The Evolution meeting starts tomorrow! (as if you didn’t already know…). Unfortunately I won’t be there in person, however my former PhD supervisor, Simon Loader (Natural History Museum London) will present a poster based on the paper I mentioned in the last post. I am sure Simon would be more than happy to talk about amphibian evolution and conservation in East Africa if you are interested. The poster is in the Comparative phylogeography poster session on Saturday 24th June.
Our new paper is now available in early view in Diversity and Distributions here
With this work, my colleagues and I show how the inclusion of phylogenetic information for amphibians can help to identify priority areas for increased conservation efforts across Eastern Africa (Fig. 1).
Although species are arguably the most fundamental measure of biodiversity on earth, they often contain high levels of genetic and morphological diversity across their geographic ranges. Even with common organisms we may often see striking patterns of differentiation below the species level which is often overlooked, and is especially relevant for local and regional conservation efforts. So how can we incorporate this intra-specific diversity into conservation assessment and planning? When we have sufficient data, we can build a molecular phylogeny (an evolutionary tree) to resolve the relationships of species, and include the major lineages that make up each of these species. Combining the geographic distribution of each of these lineages and species with its corresponding branch length on the phylogeny we can highlight areas where large amounts of evolutionary history have accumulated (see Fig. 2).
This is the theoretical basis of our new paper, where we applied these methods for close to the full assemblage of coastal forest species across Tanzania and Kenya, leading to the compilation of the largest available genetic and geographic datasets to date. We hypothesised that many of the evolutionary hotspots in this region are important refugia for biodiversity in times of past climate change, and our results support the idea that long term climatic stability, benign current climate and topographic heterogeneity facilitate the persistence of evolutionary history (Fig. 4).
Finally, by intersecting our maps with the current protected area network we established that much of the region’s evolutionary history is poorly protected, and several areas should be prioritised for conservation in the future (Fig. 5).
On Friday 28th April I will publicly defend my PhD thesis.
See below for details, my examiners are Neil Burgess, Simon Loader and Peter Nagel.
All are welcome!
Today a major manuscript that I have been working on for the past 3 years has been accepted in Diversity and Distributions – hurrah! Very happy to see this work published as it is of direct conservation relevance to the coastal forests of Eastern Africa. On top of that I submitted my PhD thesis two weeks ago – double hurrah!
I will post more updates on these two news items soon, until then I will be drinking a beer or two to celebrate…
Last month I travelled to the US to attend the International Biogeography Society meeting in Tucson, Arizona where I gave a talk on my work investigating the biodiversity of the coastal forests of Eastern Africa using amphibians. The coastal forests are highly threatened and lacking rigorous assessment across them, especially involving genetic data. I used a method which identifies places that are special because they hold unique biodiversity and indicate refugia where biodiversity has persisted over time, while it has disappeared in surrounding areas (see the method here). I combined species distribution data with genetics to map geographic concentrations of evolutionary history and used environmental and historical climate data going back to the Last Glacial Maximum (~20,000 years ago) to see if the distribution of evolutionary history correlates with areas that have remained climatically stable over time. Results suggest that they do, and reinforces the idea that these parts of the coastal forest in East Africa are an important refuge for amphibians (and potentially other groups!) during times of severe climate change.
I find these kinds of methods really great because they enable us to pinpoint important areas to prioritise areas for conservation based on evolutionary history. This is particularly important given predicted future climate change and the impacts of deforestation in the tropics.
Bryce canyon, Utah
Sabino canyon, Arizona
I posted a few months back that our paper about the new species from Ruvu South Forest Reserve near Dar es Salaam in Tanzania was in press. Now it’s published open access – you can download the paper for free here: http://www.thebhs.org/index.php?option=com_docman&task=cat_view&gid=137&Itemid=42
“A new, narrowly distributed, and critically endangered species of spiny-throated reed frog (Anura: Hyperoliidae) from a highly threatened coastal forest reserve in Tanzania”
Focusing on extraordinary organisms that are unique, or restricted to a particular area is always exciting, but sometimes even the seemingly ordinary can reveal fascinating insights into the historical biogeographic processes that have shaped the patterns of biodiversity we see today. Fairly common species found across a large area can tell us quite a lot about the effects of climate and evolution over time, especially those that have diversifed from a common ancestor into a complex of several related (but evolutionarily distinct) lineages or even species.
