Browsing by Author "Loader, Simon"

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    AMPHIBIANS OF THE AFROTROPICAL REALM
    (2008-11) Andreone, Franco; Channing, Alan; Drewes, Robert; Gerlach, Justin; Glaw, Frank; Howell, Kim; Largen, Malcolm; Loader, Simon; Lötters, Stefan; Minter, Leslie; Pickersgill, Martin; Raxworthy, Christopher J.
    Due to their permeable skin few amphibians are able to tolerate dry or salty conditions, a characteristic that has prevented most species from colonising oceanic islands. The most diverse oceanic island amphibian fauna is found in the Seychelles, an archipelago of about 115 granitic and coralline islands in the Indian Ocean, some 1,600km east of mainland Africa, and northeast of the island of Madagascar (Figure 1). Eleven native amphibian species have been recorded from the Seychelles islands, comprising both recent colonists and ancient endemics. Recent colonization by one species, the Mascarene Grass Frog Ptychadena mascariensis (LC), is probably the result of human introduction (Vences et al. 2004) in the 1800s, whilst the endemic Seychelles Treefrog Tachycnemis seychellensis (LC) is believed to be descended from a natural colonist from Madagascar (Vences et al. 2003). The remaining spe- cies are all ancient endemics that have probably existed on the island since their isolation from the Indian landmass some 65 million years ago. These species comprise the endemic frog family Sooglossidae and seven species of burrowing caecilians (Order Gymnophiona). Sooglossidae are an exceptional family in several respects. Four species are currently recognized in two genera, although recent morphological and mo- lecular data suggests that a further three species remain to be described and that the genera need to be redefined. They are all small frogs, with Gardiner's Frog Sooglossus gardineri (VU) among several species up for contention as the world's smallest frog (with adults being as small as 9mm in length). All sooglossids are found in the damp forests of the two highest islands, Mahé and Silhouette. These habitats have only seasonal or fast-flowing stems, and the sooglossids have abandoned the normal frog life-cycle in favour of ter- restrial development. The Seychelles Frog Sooglossus sechellensis (VU) lays its eggs on land and the female carries the tadpoles until they develop into frogs. Sooglossus gardineri is even more specialized, with the male guarding terrestrial eggs that hatch into 3-mm long froglets; the entire tadpole stage is passed within the egg. Thomasset's Seychelles Frog Nesomantis thomasseti (VU) has recently been discovered to have a very similar breeding strategy, but nothing is known of the reproductive behaviour of the Seychelles Palm Frog S. pipilodryas (VU). This latter species is the most recently described of the Seychelles amphibian species, having been discovered in 2000 (Gerlach and Willi 2002). It lives in the axils of endemic palms where it lay protected from discovery by the dense spines of the palm leaves. It is the only arboreal sooglossid, the other species all being associated with crevices in boulder fields or the leaf-litter and root-mat of the forest floor. The caecilian fauna of the Seychelles islands comprises six species in three endemic genera. Not surprisingly, and as with caecilians in general (see Essay 1.3), these are the least well known of all Seychelles amphib- ians. Their burrowing habits make them difficult to locate and study. For most species, their distributions are reasonably well defined and there are some observations of breeding habits. Different species appear to show the full range of reproductive strategies, form aquatic larvae, thorough to ter- restrial larvae and direct development. The limited ecological data available indicate that Grandisonia alternans (LC) is a widespread species occurring in all habitats and Hypogeophis rostratus (LC) is a similar generalist, although more associated with lowland habitats. In contrast, Praslina cooperi (VU) and some of the small Grandisonia species appear to be specialists of the high forest. Current research into this group is attempting to develop monitoring methods and to identify aspects of their ecology that are of importance to their conservation. Half of Seychelles amphibians are threatened due to their naturally restricted ranges and deteriorating habitats (five species are categorised as Least Concern, 5 Vulnerable and one Endangered). The sooglossid frogs and the caecilian Praslina cooperi have particularly restricted ranges, being associated only with the damper rain-forests. Habitat deterioration is a significant threat to the caecilian Grandisonia brevis (EN), which has a re- stricted range and occurs in habitats that are suffering from ongoing invasion by alien plant species. In addition, there is some suggestion that changes in rainfall patterns may have impacts on some species, which may result