Breeding seasonality and population dynamics of three rodent species in the Magamba Forest Reserve, Western Usambara Mountains, north-east Tanzania

We investigated breeding seasonality and population dynamics of three rodent species, Lophuromys flavopuncatus, Grammomys dolichurus and Praomys delectorum, in the Magamba Forest, Western Usambara Mountains, north‐east Tanzania. Capture–mark–recapture studies were conducted in 2002–2004. Reproductive conditions of males and females showed temporal variations, an indication of breeding seasonality. Animals were reproductively active between February and May. Rainfall in November–January was instrumental for the onset of breeding and continued throughout the wet season. The recruitment of new individuals born during the season led to highest population densities between end of May and August. Populations declined progressively towards the end of the dry season (September–October). Only P. delectorum showed a marked density increase during January–February, indicating greater survival and/or recruitment during the November–January rains. The study shows that despite a relatively stable environment of the forest reserve, rainfall has strong influence on reproduction and population dynamics, probably because of its effect on primary food resources.     

Species limits within the Praomys delectorum group (Rodentia: Muridae: Murinae) of East Africa: a morphometric reassessment and biogeographical implications

We examined approximately 600 specimens that represent the Praomys delectorum species group (Muridae: Murinae: Praomyini), a rodent complex restricted to Afromontane landscapes in East Africa and currently viewed as a single species. Morphometric analyses of 21 population samples consistently disclosed cohesive patterns of craniodental differentiation that support the recognition of three species: Praomys delectorum Thomas, confined to extreme southern Malawi; P. melanotus Allen & Loveridge, found in highlands of south‐western Tanzania and contiguous northern Malawi; and P. taitae Heller (including octomastis Hatt), distributed in mountains and foothills of southern Kenya and northern and central Tanzania. Populations of the P. delectorum group are patchily distributed in moist montane forest, most collecting localities falling within 1000–2400 m, and their range collectively coincides with the Tanganyika–Nyasa Montane Forest Group sensu Moreau. Patterns of faunal similarity derived from distributions of 65 species of terrestrial small mammals recorded from Tanzania's highlands, including the Eastern Arc Mountains, demonstrated pronounced geographical discontinuities in montane associations but failed to uncover a prominent vicariant role for the Makambako Gap. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 420–469.     

The ultrastructure of the male and female prostate of Praomys (Mastomys) natalensis

Summary Male ventral and female prostates of Praomys (Mastomys) natalensis were examined with the electron microscope. The findings support and add to information obtained with the light microscope on tissues from normal, castrated and ovariectomised animals.Our results indicate that although the female prostate may be considered a homologue of the male ventral prostate anatomically and histologically, there are differences in sub-cellular morphology and hormone dependence.Cells of the intact ventral prostate of the male are characterised by prominent dilated Golgi vesicles and electron-dense mature secretory granules seen in the apical region of the cell. In the cells of the female prostate these features are absent. These morphological differences reflect the influence of hormones upon the cells, as shown by the reduction of the dilated Golgi vesicles in the castrated male and conversely, their occasional presence in the cells of the oestrous female.Comparison of castrated and ovariectomised animals shows that the male ventral prostate is much more dependent on androgens than the female is on ovarian hormones.There are several modes of secretion in the male ventral and the female prostate. These are by acellular and cellular blebbing, by a variety of secretory vesicles into the acinar lumina, and by a system of double walled vesicles not previously described.We are grateful to Dr. R.C.B. Pugh of the Department of Pathology, St. Peter's Hospitals for helpful discussion, to Mr. P. Chaloner and Miss P. Gunter for technical assistance and also the Department of Medical Art of the Institute of Urology     

The impact of the Congo River and its tributaries on the rodent genus Praomys: speciation origin or range expansion limit?

We studied the taxonomy, distribution, and ecology of species within Praomys, a common rodent genus present in rainforests and montane forests in sub‐Saharan Africa. The taxonomy of the group is problematic, and for the sampled region of Kisangani (Democratic Republic of Congo) no prior genetic study has been published. We used a combination of molecular (cyt b sequencing) and craniometric techniques (canonical analyses of skull measurements) for the species identification of a total of 654 specimens. We confirm the presence of Praomys minor in the region, up to now only known from the type and paratype specimens. At least seven species are present in the Kisangani region, and two clades occur along both banks of the Congo River. The present‐day distribution of the genus seems to be influenced by large‐scale rainforest fragmentation related to drier periods in geological history. The Congo River could in this case constitute a modern barrier to gene flow when the climate enabled rainforest expansion. The tributaries of the Congo River play no role in limiting Praomys species distribution, apart from the Aruwimi River for Praomys jacksoni s.l. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 983–1002.     

