Densities of mammals in partially protected areas: the Katavi ecosystem of western Tanzania

1. In Africa the majority of conservation areas sanction some sort of human activities within their borders but few of them are part of community-based conservation schemes. The effectiveness of these state-owned, partially protected areas in conserving mammalian fauna is largely unknown.
2. Large and medium-sized mammal densities in three different sorts of partially protected area were compared to mammal densities in an adjacent national park in western Tanzania by driving 2953 km of strip transects over a 14-month period.
3. In a Game Controlled Area that permitted temporary settlement, cattle grazing and tourist big game hunting, mammal diversity and mammal densities were relatively high. In a Forest Reserve that permitted limited hardwood extraction and resident hunting, most large species were absent. In a third, Open Area that allowed settlement, cattle grazing, firewood collection and beekeeping activities, mammal diversity and densities were again low but some large ungulates still used the area seasonally.
4. The chief factors responsible for lowered mammal densities outside the Park were illegal hunting, especially in close proximity to town, and to a lesser extent, resident hunting quotas that were too high.
5. These data suggest that state-owned conservation areas permitting human activities within their borders cannot be relied upon as a means of conserving large and middle-sized mammals in Africa.
6. Two methods are being employed to ameliorate this problem in Africa: excluding people from conservation areas while upgrading ground protection effort, and initiation of community-based conservation schemes. As yet, however, very few quantitative data are available to evaluate the efficacy of these methods in enhancing mammal populations.     

Generic species richness and body mass in North American mammals: Support for the inverse relationship of body size and speciation rate

Generic species richness, the number of species per genus, is examined as a function of mean generic body mass for extant North American mammals. Species richness decreases as an inverse power function with increased mass, and the Spearman rank correlation coefficient of the logio transformed data is significant (r_s= ‐0.37). When the data are partitioned by trophic level, the relationship is not statistically significant for carnivores but strengthens for herbivores (r_s= ‐0.46). This interesting but incidental effect is due to the negligible number of diminutive and excessively large carnivores, which is in turn determined by foraging strategies. Alternate hypotheses for the “right‐skewed”; size distribution of modern North American mammals, such as disproportionate extinction of large species, differential species longevity, and a geographical scaling function, are rejected in favor of the proposition that elevated levels of speciation are restricted to animals of small body mass, as originally proposed by Gould and Eldredge (1977). This phenomenon is explained as a function of habitat restriction and particularly in herbivores, limited home range size. Aquatic mammals, regardless of body size, speciate rarely. Cope's Rule, the tendency of many animal groups to evolve towards large size, is understood as a probabilistic statement reflecting the phylogenetic tendencies of a disproportionately high number of small species alive at any given point in time.     

Mammals of Australian islands: factors influencing species richness

Distribution patterns of indigenous non-volant terrestrial mammals on 257 Australian islands were examined in relation to environmental parameters and the effects of human-induced disturbance during prehistoric and historic times on island species numbers. Species occurrence for individual species, for taxonomic and trophic groups, and for all species together was related to environmental parameters using regression analysis and the extreme-value function model. Patterns of occurrence were examined separately within three major biogeographic regions derived by pattern analysis. The number of species known to have occurred on these islands during historic times was adequately predicted from area alone. No statistically significant improvement in predicted species number was gained by including island elevation, mean annual rainfall, isolation from the mainland or the number of potentially competing species present on the island. Similarly, no single factor other than area was found to influence consistently the presence of individual species. We conclude that the occurrence of indigenous non-volant terrestrial mammal species on these islands indicates a relictual rather than equilibrial fauna. Visitation by Aboriginal people during prehistoric times did not significantly increase mammal extinctions on islands. Examination of patterns of species richness for a given area on a regional basis showed that islands in and around Bass Strait and Tasmania (Bass Region) were the most species-rich, islands off the northern coasts were slightly less rich, and islands off the south western coasts had fewest species. This is in contrast to the usual latitudinal gradient in species richness patterns. However, islands off the northern and eastern coasts had an overall greater number of different species. When considered in relation to the number of different species of mammals occurring within each region, islands of a given size in Bass Region typically bore a higher proportion of this species pool than other regions. The Bass Region was found to be particularly rich in macropoid herbivores and dasyurid carnivores and insectivores. Analyses indicated that there is a very strong relationship between the presence of exotics as a whole and the local extinction of native mammals. Many mammal species formerly widespread on the Australian mainland are now restricted totally to islands (nine species) or are threatened with extinction on the mainland and have island populations of conservation significance (ten species). In all, thirty-five islands protect eighteen taxa of Australian threatened mammals. The land-use and management of these islands is of considerable importance to nature conservation. The introduction of exotic mammals to these islands should be prevented; any introductions that occur should be eradicated immediately.     

Molecular evolution of the hyaluronan synthase 2 gene in mammals: implications for adaptations to the subterranean niche and cancer resistance

The naked mole-rat (NMR) Heterocephalus glaber is a unique and fascinating mammal exhibiting many unusual adaptations to a subterranean lifestyle. The recent discovery of their resistance to cancer and exceptional longevity has opened up new and important avenues of research. Part of this resistance to cancer has been attributed to the fact that NMRs produce a modified form of hyaluronan—a key constituent of the extracellular matrix—that is thought to confer increased elasticity of the skin as an adaptation for living in narrow tunnels. This so-called high molecular mass hyaluronan (HMM-HA) stems from two apparently unique substitutions in the hyaluronan synthase 2 enzyme (HAS2). To test whether other subterranean mammals with similar selection pressures also show molecular adaptation in their HAS2 gene, we sequenced the HAS2 gene for 11 subterranean mammals and closely related species, and combined these with data from 57 other mammals. Comparative screening revealed that one of the two putatively important HAS2 substitutions in the NMR predicted to have a significant effect on hyaluronan synthase function was uniquely shared by all African mole-rats. Interestingly, we also identified multiple other amino acid substitutions in key domains of the HAS2 molecule, although the biological consequences of these for hyaluronan synthesis remain to be determined. Despite these results, we found evidence of strong purifying selection acting on the HAS2 gene across all mammals, and the NMR remains unique in its particular HAS2 sequence. Our results indicate that more work is needed to determine whether the apparent cancer resistance seen in NMR is shared by other members of the African mole-rat clade.     