The Mascarene ridged frog Ptychadena mascareniensis is such an example, occuring across mainland and island areas of Africa mainly in savannah and open forest habitats and containing a number of divergent lineages with undescribed species diversity. Take a look at this new paper which investigates the evolutionary diversification of the P. mascareniensis species complex across its range and demonstrates how climatic niche evolution may have shaped current species diversity and distributions.
Fig. 1. Graphical abstract of the paper showing phylogenetic relationships, historical biogeography based on ancestral state reconstructions and bioclimatic niche of the P. mascareniensis complex.
Analyses within the paper show that there are at least ten distinct lineages of this species across Africa (7 in Africa, 3 on Madagascar, see Fig. 1) as a result of several speciation events mainly in the Miocene (over the past ~23 million years). Central Africa is identified as a diversity hotspot for these frogs with ‘out of Africa’ dispersal events to São Tomé in the west and Madagascar in the east. The P. mascareniensis from Tanzania where I focus my research appears to be the origin for the Madagascan radiation. The niches of these lineages are broadly similar in central Africa, with most tolerating similar climatic conditions (niche conservatism) but the lineages in West Africa and Madagascar exhibit very different ecological niches (niche divergence). The article is currently in press in Molecular Phylogenetics and Evolution.
Last week I travelled to Weggis, Switzerland and attended the Bioinfomatics for Adaptation Genomics Winter School 2016 ran by the ETH Zurich. I was part of an international group of 30 postdocs and PhD students focused on learning some new bioinformatic techniques to deal with NGS genomic data, which is a major part of my last PhD chapter. The five days of hands on bioinformatic analyses were absolutely great and introduced me to some software and concepts that I wasn’t yet experienced in – for example with full genome data (Erik Garrison), and GWAS (Arthur Korte).
However, the RADseq (Jon Puritz), detecting signatures of selection (Matteo Fumagalli) and inferring complex demographies (Daniel Wegmann) days were particularly relevant to my PhD project and an invaluable experience for me personally. I was extremely happy to hear the recommendations for designing NGS studies matched the major decisions that I made when I designed my own RADseq project, and looking around the room I could see that other people were also relieved to hear their experimental design was solid!
I have gained a huge amount of bioinformatic experience over the past year (mainly for RADseq data using Stacks and pyRAD) so it was great to hear about some other software I can use on my data (dDocent, ANGSD and NGStools, Fastsimcoal and ABCtoolbox). Overall I was extremely impressed with the skills and techniques we learned on this course; the organisers and instructors really did a great job, and it was massively beneficial. I would highly recommend this course to anyone wishing to take a peek inside the ‘black box’ of genomic analysis tools!
I recently wrote a paper with my colleagues at the University of Basel and collaborators in Tanzania Forest Conservation Group and the Field Museum of Chicago describing a new endemic species of Hyperolius treefrog from Ruvu South Forest Reserve near Dar es Salaam in Tanzania. The species is a member of the Hyperolius spinigularis (spiny throated reed frog) complex and is the first lowland member of an otherwise East African montane clade.
Dorsal and ventral views of the holotype of Hyperolius ruvuensis (BMNH.2002.410), held at the Natural History Museum, London.
Although the reserve is well known the species is extremely rare, having been collected only once in 2001 (four individuals). The reserve has been subjected to severe deforestation, so the discovery of this new (and probably critically endangered) species highlights the need for further conservation attention, not only in Ruvu South Forest Reserve but more broadly across the East African coastal forest belt.
The paper is in press in the Herpetological Journal, expected to be published later this year. A pre-press version of the accepted article is available here.