata in the Tianshan Mountains and Altai Mountains.

Rare and vulnerable endemic plants represent different evolutionary units that occur at different times, and protecting these species is a key issue in biological protection. Understanding the impact of the history of endangered plant populations on their genetic diversity helps to reveal evolutionary history and is crucial for guiding conservation efforts. Saussurea involucrata, a perennial alpine species mainly distributed in the Tianshan Mountains, is famous for its medicinal value but has become endangered due to over-exploitation. In the present study, we employed both nuclear and chloroplast DNA sequences to investigate the genetic distribution pattern and evolutionary history of S. involucrata. A total of 270 individuals covering nine S. involucrata populations were sampled for the amplification and sequencing of nrDNA Internal Transcribed Spacer (ITS) and chloroplast trnL-trnF, matK and ndhF-rpl32 sequences. Via calculation, we identified 7 nuclear and 12 plastid haplotypes. Among the nine populations, GL and BA were characterized by high haplotype diversity, whereas BG revealed the lowest haplotype diversity. Molecular dating estimations suggest that divergence among S. involucrata populations occurred around 0.75 Ma, coinciding with the uplift of Tianshan Mountains. Our results reveal that both isolation-by-distance (IBD) and isolation-by-resistance (IBR) have promoted genetic differentiation among populations of S. involucrata. The results from the ecological niche modeling analyses show a more suitable habitat for S. involucrata in the past than at present, indicating a historical distribution contraction of the species. This study provides new insight into understanding the genetic differentiation of S. involucrata, as well as the theoretical basis for conserving this species.

Spatiotemporal dynamics of duck harvest distributions in the Central and Mississippi flyways, 1960–2019

AbstractGeographical distributions of waterfowl exhibit annual variation in response to spatiotemporal variation in weather conditions, habitat availability, and other factors. Continuing changes in climate and land use could lead to persistent shifts of waterfowl distributions, potentially causing a mismatch with habitat conservation planning, wetland restoration efforts, and harvest management decisions informed by historical distributions. We used band recoveries and harvest records (i.e., hunter‐harvested wings) from the United States Fish and Wildlife Service Waterfowl Parts Collection Survey as indices of duck distribution in autumn and winter, and quantified intra‐annual, interannual, and interspecific variation in their geographic distributions across 6 decades (1960–2019) for 15 duck species in the Central and Mississippi flyways in North America. Specifically, we tested for annual and decadal shifts in mean latitude and longitude of recoveries for each month (Oct–Jan) by species and taxonomic guild (i.e., dabbling, diving ducks). Overall, species varied in the extent, timing, and sometimes direction, of distributional change in recoveries. From 1960–2019, mean recovery locations for dabbling ducks shifted south 105–296 km in October and 27 km in November (wings only), whereas mean latitudes shifted north 144–234 km in December and 186–301 km in January. Mean recovery locations for diving ducks shifted north 162 km in October (wings only), 84–173 km in December, and 66–120 km in January, but shifted 99–512 km south in November. Shifts in longitude were less consistent between guilds and data types. Finally, distributional change rarely accelerated during recent decades, except for southward shifts of band recoveries of diving ducks in November and northward shifts of band and wing recoveries of dabbling ducks in January. Although anecdotal accounts of large‐scale northward shifts in duck distributions are prolific in the land management and hunting communities, our data demonstrate more subtle shifts that vary considerably by species and month. Observed changes in recovery distributions could necessitate changes in timing of habitat management practices throughout the Central and Mississippi flyways and may result in fewer hunting and recreational opportunities for some species in southern states. Quantifying patterns of historical change is a necessary first step to understanding temporal and interspecific variation in waterfowl distributions, which will help with landscape‐scale conservation and management efforts in the future and enable effective communication to core constituencies regarding ongoing changes and their implications for recreational engagement.