from mid-year declines in rainfall restricting the activity and distribution of the rain-forest specialists (Gerlach 2000). Losses of several areas of marsh habitats have probably caused population declines in some species, such as another caecilian Grandisonia alternans (Gerlach 2000). There have been a number of successful conservation programmes in Seychelles, concentrating mainly on birds. Critically Endangered species have been rescued from extinction by limited habitat management, but mostly by inter-island transfers. These programmes have been to the benefit of spe- cies such as the Seychelles Magpie-robin Copsychus seychellarum and the Seychelles White-eye Zosterops modesta. Such options are not available for the amphibians due to their close dependence on their high forest or marsh-land habitats. Consequently, preservation of their habitat is essential; most species are present in protected areas, although habitat management is still required to control the spread of invasive plant species. The island with the highest diversity of amphibians (Silhouette) is currently unprotected and designation of this island as a national park would significantly enhance amphibian conservation in Seychelles. To date, there has been no evidence of any sudden amphibian decline in Seychelles, although the potential impact of an invasion by chytridiomycosis would be considerable. Monitoring programmes are in place for the frogs, and are being developed for the caecilians. Updates on research and conservation progress can be found at http://members.aol.com/jstgerlach/herps.htm
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    The biological importance of the Eastern Arc Mountain of Tanzania and Kenya
    (2007-01) Burgess, Neil D.; Butynski, Thomas M.; Cordeiro, Norbert J.; Doggart, Nike; Fjeldså, Jon; Howell, Kim; Kilahama, Felician B.; Loader, Simon; Lovett, Jon C.; Mbilinyi, Boniface P.; Menegon, Michele; Moyer, David; Nashanda, Evarist; Perkin, Andrew; Rovero, Francesco; Stanley, William T.; Stuart, Simon N.
    The Eastern Arc Mountains are renown in Africa for high concentrations of endemic species of animals and plants. Thirteen separate mountain blocks comprise the Eastern Arc, supporting around 3300 km2 of sub-montane, montane and upper montane forest, less than 30% of the estimated original forested area. At least 96 vertebrate species are endemic, split as follows: 10 mammal, 19 bird, 29 reptile and 38 amphibian species. This includes four endemic or nearly endemic species of primate – the Sanje Mangabey, the Iringa Red Colobus, the Mountain Galago and the new Kipunji monkey that forms its own monotypic genus. A further 71 vertebrate species are near-endemic. At least 800 vascular plant species are endemic, almost 10% of these being trees. These endemics include the majority of the species of African violet – Saintpaulia, a well-known flowering plant in Western households. An additional 32 species of bryophytes are also endemic. Many hundreds of invertebrates are also likely to be endemic, with data for butterflies, millipedes and dragonflies indicating potential trends in importance. Seventy-one of the endemic or near-endemic vertebrates are threatened by extinction (8 critical, 27 endangered, 36 vulnerable), with an additional seven wide ranging threatened species. Hundreds of plant species are also threatened. Most Eastern Arc endemics are closed-forest specialists and comprise taxa with an ancient history and those of more recent origin, including some possessing ancient affinities with taxa from West Africa, Madagascar, and even South America and Southeast Asia. Mountain block prioritisation for biodiversity conservation shows that Udzungwas, East Usambaras and Ulugurus are the most important blocks, with other important blocks being the Ngurus and West Usambaras. Rankings are correlated closely with the area of remaining forest. Most of the remaining forest is found within nearly 150 Government Forest Reserves, with 106 of these managed nationally for water catchment, biodiversity and soil conservation and where forest exploitation is not allowed. Outside these areas most forest has been cleared, except in small village burial/sacred sites, a few Village Forest Reserves, and inaccessible areas. In most Eastern Arc Mountains the local populations have not encroached beyond the reserve boundaries to develop farms, but forest resources within the boundaries are used for fuel and building materials and some forests are heavily degraded. Fire is also a problem as it enters and destroys forests during the dry seasons. The future of the biodiversity on the Eastern Arc Mountains is closely tied to management policies and capacity of the Tanzania Forestry and Beekeeping Division, Tanzania National Parks Authority, and Kenya Forest Department. Supporting these agencies in their mandated job is an essential conservation investment over the longer term.
