The Epidemiological Investigation of Yersinia pestis, Francisella tularensis, and Arenavirus Infections in Small Mammals in Northwestern Iran.

Background: The control and prevention of rodent-borne diseases are mainly based on our knowledge of ecology and the infectious status of their reservoir hosts. This study aimed to evaluate the prevalence of Francisella tularensis, Yersinia pestis, and arenavirus infections in small mammals and to assess the potential of disease occurrence in East Azerbaijan, northwest of Iran, in 2017 and 2018. Methods: Spleen and lung samples were obtained from all trapped small mammals. The real-time quantitative PCR (qPCR) method was used to detect nucleic acid sequences of F. tularensis, Y. pestis, and arenaviruses. Serum samples were tested for antibodies indicating the host response to F. tularensis and Y. pestis infections using the standard tube agglutination test and enzyme-linked immunosorbent assay (ELISA), respectively. Results: A total of 205 rodents, four Eulipotyphla, and one carnivore were captured. The most common rodent species captured (123 of 205 rodents, 60%) belonged to the genus Meriones (mainly Persian jird, Meriones persicus). In total, 317 fleas were removed from trapped animals. Flea species belonged to Xenopsylla buxtoni, Xenopsylla nuttalli, Stenoponia tripectinata, Paraceras melis, Ctenophthalmus rettigi smiti, Rhadinopsylla bivirgis, Paradoxopsyllus grenieri, and Nosopsyllus iranus. Using the qPCR tests, five spleen samples from M. persicus were positive for F. tularensis. The qPCR tests were negative for the detection of Y. pestis and arenaviruses. Finally, all serum samples tested were negative for antibodies against Y. pestis and F. tularensis. Conclusions: F. tularensis was the only zoonotic agent detected in rodents captured in East Azerbaijan. However, the diversity of trapped rodents and fleas provides the potential for the spread of various rodent-borne viral and bacterial diseases in the studied areas.

Adaptation in brain structure and respiratory and olfactory structures across environmental gradients in African and North American muroid rodents.

Morphometric studies of 3D micro CT-scanned images can provide insights into the evolution of the brain and sensory structures but such data are still scarce for the most diverse mammalian order of rodents. From reviewed and new data, we tested for convergence to extreme aridity and high elevation in the sensory and brain morphology of rodents, from morphometric data from micro-CT X-ray scans of 174 crania of 16 species of three distantly related African murid (soft-furred mice, Praomyini, laminate-toothed rats, Otomyini, and gerbils, Gerbillinae) clades and one North American cricetid (deer mice and white-footed mice, Peromyscus) clade. Recent studies demonstrated convergent evolution acting on the oval window area of the cochlea (enlarged in extremely arid-adapted species of Otomyini and Gerbillinae) and on endocranial volume (reduced in high elevation taxa of Otomyini and Peromyscus). However, contrary to our predictions, we did not find evidence of convergence in brain structure to aridity, or in the olfactory/respiratory system (turbinate bones) to high elevation. Brain structure differed, particularly in the petrosal lobules of the cerebellum and the olfactory bulbs, between Otomyini and Gerbillinae, with extreme arid-adapted species in each clade being highly divergent (not convergent) from other species in the same clade. We observed greater "packing" of the maxillary turbinate bones, which have important respiratory functions, in Peromyscus mice from high and low elevations compared to the high-elevation African Praomyini, but more complex patterns within Peromyscus, probably related to trade-offs in respiratory physiology and heat exchange in the nasal epithelium associated with high-elevation adaptation.

Quaternary rodents of South Africa: A companion guide for cranio-dental identification.

Rodentia is the most species-rich order among mammals. The Republic of South Africa harbours a high rodent diversity whose taxonomy and phylogeny have been extensively studied using genetic tools. Such advances have led to the establishment of new faunal lists for the country. Because rodents are frequently recovered from archaeological cave site material and owl pellets, and constitute prime material for studying both past and present environmental conditions, it is necessary to characterize their osteological remains. The skull and teeth are the most useful diagnostic skeletal elements preserved in modern and fossil accumulations. This key provides updated craniodental criteria for identifying rodent genera found in Quaternary deposits, and modern material from the Republic of South Africa, thus facilitating research on past and present rodent diversity.

