Yonas Meheretu

High Diversity of RNA Viruses in Rodents, Ethiopia

We investigated synanthropic small mammals in the Ethiopian Highlands as potential reservoirs for human pathogens and found that 2 rodent species, the Ethiopian white-footed mouse and Awash multimammate mouse, are carriers of novel Mobala virus strains. The white-footed mouse also carries a novel hantavirus, the second Murinae-associated hantavirus found in Africa.

Pan-African phylogeny of Mus (subgenus Nannomys) reveals one of the most successful mammal radiations in Africa

BackgroundRodents of the genus Mus represent one of the most valuable biological models for biomedical and evolutionary research. Out of the four currently recognized subgenera, Nannomys (African pygmy mice, including the smallest rodents in the world) comprises the only original African lineage. Species of this subgenus became important models for the study of sex determination in mammals and they are also hosts of potentially dangerous pathogens. Nannomys ancestors colonized Africa from Asia at the end of Miocene and Eastern Africa should be considered as the place of their first radiation. In sharp contrast with this fact and despite the biological importance of Nannomys, the specimens from Eastern Africa were obviously under-represented in previous studies and the phylogenetic and distributional patterns were thus incomplete.ResultsWe performed comprehensive genetic analysis of 657 individuals of Nannomys collected at approximately 300 localities across the whole sub-Saharan Africa. Phylogenetic reconstructions based on mitochondrial (CYTB) and nuclear (IRBP) genes identified five species groups and three monotypic ancestral lineages. We provide evidence for important cryptic diversity and we defined and mapped the distribution of 27 molecular operational taxonomic units (MOTUs) that may correspond to presumable species. Biogeographical reconstructions based on data spanning all of Africa modified the previous evolutionary scenarios. First divergences occurred in Eastern African mountains soon after the colonization of the continent and the remnants of these old divergences still occur there, represented by long basal branches of M. (previously Muriculus) imberbis and two undescribed species from Ethiopia and Malawi. The radiation in drier lowland habitats associated with the decrease of body size is much younger, occurred mainly in a single lineage (called the minutoides group, and especially within the species M. minutoides), and was probably linked to aridification and climatic fluctuations in middle Pliocene/Pleistocene.ConclusionsWe discovered very high cryptic diversity in African pygmy mice making the genus Mus one of the richest genera of African mammals. Our taxon sampling allowed reliable phylogenetic and biogeographic reconstructions that (together with detailed distributional data of individual MOTUs) provide a solid basis for further evolutionary, ecological and epidemiological studies of this important group of rodents.

Bartonella Prevalence and Genetic Diversity in Small Mammals from Ethiopia

More than 500 small mammals were trapped at 3 localities in northern Ethiopia to investigate Bartonella infection prevalence and the genetic diversity of the Bartonella spp. We extracted total DNA from liver samples and performed PCR using the primers 1400F and 2300R targeting 852 bp of the Bartonella RNA polymerase beta subunit (rpoB) gene. We used a generalized linear mixed model to relate the probability of Bartonella infection to species, season, locality, habitat, sex, sexual condition, weight, and ectoparasite infestation. Overall, Bartonella infection prevalence among the small mammals was 34.0%. The probability of Bartonella infection varied significantly with species, sex, sexual condition, and some locality, but not with season, elevation, habitat type, animal weight, and ectoparasite infestation. In total, we found 18 unique Bartonella genotypes clustered into 5 clades, 1 clade exclusively Ethiopian, 2 clades clustered with genotypes from central and eastern Africa, and the remaining 2 clades clustered with genotypes and species from Africa and Asia. The close relatedness of several of our Bartonella genotypes obtained from the 3 dominant rodent species in Tigray with the pathogenic Bartonella elizabethae from Rattus spp. in Asia indicates a potential public health threat.

Enigmatic Ethiopian endemic rodent Muriculus imberbis (Rüppell 1842) represents a separate lineage within genus Mus

Abstract The phylogenetic position of the Ethiopian striped mouse (Muriculus imberbis) has remained obscure since its description. Here, we report, for the first time, the phylogenetic analysis of this species using mitochondrial (cytochrome b) and nuclear (interphotoreceptor binding protein) gene sequences obtained from a specimen recently caught in the Galama Mountain in the south-central Ethiopian highland region. The recent finding of the species in ericaceous shrub in the Afroalpine habitat is remarkable, as decades of attempts to capture it in this habitat failed, probably because of inappropriate trapping methods. Our analyses strongly suggest that the Ethiopian striped mouse does not belong to a distinct monotypic genus, but to the genus Mus, as the ancient lineage of the African subgenus Nannomys.

