Mammalian Group Research Articles

Inhibition of HMGA2 binding to AT-rich DNA by its negatively charged C-terminus.

The mammalian high mobility group protein AT-hook 2 (HMGA2) is a small DNA-binding protein that specifically targets AT-rich DNA sequences. Structurally, HMGA2 is an intrinsically disordered protein (IDP), comprising three positively charged 'AT-hooks' and a negatively charged C-terminus. HMGA2 can form homodimers through electrostatic interactions between its 'AT-hooks' and C-terminus. This suggests that the negatively charged C-terminus may inhibit DNA binding by interacting with the positively charged 'AT-hooks.' In this paper, we demonstrate that the C-terminus significantly influences HMGA2's DNA-binding properties. For example, the C-terminal deletion mutant HMGA2Δ95-108 binds more tightly to the AT-rich DNA oligomer FL814 than wild-type HMGA2. Additionally, a synthetic peptide derived from the C-terminus (the C-terminal motif peptide or CTMP) strongly inhibits HMGA2's binding to FL814, likely by interacting with the 'AT-hooks,' as shown by various biochemical and biophysical assays. Molecular modeling demonstrates that electrostatic interactions and hydrogen bonding are the primary forces driving CTMP's binding to the 'AT-hooks.' Intriguingly, we found that hydration does not play a role in HMGA2-DNA binding. These results suggest that the highly negatively charged C-terminus of HMGA2 plays a critical role in regulating its DNA-binding capacity through autoinhibition, likely facilitating the target search process for AT-rich DNA sequences.

Cingulate to septal circuitry facilitates the preference to affiliate with large peer groups

Despite the prevalence of large-group living across the animal kingdom, no studies have examined the neural mechanisms that make group living possible. Spiny mice, Acomys, have evolved to live in large groups and exhibit a preference to affiliate with large over small groups. Here, we determine the neural circuitry that facilitates the drive to affiliate with large groups. We first identify an anterior cingulate cortex (ACC) to lateral septum (LS) circuit that is more responsive to large than small groups of novel same-sex peers. Using chemogenetics, we then demonstrate that this circuit is necessary for both male and female group investigation preferences but only males' preference to affiliate with larger peer groups. Furthermore, inhibition of the ACC-LS circuit specifically impairs social, but not nonsocial, affiliative grouping preferences. These findings reveal a key circuit for the regulation of mammalian peer group affiliation.

Distinct Genes with Similar Functions Underlie Convergent Evolution in Myotis Bat Ecomorphs.

Convergence offers an opportunity to explore to what extent evolution can be predictable when genomic composition and environmental triggers are similar. Here, we present an emergent model system to study convergent evolution in nature in a mammalian group, the bat genus Myotis. Three foraging strategies-gleaning, trawling, and aerial hawking, each characterized by different sets of phenotypic features-have evolved independently multiple times in different biogeographic regions in isolation for millions of years. To investigate the genomic basis of convergence and explore the functional genomic changes linked to ecomorphological convergence, we sequenced and annotated 17 new genomes and screened 16,426 genes for positive selection and associations between relative evolutionary rates and foraging strategies across 30 bat species representing all Myotis ecomorphs across geographic regions as well as among sister groups. We identify genomic changes that describe both phylogenetic and ecomorphological trends. We infer that colonization of new environments may have first required changes in genes linked to hearing sensory perception, followed by changes linked to fecundity and development, metabolism of carbohydrates, and heme degradation. These changes may be linked to prey acquisition and digestion and match phylogenetic trends. Our findings also suggest that the repeated evolution of ecomorphs does not always involve changes in the same genes but rather in genes with the same molecular functions such as developmental and cellular processes.

Xinyang flavivirus, from Haemaphysalis flava ticks in Henan Province, China, defines a basal, likely tick-only Orthoflavivirus clade.

