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A genomic perspective on the origins, evolution and adaptation of Galapagos Iguanas


Project Description

Overview: The revolution in sequencing technology and genomic science in recent years is now allowing evolutionary biologists to dissect the genetic basis of adaptation and population histories of non-model organisms in unprecedented detail. Key questions related to adaptation include, the type and number of genetic changes which underpin the evolution of new phenotypes, the strength and time scales for selection, the extent of parallel and convergent evolution among different taxa, and the nature of environmental and ecological factors which drive natural selection. Understanding these mechanisms not only provides fundamental insights into the process of evolution, but is also important for assessing species vulnerability and responses to potential future environmental change.

This project provides a unique opportunity to examine adaptation and evolutionary history in an iconic set of species for evolutionary biologists, the marine (Amblyrhynchus cristatus) and land iguanas (Conolophus sp) of the Galapagos archipelago. Both genera of Galapagos iguanas originate from the same common ancestor, which diverged around 10.5 million years ago, with both groups subsequently spreading across the archipelago. Land iguanas diversified to form 3 species - Conolophus subcristatus, native to six islands, and Conolophus pallidus, which is restricted to Santa Fe. The third species Conolophus marthae, known as the pink iguana, is only found on Volcan Wolf at the northern end of Isabela. It was only recently recognised as forming a genetically and ecologically distinct species and is now considered endangered due to its small population size and restricted distribution.

The process of divergence and diversification among these iguanas has generated many novel adaptations over relatively short evolutionary timescales – most strikingly adaptation to diving and the marine environment in Amblyrhynchus cristatus, which is the world’s only fully marine lizard. Land iguanas have their own adaptations to the harsh terrestrial environment in the Galapagos, including diet, tolerance of arid conditions and fluctuating resources, as well as various differences in morphology and pigmentation. This provides an amazing natural model system for evolutionary biologists to characterise the genomic basis of adaptation and novel phenotypes; the process of speciation, including mechanisms that prevent hybridization and genetic introgression; as well as characterising the origins and history of iguana populations. These can be linked with palao- and present environmental data to yield a better understanding of the environmental and ecological conditions which drove the evolution of these species.

The project is a collaboration between Dr Simon Goodman and Dr Mary O’Connell at the University of Leeds, and Dr Gabriele Gentile at the University of Rome Tor Vegata. Dr Gentile has been pioneering the study and conservation of pink iguanas for many years. The student will spend time working in both Leeds and Rome.

Multiple genome sequences for all land and marine iguana species are currently being generated, as a result of a collaboration between the University of Rome Tor Vegata and the Universiti Kebangsaan Malaysia (Prof. Mohd Firdaus Raih) and will be completed shortly. The aims for the PhD project include:

1. Complete the annotation of the nuclear and mitochondrial genomes of Galapagos iguanas.
2. Use comparative genomic and molecular evolutionary approaches to detect signatures of selection at a genome-wide scale.
3. Identify genes and other sequence variation related to adaptation to diving and other evolutionary trajectories, such as patterns of
pigmentation, and DNA repair driven by selection or drift.
4. Use nuclear genome data to investigate the interaction between pigmentation, DNA repair system genes and their possible role in
determining rates of molecular evolution along different lineages.
5. Use mtDNA and its methylation patterns to provide insights on the level of expression and regulation of mitochondrial genes and its
possible link with metabolic rates, which may ultimately influence rates of molecular evolution of mtDNA.
6. There is potential to generate additional data at a population scale to conduct high resolution analyses of population history in land and marine iguanas.

Expected outcomes: New knowledge on the molecular adaptions underpinning the evolution of iguanas in Galapagos, and phenotypic novelty more generally; a detailed understanding of the way environmental factors drive the evolution of novel adaptations; insights into the population demographic history of Galapagos iguanas in relation to past environmental change; generation of data relevant to the conservation management of Galapagos iguana populations.

Funding Notes

Hons degree and/or Masters in a topic relating to Biology, Zoology, Ecology, Genetics, Biodiversity, Evolution, Bioinformatics, Maths & Biology etc. An interest in working at the interface of ecology, biodiversity and population/evolutionary genomics is desirable. Prior experience of bioinformatics is helpful but not essential. However interest in developing skills in bioinformatics and computing is important.

UK/EU competition funding, the studentship will cover fees and stipend (c.£14,296) for 3.5 years.

Interviews February. Informal inquiries to Dr Simon Goodman:

Applications must be submitted via the University of Leeds website:

More details: View Website, View Website

References

Geist DJ, Snell H, Snell H, Goddard C, Kurz MD (2014) A paleogeographic model of the Galápagos Islands and biogeographical and evolutionary implications. In The Galápagos: a natural laboratory for the earth sciences (eds Karen SH, Mittelstaedt E, d'Ozouville N, Graham DW), pp. 145–166. New York, NY: John Wiley and Sons.
Gentile G, Fabiani A, Marquez C, Snell HL, Snell HM, Tapia W, Sbordoni V (2009) An overlooked pink species of land iguana in the Galápagos. Proc. Natl Acad. Sci. USA 106, 507–511.
Keane et al. (2015) Insights into the evolution of longevity from the bowhead whale genome. Cell Reports 10 112-122.
Liu et al. (2014) Population genomics reveal recent speciation and rapid evolutionary adaptation in polar bears Cell 157 785-794.
Macleod A, Rodríguez A, Vences M, Orozco-Terwengel P, García C, Trillmich F, Gentile G, Caccone A, Quezada G, Steinfartz S (2015) Hybridization masks speciation in the evolutionary history of the Galápagos marine iguana. Proc. R. Soc. B 282: 20150425.
Parent CE, Caccone A, Petren K (2008) Colonization and diversification of Galápagos terrestrial fauna: a phylogenetic and biogeographical synthesis. Phil. Trans. R. Soc. B 363, 3347–3361.
Rassmann K (1997) Evolutionary age of the Galápagos iguanas predates the age of the present Galápagos Islands. Mol. Phylogenet. Evol. 7, 158–172.
Steinfartz S, et al. 2009 Progressive colonization and restricted gene flow shape island-dependent population structure in Galápagos marine iguanas (Amblyrhynchus cristatus). BMC Evol. Biol. 9, 297.
Townsend TM, Mulcahy DG, Noonan BP, Sites JW, Kuczynski CA, Wiens JJ, Reeder TW (2011) Phylogeny of iguanian lizards inferred from 29 nuclear loci, and a comparison of concatenated and species-tree approaches for an ancient, rapid radiation. Mol. Phylogenet. Evol. 61, 363–380.
Wikelski M (2005) Evolution of body size in Galapagos marine iguanas. Proc. R. Soc. B 272, 1985–1993.

How good is research at University of Leeds in Biological Sciences?

FTE Category A staff submitted: 60.90

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