Friday 31 May 2013

Amphibian chytrid disease likely originated in Africa

English

Amphibian chytridiomycosis is an infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), and is widely believed to be the cause of catastrophic worldwide declines in amphibian populations. In Gabon, the fungus has been identified in two National Parks (Monts de Cristal and Ivindo; Bell et al., 2011), but not in other areas studied (Lope, Lastourville and Lebamba; Daversa et al., 2011; Gamba and Libreville; Gratwicke et al., 2011), and with no evidence of associated disease or mortality, so its epidemiology and impacts on native amphibians is not yet fully understood.
Two new studies out this month shed light on the origin of the disease and its global spread. The first, published in PNAS , is a phylogenetic study that suggests the recent pandemic strain is much older than previously research had suggested and evolved thousands of years ago, predating the recent global epidemic (Rosenblum et al., 2013). The researchers suggest the disease is most likely endemic in some parts of its range, such as Africa or Asia, but is a novel pathogen in other areas, and blame recent globalization through trade as the most likely cause of its spread.
Other research supports this. Xenopus laevis, the south African clawed frog, has long been suspected of spreading the disease: the species has been traded globally since the 1900’s, and the earliest known case of the fungus was found in native populations in South Africa. By examining museum specimens from as far back as 1871, a new study published in PLOS One is the first to find evidence of Bd fungus in recent, introduced feral populations of Xenopus in North America, as well as in older, native populations from Africa (Vredenburg et al., 2013). This study supports the hypothesis that Bd was present as a stable, endemic infection in Xenopus populations in Africa prior to their worldwide distribution likely via international live-amphibian trade.
Further research is required to understand if Bd is an introduced or endemic infection in Gabon, and how prevalent and pathogenic it is among native amphibian species.
References
Rosenblum EB, James TY, Zamudio KR, Poorten TJ, Ilut D, Rodriguez D, Eastman JM, Richards-Hrdlicka K, Joneson S, Jenkinson TS, Longcore JE, Parra Olea G, Toledo LF, Arellano ML, Medina EM, Restrepo S, Flechas SV, Berger L, Briggs CJ, Stajich JE, 2013. Complex history of the amphibian-killing chytrid fungus revealed with genome resequencing data. Proceedings of the National Academy of Sciences.10.1073/pnas.1300130110

Vredenburg V, Stephen A. Felt S, Morgan E, McNally S, Wilson S, Green S, 2013. Prevalence of Batrachochytrium dendrobatidis in Xenopus Collected in Africa (1871–2000) and in California (2001–2010). PloS one 8:e63791. 

Gratwicke, B., Alonso, A., Elie, T., Kolowski, J., Lock, J., Rotzel, N., Sevin, J. & Fleischer., R.C. (2011) Batrachochytrium dendrobatidis not detected on amphibians from two lowland sites in Gabon, Africa. Herpetological Review, 42, 69–71.
Bell RC, Gata Garcia A V, Stuart BL, Zamudio KR (2011) High Prevalence of the Amphibian Chytrid Pathogen in Gabon. EcoHealth 8: 116–120.
Daversa D, Bosch J, Jeffery K (2011) First survey of the disease-causing fungus, Batrachochytrium dendrobatidis, in amphibian populations of tropical areas of Gabon, Africa. Herpetological Review 42: 67–69.

New analysis of Hawkmoth biodiversity shows hotspot in Cameroon


Many taxa, especially invertebrates, remain biogeographically highly understudied and even baseline assessments are missing in many areas. A new study attempts to examine patterns of species diversity and inventory completeness for the hawkmoths of Africa.

A new genus of African Vesper Bat, with species updates for Gabon

English

A new genus of rare African vespertilionid bat has been described from South Sudan (Reeder et al.,2013). Niumbaha sp replaces Glauconycteris superba on the basis of cranial and external morphological comparisons. In the same study, museum specimens were re-examined and a new country record for Gabon, Glauconycteris curryae was recorded. Another species of Glauconycteris, G. argentata was recently recorded for the first time in Gabon (Peereboom et al., 2012).

References  
Reeder DM, Helgen KM, Vodzak ME, Lunde DP, Ejotre I (2013) A new genus for a rare African vespertilionid bat: insights from South Sudan. Zookeys (285): 89-115.

Peereboom D, van Lieshout S, Jeffery KJ, Bergmans W (2012) First record and echolocation call of Glauconycteris argentata (Dobson, 1875) from Gabon. African Bat Conservation News 27: 3–5.



More intense rainfall could increase woody plant encroachment



Forest encroachment into savannah systems is a phenomenon being observed across Gabon and Central Africa. While it is not clear what environmental factors are driving this vegetation change in Gabon, factors such as fire, grazing and CO2 concentrations have been used elsewhere as explanations.
A new study published online in Nature Climate Change shows that increases in precipitation intensity, but not total precipitation, increased aboveground woody plant growth and decreased aboveground grass growth in a savannah system in Kruger NP, South Africa, by driving soil water deeper into the soil, enabling woody plants to increase their rooting depths. Woody plant encroachment may continue in the future should precipitation intensity increase.

Kulmatiski A, Beard KH (2013) Woody plant encroachment facilitated by increased precipitation intensity. Nature Climate Change advance online publication.

Fenced reserves more effective at conserving lions than unfenced.



A new study published in this month’s Ecology letters compares the effectiveness of two approaches to protecting African lion populations; physical separation of animals in fenced reserves compared to unfenced protected areas.

Friday 3 May 2013

New PhD Thesis available on the Ecology of Red-Capped Mangabeys in Sette Cama, Gabon

A new study on the ecology of Red-Capped Mangabeys (Cercocebus torquatus) is available for download online. Catherine Cooke from The Ohio State University habituated a group of about 70 mangabeys in Sette Cama, Gabon, in 2008-2009, and studied feeding ecology, ranging patterns and positional behaviour, comparing to closely related species such as mandrills and grey-cheeked mangabeys.

Her thesis is available online at this address:
http://rave.ohiolink.edu/etdc/view.cgi?acc_num=osu1354500922

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