Counter-gradient variation and the expensive tissue hypothesis explain parallel brain size reductions at high elevation in cricetid and murid rodents.

To better understand functional morphological adaptations to high elevation (> 3000 m above sea level) life in both North American and African mountain-associated rodents, we used microCT scanning to acquire 3D images and a 3D morphometric approach to calculate endocranial volumes and skull lengths. This was done on 113 crania of low-elevation and high-elevation populations in species of North American cricetid mice (two Peromyscus species, n = 53), and African murid rodents of two tribes, Otomyini (five species, n = 49) and Praomyini (four species, n = 11). We tested two distinct hypotheses for how endocranial volume might vary in high-elevation populations: the expensive tissue hypothesis, which predicts that brain and endocranial volumes will be reduced to lessen the costs of growing and maintaining a large brain; and the brain-swelling hypothesis, which predicts that endocranial volumes will be increased either as a direct phenotypic effect or as an adaptation to accommodate brain swelling and thus minimize pathological symptoms of altitude sickness. After correcting for general allometric variation in cranial size, we found that in both North American Peromyscus mice and African laminate-toothed (Otomys) rats, highland rodents had smaller endocranial volumes than lower-elevation rodents, consistent with the expensive tissue hypothesis. In the former group, Peromyscus mice, crania were obtained not just from wild-caught mice from high and low elevations but also from those bred in common-garden laboratory conditions from parents caught from either high or low elevations. Our results in these mice showed that brain size responses to elevation might have a strong genetic basis, which counters an opposite but weaker environmental effect on brain volume. These results potentially suggest that selection may act to reduce brain volume across small mammals at high elevations but further experiments are needed to assess the generality of this conclusion and the nature of underlying mechanisms.

Incongruences between morphology and molecular phylogeny provide an insight into the diversification of the Crocidura poensis species complex.

Untangling the factors of morphological evolution has long held a central role in the study of evolutionary biology. Extant speciose clades that have only recently diverged are ideal study subjects, as they allow the examination of rapid morphological variation in a phylogenetic context, providing insights into a clade's evolution. Here, we focus on skull morphological variability in a widely distributed shrew species complex, the Crocidura poensis species complex. The relative effects of taxonomy, size, geography, climate and habitat on skull form were tested, as well as the presence of a phylogenetic signal. Taxonomy was the best predictor of skull size and shape, but surprisingly both size and shape exhibited no significant phylogenetic signal. This paper describes one of the few cases within a mammal clade where morphological evolution does not match the phylogeny. The second strongest predictor for shape variation was size, emphasizing that allometry can represent an easily accessed source of morphological variability within complexes of cryptic species. Taking into account species relatedness, habitat preferences, geographical distribution and differences in skull form, our results lean in favor of a parapatric speciation model within this complex of species, where divergence occurred along an ecological gradient, rather than a geographic barrier.

Expert range maps of global mammal distributions harmonised to three taxonomic authorities.

Aim: Comprehensive, global information on species' occurrences is an essential biodiversity variable and central to a range of applications in ecology, evolution, biogeography and conservation. Expert range maps often represent a species' only available distributional information and play an increasing role in conservation assessments and macroecology. We provide global range maps for the native ranges of all extant mammal species harmonised to the taxonomy of the Mammal Diversity Database (MDD) mobilised from two sources, the Handbook of the Mammals of the World (HMW) and the Illustrated Checklist of the Mammals of the World (CMW). Location: Global. Taxon: All extant mammal species. Methods: Range maps were digitally interpreted, georeferenced, error-checked and subsequently taxonomically aligned between the HMW (6253 species), the CMW (6431 species) and the MDD taxonomies (6362 species). Results: Range maps can be evaluated and visualised in an online map browser at Map of Life (mol.org) and accessed for individual or batch download for non-commercial use. Main conclusion: Expert maps of species' global distributions are limited in their spatial detail and temporal specificity, but form a useful basis for broad-scale characterizations and model-based integration with other data. We provide georeferenced range maps for the native ranges of all extant mammal species as shapefiles, with species-level metadata and source information packaged together in geodatabase format. Across the three taxonomic sources our maps entail, there are 1784 taxonomic name differences compared to the maps currently available on the IUCN Red List website. The expert maps provided here are harmonised to the MDD taxonomic authority and linked to a community of online tools that will enable transparent future updates and version control.

