Relative time scales reveal multiple origins of parallel disjunct distributions of African caecilian amphibians

Parallel patterns of distribution in different lineages suggest a common cause. Explanations in terms of a single biogeographic event often imply contemporaneous diversifications. Phylogenies with absolute time scales provide the most obvious means of testing temporal components of biogeographic hypotheses but, in their absence, the sequence of diversification events and whether any could have been contemporaneous can be tested with relative date estimates. Tests using relative time scales have been largely overlooked, but because they do not require the calibration upon which absolute time scales depend, they make a large amount of existing molecular data of use to historical biogeography and may also be helpful when calibration is possible but uncertain. We illustrate the use of relative dating by testing the hypothesis that parallel, disjunct east/west distributions in three independent lineages of African caecilians have a common cause. We demonstrate that at least two biogeographic events are implied by molecular data. Relative dating analysis reveals the potential complexity of causes of parallel distributions and cautions against inferring common cause from common spatial patterns without considering the temporal dimension.     

A stem-group caecilian (Lissamphibia: Gymnophiona) from the Lower Cretaceous of North Africa

Of living amphibian groups, the limbless burrowing caecilians are amongst the most highly specialised, but are the least known. Their fossil record is extremely poor, leaving unresolved questions as to their origins, relationships and early distribution. We describe here caecilian remains from a Lower Cretaceous (Berriasian) microfossil locality near Anoual, Morocco. This material represents the second oldest record for the group, after the Jurassic Eocaecilia of North America, and the earliest caecilian record for Gondwana. It forms the basis of a new genus, Rubricacaecilia , which appears slightly more derived than Eocaecilia , but lacks major features of crown-group taxa. We support the use of Apoda Oppel, 1811 for the crown-group alone, and Gymnophiona Rafinesque 1814 for the clade comprising stem-group taxa + Apoda.     

Demography and life history of a viviparous Central African caecilian amphibian

Many tropical ecosystems support exceptional levels of amphibian diversity, but in contrast to their temperate counterparts, many aspects of their biology are little studied and poorly understood. Demographic studies give valuable insights into the age structure and life histories of amphibian populations, thus they are of high importance in making accurate and precise conservation assessments in the light of current global amphibian declines. We analysed age structure and growth in a population of the viviparous caecilian Geotrypetes seraphini , a caecilian amphibian from Mount Cameroon, Central Africa, by using skeletochronology. We detected lines of arrested growth (LAG) in mid-body vertebrae and interpreted them as indicators of a seasonal growth pattern. We expect that LAG are materialized at a rate of one per year. In our sample male reach sexual maturity at an early age (age class 0+), whereas females mature later (age class 1+). Maximum longevity in our sample was estimated at 4+ years. Body size (total length) was significantly smaller in males than in females. Our study shows that skeletochronology is a highly suitable method to determine caecilian growth and age. Caecilian amphibians show a high diversity of reproductive modes including unusual brood care and parental investment strategies. In order to deepen our understanding of their ecology and evolution, many more demographic studies on other species and lineages are needed.     

The Effect of Wildlife Conservation on Local Perceptions of Risk and Behavioral Response

In this study, we examine the effect of Tarangire National Park (TNP) on local perceptions of risk and how these perceptions may influence behavioral responses. Data were collected during 2004–2005 through household surveys and participatory risk mapping (PRM) in eight villages east of TNP. By identifying and rank-ordering respondents’ perceived risks, PRM enhances understanding of the nature and variation of risks faced within a population by distinguishing between the incidence and severity of subjective risk perceptions. Results indicate that proximity to the park has a strong effect on the type and severity of perceived risks. Within villages close to the park, however, behavioral response to perceived risks varies considerably. This study contributes to an appreciation of how behavioral response to environmental and socioeconomic factors is mediated by human perception.

The diet of Pteropus voeltzkowi, an endangered fruit bat endemic to Pemba Island, Tanzania

The diet of the Pemba flying fox Pteropus voeltzkowi , a species endemic to the island of Pemba off Tanzania, was investigated. Faecal pellets, ejecta and dropped fruits were collected from under roosts to facilitate dietary analysis. This was supplemented by data from local villagers and school students. The main component of the diet was mango ( Mangifera indica ), but bats also ate breadfruit ( Artocarpus altilis ), figs ( Ficus spp.), flowers, leaves, and other fruit. Pollen from at least five plant species was also found in faecal pellets. Pteropus voeltzkowi may be one of the only species on the island that disperses larger seeds. The germination rate of bat‐ingested seeds was higher than that for seeds from ripe fruit, and this appeared to be linked to selective ingestion of viable seeds by bats.     