Evaluating the determinants of participation in conservancy land leases and its impacts on household wealth in the Maasai Mara, Kenya: Equity and gender implications

Understanding the impact of conservation interventions on local communities is important in determining their effects on livelihoods and wellbeing. However, impacts are often not uniform and there are important equity dimensions when evaluating interventions. Therefore, in this paper, we investigate determinants of participation in conservation land leases in the Mara Conservancies in southern Kenya and its impact on household wealth. We find that land ownership determines who can participate in and benefit from conservancy land lease payments, and by how much. The design of the land lease payment scheme therefore has the potential to reinforce and, in cases, amplify existing inequities as it is built upon a legacy of unequal historical land distribution processes that limit the participation of women and poor landless households. We observed significantly higher incomes amongst participant households compared to non-participants, but these differences disappeared after propensity score matching. These results suggest that the differences were not caused by participation in conservancies. Our findings suggest that the design and outcomes of land-based conservation or payment for ecosystem services schemes should consider historic and existing land tenure systems if they are to reduce inequality.

Biogeography and environmental preferences of Butia yatay (Mart.) Becc.

During the Quaternary, Chaco Phytogeographic Domain (Chaco) flora in subtropical South America experienced temperature and humidity fluctuations, primarily driven by wind dynamics, leading to significant shifts in species distribution. The palm Butia yatay is endemic to the Chaco and thrives in areas characterized by a warm-rainy climate and mostly restricted to sandy soils. To investigate the current geographic distribution of suitable habitat for B. yatay while assessing the significance of soil variables, we employed two distinct algorithms in species distribution modeling (SDM). We also determined whether the distribution of B. yatay has changed since the Pleistocene and whether these changes align with previously proposed Pleistocene refugia. In the present SDMs, we considered two separate sets of predictors, one set with bioclimatic variables only and the other set with bioclimatic topographic and soil variables. Additionally, we reconstructed the historical geographic distribution of suitable habitats using bioclimatic data. Our results suggested that the primary determinants of B. yatay's current distribution include precipitation and temperature of the driest month and soil cation exchange capacity. Incorporating soil variables affected the estimated size and range of suitable areas. Projections into the past indicated similar suitable habitat distributions during interglacial periods compared with the present. During the Last Glacial Maximum, climatically suitable habitat may have shifted northward, partially overlapping with previously suggested Pleistocene refugia located between the Paraná and Uruguay Rivers. These findings indicate the main factors driving the distribution and ecology of B. yatay and enhance understanding of subtropical flora shifts during the Quaternary. The approach also may prove valuable for other studies within the Chaco.

European River Lamprey Lampetra fluviatilis (Petromyzontidae) of the Pskov Lakeland: Current State of Isolated Populations

Small freshwater (resident) populations of the European river lamprey Lampetra fluviatilis from an isolated from the sea upper part of a river system with numerous lakes (the upper reaches of tributaries of the Daugava River and Lake Peipus, Pskov Oblast, Russia) have been studied. Adult individuals of the lamprey have been attributed to common and large size groups; adults are similar to other resident lamprey from the Baltic Sea basin. The presence of larvae of different size and age groups indicates regular spawning of the European river lamprey in the studied watersheds. Analysis of the modern and historical (before the isolation) distribution of lamprey revealed a reduction in habitats and a decrease in the number of individuals. Dam-associated disruption of migration routes led to the disappearance of anadromous form, and consequently, disappearance of resident lamprey from most of the studied waterbodies. We attribute the decrease in the number of rivers inhabited by lamprey and abundance of the lamprey both to anthropogenic factors (direct blocking of an access of anadromous form of the lamprey to spawning grounds by hydraulic construction) and to the characteristics of the studied area. The richness of the river system with lentic waterbodies makes it suitable for lamprey inhabitation with an influx of large anadromous individuals capable of crossing such reservoirs in search of spawning sites.

Wild Ungulates Constitute the Basis of the Diet of the Iberian Wolf in a Recently Recolonized Area: Wild Boar and Roe Deer as Key Species for Its Conservation.