Skull morphological evolution in Malagasy endemic Nesomyinae rodents.

Madagascar is a large island to the south-east of Africa and in many ways continental in size and ecological complexity. Here we aim to define how skull morphology of an endemic and monophyletic clade of rodents (sub-family Nesomyinae), that show considerable morphological variation, have evolved and how their disparity is characterized in context of the geographical and ecological complexity of the island. We performed a two-dimensional geometric morphometric analysis on 370 dorsal and 399 ventral skull images of 19 species (comprising all nine extant endemic genera) and tested the influence of three ecological parameters (climate, locomotor habitat and nychthemeral cycle) in a phylogenetic context on size and shape. The results indicate that skull shape appears to importantly reflect phylogeny, whereas skull size does not carry a significant phylogenetic signal. Skull shape is significantly influenced by climate while, skull size is not impacted by any of the ecological factors tested, which is controversial to expectations in an insular context. In conclusion, Nesomyinae must have evolved under unusual types of local constraints, preventing this radiation from demonstrating strong ecological release.

The Thorny Issue of African Porcupines: a New Mandible of Hystrix makapanensis from Olduvai Gorge (Tanzania) and Rediagnosis of the Species.

Several porcupine taxa are reported from the middle Miocene to the early Holocene in the Old World. Among these, five species of the subfamily Hystricinae occurred in Africa approximately in the last 6 Ma: the extinct Hystrix makapanensis, Hystrix leakeyi, and Xenohystrix crassidens and the still living Hystrix africaeaustralis and Hystrix cristata. The large-sized H. makapanensis is reported from numerous sites in East and South Africa between the early Pliocene and Early Pleistocene. In this paper, we describe a new mandible of H. makapanensis from the world-renowned Tanzanian paleontological and archeological site of Olduvai Gorge (HWK West; lowermost Bed II; ca. 1.8-1.7 Ma). The discovery of the new mandible triggered a comprehensive review of the entire African record of H. makapanensis. In particular, we describe or re-analyze the samples from South Africa (Makapansgat Limeworks, Gondolin, Kromdraai, Swartkrans, and Sterkfontein), Tanzania (Olduvai and Laetoli), Ethiopia (Omo Shungura and Hadar), and Kenya (Chemeron), enriching the quantity of specimens confidently referable to this species and above all improving the information on its craniodental anatomy. On this basis, we: (1) propose an emended diagnosis of H. makapanensis; (2) point out the morphological and biometric differences between H. makapanensis and other African Hystricinae (also in terms of body mass); and (3) broaden the knowledge on the geographical and chronological distribution of this extinct species. Supplementary Information: The online version contains supplementary material available at 10.1007/s10914-021-09588-z.

Nuclear phylogenomics, but not mitogenomics, resolves the most successful Late Miocene radiation of African mammals (Rodentia: Muridae: Arvicanthini).