The roles of rivers and Pleistocene refugia in shaping genetic diversity in Praomys misonnei in tropical Africa

Aim This study aims to elucidate the phylogeography of the murid rodent Praomys misonnei and to document whether or not rain forest refugia and rivers structure patterns of diversity within this species. Location Tropical Africa, from Ghana to Kenya. Methods Patterns of genetic structure and signatures of population history (cytochrome b gene) were assessed in a survey of 229 individuals from 54 localities. Using maximum likelihood, Bayesian, network and genetic structure analyses, we inferred intra‐specific relationships and tested hypotheses for historical patterns of gene flow within P. misonnei. Results Our phylogenetic analyses reveal a strong phylogeographical structure. We identified four major geographical clades within P. misonnei: one clade in Ghana and Benin, a Nigerian clade, a West Central African clade and a Central and East African clade. Several subclades were identified within these four major clades. A signal of population expansion was detected in most clades or subclades. Coalescence within all of the major clades of P. misonnei occurred during the Middle Pleistocene and/or the beginning of Late Pleistocene. Main conclusions Our results suggest a role for both Pleistocene refugia and rivers in structuring genetic diversity in P. misonnei. This forest‐dwelling rodent may have been isolated in a number of forest fragments during arid periods and expanded its range during wetter periods. Potential forest refugia may have been localized in Benin–Ghana, south‐western Cameroon, southern Gabon, northern Gabon and eastern Democratic Republic of Congo–western Uganda. The Niger and/or the Cross Rivers, the Oubangui‐Congo, Sanaga, Ogooue and/or Ivindo Rivers probably stopped the re‐expansion of the species from relict areas.     

Demographic aspects of sympatric Praomys jacksoni and P. stella in a tropical lowland forest in Kakamega, Kenya

Populations of coexisting tropical forest rodents Praomys jacksoni and P. (Hylomyscus) stella were investigated to test whether lower relative densities in regenerating forest compared with mature forest were because of poor health and/or reduced chances for females to breed. Relative frequencies, litter size, mass, length of embryos, presence or absence of ecto‐ and/ or endoparasites, and liver condition were recorded and analysed. Higher numbers of either species occurred in the mature compared with regenerating forest. Mottled livers and endoparasites were associated with heavier rodents; litter size related positively to mass of pregnant females in both species. Litter size, embryo size, sex ratios, liver condition, and infestation of ecto‐ and endoparasites were independent of forest and species. Apparently, reduced female density in regenerating forest had no breeding cost on individual females occurring there.     

New polymorphic microsatellite loci for rodents of the genus Mastomys using PCR multiplexing,and cross‐species amplification in Myomys and Praomys

The Praomys complex contains some of the most important agricultural pests of Africa, including Mastomys species. We describe the development of nine supplementary microsatellite markers isolated from Mastomys huberti. We show the potential utility of M. huberti microsatellites as population markers for two other species of Mastomys, and two other species of the Praomys complex, Myomys daltoni and Praomys cf. rostratus.     

Effects of forest disturbance on the fitness of an endemic rodent in a biodiversity hotspot

Praomys delectorum occurs abundantly in both disturbed and intact forests in the Ukaguru Mountains within the Eastern Arc Mountains (EAM), Morogoro, Tanzania. While previous studies have reported that anthropogenic disturbances such as grazing, wood cutting, and harvesting have a positive effect on the population density of P. delectorum, the impact of habitat disturbance on its demographic traits is still unknown. We performed a capture–mark–recapture study in both disturbed and intact forests from June 2018 to February 2020 in order to investigate the effects of habitat disturbance on abundance and two demographic traits: survival and maturation of P. delectorum in the Ukaguru Mountains. We found no variation in abundance or maturation between intact and disturbed forests, but habitat type did affect survival. However, this effect was sex‐dependent since female survival was higher in disturbed forests, while male survival remained similar across the two forest types potentially due to differences in predation pressure or food availability between the two habitats. Continuous demographic monitoring of P. delectorum in EAM is necessary given that the increasing human population surrounding the landscape is leading to higher deforestation rates and expansion of the pine plantation in the forest reserve.