Sighting frequency and food habits of the leopard tortoise, Geochelone pardalis, in northern Tanzania

Sighting frequency and food habits of the leopard tortoise (Geochelone pardalis) were studied in northern Tanzania from October 1993 to June 1996. Sighting frequency varied significantly between protected (0.22 mhr^?1) and unprotected sites (0.59 mhr^?1), and between Arusha (0.27 mhr^?1) and Serengeti sites (0.56 mhr^?1). The tortoise diet comprised mostly plants (97.8%) and rarely inorganic matter (2.2%). A total of 47 plant species from 21 families was eaten. Forbs made up 74.5% of the plant items and monocots the remainder. Succulents contributed 51.0% of the plant items eaten while grasses and legumes accounted for 16.8% and 13.5%, respectively. Some plant items were eaten more frequently than their occurrence in the habitats.     

A revised stratigraphic framework for Olduvai Gorge Bed I based on tuff geochemistry

Olduvai Gorge, Tanzania has rich records of Plio-Pleistocene fauna and flora, hominin fossils, and stone artifacts preserved between well-dated tephra layers (tuffs). Accurate correlation between sites in the two million year section is complicated by faulting, erosion, change in physical appearance of the tuffs, and quality of preservation. Traditional tuff geochemical techniques using glass cannot be applied because of poor glass preservation, and previous physical mapping has led to miscorrelations in Bed I. A new approach, using a combination of glass and mineral compositions (feldspar, augite, hornblende, and oxides) produced successful geochemical fingerprints for all ten major Bed I (∼2.03-1.79 Ma) tuffs. These fingerprints make available a reliable means for correlating specific tuffs between the well-dated "Junction" sites, such as FLK and HWK, and less well-dated sites at the basin margins. The new correlations provide a high-resolution stratigraphic framework for Bed I and correct previous miscorrelations in the west of the basin. Olduvai Hominin 65, from western Olduvai, was recovered from a level between Tuff IC and the Ng’eju Tuff, and therefore dates to 1.79-1.84 Ma.     

Révision du genre Perrindema Lacroix 1997 (Insecta : Coleoptera : Scarabaeoidea : Melolonthidae : Pachydeminae)

La synonymie entre Perrindema Lacroix 1997, et Zanitanus Lacroix 2001, est proposée. Le genre Perrindema est révisé. Une nouvelle combinaison est établie pour Cephaloncheres lindiensis Moser 1919. Deux nouvelles espèces sont décrites du Mozambique : Perrindema quiterajoensis n. sp. et P. pembaensis n. sp. Un historique du genre est donné ainsi qu’une clé de détermination. La position systématique de ce genre au sein des Pachydemini Burmeister 1855, est discutée. La conservation de l’utilisation du nom Pachydeminae au détriment de Tanyproctinae Erichson 1847, est argumentée.     

Assessing the conservation status of soil‐dwelling vertebrates: Insights from the rediscovery of Typhlops uluguruensis (Reptilia: Serpentes: Typhlopidae)

Soil‐dwelling amphibians and reptiles are relatively poorly studied and understood. Difficulties in sampling these taxa in their subterranean habitats might impede assessments of their conservation status. We explore this issue with a case study of the burrowing scolecophidian snake Typhlops uluguruensis, endemic to the Uluguru Mountains in the Eastern Arc of Tanzania. Despite recent standard faunistic surveys, there have been no reported sightings or collections of T. uluguruensis since the type series of four specimens was collected in 1926. Intensive replacement of forest by agriculture in the vicinity of the type locality had led to concern about the conservation status of this and other species. We report the rediscovery of T. uluguruensis in low intensity agriculture adjacent to human habitation, and close to the type locality. We compare the new material with the type series, and discuss the implications of this rediscovery for conservation assessments of small, soil‐dwelling lower vertebrates. We advise caution in determining conservation status when, as is usually the case, no special sampling of the soil has been carried out. Additionally, relatively neglected disturbed habitats should also be given more attention. Standard sampling methods for soil‐dwelling vertebrates need to be further developed and established.     

Evidence of seasonal migration in a tropical subterranean vertebrate

Many animals undergo migrations that depend on a range of biotic or abiotic factors provoking daily, seasonal or annual movement of individuals and/or populations. Temperate amphibians frequently have their life cycles dominated by annual temperature fluctuations, but in the tropics it is often presumed that distinct rainy seasons will influence amphibians more than small changes in temperature. Here, we direct the seasonal changes in abundance hypothesis to a caecilian amphibian Boulengerula boulengeri found in monthly randomized quantitative surveys in the top 30 cm of soil. Meteorological data are used to interpret the significant changes found in relation to rainfall and temperature variables. Instead of the expected correlation of migration with rainfall, we find that frequency varies significantly and positively with temperature. In addition, data on the depth at which individual caecilians are collected suggest that animals undergo a vertical (rather than horizontal) migration within the soil. This is the first example of vertical migrations with temperature (as opposed to rainfall) of any tropical subterranean fauna. We discuss the possible influences that stimulate migration in this species (abiotic factors, feeding, reproduction and predation). The ecology of caecilians has lagged behind that of all other tetrapods, and this study has importance for future ecological studies, as well as biodiversity assessments and monitoring methodologies.