The Iberian wolf (Canis lupus signatus) is recolonizing historical distribution areas after decades of absence. As in other human-dominated landscapes, finding a balance to protect this species by favoring recolonization and mitigating human-wildlife conflicts is a challenge. Since wolves are often generalist opportunistic predators, we studied their diet composition in central Spain to evaluate the consumption of domestic ungulates and provide reliable data that could help local authorities to deal with the current wolf-cattle ranchers conflict and coexistence. Diet composition (% prey occurrence, % prey ingested biomass) was analyzed through the identification of prey hairs present in 671 scats collected between 2017 and 2021. The wolves fed more on wild ungulates (82% occurrence) than domestic ones (18%). Wild boar (Sus scrofa, 44% occurrence) and roe deer (Capreolus capreolus, 35%) were the most consumed prey. The wolves positively selected these two species. The wolves' diets varied between seasons, years, and forest regions, but a diet based on wild ungulates predominated over domestic ones. Food niche breadth showed variations depending on seasons and years. Preserving the availability and diversity of wild ungulates may favor reducing livestock attacks and would be an achievable goal that would help to conserve this species and reduce conservation conflicts.

Limited congruence in phylogeographic patterns observed for riverine predacious beetles sharing distribution along the mountain rivers

Riverine predacious beetles (RPB) (Carabidae, Staphylinidae) are highly diverse and numerous elements of riverine ecosystems. Their historical and contemporary distribution and diversity are highly dependent on natural flow regimes and topography of watercourses. Despite broad knowledge of their ecology, data on population genetic diversity and connectivity are lacking. This study aimed to fill this gap in order to solve two principal hypotheses assuming (i) congruence of phylogeographic patterns observed for RPB indicating that they share a common history and the ecological adaptations to the dynamic environment, (ii) genetic structuration of populations according to river basins. The Carpathian populations of four ground beetles and three rove beetles were examined using cytochrome oxidase and arginine kinase sequencing. There are substantial differences in RPB demographic history and current genetic diversity. Star-like phylogeny of Bembidion and complex haplotype networks of Paederus/Paederidus, with some haplotypes being drainage-specific and others found in distant populations, indicate a general lack of isolation by distance. Signs of recent demographic expansion were detected for most RPB with the latest population collapse for some rove beetles. To some extent, migration of examined species has to be limited by watersheds. Observed phylogeographic patterns are essential for correctly understanding RPB meta-population functioning.

Opposing genetic patterns of range shifting temperate and tropical gastropods in an area undergoing tropicalisation

AbstractAimThe poleward range expansion of tropical species, and range contraction of temperate species (known as tropicalisation) has mainly been studied from an ecological perspective, with little research on its genetic consequences. Here, we used distributional and genetic data to document the consequences of tropicalisation in rocky shore gastropods and assess more broadly the future implications of tropicalisation on phylogeographic patterns.LocationNineteen sampling sites along >3000 km of the eastern Pacific rocky intertidal zone, from the tip of the Baja California Peninsula to southern California.TaxonTemperate gastropods: Lottia conus, L. strigatella, Fissurella volcano and Tegula gallina.Tropical gastropods: Fissurella rubropicta, Nerita funiculata and N. scabricosta.MethodsWe determine historical and modern distributions of tropical and temperate species by combining historical records with current field surveys. Using a section of the cytochrome oxidase subunit I gene, we utilised comparative phylogeography, analysis of molecular variance, FST pairwise comparison, mismatch distributions of haplotype differences and neutrality tests to detect genetic signatures of tropicalisation and to better understand its consequences.ResultsWe identified range contractions in two temperate species and range expansion in all three tropical species. We detected genetic signatures of range expansion in the tropical species through unimodal distributions of pairwise haplotype differences and strongly negative values for the Fu and Li D and F* statistics. We found population subdivision and phylogeographic breaks in three temperate species, although the geographic location of the breaks differed among species.Main ConclusionsGenetic signatures and field surveys indicate recent range expansions in tropical species, supporting tropicalisation along the studied coastline. Conversely, we found phylogeographic breaks in temperate species, suggesting that tropicalisation may cause genetic erosion of evolutionary distinct lineages with range‐contraction. The different locations of the phylogeographic breaks among temperate species suggests that some barriers are species specific.