The tribe Arvicanthini (Muridae: Murinae) is a highly diversified group of rodents (ca. 100 species) and with 18 African genera (plus one Asiatic) represents probably the most successful adaptive radiation of extant mammals in Africa. They colonized a broad spectrum of habitats (from rainforests to semi-deserts) in whole sub-Saharan Africa and their members often belong to most abundant parts of mammal communities. Despite intensive efforts, the phylogenetic relationships among major lineages (i.e. genera) remained obscured, which was likely caused by the intensive radiation of the group, dated to the Late Miocene. Here we used genomic scale data (377 nuclear loci; 581,030 bp) and produced the first fully resolved species tree containing all currently delimited genera of the tribe. Mitogenomes were also extracted, and while the results were largely congruent, there was less resolution at basal nodes of the mitochondrial phylogeny. Results of a fossil-based divergence dating analysis suggest that the African radiation started early after the colonization of Africa by a single arvicanthine ancestor from Asia during the Messinian stage (ca. 7 Ma), and was likely linked with a fragmentation of the pan-African Miocene forest. Some lineages remained in the rain forest, while many others successfully colonized broad spectrum of new open habitats (e.g. savannas, wetlands or montane moorlands) that appeared at the beginning of Pliocene. One lineage even evolved partially arboricolous life style in savanna woodlands, which allowed them to re-colonize equatorial forests. We also discuss delimitation of genera in Arvicanthini and propose corresponding taxonomic changes.

Multilocus phylogeny of African striped grass mice (Lemniscomys): Stripe pattern only partly reflects evolutionary relationships.

Murine rodents are one of the most evolutionary successful groups of extant mammals. They are also important for human as vectors and reservoirs of zoonoses and agricultural pests. Unfortunately, their fast and relatively recent diversification impedes our understanding of phylogenetic relationships and species limits of many murine taxa, including those with very conspicuous phenotype that has been frequently used for taxonomic purposes. One of such groups are the striped grass mice (genus Lemniscomys), distributed across sub-Saharan Africa in 11 currently recognized species. These are traditionally classified into three morphological groups according to different pelage colouration on the back: (a) L. barbarus group (three species) with several continuous pale longitudinal stripes; (b) L. striatus group (four species) with pale stripes diffused into short lines or dots; and (c) L. griselda group (four species) with a single mid-dorsal black stripe. Here we reconstructed the most comprehensive molecular phylogeny of the genus Lemniscomys to date, using the largest currently available multi-locus genetic dataset of all but two species. The results show four main lineages (=species complexes) with the distribution corresponding to the major biogeographical regions of Africa. Surprisingly, the four phylogenetic lineages are only in partial agreement with the morphological classification, suggesting that the single-stripe and/or multi-striped phenotypes evolved independently in multiple lineages. Divergence dating showed the split of Lemniscomys and Arvicanthis genera at the beginning of Pleistocene; most of subsequent speciation processes within Lemniscomys were affected by Pleistocene climate oscillations, with predominantly allopatric diversification in fragmented savanna biome. We propose taxonomic suggestions and directions for future research of this striking group of African rodents.

Life history and habitat do not mediate temporal changes in body size due to climate warming in rodents.

Temporal changes in body size have been documented in a number of vertebrate species, with different contested drivers being suggested to explain these changes. Among these are climate warming, resource availability, competition, predation risk, human population density, island effects and others. Both life history traits (intrinsic factors such as lifespan and reproductive rate) and habitat (extrinsic factors such as vegetation type, latitude and elevation) are expected to mediate the existence of a significant temporal response of body size to climate warming but neither have been widely investigated. Using examples of rodents, we predicted that both life history traits and habitat might explain the probability of temporal response using two tests of this hypothesis. Firstly, taking advantage of new data from museum collections spanning the last 106 years, we investigated geographical and temporal variation in cranial size (a proxy for body size) in six African rodent species of two murid subfamilies (Murinae and Gerbillinae) of varying life history, degree of commensality, range size, and habitat. Two species, the commensal Mastomys natalensis, and the non-commensal Otomys unisulcatus showed significant temporal changes in body size, with the former increasing and the latter decreasing, in relation with climate warming. Commensalism could explain the increase in size with time due to steadily increasing food availability through increased agricultural production. Apart from this, we found no general life history or habitat predictors of a temporal response in African rodents. Secondly, in order to further test this hypothesis, we incorporated our data into a meta-analysis based on published literature on temporal responses in rodents, resulting in a combined dataset for 50 species from seven families worldwide; among these, 29 species showed no significant change, eight showed a significant increase in size, and 13 showed a decline in size. Using a binomial logistic regression model for these metadata, we found that none of our chosen life history or habitat predictors could significantly explain the probability of a temporal response to climate warming, reinforcing our conclusion based on the more detailed data from the six African species.