New discoveries on the ecology and echolocation of the heart-nosed bat Cardioderma cor with a contribution to the phylogeny of Megadermatidae

In this study we report findings in roosting ecology, ectoparasites, echolocation characteristics and the phylogenetic position of Cardioderma cor, an impressive bat species that is distributed throughout the savannas and woodlands of eastern Africa. For individuals caught in Mago National Park, Ethiopia, we recorded broadband frequency-modulated ultrasound signals having very short duration (2 ms) with three harmonic components. The mean peak frequency of the first harmonic was 50.4 kHz and the mean inter-signal interval was 186 ms. Phylogenetic reconstructions of all known species from the family Megadermatidae based on DNA sequences of two mitochondrial and four nuclear genes yielded incongruent topologies (both Bayesian inference and maximum likelihood analysis) with only weak support for nodes. The phylogeny that combined all six loci into a species tree was not congruent with any previous inference based on dental or cranial characteristics, but it suggested separate generic status of two Megaderma species. However, additional genetic data are necessary to resolve the phylogeny of Megadermatidae, a group that probably evolved by simultaneous divergence of all five extant lineages.

Ecological role of the giant root-rat (Tachyoryctes macrocephalus) in the Afroalpine ecosystem

Rodents with prevailing subterranean activity usually play an important role in the ecosystems of which they are a part due to the combined effect of herbivory and soil perturbation. This is the case for the giant root-rat Tachyoryctes macrocephalus endemic to the Afroalpine ecosystem of the Bale Mountains, Ethiopia. We studied the impact of root-rats on various ecosystem features within a 3.5-ha study locality dominated by Alchemilla pasture, which represents an optimal habitat for this species, in 2 periods of a year. The root-rats altered plant species composition, reducing the dominant forb, Alchemilla abyssinica, while enhancing Salvia merjame and a few other species, and reduced vegetation cover, but not the fresh plant biomass. Where burrows were abandoned by root-rats, other rodents took them over and A. abyssinica increased again. Root-rat burrowing created small-scale heterogeneity in soil compactness due to the backfilling of some unused burrow segments. Less compacted soil tended to be rich in nutrients, including carbon, nitrogen and phosphorus, which likely affected the plant growth on sites where the vegetation has been reduced as a result of root-rat foraging and burrowing.

Reproduction and survival of rodents in crop fields: the effects of rainfall, crop stage and stone-bund density

Abstract Context. Reproduction and survival are two of the most important demographic factors that play a major role in changing population abundances of pest species over time and space, solid understanding of which is a useful input to forecast future population changes for proactive management. Aims. We investigated the effects of rainfall, crop-development stage and density of stone bunds on reproductive patterns, and the effects of stone-bund density and sex on survival probabilities of two widespread rodent species (Mastomys awashensis and Arvicanthis dembeensis) in Ethiopian highlands. Methods. Rodent population dynamics were monitored from April 2007 to February 2011, using capture–mark–recapture (CMR) technique in four 60 × 60 m permanent square grids for four consecutive cropping seasons. Two of the grids represented fields with low stone-bund density (LSBD, ∼15 m apart) and the other two represented fields with high stone-bund density (HSBD, ∼10 m apart). Key results. Reproduction was seasonal, commencing during the wet season following the rain and continuing through the early dry season. We found an increase in the abundance of reproductively active female individuals of both species towards the milky and fruiting crop stages and around harvest period. We found no strong difference in survival probability between the two rodent species with variation in stone-bund density and sex. Conclusions. Stone bunds play a minor role in the reproduction and survival of the rodent species at the observed abundances. Implications. In terms of pest management, the high local survival rates estimated for both rodent species matter more than survival differences owing to variations in stone-bund density and sex.

Importance of Lake Ashenge, a Small Important Bird Area in Northern Ethiopia, to Palaearctic and Other Migratory Birds

Tropical inland lakes harbour a variety of waterbirds and provide a wintering habitat for Palaearctic and other migratory birds. However, the importance of the lakes as a temporary site for migrant bird populations has not been adequately studied. The point count method was used to study waterbird species diversity and abundance in Lake Ashenge, in the semi-arid region of northern Ethiopia, with the main aim to underscore the lakes importance as a stop-over site for Palaearctic and other migratory birds. A total of 36 species belonging to 14 waterbird families were encountered. Fifteen of the species were resident birds, including the endemic Wattled Ibis (Bostrychia carunculata), and 14 of the species were Palaearctic migrants, including the globally Near-Threatened Ferruginous Duck (Ayithya nyroca) and Maccoa Duck (Oxyura maccoa). Significant temporal variation in diversity and abundance was observed during the study period; diversity was highest (Shannon-Wiener H′ = 1.98) in the dry season (December/January) and lowest (H′ = 1.11) in the rainy season (August/September), whereas mean abundance was highest (c. 4219 individuals) in the post-rainy season (October/November) and lowest (c. 2631 individuals) in the dry season. Increased abundance of Palaearctic species towards the dry season increased species diversity,but may have caused displacement of resident birds resulting in lower overall abundance in this season. This study provides a new distributional record for Maccoa Duck, highlights the significance of the lake for several waterbird species and calls for its protection.