A century-long record of polycyclic aromatic hydrocarbon deposition in the Old Yellow River Estuary, China

Polycyclic aromatic hydrocarbons (PAHs) are potential geochemical indicators for assessing the impact of human activities and can be used to reconstruct historical human activities. This study collected a 108 cm sediment core from the 5th lobe of the Yellow River Delta for the first time and analyzed the historical distribution characteristics of PAHs in this area. The results showed that the sedimentation history of the core was from 1908 to 2014. The average value of PAHs was 28.93 ng/g. Biomass and coal combustion sources were the main sources of PAHs in the low-value areas, while oil spill sources were the main sources in the significantly higher PAHs areas in the 1960s, mid-1980s, late 1990s, and late 2010s, which was consistent with the development history of Shengli Oilfield. Compared with global estuaries, the historical industrial activity intensity in this area was weaker.

Population genetics of Leptoglossus clypealis (Hemiptera: Coreidae) in the Western United States.

The leaffooted bug, Leptoglossus clypealis Heidemann, is a seed-feeding economic pest of crops including almonds and pistachios. The historical distribution of L. clypealis has been considered to be West of the Mississippi in the United States. L. clypealis was recently found in sorghum in the Coastal Bend of Texas, representing a new host record and new collection locality. This study investigated the genetic diversity of L. clypealis museum voucher samples from the Western United States (i.e., Texas, California, and Idaho) collected from 1994 to 2019, including the L. clypealis samples from the Coastal Bend. Eleven new sequences were obtained. Sample sequences were compared with public sequences of L. clypealis from the Western United States. The mitochondrial DNA cytochrome oxidase 1 (mtDNA COI) barcode gene region revealed differences among and within the collection regions. Texas, Idaho, and California all had samples with unique genotypes, and the combined dataset had a haplotype diversity of 1.0. The Texas specimens recently collected in the Coastal Bend did not match genotypes from California or Idaho, and it is unlikely they were recently introduced. Overall, L. clypealis from Texas, Idaho, and California have a high level of genetic diversity, and the 3 regions appear to be within the native range of the species.

Distribution patterns of Quercus ilex from the last interglacial period to the future by ecological niche modeling.

The plants' geographic distribution is affected by natural or human-induced climate change. Numerous studies at both the global and regional levels currently focus on the potential changes in plant distribution areas. Ecological niche modeling can help predict the likely distribution of species according to environmental variables under different climate scenarios. In this study, we predicted the potential geographic distributions of Quercus ilex L. (holm oak), a keystone species of the Mediterranean ecosystem, for the Last Interglacial period (LIG: ~130 Ka), the Last Glacial Maximum (LGM: ~22 Ka), mid-Holocene (MH: ~6 Ka), and future climate scenarios (Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios) for 2050-2070 obtained from CCSM4 and MIROC-ESM global climate scenarios respectively. The models were produced with algorithms from the R-package "biomod2" and assessed by AUC of the receiver operating characteristic plot and true skill statistics. Aside from BIOCLIM (SRE), all model algorithms performed similarly and produced projections that are supported by good evaluation scores, although random forest (RF) slightly outperformed all the others. Additionally, distribution maps generated for the past period were validated through a comparison with pollen data acquired from the Neotoma Pollen Database. The results revealed that southern areas of the Mediterranean Basin, particularly coastal regions, served as long-term refugia for Q. ilex, which was supported by fossil pollen data. Furthermore, the models suggest long-term refugia role for Anatolia and we argue that Anatolia may have served as a founding population for the species. Future climate scenarios indicated that Q. ilex distribution varied by region, with some areas experiencing range contractions and others range expands. This study provides significant insights into the vulnerability of the Q. ilex to future climate change in the Mediterranean ecosystem and highlights the crucial role of Anatolia in the species' historical distribution.

