No Oguge

Cytogenetics of a new cytotype of African Mus (subgenus Nannomys) minutoides (Rodentia, Muridae) from Kenya: C- and G- banding and distribution of (TTAGGG) n telomeric sequences

We present the results of a cytogenetic study on Mus (Nannomys) minutoides from Kenya by means of C- and G- banding and in-situ fluorescence hybridization (FISH) to localize the telomeric sequences. The karyotype is characterized by the occurrence of several Rb chromosomes Rb(1.X), Rb(1.Y). Rb(2.17), Rb(3.13), Rb(4.10), Rb(5.11), Rb(6.7), Rb(8.12), not previously described for this species. This finding suggests a high level of chromosomal diversification, which means it is possible to consider this cytotype as a new, well-differentiated, chromosomal lineage within the subgenus. The C-banding of the metaphases illustrated conspicuous blocks of centromeric heterochromatin at the paracentromeric regions of all telocentric chromosomes. Centromeric heterochromatin is not visible on all biarmed chromosomes. Following hybridization with telomeric probes, bright interstitial telomeric sequence (ITS) fluorescence signals are evident at the pericentromeric area of all Rb chromosomes, with the exception of Rb(2.17). Considering the localization of the C-positive heterochromatin and of the telomeric sequences, the events leading to the Kenyan cytotype from an all-telocentric condition probably included two steps: first, fusion without loss of heterochromatin and pericentromeric telomeric sequences; second, the reduction of the C-positive satellite DNA followed by the amplification of telomeric sequences in the C-negative paracentromeric region of Rb chromosomes. The presence of a single Rb(2.17) without ITS indicates possible variations of this mechanism.

International citizen science: making the local global

The Earthwatch Institute is an international non-profit organization that works with scientists and scientific institutions to develop citizen-science-based research and environmental monitoring programs. Each year, Earthwatch supports close to 80 different projects in more than 30 countries and recruits over 3000 volunteers to aid scientists in collecting data. Participants recruited by Earthwatch seek to tap into their passion for learning about science by volunteering to act as assistants for authentic research projects.

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.

Diversity and structure of shrew communities in montane forests of southeast Kenya

Summary As a step towards setting conservation priorities for declining moist forests in southeast Kenya, we assessed for small mammal diversity and distribution. These habitats are under severe pressure due to increased demand an forests products and arable land, yet there is a dearth of information an impacts an biodiversity. Over an eight-month period, we used a combination of box and pitfall traps with drift fences to study 13 forest fragments in five geographic areas ranging between 3°28′−4°10′ S and 38°28′−39°2b′ E. We recorded 12 species including 10 soricids and two macroscelids in 31440 trap nights. Diversity estimates using rarefaction method indicate a species richness of 12, consistent with our collection. There were six unique species, each limited in distribution to one forest fragment. Our record of Crocidura cf. selina in Kyulu Hills is the first outside Mabira forest in Uganda where it is considered endemic and endangered. We also report the first record of C. fuscomurina in Kenya, white those of C. Luna and Suncus megalura are first in the southeast of the country. By providing new ranges to four species, our study is of significance to the biogeography and conservation of forest small mammals in the region.

Mitochondrial DNA diversity and population structure of a forest-dependent rodent, Praomys taitae (Rodentia: Muridae) Heller 1911, in the fragmented forest patches of Taita Hills, Kenya

The population genetic structure of the forest-dependent rodent, Praomys taitae, sampled from nine indigenous forest fragments distributed over three ranges of the Taita Hills in Kenya, was deter- mined using mitochondrial DNA (mtDNA) control region sequence variation. Thirty-three unique haplotypes were observed in a total sample of 132 individuals, whereas the number of different haplotypes per population ranged from two to 10. An overall low nucleotide diversity of 0.9% was observed in the total sample but varied widely between populations (0.2-1.3%). Significant genetic differentiation was observed in 30 of the 36 possible pair-wise comparisons between populations, while a hierarchical AMOVA revealed signifi- cant genetic subdivision between groups of populations on the three hill ranges of Dabida, Mbololo and Kyulu (FCT = 0.404, P < 0.01), among populations on each of the hill ranges (FSC = 0.112, P < 0.01) and among populations in the total sample (FST = 0.471, P < 0.001). Demographic history analyses based on pair-wise nucleotide sequence mismatch distributions revealed that all the populations were in mutation-drift disequilibrium except the popu- lations of the Kyulu and Ronge forest fragments.