Tick-borne orthoflaviviruses (TBFs) are classified into three conventional groups based on genetics and ecology: mammalian, seabird and probable-TBF group. Recently, a fourth basal group has been identified in Rhipicephalus ticks from Africa: Mpulungu flavivirus (MPFV) in Zambia and Ngoye virus (NGOV) in Senegal. Despite attempts, isolating these viruses in vertebrate and invertebrate cell lines or intracerebral injection of newborn mice with virus-containing homogenates has remained unsuccessful. In this study, we report the discovery of Xinyang flavivirus (XiFV) in Haemaphysalis flava ticks from Xìnyáng, Henan Province, China. Phylogenetic analysis shows that XiFV was most closely related to MPFV and NGOV, marking the first identification of this tick orthoflavivirus group in Asia. We developed a reverse transcriptase quantitative PCR assay to screen wild-collected ticks and egg clutches, with absolute infection rates of 20.75 % in adult females and 15.19 % in egg clutches, suggesting that XiFV could be potentially spread through transovarial transmission. To examine potential host range, dinucleotide composition analyses revealed that XiFV, MPFV and NGOV share a closer composition to classical insect-specific orthoflaviviruses than to vertebrate-infecting TBFs, suggesting that XiFV could be a tick-only orthoflavivirus. Additionally, both XiFV and MPFV lack a furin cleavage site in the prM protein, unlike other TBFs, suggesting these viruses might exist towards a biased immature particle state. To examine this, chimeric Binjari virus with XIFV-prME (bXiFV) was generated, purified and analysed by SDS-PAGE and negative-stain transmission electron microscopy, suggesting prototypical orthoflavivirus size (~50 nm) and bias towards uncleaved prM. In silico structural analyses of the 3'-untranslated regions show that XiFV forms up to five pseudo-knot-containing stem-loops and a prototypical orthoflavivirus dumbbell element, suggesting the potential for multiple exoribonuclease-resistant RNA structures.

Unraveling the diversity of Trypanosoma species from Central Mexico: molecular confirmation on the presence of Trypanosoma dionisii and novel Neobat linages

Bats are one of the groups of mammals with the highest number of associated Trypanosoma taxa. There are 50 Trypanosoma species and genotypes infecting more than 75 species of bats across five continents. However, in Mexico, the inventory of species of the genus Trypanosoma associated with bats is limited to only two species (Trypanosoma vespertilionis and Trypanosoma cruzi) even though 140 species of bats inhabit this country. Specifically, 91 bat species have been recorded in the state of Veracruz, but records of trypanosomatids associated with this mammalian group are absent. Due to the complex Trypanosoma–bat relationship, the high diversity of bat species in Veracruz, as well as the lack of records of trypanosomatids associated with bats for this state, the aim of this work was to analyze the diversity of species of the genus Trypanosoma and their presence from a bat community in the central area of the state of Veracruz, Mexico. During the period of January to August 2022 in the Tequecholapa Environmental Management Unit where bats were collected using mist nets and blood samples were obtained from their thumbs. We extracted genetic material and amplified a fragment of 800 bp of the 18S ribosomal gene of the genus Trypanosoma by conventional PCR. The positive amplicons were sequenced, and phylogenetic reconstruction was performed to identify the parasite species. A total of 285 bats (149♀, 136♂) belonging to 13 species from 10 genera and a single family (Phyllostomidae) were collected. Twenty-three specimens from six species tested positive for the presence of Trypanosoma dionisii, Trypanosoma sp. Neobat 4, and a potential novelty species provisionally named as Trypanosoma sp. Neobat 6. The results of the present work increase the number of species of the genus Trypanosoma infecting bats in Mexico and in the Neotropical region.

Single-Cell Analysis of Rohon-Beard Neurons Implicates Fgf Signaling in Axon Maintenance and Cell Survival.