Revisiting conservation units for the endangered mountain yellow-legged frog species complex (Rana muscosa, Rana sierrae) using multiple genomic methods

Insights from conservation genomics have dramatically improved recovery plans for numerous endangered species. However, most taxa have yet to benefit from the full application of genomic technologies. The mountain yellow-legged frog species complex, Rana muscosa and Rana sierrae, inhabits the Sierra Nevada mountains and Transverse/Peninsular Ranges of California and Nevada. Both species have declined precipitously throughout their historical distributions. Conservation management plans outline extensive ongoing recovery efforts but are still based on the genetic structure determined primarily using a single mitochondrial sequence. Our study used two different sequencing strategies – amplicon sequencing and exome capture – to refine our understanding of the population genetics of these imperiled amphibians. We used buccal swabs, museum tissue samples, and archived skin swabs to genotype frog populations across their range. Using the amplicon sequencing and exome capture datasets separately and combined, we document five major genetic clusters. Notably, we found evidence supporting previous species boundaries within Kings Canyon National Park with some exceptions at individual sites. Though we see evidence of genetic clustering, especially in the R. muscosa clade, we also found evidence of some admixture across cluster boundaries in the R. sierrae clade, suggesting a stepping-stone model of population structure. We also find that the southern R. muscosa cluster had large runs of homozygosity and the lowest overall heterozygosity of any of the clusters, consistent with previous reports of marked declines in this area. Overall, our results clarify management unit designations across the range of an endangered species and highlight the importance of sampling the entire range of a species, even when collecting genome-scale data.

Blechnum spicant (Blechnaceae) in the Ukrainian flora

The article contains data about the historical and current distribution patterns of Blechnum spicant (Blechnaceae) in Ukraine. This species is quite common in the Carpathian Mountains but is very rare in other regions of Ukraine. Until recently, there were only two known localities of B. spicant in the Western Forest-Steppe (within the Podolian Upland) and only one in Crimea. We discovered one new locality of B. spicant in the Polissian (Polesian) Lowland, in Volyn Region. The article provides phytosociological and topographic data on the Polissian population. This population consists of two sub-populations, which are located not far from each other. Both of them were found in an immature birch-pine forest aged approximately 20 years, in an area of former agricultural lands. We summarise the data on the general distribution of B. spicant in Ukraine. The article also provides phytosociological, biotopic and populational information on localities of B. spicant.

Stable habitat supports long-term persistence of critically endangered western black crested gibbon

Stable habitat provides sufficient food to sustain large species populations, and becomes a refuge under increasing environmental stress. Stable habitat also becomes a population source and re-expand hotspot once the stress decreases. Thus, identifying and protecting stable habitat is key to species’ long-term persistence. We identified the stable habitat for critically endangered western black crested gibbon (Nomascus concolor) in Mt. Wuliang, where one of two largest populations of this species lives in. We collected gibbon historical distribution data, and modeled the potential habitat in Mt. Wuliang during 2000, 2010, and 2020. We identified the stable habitat by overlaying the potential habitat layers from the three time periods and excluded habitat patches smaller than the species’ home range. Gibbon habitats continuously expanded from 2000 to 2010 (+13%), and from 2010 to 2020 (+6%), indicating that gibbon habitats are recovering at Mt. Wuliang. Stable habitat was 304 km2, mainly located at mid-elevation (2 100 – 2 600 m). Nearly all (99%) gibbon groups occupied stable habitat in each period at a mean density of 0.34 groups/ km2. Gibbon population density in the Wuliangshan National Nature Reserve (WNNR, 0.44 groups/ km2) was 83% greater than that density outside WNNR (0.24 groups/ km2). However, only 50% of stable habitat was within WNNR. Thirteen stable habitat patches located outside WNNR require urgent conservation interventions. Stable habitat in protected area is sufficient to ensure the persistence of these gibbons, but we still need to involve stable habitat outside protected area to sustain population recovery in the future.