Climate Change and the Emergence of Helter-Skelter Livelihoods Among the Pastoralists of Samburu East District, Kenya

Due to climate change, northern Kenya is experiencing intense droughts at shorter intervals with intermittent high precipitation and flooding. This has a major impact on livelihoods of the pastoral community, whose ways of life revolve around the availability of pasture and water for their livestock. Our study set out to determine the Samburu people’s perception of climate change and how they cope with its effects. Such information is important in developing evidence-based policies on adaptation strategies for African dry-lands. Our study undertook a survey of knowledge, attitudes and life histories among the Samburu communities using semi-structured questionnaires and focus group discussions. Respondents indicated that climate change leads to soil erosion, local extinction of some faunal species, water and pasture scarcity, and intensification of conflicts over resources. This has negatively impacted on their livelihoods due to food shortage, human and livestock diseases, social and family instability, and general insecurity.

Fostering the Use of Rainwater for Off-Season Small-Scale Irrigation in Arid and Semi-arid Areas of Kenya

Water scarcity is a constraint to rainfed agriculture in tropical arid and semi-arid environments. This situation is likely to be exacerbated by climate change. Further, sub-Saharan Africa is expected to experience increased consumption of food, energy and water resources due to rapidly growing economies and urban populations. This calls for innovative and appropriate technologies to support production systems amid the changing climate. Collection, storage and use of rainwater for off-season irrigation, if combined with climate-smart agriculture, have the potential to improve food security and income for smallholder farmers. Replication, scaling-up and transfer of integrated rainwater harvesting (RWH) irrigation management systems require a multidimensional assessment of existing technologies and their use. This study sets out to assess and map best practices in RWH irrigation systems in dryland agro-ecosystems in Kenya. We used both primary and secondary sources in our evaluation. Primary data was based on key informant interviews of institutions and practitioners, and stakeholder workshops in RWH. Secondary sources included journals, technical reports and other relevant publications. Our study identified adoption of place-specific rainwater harvesting systems. These included in situ, micro- and macro-catchment technologies. While the in situ and micro-catchment systems included soil conservation measures, macro-catchment systems were run-off-based. Our finding shows that arid and semi-arid areas of Kenya have high potential for climate resilient food production if RWH irrigation technologies are adopted and scaled up, hence the need for policies that would promote adoption of context-specific rainwater harvesting technologies for different climatic, bio-physical, socio-economic and cultural conditions. This will enhance adaptive capacities of smallholder farmers and reduce their vulnerabilities to climate change while increasing food production to meet growing demand in the country with a view to contributing to sustainable development.

Using Rainwater for Off-Season Small-Scale Irrigation in Arid and Semi-arid Areas of Sub-Saharan Africa: Key Working Principles and Best Practices

The performance and cost-efficiency of off-season small-scale irrigation in arid and semi-arid areas of sub-Saharan Africa can be optimised by means of off-season rainwater harvesting irrigation management (RWHI), which is a subset of rainwater harvesting technologies and practices that allows concentrating and storing rainwater to be used for off-season small-scale irrigation of high-value crops in arid and semi-arid areas. A RWHI system has three main components, i.e. rainwater/runoff collection catchment, rainwater/runoff storage facility, and a low-cost irrigation system that applies water to the crop area during dry periods. Best practices for RWHI management at household level are upgraded on-farm ponds and/or low-cost roof catchments connected to manual pumping systems and low-cost drip irrigation kits. Total costs for storage capacities of 50–100 m3 range from 1000 to 3000 USD and present cost-efficiencies of 26–50 USD/m3 of irrigated water. At community level, hillside earth dams, rock catchments, alluvial shallow groundwater, subsurface dams and sand storage dams can be connected to mechanised/manual pumping systems and low-cost drip irrigation kits. RWHI systems which use subsurface dams made of soil present the highest cost-efficiency (3 USD/m3 of irrigated water). Further, RWHI technologies are clearly site-specific. Therefore, replication and scaling-up needs to strictly consider multi-dimensional physical and hydrogeological suitability factors coupled with the cost-efficiency and specific technical considerations of the technologies and practices. In addition, the technical and financial capability of the beneficiaries coupled with the revenue potential of the RWHI systems plays a crucial role in the replication of RWHI technologies.