Peripheral sensory neurons are a critical part of the nervous system that transmit a multitude of sensory stimuli to the central nervous system. During larval and juvenile stages in zebrafish, this function is mediated by Rohon-Beard somatosensory neurons (RBs). RBs are optically accessible and amenable to experimental manipulation, making them a powerful system for mechanistic investigation of sensory neurons. Previous studies provided evidence that RBs fall into multiple subclasses; however, the number and molecular makeup of these potential RB subtypes have not been well defined. Using a single-cell RNA sequencing (scRNA-seq) approach, we demonstrate that larval RBs in zebrafish fall into three, largely nonoverlapping classes of neurons. We also show that RBs are molecularly distinct from trigeminal neurons in zebrafish. Cross-species transcriptional analysis indicates that one RB subclass is similar to a mammalian group of A-fiber sensory neurons. Another RB subclass is predicted to sense multiple modalities, including mechanical stimulation and chemical irritants. We leveraged our scRNA-seq data to determine that the fibroblast growth factor (Fgf) pathway is active in RBs. Pharmacological and genetic inhibition of this pathway led to defects in axon maintenance and RB cell death. Moreover, this can be phenocopied by treatment with dovitinib, an FDA-approved Fgf inhibitor with a common side effect of peripheral neuropathy. Importantly, dovitinib-mediated axon loss can be suppressed by loss of Sarm1, a positive regulator of neuronal cell death and axonal injury. This offers a molecular target for future clinical intervention to fight neurotoxic effects of this drug.

Rodents show darker and redder coloration in warm and rainy environments

AbstractAimAnimal coloration varies in response to environmental conditions. One well‐known principle, Gloger's rule, suggests that warmer and wetter environments lead to more pigmented animals. Yet, the original formulation lacks differentiation between the two primary melanin pigments: eumelanin and pheomelanin. We examined spatial eumelanin and pheomelanin variation to unravel the impact of various ecological factors on pigment deposition, and to assess support for the complex version of Gloger's rule.LocationSouth America.Time PeriodContemporary.Major Taxa StudiedSigmodontine rodents.MethodsWe extracted pelage color data from 231 species and quantified the geographic variation in eu‐ and pheomelanin deposition. We performed linear multiple regression to investigate the influence of temperature, precipitation, predator diversity, and UVA‐B radiance in eumelanin (lightness) and pheomelanin (redness).ResultsOur findings support the original formulations of Gloger's rule. Rodents in warmer and rainier regions, which also entails greater exposure to UV radiation and a diverse range of predators, exhibit darker‐colored pelage. In addition, redder rodents prevail in warmer environments. However, contrary to the rule predictions, we observe a reversal for reddish patterns in relation to precipitation, with rainier regions showcasing more intense red rodents.Main ConclusionsOur study breaks new ground by investigating previously unexplored facets of Gloger's rule in a continental mammalian group. We discovered compelling evidence that darker and redder coloration aligns closely with temperature and rainfall gradients. Although we found support for eumelanin–pelage predictions, expectations for pheomelanin pigmentation were only partially met. Our results might suggest that selective pressures act differently on dark and reddish coloration, revealing that coloration patterns in response to climate are more intricate than previously formulated.

Derived faunivores are the forerunners of major synapsid radiations.

Evolutionary radiations generate most of Earth's biodiversity, but are there common ecomorphological traits among the progenitors of radiations? In Synapsida (the mammalian total group), 'small-bodied faunivore' has been hypothesized as the ancestral state of most major radiating clades, but this has not been quantitatively assessed across multiple radiations. To examine macroevolutionary patterns in a phylogenetic context, we generated a time-calibrated metaphylogeny ('metatree') comprising 1,888 synapsid species from the Carboniferous through the Eocene (305-34 Ma) based on 269 published character matrices. We used comparative methods to investigate body size and dietary evolution during successive synapsid radiations. Faunivory is the ancestral dietary regime of each major synapsid radiation, but relatively small body size is only established as the common ancestral state of radiations near the origin of Mammaliaformes in the Late Triassic. The faunivorous ancestors of synapsid radiations typically have numerous novel characters compared with their contemporaries, and these derived traits may have helped them to survive faunal turnover events and subsequently radiate.