Origin of endemic species in a moderately isolated ancient lake: The case of a snakehead in Inle Lake, Myanmar

AbstractInle Lake is an ancient lake in Myanmar, which is an important area with unique and diverse fauna. Its ichthyofauna is believed to have formed non‐radiatively, but the historical processes are poorly understood. To elucidate the mechanisms that shape species diversity in this moderately isolated biogeographical ‘island’, this study focused on a typical endemic fish of Inle Lake, Channa harcourtbutleri (Channidae, Anabantiformes), with its widely distributed sister species, C. limbata, and estimated the historical distribution and diversification processes of the endemic fish based on genome‐wide polymorphism (MIG‐seq) and mitochondrial DNA data. Channa harcourtbutleri contained two genetically and morphologically distinct groups inhabiting Inle Lake and the surrounding rivers respectively. These two groups were genetically the closest to each other; however, the riverine group showed some similarity to the closely related species, C. limbata from Southeast Asia. The mtDNA haplotypes of the endemic species were not monophyletic; most of the riverine group had haplotypes identical or close to those of C. limbata from the upper Irrawaddy and Salween rivers. The time tree suggested that C. harcourtbutleri diverged from C. limbata in the early Pleistocene and then experienced secondary contact with C. limbata in the late Pleistocene. Genetic and morphological differentiation within C. harcourtbutleri suggests that local adaptation to different environments has played an important role for the coexistence of its two forms with some reproductive isolation. Further, the results highlight the importance of multiple colonization and allopatric speciation in shaping biodiversity in the long‐term, moderately isolated environments.

Distributionally robust location-allocation with demand and facility disruption uncertainties in emergency logistics

Emergency logistics is vital to disaster relief management. In this paper we develop a distributionally robust optimization model (DROM) for optimizing the locations of distribution centres and backup warehouses, and the distribution of disaster relief supplies in emergency logistic networks by minimizing the expected total cost and the total delivery time. Based on limited historical distribution information, the model considers uncertain demand and uncertain facility disruptions, and describes their distributions through ambiguity sets. Following the adaptability and tractability of the ambiguity sets, we show that the model can be equivalently re-formulated as a mixed-integer linear program. To solve the model, we propose an exact algorithm based on Benders decomposition (BD). We also introduce an in-out Benders cut generation strategy to improve the efficiency of the BD algorithm. Finally, we perform extensive numerical studies to test the performance of the BD algorithm, ascertain the benefits of the proposed DROM over the corresponding deterministic and stochastic models, and examine the impacts of the key model parameters to gain managerial insights.

Risk-averse stochastic dynamic power dispatch based on deep reinforcement learning with risk-oriented Graph-Gan sampling

The increasing penetration of renewable energy sources (RES) brings volatile stochasticity, which significantly challenge the optimal dispatch of power systems. This paper aims at developing a cost-effective and robust policy for stochastic dynamic optimization of power systems, which improves the economy as well as avoiding the risk of high costs in some critical scenarios with small probability. However, it is hard for existing risk-neutral methods to incorporate risk measure since most samples are normal. For this regard, a novel risk-averse policy learning approach based on deep reinforcement learning with risk-oriented sampling is proposed. Firstly, a generative adversarial network (GAN) with graph convolutional neural network (GCN) is proposed to learn from historical data and achieve risk-oriented sampling. Specifically, system state is modelled as graph data and GCN is employed to capture the underlying correlation of the uncertainty corresponding to the system topology. Risk knowledge is the embedded to encourage more critical scenarios are sampled while aligning with historical data distributions. Secondly, a modified deep reinforcement learning (DRL) with risk-measure under soft actor critic framework is proposed to learn the optimal dispatch policy from sampling data. Compared with the traditional deep reinforcement learning which is risk-neutral, the proposed method is more robust and adaptable to uncertainties. Comparative simulations verify the effectiveness of the proposed method.

