The accelerating influence of humans on mammalian macroecological patterns over the late Quaternary

The transition of hominins to a largely meat-based diet ~1.8 million years ago led to the exploitation of other mammals for food and resources. As hominins, particularly archaic and modern humans, became increasingly abundant and dispersed across the globe, a temporally and spatially transgressive extinction of large-bodied mammals followed; the degree of selectivity was unprecedented in the Cenozoic fossil record. Today, most remaining large-bodied mammal species are confined to Africa, where they coevolved with hominins. Here, using a comprehensive global dataset of mammal distribution, life history and ecology, we examine the consequences of “body size downgrading” of mammals over the late Quaternary on fundamental macroecological patterns. Specifically, we examine changes in species diversity, global and continental body size distributions, allometric scaling of geographic range size with body mass, and the scaling of maximum body size with area. Moreover, we project these patterns toward a potential future scenario in which all mammals currently listed as vulnerable on the IUCN\u27s Red List are extirpated. Our analysis demonstrates that anthropogenic impact on earth systems predates the terminal Pleistocene and has grown as populations increased and humans have become more widespread. Moreover, owing to the disproportionate influence on ecosystem structure and function of megafauna, past and present body size downgrading has reshaped Earth\u27s biosphere. Thus, macroecological studies based only on modern species yield distorted results, which are not representative of the patterns present for most of mammal evolution. Our review supports the concept of benchmarking the “Anthropocene” with the earliest activities of Homo sapiens

Transrectal ultrasonography of the adrenal glands in donkeys (Equus asinus)

Little information is available for medical imaging in donkeys and no report about adrenal glands ultrasonography can be found in scientific literature. The feasibility of transrectal ultrasonography of the adrenal glands was tested on 30 healthy donkeys using a 10 MHz linear transducer. Mean age of animals was 10.7 ±4.8 years, mean weight 275.0 ±62.9 Kg and mean height 126.7 ±7.1 cm. The left adrenal gland was visualized in all donkeys. The right gland ultrasonography was not feasible in seven animals with a height less than 116 cm. The left gland was visualized as a linear or slightly curved structure, the right gland was most often S-shaped. In both glands, an hypechoic peripheral zone was identified as the cortex with an inner, hyperechoic medulla. The length was 5.49 ±1.90 cm and 5.15 ±1.10 cm for right and left gland, respectively. Right gland whole and medullary thickness were 0.71 ±0.11 cm and 0.24 ±0.09 cm, 0.65 ±0.13 cm and 0.21 ±0.07 cm, 0.56 ±0.17 cm and 0.25 ±0.07 cm for cranial pole, middle point and caudal pole respectively. Left gland whole and medullary thickness were 0.69 ±0.13 cm and 0.25 ±0.09 cm, 0.66 ±0.13 cm and 0.23 ±0.09 cm, 0.57 ±0.15 cm and 0.26 ±0.09 cm for cranial pole, middle point and caudal pole respectively. There was a significant correlation between height and the entire length of the left gland. Ultrasonography of the adrenal glands is a suitable tool for evaluation of both adrenal glands in most of the donkey. The size is a limiting factor for proper visualization of the right gland

Distribution, diversity and evolution of endogenous retroviruses in perissodactyl genomes

The evolution of mammalian genomes has been shaped by interactions with endogenous retroviruses (ERVs). In this study, we investigated the distribution and diversity of ERVs in the mammalian order Perissodactyla, with a view to understanding their impact on the evolution of modern equids (family Equidae). We characterize the major ERV lineages in the horse genome in terms of their genomic distribution, ancestral genome organization and time of activity. Our results show that subsequent to their ancestral divergence from rhinos and tapirs, equids acquired four novel ERV lineages. We show that two of these proliferated extensively in the lineage leading to modern horses, and one contains loci that are actively transcribed in specific tissues. In addition, we show that the white rhinoceros has resisted germline colonisation by retroviruses for over 54 million years - longer than any other extant mammalian species. The map of equine ERVs that we provide here will be of great utility to future studies aiming to investigate the potential functional roles of equine ERVs, and their impact on equine evolution

THE HIPPARIONINE HORSES (PERISSODACTYLA: MAMMALIA) FROM THE LATE MIOCENE OF TIZI N’TADDERHT (SOUTHERN OUARZAZATE BASIN; CENTRAL HIGH ATLAS; MOROCCO)

The fossiliferous locality of Tizi N’Tadderht, already known in the literature , has yielded a significant vertebrate fossil association as it represents the first documentation of a Late Miocene vertebrate fauna in the western area of North Africa. The group of fossil Equidae here analyzed had been preliminarly studied by previous authors, who identified the following hipparionini species: aff. Cremohipparion periafricanum, Hippotheriini gen. et sp. indet., and cf. Hippotherium primigenium. The sample retrieved from the considered area has been revised through the description of the morphologies and the dimensional measurements analysis. Then, it has been compared with the collection of fossil Equidae of the Libyan fossil site of As Sahabi, where the following species of Equidae hipparionini are represented: Sivalhippus sp., Eurygnathohippus feibeli and Cremohipparion mattewi. The revision of the Tizi N’Tadderht association led to the identification of the following species: Hippotherium sp. (characterized by large size); Eurygnathohippus cf. feibeli (a medium-sized Equidae; for the first time recognized in the Tizi N’Tadderht site); aff. Cremohipparion periafricanum (distinguished for its small size, as previously hypothesized in literature). The discovery of Eurygnathohippus cf. feibeli at Tizi N’Tadderht is of particular importance as it extends the paleogeographic record of this Hipparion species present in other African sites, showing that it is well represented in the fossil record of the Late Miocene

Scaling of the risk landscape drives optimal life history strategies and the evolution of grazing

Consumers face numerous risks that can be minimized by incorporating different life-history strategies. How much and when a consumer adds to its energetic reserves or invests in reproduction are key behavioral and physiological adaptations that structure much of how organisms interact. Here we develop a theoretical framework that explicitly accounts for stochastic fluctuations of an individual consumer's energetic reserves while foraging and reproducing on a landscape with resources that range from uniformly distributed to highly clustered. First, we show that optimal life-history strategies vary in response to changes in the mean productivity of the resource landscape, where depleted environments promote reproduction at lower energetic states, greater investment in each reproduction event, and smaller litter sizes. We then show that if resource variance scales with body size due to landscape clustering, consumers that forage for clustered foods are susceptible to strong Allee effects, increasing extinction risk. Finally, we show that the proposed relationship between consumer body size, resource clustering, and Allee effect-induced population instability offers key ecological insights into the evolution of large-bodied grazing herbivores from small-bodied browsing ancestors.Comment: 9 pages, 5 figures, 3 Supplementary Appendices, 2 Supplementary Figure

Trypanosoma equiperdum in the horse : a neglected threat?

Dourine is a contagious disease caused by Trypanosoma equiperdum that is transmitted directly from animal to animal during coitus. Dourine is known as an important disease in many countries, and it threatens equidae worldwide. It is reported to be widespread in South America, Eastern Europe, Russia, Mongolia, Namibia and Ethiopia. The disease can be carried to various parts of the world through the transportation of infected animals and semen. Since knowledge of the prepatent infectiousness of a recently infected animal is lacking, introduction of the disease is in principle an ever-present threat. Definitive diagnosis depends on the identification of the parasite by means of direct microscopy. This is rarely possible in practice and therefore, diagnosis in the field is based on the observation of typical clinical signs, together with serological tests. This paper is an endeavour to review briefly and compile information on the appearance and importance of Dourine in terms of its epidemiological and clinical features, as well as on its diagnosis, treatment and prognosis