Population genomic analysis reveals distinct demographics and recent adaptation in the black flying fox (Pteropus alecto)

As the only mammalian group capable of powered flight, bats have many unique biological traits. Previous comparative genomic studies in bats have focused on long-term evolution. However, the micro-evolutionary processes driving recent evolution are largely under-explored. Using resequencing data from 50 black flying foxes (Pteropus alecto), one of the model species for bats, we find that black flying fox has much higher genetic diversity and lower levels of linkage disequilibrium than most of the mammalian species. Demographic inference reveals strong population fluctuations (>100 fold) coinciding with multiple historical events including the last glacial change and Toba super eruption, suggesting that the black flying fox is a very resilient species with strong recovery abilities. While long-term adaptation in the black flying fox is enriched in metabolic genes, recent adaptation in the black flying fox has a unique landscape where recently selected genes are not strongly enriched in any functional category. The demographic history and mode of adaptation suggest that black flying fox might be a well-adapted species with strong evolutionary resilience. Taken together, this study unravels a vibrant landscape of recent evolution for the black flying fox and sheds light on several unique evolutionary processes for bats comparing to other mammalian groups.

Insights into the formation and diversification of a novel chiropteran wing membrane from embryonic development

BackgroundThrough the evolution of novel wing structures, bats (Order Chiroptera) became the only mammalian group to achieve powered flight. This achievement preceded the massive adaptive radiation of bats into diverse ecological niches. We investigate some of the developmental processes that underlie the origin and subsequent diversification of one of the novel membranes of the bat wing: the plagiopatagium, which connects the fore- and hind limb in all bat species.ResultsOur results suggest that the plagiopatagium initially arises through novel outgrowths from the body flank that subsequently merge with the limbs to generate the wing airfoil. Our findings further suggest that this merging process, which is highly conserved across bats, occurs through modulation of the programs controlling the development of the periderm of the epidermal epithelium. Finally, our results suggest that the shape of the plagiopatagium begins to diversify in bats only after this merging has occurred.ConclusionsThis study demonstrates how focusing on the evolution of cellular processes can inform an understanding of the developmental factors shaping the evolution of novel, highly adaptive structures.

The importance of the Andes in the evolutionary radiation of Sigmodontinae (Rodentia, Cricetidae), the most diverse group of mammals in the Neotropics

The Andean mountains stand out for their striking species richness and endemicity that characterize many emblematic Neotropical clades distributed in or around these mountains. The radiation of the Sigmodontinae subfamily, the most diversified mammalian group in the Neotropics, has been historically related to Andean orogenesis. We aim to evaluate this interplay between geological processes and biological responses through the diversification dynamics, the biogeographical history, and the range evolution of the subfamily. For these, we built the most comprehensive phylogeny and gathered 14,836 occurrences for the subfamily. We identified one shift in the speciation rate in the genus Akodon, which suffered their Andean radiation after the arrival of non-Andean ancestors. Our biogeographic analyses show multiple dispersal paths throughout the evolution that allowed this subfamily to colonize all Neotropics. The Northern Andes and Central-Southern Andes were the most important sources of diversity. In addition, the Central-Southern Andes were the most relevant sink, receiving the highest number of lineages. The Andean region exhibited higher speciation and turnover rates than non-Andean regions. Thus, our results support the crucial role of the Andean Mountains in the Sigmodontinae radiation, acting as a "macroevolutionary cradle" and "species attractor" for several sigmodontine lineages at different times, and as a "species pump" becoming the biogeographic source of multiple widely distributed neotropical lineages. Then, complex macroevolutionary dynamics would explain these rodents' high extant Andean diversity and their wide distribution in the Neotropics.

Characterization of a novel Hoxa5eGFP mouse line.