Tracking the Near Eastern origins and European dispersal of the western house mouse.

The house mouse (Mus musculus) represents the extreme of globalization of invasive mammals. However, the timing and basis of its origin and early phases of dispersal remain poorly documented. To track its synanthropisation and subsequent invasive spread during the develoment of complex human societies, we analyzed 829 Mus specimens from 43 archaeological contexts in Southwestern Asia and Southeastern Europe, between 40,000 and 3,000 cal. BP, combining geometric morphometrics numerical taxonomy, ancient mitochondrial DNA and direct radiocarbon dating. We found that large late hunter-gatherer sedentary settlements in the Levant, c. 14,500 cal. BP, promoted the commensal behaviour of the house mouse, which probably led the commensal pathway to cat domestication. House mouse invasive spread was then fostered through the emergence of agriculture throughout the Near East 12,000 years ago. Stowaway transport of house mice to Cyprus can be inferred as early as 10,800 years ago. However, the house mouse invasion of Europe did not happen until the development of proto urbanism and exchange networks - 6,500 years ago in Eastern Europe and 4000 years ago in Southern Europe - which in turn may have driven the first human mediated dispersal of cats in Europe.

Dating the skull from Broken Hill, Zambia, and its position in human evolution.

The cranium from Broken Hill (Kabwe) was recovered from cave deposits in 1921, during metal ore mining in what is now Zambia1. It is one of the best-preserved skulls of a fossil hominin, and was initially designated as the type specimen of Homo rhodesiensis, but recently it has often been included in the taxon Homo heidelbergensis2-4. However, the original site has since been completely quarried away, and-although the cranium is often estimated to be around 500 thousand years old5-7-its unsystematic recovery impedes its accurate dating and placement in human evolution. Here we carried out analyses directly on the skull and found a best age estimate of 299 ± 25 thousand years (mean ± 2σ). The result suggests that later Middle Pleistocene Africa contained multiple contemporaneous hominin lineages (that is, Homo sapiens8,9, H. heidelbergensis/H. rhodesiensis and Homo naledi10,11), similar to Eurasia, where Homo neanderthalensis, the Denisovans, Homo floresiensis, Homo luzonensis and perhaps also Homo heidelbergensis and Homo erectus12 were found contemporaneously. The age estimate also raises further questions about the mode of evolution of H. sapiens in Africa and whether H. heidelbergensis/H. rhodesiensis was a direct ancestor of our species13,14.

The phylogeny of the African wood mice (Muridae, Hylomyscus) based on complete mitochondrial genomes and five nuclear genes reveals their evolutionary history and undescribed diversity.

Wood mice of the genus Hylomyscus, are small-sized rodents widely distributed in lowland and montane rainforests in tropical Africa, where they can be locally abundant. Recent morphological and molecular studies have increased the number of recognized species from 8 to 18 during the last 15 years. We used complete mitochondrial genomes and five nuclear genes to infer the number of candidate species within this genus and depict its evolutionary history. In terms of gene sampling and geographical and taxonomic coverage, this is the most comprehensive review of the genus Hylomyscus to date. The six species groups (aeta, alleni, anselli, baeri, denniae and parvus) defined on morphological grounds are monophyletic. Species delimitation analyses highlight undescribed diversity within this genus: perhaps up to 10 taxa need description or elevation from synonymy, pending review of type specimens. Our divergence dating and biogeographical analyses show that diversification of the genus occurred after the end of the Miocene and is closely linked to the history of the African forest. The formation of the Rift Valley combined with the declining global temperatures during the Late Miocene caused the fragmentation of the forests and explains the first split between the denniae group and remaining lineages. Subsequently, periods of increased climatic instability during Plio-Pleistocene probably resulted in elevated diversification in both lowland and montane forest taxa.