A detailed redescription of the mesoderm/neural crest cell boundary in the murine orbitotemporal region integrates the mammalian cranium into a pan-amniote cranial configuration

The morphology of the mammalian chondrocranium appears to differ significantly from those of other amniotes, since the former possesses uniquely developed brain and cranial sensory organs. In particular, a question has long remained unanswered as to the developmental and evolutionary origins of a cartilaginous nodule called the ala hypochiasmatica. In this study, we investigated the embryonic origin of skeletal elements in the murine orbitotemporal region by combining genetic cell lineage analysis with detailed morphological observation. Our results showed that the mesodermal embryonic environment including the ala hypochiasmatica, which appeared as an isolated mesodermal distribution in the neural crest-derived prechordal region, is formed as a part of the mesoderm that continued from the chordal region during early chondrocranial development. The mesoderm/neural crest cell boundary in the head mesenchyme is modified through development, resulting in the secondary mesodermal expansion to invade into the prechordal region. We thus revealed that the ala hypochiasmatica develops as the frontier of the mesodermal sheet stretched along the cephalic flexure. These results suggest that the mammalian ala hypochiasmatica has evolved from a part of the mesodermal primary cranial wall in ancestral amniotes. In addition, the endoskeletal elements in the orbitotemporal region, such as the orbital cartilage, suprapterygoid articulation of the palatoquadrate, and trabecula, some of which were once believed to represent primitive traits of amniotes and to be lost in the mammalian lineage, have been confirmed to exist in the mammalian cranium. Consequently, the mammalian chondrocranium can now be explained in relation to the pan-amniote cranial configuration.     

Home Range and Movement Patterns of White-lipped Peccary (Tayassu pecari) Herds in the Northern Brazilian Amazon1

Two white-lipped peccary (Tayassu pecari) herds were radio-tracked for 5 and 13 mo, respectively, on Maracá Island Ecological Reserve, Roraima, Brazil. Home range size was 109.6 km² for the larger herd (130 animals) and 21.8 km² for the smaller herd (53 animals). Neither herd migrated or moved nomadically during the study period. The herd with the longer observation period increased its home range size during the flooded season by including new sites not used in the nonflooded season and continuing to use the nonflooded season sites. This pattern of simultancously using distinct seasonal ranges also occurred between the rainy and dry periods and the herd regularly and predictably returned to favored feeding sites. Population declines and disappearances in this study and others may have been caused by in situ mortality rather than by long-distance movements.     

Evolution of a non-flying mammal-dependent pollination system in Asian Mucuna (Fabaceae)

Pollinator shifts are often related to speciation in angiosperms, and the relationship between them has been discussed in several plant taxa. Although limited information on plants pollinated by non-flying mammals in Central and South America and Africa is available, related research has not been conducted in Asia. Herein, I summarize the available knowledge of pollination in Asian Mucuna (Fabaceae), a genus mainly distributed in the tropics, and discuss the evolution of plants pollinated by non-flying mammals in Asia. Nineteen pollinator species have been recorded and pollination systems have been categorized into four types. An examination of the relationship between Mucuna species and their pollinators from the lineage perspective revealed that all species in Mucuna, subgenus Macrocarpa, which are distributed in Asia, are pollinated exclusively by non-flying mammals. Additionally, plants pollinated by non-flying mammals were found to have diverged from bat-pollinated and non-flying mammal-pollinated plants, while plants pollinated by non-flying mammals have evolved multiple times. This is a unique example of evolutionary transition. I hypothesize that the diversification of squirrel species in tropical Asia may have led to the speciation and diversification of Mucuna in Asia. Furthermore, the behavioural and ecological characteristics of bats and birds in Asia differ from the characteristics of those in other regions, implying that Asian Mucuna species do not rely on bat or bird pollinators. The adaptation of floral characteristics to pollinators is not well understood in Asia. Mammal-pollinated plants in Asia may have evolved differently from those in other regions and have unique pollination systems.     

Microvertebrates preserved in mammal burrows from the Holocene of the Argentine Pampas: a taphonomic and paleoecological approach

Microvertebrates are a major component of many assemblages recovered from the Quaternary of the Argentine Pampas. The main goal of this paper is to analyse the taphonomic history of a Holocene microfossil bonebed, recovered from the infilling of a burrow. Evidences suggest the plains vizcacha Lagostomus maximus as the putative producer of the burrow. The assemblage includes individuals belonging to different taxa of mammals (marsupials and rodents) and reptiles (snakes). Taphonomic features suggest that the accumulation inside the burrow was related to flooding processes in the plain. The burrow was a natural trap that favoured the accumulation and preservation of remains corresponding to individuals from different sources. According to the taphonomic evidence, some individuals (Lagostomus maximus, Lestodelphys halli and Serpentes indet.) died inside the burrow, whereas others (Microcavia australis, Reithrodon auritus and Ctenomys sp.) died outside the burrow, and after a time of being exposed on the surface their remains were transported by surface run-offs into the burrow. The record of Lestodelphys halli and Serpentes indet. in the burrow produced by Lagostomus maximus could be related to a circumstantial use. Mammal burrows are a significant taphonomic mode for the late Cenozoic of the Argentine Pampas.