Hox genes encode transcription factors that are important for establishing the body plan. Hoxa5 is a member of the mammalian Hox5 paralogous group that regulates the patterning and morphology of the cervical-thoracic region of the axial skeleton. Hoxa5 also plays crucial functions in lung morphogenesis. We generated a Hoxa5eGFP reporter mouse line using CRISPR technology, allowing real-time visualization of Hoxa5 expression. Hoxa5eGFP recapitulates reported embryonic Hoxa5 mRNA expression patterns. Specifically, Hoxa5eGFP can be visualized in the developing mouse neural tube, somites, lung, diaphragm, foregut, and midgut, among other organs. In the stomach, posteriorly biased Hoxa5eGFP expression correlates with a drastic morphological reduction of the corpus in Hox5 paralogous mutants. Expression of Hoxa5eGFP in the lung continues in all lung fibroblast populations through postnatal and adult stages. We identified cell types that express Hoxa5 in postnatal and adult mouse lungs, including various fibroblasts and vascular endothelial cells. This reporter line will be a powerful tool for studies of the function of Hoxa5 during mouse development, homeostasis, and disease processes.

Goats Naturally Infected with the Spanish Goat Encephalitis Virus (SGEV): Pathological Features and An Outbreak

In autumn 2011, a disease outbreak caused by Spanish goat encephalitis virus (SGEV) was reported in a herd of goats from Asturias (north-western Spain), expanding the known geographic distribution of tick-borne encephalitis in Europe. The virus was classified as a new subtype (subspecies) within the Louping-ill virus species of the mammalian tick-borne flavivirus group. The aims of the present study were to describe the pathology in goats naturally infected with SGEV, as well as discuss the pathogenesis of the disease in that outbreak. A total of 22/85 (25.88%) goats (20 adults and 2 kids) died between October 2011 and June 2012, showing neurological clinical signs. Over three years, the mortality rate in the herd reached 100%. Neuropathological lesions caused by SGEV were severe and widespread throughout the central nervous system but were more severe and numerous in the proximal cervical spinal cord, medulla oblongata, pons and cerebellar cortex. They consisted of neuron necrosis, neuronophagia, mononuclear inflammatory cell perivascular cuffs (lymphocytes, plasma cells and macrophages) and gliosis. The distribution of viral antigens was restricted to the cytoplasm of neurons in several brain areas but not associated with inflammatory foci nor inflammatory cells. SGEV should be considered a significant pathogen of goats that results in severe neurological clinical disease and high mortality.

Perceptions and uses of pangolins (Pholidota) among remote rural communities in the Republic of the Congo: A baseline study from the Odzala‐Kokoua National Park

AbstractHabitat loss and overexploitation are the most severe threats to wild animals in Central Africa. One mammalian group under pressure from hunting is the Pholidota (pangolins), with three species of pangolin inhabiting the region. While local uses of pangolins have been investigated in several Central African countries, data originating from the Republic of the Congo are lacking. To address this knowledge gap, we conducted a semistructured questionnaire survey in 65 rural communities around the Odzala‐Kokoua National Park. Our research focused on collecting baseline information on local knowledge of species ecology, and perceived economic values and uses of pangolins in local communities. We identified significant differences in our data corresponding to respondents' sociocultural and demographic profiles in the surveyed villages. Recognition of pangolins was high (98.2%), we recorded 22 traditional medicinal or cultural uses of pangolins by respondents, and the taste of pangolin meat was ranked highly (71.3%). Respondents based along the northern boundary of the park were more familiar with pangolins and the market value of their meat and scales, which could be due to better quality roads in the area and proximity to Cameroon. We then provide guidelines for further research to better understand the dynamics of local use, needed for conservation policy and actions.