Out of Africa: demographic and colonization history of the Algerian mouse (Mus spretus Lataste).

North Africa is now recognized as a major area for the emergence and dispersal of anatomically modern humans from at least 315 kya. The Mediterranean Basin is thus particularly suited to study the role of climate versus human-mediated changes on the evolutionary history of species. The Algerian mouse (Mus spretus Lataste) is an endemic species from this basin, with its distribution restricted to North Africa (from Libya to Morocco), Iberian Peninsula and South of France. A rich paleontological record of M. spretus exists in North Africa, suggesting hypotheses concerning colonization pathways, and the demographic and morphologic history of this species. Here we combined genetic (3 mitochondrial DNA loci and 18 microsatellites) and climatic niche modeling data to infer the evolutionary history of the Algerian mouse. We collected 646 new individuals in 51 localities. Our results are consistent with an anthropogenic translocation of the Algerian mouse from North Africa to the Iberian Peninsula via Neolithic navigators, probably from the Tingitane Peninsula. Once arrived in Spain, suitable climatic conditions would then have favored the dispersion of the Algerian mice to France. The morphological differentiation observed between Spanish, French and North African populations could be explained by a founder effect and possibly local adaptation. This article helps to better understand the role of climate versus human-mediated changes on the evolutionary history of mammal species in the Mediterranean Basin.

Associated tympanic bullar and cochlear hypertrophy define adaptations to true deserts in African gerbils and laminate-toothed rats (Muridae: Gerbillinae and Murinae).

Hearing capabilities in desert rodents such as gerbils and heteromyids have been inferred from both anatomical and ecological aspects and tested with experiments and theoretical models. However, very few studies have focused on other desert-adapted species. In this study, a refined three-dimensional morphometric approach was used on three African rodent tribes (Otomyini, Taterillini and Gerbillini) to describe the cochlear and tympanic bullar morphology, and to explore the role of phylogeny, allometry and ecology to better understand the underlying mechanism of any observed trends of hypertrophy in the bulla and associated changes in the cochlea. As a result, desert-adapted species could be distinguished from mesic and semi-arid taxa by the gross cochlear dimensions, particularly the oval window, which is larger in desert species. Bullar and cochlear modifications between species could be explained by environment (bulla and oval window), phylogeny (cochlear curvature gradient) and/or allometry (cochlear relative length, oval window and bulla) with some exceptions. Based on their ear anatomy, we predict that Desmodillus auricularis and Parotomys brantsii should be sensitive to low-frequency sounds, with D. auricularis sensitive to high-frequency sounds, too. This study concludes that in both arid and semi-arid adapted laminate-toothed rats and gerbils there is bulla and associated cochlea hypertrophy, particularly in true desert species. Gerbils also show tightly coiled cochlea but the significance of this is debatable and may have nothing to do with adaptations to any specific acoustics in the desert environment.

Notes on the distribution and phylogeography of two rare small Gerbillinae (Rodentia, Muridae) in Morocco: Gerbillus simoni and Gerbillus henleyi.

Even though Gerbillinae rodents represent an important part of the mammalian fauna in North Africa, many gaps remain in our understanding of the distribution, ecology, evolution, and systematics of some lesser known species in this family. We present in this study the most recent findings on two of these species. The first species, Gerbillus simoni Lataste, 1881, is a short-tailed, small gerbil, endemic to North Africa. In Morocco, it is present only in a small area in the northeast, where it has not been caught since 1970. In 2014, we captured a small gerbil in this region that was identified as G. simoni based on morphology and molecular data (cytochrome b gene sequencing). This study represents the first genetic characterization of G. simoni in Morocco and the first one outside Tunisia. Populations from Morocco and Tunisia (mainland and Kerkennah Islands) show very little genetic differentiation. The second species, Gerbillus henleyi de Winton, 1903, is a long-tailed small gerbil that lives in the Sahel and North Africa with an extension to the Middle East. In Morocco, this species was only known in the southwest. Between 2014 and 2015, we have captured four gerbils in the northeast of the country, which were confirmed genetically and morphologically as belonging to this species. This represents an extension of its known distribution of about 370km to the northeast of the country. These new Moroccan specimens form a distinct lineage. High genetic diversity is observed throughout the geographic range of G. henleyi, suggesting the existence of several cryptic species.