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    A celebration of the works of John Charles Poynton
    (2013-05) Loader, Simon; Menegon, Michele; Howell, Kim; Müller, Hendrik
    The 15th meeting of the African Amphibian Working Group celebrated thecontributions of John Charles Poynton to African Herpetology. The meeting, inTrento, Italy, was timed to commemorate John’s 81st birthday (in May 2012), and hepresented a keynote speech that focused on a topic that has long fascinated him  theAfrotemperate amphibian fauna. His presentation is published here, in a modifiedform, for this special issue of African Journal of Herpetology (Poynton 2013). Otherpapers on the main themes of John’s research are also included in this issue, whichinclude biogeography (Loader et al. 2013; Schreiner et al. 2013), taxonomy (Cruzet al. 2013) and morphology (Wilkinson et al. 2013)
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    Persistence and stability of Eastern Afromontane forests: Evidence from brevicipitid frogs
    (2014-03) Loader, Simon; Ceccarelli, Fadia S.; Menegon, Michele; Howell, Kim; Kassahun, Roman; Mengistu, Abebe A.; Saber, Samy; Gebresenbet, Fikirte; de Sá, Rafael O.; Davenport, Tim R. B.; Larson, Joanna G.; Müller, Hendrik; Wilkinson, Mark; Gower, David
    AimThe persistence and stability of habitats through time are considered predictors of high levels of biodiversity in some environments. Long-term habitat persistence and stability may explain the species-rich, endemic forest fauna and flora of the Eastern Afromontane Biodiversity Region (EABR). Using complementary phylogenetic and biogeographical approaches, we examine evolutionary patterns in EABR brevicipitid frogs. Using these data, we test whether brevicipitid history reflects patterns of long-term forest persistence and/or stability across the EABR.LocationEast Africa.MethodsA dated phylogeny for brevicipitids was constructed using two nuclear and three mitochondrial markers. Alternative diversification models were used to determine signal for constant or varying net diversification rates. Using our dated tree, we identified areas of high phylogenetic diversity (PD), and inferred ancestral areas using likelihood and Bayesian approaches.ResultsBrevicipitids have a long history, with generic diversification among extant lineages pre-dating the Oligocene (> 33 Ma). Ancestral-area reconstructions indicate the presence of brevicipitids in the EABR since the Oligocene, and support a scenario of palaeoendemics surviving in EABR refugia. Ancestral-area reconstructions indicate that the central Eastern Arc Mountains (EAM) formed the initial centre of diversification of forest brevicipitids. Measures of PD show that diversity varies across the EABR but is highest in the EAM. Constant net diversification rate in brevicipitids is a significantly better fit than alternative, rate-variable models.Main conclusionsThe degree of persistence of forest habitats appears to be a contributing factor to the varying levels of diversity across the EABR in brevicipitids (and other organisms). In contrast to the Southern Highlands and Ethiopian Bale Mountains, the EAM stands out as an area that enabled the constant accumulation of brevicipitid species over a long period of time.