The earliest segmental sternum in a Permian synapsid and its implications for the evolution of mammalian locomotion and ventilation

The sternum is a stabilizing element in the axial skeleton of most tetrapods, closely linked with the function of the pectoral girdle of the appendicular skeleton. Modern mammals have a distinctive sternum characterized by multiple ossified segments, the origins of which are poorly understood. Although the evolution of the pectoral girdle has been extensively studied in early members of the mammalian total group (Synapsida), only limited data exist for the sternum. Ancestrally, synapsids exhibit a single sternal element and previously the earliest report of a segmental sternum in non-mammalian synapsids was in the Middle Triassic cynodont Diademodon tetragonus. Here, we describe the well-preserved sternum of a gorgonopsian, a group of sabre-toothed synapsids from the Permian. It represents an ossified, multipartite element resembling the mammalian condition. This discovery pulls back the origin of the distinctive “mammalian” sternum to the base of Theriodontia, significantly extending the temporal range of this morphology. Through a review of sternal morphology across Synapsida, we reconstruct the evolutionary history of this structure. Furthermore, we explore its role in the evolution of mammalian posture, gait, and ventilation through progressive regionalization of the postcranium as well as the posteriorization of musculature associated with mammalian breathing.

Fluorescence and UV–visible reflectance in the fur of several Rodentia genera

Mammals are generally brown in colour, but recent publications are showing that they may not be as uniform as once assumed. Monotremes, marsupials, and a handful of eutherians reflect various colours when lit with UV light, mostly purple. Because of these still scarce records, we aimed to explore UV reflectance among rodent genera, the most diverse mammalian group, and the group of eutherians with the most common records of biofluorescence. Here we report structures like nails and quills reflected green, but for most genera, it was faded. However, Hystrix, Erethizon, and Ctenomys showed intense and contrasting green glow, while Chaetomys presented a vivid orange anogenital. The main available explanation of fluorescence in mammals relies on porphyrin. This explanation applies to the cases like Chaetomys, where specimens showed anogenital orange biofluorescence, but does not apply to the green biofluorescence we observed. In our sample, because the structures that reflected green were all keratinized, we have reasons to believe that biofluorescence results from keratinization and is a structurally-based colouration. However, not all spines/quills equally biofluoresced, so we cannot rule out other explanations. Since Rodentia is the most common mammalian group with reports on biofluorescence, this trait likely serves various functions that match the species diversity of this group.

Exploring the Conformational and Binding Dynamics of HMGA2·DNA Complexes Using Trapped Ion Mobility Spectrometry-Mass Spectrometry.

The mammalian high mobility group protein AT-hook 2 (HMGA2) is an intrinsically disordered DNA-binding protein expressed during embryogenesis. In the present work, the conformational and binding dynamics of HMGA2 and HMGA2 in complex with a 22-nt (DNA22) and a 50-nt (DNA50) AT-rich DNA hairpin were investigated using trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) under native starting solvent conditions (e.g., 100 mM aqueous NH4Ac) and collision-induced unfolding/dissociation (CIU/CID) as well as solution fluorescence anisotropy to assess the role of the DNA ligand when binding to the HMGA2 protein. CIU-TIMS-CID-MS/MS experiments showed a significant reduction of the conformational space and charge-state distribution accompanied by an energy stability increase of the native HMGA2 upon DNA binding. Fluorescence anisotropy experiments and CIU-TIMS-CID-MS/MS demonstrated for the first time that HMGA2 binds with high affinity to the minor groove of AT-rich DNA oligomers and with lower affinity to the major groove of AT-rich DNA oligomers (minor groove occupied by a minor groove binder Hoechst 33258). The HMGA2·DNA22 complex (18.2 kDa) 1:1 and 1:2 stoichiometry suggests that two of the AT-hook sites are accessible for DNA binding, while the other AT-hook site is probably coordinated by the C-terminal motif peptide (CTMP). The HMGA2 transition from disordered to ordered upon DNA binding is driven by the interaction of the three basic AT-hook residues with the minor and/or major grooves of AT-rich DNA oligomers.

Exploring the Conformations and Binding Location of HMGA2·DNA Complexes Using Ion Mobility Spectrometry and 193 nm Ultraviolet Photodissociation Mass Spectrometry.

