SUPERVISION :
– LE GOFF Rémy, PhD student, UMR MARBEC, Université de Montpellierremy.le-goff@umontpellier.fr
– LEPRIEUR Fabien, Full Professor, UMR MARBEC, Université de Montpellierfabien.leprieur@umontpellier.fr
INTERNSHIP PERIOD : January -February 2025 – June 2025
STUDENT PROFIL :
– Master student in ecology, evolution or related
– Interest in marine ecology, diversity patterns and macroevolution
– Coding proficiency in R or Python•Experience in statistical modelling
CONTEXT :
In the tree of life, fish clade (Actinopterygii) exhibits one of the richest species and morphological diversity. The remarkable diversity in morphology has facilitated global distribution and occupation of wide variety of ecological niches. This has resulted in varying levels of species (and trait) diversity among clades within Actinopterygii.
Two non-mutually exclusive hypotheses have been proposed to explain the high level of diversity (among others). The first hypothesis attributes it to the age of the clades, referred to as the “time-for-speciation” model. The older a clade, the more time it has had to diversify and accumulate species diversity(1). The second hypothesis suggests differential diversification rates among clades, which lead to differences in species diversity within the same time frame (1).
The student will explore both hypotheses using tropical reef fishes as a biological model. Varying levels of species diversity are also observed in tropical reef fishes along the longitudinal gradient, with the Indo-Australian Archipelago being considered as main biodiversity hotspot (2) However, the relative influence of ecological and evolutionary processes driving this biogeographic pattern remain a subject of debate (3; 4). Trait evolution is expected to play a significant role in the diversification dynamics of tropical reef fishes (first PhD Chapter Rémy Le Goff). In that context, the goal of this internship is to investigate the relationship between traits, diversification, and fish diversity a both the clade level but also within a biogeographic framework.
The student will address two key questions: Are older clades the most diverse? Is there a link between clade diversity and trait disparity?
APPROACHES :
The first approach aim to link trait disparity to clade age and clade richness, through a correlative approach. Disparity is expected to increase over time, in a cumulative way, leading to broader ecological niche (5). Alternatively, a saturation process may occur where disparity increase up to a maximum, constrained by the available ecological niche (independence of the niche with disparity)(3).Disparity may be independent of the clade age since its evolution could be clade specific due to various biotic interactions and/or abiotic constraints.
This study will require defining the clades of interest, extracting the trait and calculating the trait disparity of each clades, evaluating the divergence age of it and then performing statistical analysis. Using different published trait databases (Fishbase(6), Trophy from Siqueira et al (7)), the student will first measure the disparity in the major monophyletic clades using mFDR package (8). This disparity will be used, along side Phylogenetic Regression method (9), to explore the link between species richness, clade age and trait disparity. This will involve phylogeny manipulation and applying statistical models using R.
The second approach consists in exploring the role of species traits in shaping the diversification of tropical reef fishes within a biogeographic context. For this purpose, the student will be asked to explore the SSE framework (10) and its recent development(10; 11) that accounts for the influence of past and current environmental conditions. This framework allows for the simultaneous estimation of trait evolution parameters (e.g., transition matrix or continuous parameter) alongside diversification parameters (e.g., speciation, extinction). These approach would integrate the global trait evolution approach in a biogeographic context. Geographic environmental variations (past and present) are supposed to play a major role in the actual spatial diversity patterns. The student will have to discuss a model to use, process the data, run the analysis and control for uncertainty.Lab Unit and
LOCATION
The internship will take place in the UMR MARBEC (Montpellier, CNRS, Ifremer, IRD, Universitéde Montpellier). MARBEC (MARine Biodiversity Exploitation and Conservation) is a mixed labunit which focus on the marine realm in a variety of aspects (sociology, conservation, ecotoxicology,genetics, fisheries, evolution and many other). Based on 3 sites (Sète, Montpellier and Palavas lesflots), the internship will be based in Montpellier, at the University of Montpellier. Research on this site are mainly on diversity ecology and evolution linked to climate change. The student will join a dynamic team of PhD students, postdoctoral researchers, and other students working on various subjects.
Rémy Le Goff, a PhD student, will be the main supervisor, as theinternship is part of his PhD project. His research focuses on the role of biotic and abiotic interactions in the diversification of tropical reef fishes. Fabien Leprieur, full professor and thesis supervisor of Rémy Le Goff, will also co-supervise this internship.The internship will take place between January 2025 and May 2025 or February to June 2025.
BIBLIOGRAPHY
[1] Ricklefs, R.E.,Estimating diversification rates from phylogenetic information. Trends in Ecology &Evolution, 22(2007)(11): 601–610. ISSN 01695347. doi:10.1016/j.tree.2007.06.013.
[2] Pellissier, L.; Leprieur, F.; Parravicini, V. ,Quaternary coral reef refugia preserved fish diversity.Science, 344(2014)(6187): 1016–1019. ISSN 0036-8075, 1095-9203. doi:10.1126/science.1249853.
[3] Burbrink, F.T.; Chen, X.; Myers, E.A. ,Evidence for determinism in species diversification and contin-gency in phenotypic evolution during adaptive radiation. Proceedings of the Royal Society B: BiologicalSciences, 279(2012)(1748): 4817–4826. ISSN 0962-8452, 1471-2954. doi:10.1098/rspb.2012.1669.
[4] Rabosky, D.L.,Ecological Limits on Clade Diversification in Higher Taxa. The American Naturalist,173(2009)(5): 662–674. ISSN 0003-0147, 1537-5323. doi:10.1086/597378.
[5] Claramunt, S.,DISCOVERING EXCEPTIONAL DIVERSIFICATIONS AT CONTINENTAL2
SCALES: THE CASE OF THE ENDEMIC FAMILIES OF NEOTROPICAL SUBOSCINE PASSER-INES. Evolution, 64(2010)(7): 2004–2019. ISSN 0014-3820. doi:10.1111/j.1558-5646.2010.00971.x.
[6] Froese, R. Pauly, D.,FishBase. World Wide Web electronic publication, (2017 (version du 10/2017)).
[7] Siqueira, A.C.; Morais, R.A.; Bellwood, D.R. ,Trophic innovations fuel reef fish diversification. NatureCommunications, 11(2020)(1): 2669. ISSN 2041-1723. doi:10.1038/s41467-020-16498-w.
[8] Magneville, C.; Loiseau, N.; Albouy, C. [ 2024].mFD: Compute and Illustrate the Multiple Facets ofFunctional Diversity.
[9] Symonds, M.R.E. Blomberg, S.P. [2014];A Primer on Phylogenetic Generalised Least Squares. L.Z.Garamszegi (),Modern Phylogenetic Comparative Methods and Their Application in Evolutionary Bi-ology, ( 105–130) (Springer Berlin Heidelberg, Berlin, Heidelberg). ISBN 978-3-662-43549-6 978-3-662-43550-2. doi:10.1007/978-3-662-43550-2_5.
[10] Morlon, H.; Andréoletti, J.; Barido-Sottani, J. ,Phylogenetic Insights into Diversification. Annual Re-view of Ecology, Evolution, and Systematics, (2024). ISSN 1543-592X, 1545-2069. doi:10.1146/annurev-ecolsys-102722-020508.
[11] Swiston, S.K. Landis, M.J. [ 2023];Testing relationships between multiple regional features andbiogeographic processes of speciation, extinction, and dispersal. Preprint, Evolutionary Biology.doi:10.1101/2023.06.19.545613.
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