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    Phylogenetic relationships of African Microhylid frogs inferred from DNA sequences of mitochondrial 12S and 16S ribosomal rRNA genes. Org, Divers Evol 4:227-235
    (2004-12) Loader, Simon; Gower, David; Howell, Kim; Doggart, Nike; Rödel, Mark O.; Clarke, Barry T.; de Sá, Rafael O.; Cohen, Bernard L.; Wilkinson, Mark
    The phylogenetic relationships of microhylid frogs are poorly understood. The first molecular phylogeny for continental African microhylids is presented, including representatives of all subfamilies, six of the eight genera, and the enigmatic hemisotid Hemisus. Mitochondrial 12S and 16S rRNA sequence data were analysed using parsimony, likelihood and Bayesian methods. Analyses of the data are consistent with the monophyly of all sampled subfamilies and genera. Hemisus does not nest within either brevicipitines or non-brevicipitines. It is possibly the sister group to brevicipitines, in which case brevicipitines might not be microhylids. Phrynomantis and Hoplophryne potentially group with non-African, non-brevicipitine microhylids, in agreement with recent morphological and molecular data. Within brevicipitines, Breviceps is recovered as the sister group to a clade of Callulina+Spelaeophryne+Probreviceps. The relationships among the genera within this latter clade are unclear, being sensitive to the method of analysis. Optimal trees suggest the Probreviceps macrodactylus subspecies complex might be paraphyletic with respect to P. uluguruensis, corroborating preliminary morphological studies indicating that P. m. rungwensis may be a distinct species. P. m. loveridgei may be paraphyletic with respect to P. m. macrodactylus, though this is not strongly supported. Some biogeographic hypotheses are examined in light of these findings.
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    A remarkable young Scolecomorphus vittatus (Amphibia: Gymnophiona Scolecomorphidae) from the North Pare Mountains, Tanzania
    (2002-12) Loader, Simon; Wilkinson, Mark; Gower, David; Msuya, Charles A.
    A description is given of the external morphology of a single young caecilian (gymnophionan) amphibian from the North Pare Mountains, Tanzania, referable to Scolecomorphus vittatus (Boulenger, 1895). This is the smallest known free-living Scolecomorphus, and it is characterized by many remarkable features previously unrecorded for any life-history stage of any caecilian. The cheeks have conspicuous, posteroventrally divergent paraoral processes that border a concavity on the ventral surface of the snout. The mandibles are very flexible about their articulation with the cranium, and they have a broader curvature than the upper jaw. The dentition is heterogeneous, with adult-like monocusped teeth in single rows, but also some supernumerary teeth, some of which are bicornute. The posterior parts of the paraoral processes bear a small number of monocuspid teeth that lie outside, and project away from, the mouth. The nuchal region of the body bears a distinctive concavity on the underside of the throat, bordered by longitudinal ridges that terminate in fleshy nipples. All of these features are unknown in adult Scolecomorphus, and many are unique for caecilians, and they suggest a highly distinctive life-history stage. The discovery and description of this specimen adds substantially to the currently meagre information on the life history of scolecomorphids and of the diversity of caecilian reproductive biology. Two modes of viviparity in caecilians are identified, with S. vittatus resembling the caeciliid Geotrypetes in giving birth to small altricial young that seem to require extended post-parturition parental care.
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    Reproduction in Brevicipitid Frogs (Amphibia: Anura: Brevicipitidae)—Evidence From Probreviceps M. Macrodactylus
    (2007-09) Müller, Hendrik; Loader, Simon; Ngalason, Wilirk; Howell, Kim; Gower, David
    An egg clutch of the Tanzanian brevicipitid frog, Probreviceps m. macrodactylus, is described for the first time. The single clutch consists of 32 eggs and 21 infertile, jelly-filled capsules, tightly bound together by a thin, tough outer layer. The infertile capsules are concentrated toward the top of the clutch. The eggs were found in a dry season, and were perhaps likely to hatch at the onset of the short rains. The specific identification is confirmed through analysis of mitochondrial DNA sequence data. Eggs are yolky and large, about 8 mm in diameter (including capsule), suggesting that P. m. macrodactylus has a direct mode of development. The embryos observed were in an early developmental stage and showed the early division of the brain and anlagen of three pairs of visceral arches. Brevicipitid reproduction and development are poorly known, but a review of the existing literature and parsimonious optimization of simple characters onto a phylogenetic framework suggest that direct development is a derived condition characterizing the whole clade.