[Craniometrical study of the species complex of Meriones shawii-grandis (Mammalia: Rodentia) in Morocco, in Algeria and in Tunisia]. / Étude craniométrique du complexe d'espèces Meriones shawii­grandis (Mammalia : Rodentia) au Maroc, en Algérie et en Tunisie.

In North Africa, the rodents of the species complex Meriones shawii-grandis have a considerable ecological, economic and epidemiological importance. Until now, the systematics of these species was subject to discussion due to the presence of populations displaying high morphological variability. By means of an approach of traditional morphometrics based on cranial distances and by using the method of the log shape-ratio, we attempt to characterize morphologically these two taxa. The results show significant differences in size and shape between the specimens of Morocco, on the one hand, and those of Algeria and Tunisia, on the other hand. The samples of Morocco that have been molecularly typed and attributed to M. grandis have larger tooth rows and narrower skulls, as well as relatively small tympanic bullae. On the other hand, those of Algeria and Tunisia assigned to M. shawii are characterized by small tooth rows and wide skulls with well-developed tympanic bullae. The morphological distance is relatively strong between both clades (79.5%), which corresponds to the molecular distance. However, the discriminant analysis performed after molecularly-typed specimens allows the correct classification of only 91.8% of the individuals.

Reconstructing Asian faunal introductions to eastern Africa from multi-proxy biomolecular and archaeological datasets.

Human-mediated biological exchange has had global social and ecological impacts. In sub-Saharan Africa, several domestic and commensal animals were introduced from Asia in the pre-modern period; however, the timing and nature of these introductions remain contentious. One model supports introduction to the eastern African coast after the mid-first millennium CE, while another posits introduction dating back to 3000 BCE. These distinct scenarios have implications for understanding the emergence of long-distance maritime connectivity, and the ecological and economic impacts of introduced species. Resolution of this longstanding debate requires new efforts, given the lack of well-dated fauna from high-precision excavations, and ambiguous osteomorphological identifications. We analysed faunal remains from 22 eastern African sites spanning a wide geographic and chronological range, and applied biomolecular techniques to confirm identifications of two Asian taxa: domestic chicken (Gallus gallus) and black rat (Rattus rattus). Our approach included ancient DNA (aDNA) analysis aided by BLAST-based bioinformatics, Zooarchaeology by Mass Spectrometry (ZooMS) collagen fingerprinting, and direct AMS (accelerator mass spectrometry) radiocarbon dating. Our results support a late, mid-first millennium CE introduction of these species. We discuss the implications of our findings for models of biological exchange, and emphasize the applicability of our approach to tropical areas with poor bone preservation.

Host evolution in Mastomys natalensis (Rodentia: Muridae): An integrative approach using geometric morphometrics and genetics.

The commensal rodent Mastomys natalensis is the natural reservoir of Lassa arenavirus (LASV), which causes hemorrhagic fever in West Africa. To study a possible effect of the virus on phenotypic and genotypic variation of its persistently infected host, we compared LASV-positive and non-infected wild-caught M. natalensis. The LASV effects on the phenotypic variation were explored using standard external morphometric measurements, geometric morphometric analyses of the cranial size and shape, and brain case volume. The genetic variability of M. natalensis specimens was assessed using 9 polymorphic microsatellite markers. Independent of sex and age, LASV-infected animals had smaller external body measurements, reproductive organs, skull size and brain case volume. Cranial shape differences between the 2 groups are represented by a lateral constriction of the entire skull. The genetic variability revealed consanguinity only among the LASV-positive rodents. We hypothesize that growth impairment may result in a selective disadvantage for LASV-infected M. natalensis, leading to a preferably commensal lifestyle in areas where the LAVS is endemic and, thereby, increasing the risk of LASV transmission to humans.