East Fennoscandian Ecological Corridors and Their Role in the Formation of the Modern Mammal Fauna of the Region

The article deals with the functioning of ecological corridors as passages to central regions of Eastern Fennoscandis for mammals characterized by population oscillations, high migratory activity, and the consequential dispersal beyond the historical distribution ranges (wild boar, roe deer). We also discuss the invasions of new species in Eastern Fennoscandia as a result of introductions and natural dispersal (muskrat, American mink, Canadian beaver, racoon dog, white-tailed and sika deer).

Reconstructed Global Invasion and Spatio-Temporal Distribution Pattern Dynamics of Sorghum halepense under Climate and Land-Use Change.

Sorghum halepense competes with crops and grass species in cropland, grassland, and urban environments, increasing invasion risk. However, the invasive historical dynamics and distribution patterns of S. halepense associated with current and future climate change and land-use change (LUC) remain unknown. We first analyzed the invasive historical dynamics of S. halepense to explore its invasion status and expansion trends. We then used a species distribution model to examine how future climate change and LUC will facilitate the invasion of S. halepense. We reconstructed the countries that have historically been invaded by S. halepense based on databases with detailed records of countries and occurrences. We ran biomod2 based on climate data and land-use data at 5' resolution, assessing the significance of environmental variables and LUC. Sorghum halepense was widely distributed worldwide through grain trade and forage introduction, except in Africa. Europe and North America provided most potential global suitable habitats (PGSHs) for S. halepense in cropland, grassland, and urban environments, representing 48.69%, 20.79%, and 84.82%, respectively. The future PGSHs of S. halepense increased continuously in the Northern Hemisphere, transferring to higher latitudes. Environmental variables were more significant than LUC in predicting the PGSHs of S. halepense. Future PGSHs of S. halepense are expected to increase, exacerbating the invasion risk through agricultural LUC. These results provide a basis for the early warning and prevention of S. halepense worldwide.

Predictive use of modern reference osteological collections for disentangling the shape of Eurasian equid cheek teeth and metapodials in archaeological material

AbstractEquids have shaped past Eurasian societies in many ways. This applies in particular to domestic horses, donkeys, and their hybrids. Key to documenting modes of exploitation and cultural trajectories in past societies is the correct taxonomic classification of tooth and bone specimens found in archaeological sites. However, close osteomorphological resemblance of wild and domestic equids and their economically valuable hybrids, that is, mules and hinnies, complicates the identification of intentionally fragmented or naturally damaged archaeological specimens. Here, we apply geometric morphometrics (GM) to mandibular teeth and metapodials, two skeletal elements commonly found in archaeological collections and known for their diagnostic properties using traditional morphometric methods. We registered a statistically representative set of 2D and 3D coordinates on mandibular teeth (P3, P4, M1, and M2) and metapodials of 92 domestic horses (Equus caballus Linnaeus, 1758), 70 domestic donkeys (Equus asinus Linnaeus, 1758), 30 hybrids, and 63 Asiatic wild asses (Equus hemionus Pallas, 1775). Taxonomic classification of these 255 specimens considered both shape and form, applying linear discriminant analysis, k‐nearest neighbors algorithm, and artificial neural networks to seven combinations of taxa. We obtained correct classifications in over 87% and 80%, respectively, of the premolars and molars and in over 93% and 89%, respectively, of the metacarpals and metatarsals. This modern dataset was then used to classify equid specimens from three archaeological sites in the Middle East already analyzed morphologically. Taking into account the past zoogeography of wild equids and the historical distribution of their domesticated descendants and hybrids, the GM approach presented in this study offers the possibility to morphologically classify archaeological equids with far greater certainty than has been the case so far.