Although it is widely accepted that protein function is largely dependent on its structure, intrinsically disordered proteins (IDPs) lack defined structure but are essential in proper cellular processes. Mammalian high mobility group proteins (HMGA) are one such example of IDPs that perform a number of crucial nuclear activities and have been highly studied due to their involvement in the proliferation of a variety of disease and cancers. Traditional structural characterization methods have had limited success in understanding HMGA proteins and their ability to coordinate to DNA. Ion mobility spectrometry and mass spectrometry provide insights into the diversity and heterogeneity of structures adopted by IDPs and are employed here to interrogate HMGA2 in its unbound states and bound to two DNA hairpins. The broad distribution of collision cross sections observed for the apo-protein are restricted when HMGA2 is bound to DNA, suggesting that increased protein organization is promoted in the holo-form. Ultraviolet photodissociation was utilized to probe the changes in structures for the compact and elongated structures of HMGA2 by analyzing backbone cleavage propensities and solvent accessibility based on charge-site analysis, which revealed a spectrum of conformational possibilities. Namely, preferential binding of the DNA hairpins with the second of three AT-hooks of HMGA2 is suggested based on the suppression of backbone fragmentation and distribution of DNA-containing protein fragments.

TLR7 and TLR8 evolution in lagomorphs: different patterns in the different lineages.

Toll-like receptors (TLRs) are one of the most ancient and widely studied innate immune receptors responsible for host defense against invading pathogens. Among the known TLRs, TLR7 and TLR8 sense and recognize single-stranded (ss) RNAs with a dynamic evolutionary history. While TLR8 was lost in birds and duplicated in turtles and crocodiles, TLR7 is duplicated in some birds, but in other tetrapods, there is only one copy. In mammals, with the exception of lagomorphs, TLR7 and TLR8 are highly conserved. Here, we aim to study the evolution of TLR7 and TLR8 in mammals, with a special focus in the order Lagomorpha. By searching public sequence databases, conducting evolutionary analysis, and evaluating gene expression, we were able to confirm that TLR8 is absent in hares but widely expressed in the European rabbit. In contrast, TLR7 is absent in the European rabbit and quite divergent in hares. Our results suggest that, in lagomorphs, more in particular in leporids, TLR7 and TLR8 genes have evolved faster than in any other mammalian group. The long history of interaction with viruses and their location in highly dynamic telomeric regions might explain the pattern observed.

Diet of small mammals in semi‐deciduous forest fragments in Central Brazil

AbstractMarsupials and rodents are two of the most specious mammalian group, displaying a variety of diet and feeding habits. However, the knowledge about diet for several small mammal species is scant in the scientific literature, and most species are classified as insectivore–omnivore (marsupials), or frugivore–graminivore (rodents). In this study, we described diet composition based on digestive tract contents of 12 species of small mammals (7‐rodents and 5‐marsupials), in semi‐deciduous forest fragments of Central Brazil. We analysed 47 digestive tract contents belong to Calomys tener (10), Oecomys bicolor (10), Gracilinanus agilis (6), Marmosa murina (5), Rhipidomys macrurus (5), Calomys expulsus (2), Cryptonanus chacoensis (2), Monodelphis kunsi (2), Oecomys catherinae (2), Caluromys philander (1), Oligoryzomys mattogrossae (1) and Necromys lasiurus (1). We found parts of arthropods and fruits in the digestive tract of all species, with the exception of N. lasiurus, which contained only arthropods. The most representative arthropod taxa were Hymenoptera (present in 11 species), Coleoptera (9 spp.), Arachnida (7 spp.) and Isoptera (6 spp.). The seeds of Piperaceae (present in 3 small mammal species), Myrtaceae (2 spp.) and Poaceae (1 sp.) were also identified. This study reports the first records of diet composition for the marsupials C. chacoensis and M. murina, and rodents C. expulsus, C. tener, O. bicolor, O. catherinae and R. macrurus. Our findings contribute to understanding the diet composition and natural history of the Brazilian Savanna small mammals.