Pascal O. Title, PhD
Environmental Resilience Institute | Indiana University
I am an evolutionary ecologist who integrates geographic distributions, phylogenies and trait data to better understand global diversity patterns and the processes that have generated them.
I am currently an Assistant Research Scientist and Species Distribution Modeling Fellow at the Environmental Resilience Institute at Indiana University. I earned my PhD at the University of Michigan and the Museum of Zoology, and my Masters at San Diego State University. By combining species occurrences and environmental spatial data with macroevolutionary and macroecological approaches, I explore how species are responding to climatic change, and how they might be expected to respond over the course of the next century.
You can contact me at ptitle [at] iu.edu.
Large-scale patterns of diversity
In my work, I explore the distribution of species diversity to better understand species ecology, evolutionary history and the assembly of continental biotas. In particular, I leverage the data-rich global network of natural history museums and pair species occurrence data with phenotypic data, phylogenies, geographic range and environmental data to investigate processes that have contributed to these patterns across continents.
I have been particularly interested in a few empirical systems:
Australian squamates: Australia is home to over one thousand species of lizards and snakes, belonging to 12 major radiations that exhibit different geographic distributions. This system of replicated diversification makes for an ideal system to study the spatial distribution of species radiations over evolutionary time.
Marine fishes: I am also interested in understanding how the biogeographic dispersal of species over time has contributed to the patterns in species richness and phylogenetic diversity that we see today. In particular, I am applying phylogenetic biogeographic models to better understand global patterns in marine fish diversity.
Tanagers: The tanager family is the largest radiation of songbirds in the Neotropics. For my Masters work at San Diego State University, I explored how shifts into different regions of climatic space may have facilitated the diversification of this group of birds. Tanagers offer a great system to explore the interplay between diversification, trait evolution and geographic occupation. This work is in collaboration with past and present members of Kevin Burns’ lab at SDSU.
Species response to climate change
Climatic conditions across the globe have been shifting over the last century, with changes in temperature and precipitation regimes. Climatic stability is also decreasing in many regions, with greater incidence of extreme weather events. As a result, species’ geographic distributions have been shifting, as these species track their optimal climatic and environmental conditions. I am interested in quantifying the degree of geographic range shifting across species, and seek to understand what makes a species more or less likely to shift its range. This work is in collaboration with other members of the Environmental Resilience Institute.
Species Distribution Modeling
A species’ geographic range is the result of a multitude of processes, including a species’ physiological response to climatic conditions, dispersal abilities, historical biogeography and interactions with other species. Our ability to model these geographic ranges is also dependent on the availability of species occurrence records, appropriate climatic and environmental datasets, and an understanding of the potential biases that exist in occurrence databases. I am interested in developing tools and resources for species distribution modeling.
A major question in biology is why species diversity is unevenly distributed geographically, through time, and across the tree of life. In order to address this question, we need to be able to properly quantify diversification patterns across phylogenies, which necessitates the development and evaluation of diversification methods. I have been involved with the development of BAMM, an approach for identifying diversification shifts on phylogenies, primarily through contributions to the BAMMtools R package. I have also conducted simulation work to better understand how different diversification metrics perform under a variety of scenarios.
Code & Datasets
R packages that I maintain and contribute to:
Provides tools to process and interrogate analyses conducted with BAMM.
Functions to generate the ENVIREM set of climatic rasters.
Miscellaneous tools for cleaning species occurrence records and generating geographic range polygons via alpha hulls.
Platform for integrating geographic range, phylogeny and morphometric data. In development.
bammCheck.R: R function to generate a plot containing information for diagnosing the convergence of a BAMM analysis.
von May R., Biggi E., Cárdenas H., Diaz M.I., Alarcón C., Herrera V., Santa-Cruz R., Tomasinelli F., Westeen E.P., Sánchez-Paredes C.M., Larson J.G., Title P.O., Grundler M.R., Grundler M.C., Rabosky A.R.D., Rabosky D.L. 2019. Ecological interactions between arthropods and small vertebrates in a lowland Amazon rainforest. Amphibian & Reptile Conservation 13:65–77 (e169).
Title P.O., Rabosky D.L. 2019. Tip rates, phylogenies and diversification: What are we estimating, and how good are the estimates? Methods in Ecology and Evolution. 10:821–834.
** featured in the MEE virtual issue: Phylogenetics and Comparative Methods: The Bright and Dark Sides
Singhal S., Huang H., Grundler M.R., Marchán-Rivadeneira M.R., Holmes I., Title P.O., Donnellan S.C., Rabosky D.L. 2018. Does Population Structure Predict the Rate of Speciation? A Comparative Test across Australia’s Most Diverse Vertebrate Radiation. The American Naturalist. 192:432–447.
Rabosky D.L.*, Chang J.*, Title P.O.*, Cowman P.F., Sallan L., Friedman M., Kaschner K., Garilao C., Near T.J., Coll M., Alfaro M.E.* 2018. An inverse latitudinal gradient in speciation rate for marine fishes. Nature. 559:392–395.
* denotes equal contribution to this work
Title P.O., Bemmels J.B. 2018. ENVIREM: an expanded set of bioclimatic and topographic variables increases flexibility and improves performance of ecological niche modeling. Ecography. 41:291–307. Project website
Singhal S., Huang H., Title P.O., Donnellan S.C., Holmes I., Rabosky D.L. 2017. Genetic diversity is largely unpredictable but scales with museum occurrences in a species-rich clade of Australian lizards. Proceedings of the Royal Society B: Biological Sciences. 284:20162588.
Title, P.O. and D.L. Rabosky. 2017. Do Macrophylogenies Yield Stable Macroevolutionary Inferences? An Example from Squamate Reptiles. Systematic Biology 66: 843-856.
Bemmels, J.B., P.O. Title, J. Ortego and L.L. Knowles. 2016. Tests of species‐specific models reveal the importance of drought in postglacial range shifts of a Mediterranean‐climate tree: insights from iDDC modelling and ABC model selection. Molecular Ecology 25: 4889-4906.
Davis Rabosky, A.R., C.L. Cox, D.L. Rabosky, P.O. Title, I. Holmes, A. Feldman and J.A. McGuire. 2016. Coral snakes predict the evolution of mimicry across New World snakes. Nature Communications 7:11484.
Klicka, L.B., B.E. Kus, P.O. Title and K.J. Burns. 2015. Conservation genomics reveals multiple evolutionary units within Bell's Vireo (Vireo bellii). Conservation Genetics: 1-17.
Rabosky, D.L., P.O. Title and H. Huang. 2015. Minimal effects of latitude on present-day speciation rates in New World birds. Proc. R. Soc. B 282: 20142889.
Title, P.O. and K.J. Burns. 2015. Rates of climatic niche evolution are correlated with species richness in a large and ecologically diverse radiation of songbirds. Ecology Letters 18: 433-440.
** featured in the GBIF Science Review 2016
Burns, K.J., A.J. Shultz, P.O. Title, N.A. Mason, F.K. Barker, J. Klicka, S.M. Lanyon and I.J. Lovette. 2014. Phylogenetics and diversification of tanagers (Passeriformes: Thraupidae), the largest radiation of Neotropical songbirds. Molecular Phylogenetics and Evolution 75: 41-77.
Rabosky, D.L., M.C. Grundler, C. Anderson, P.O. Title, J.J. Shi, J.W. Brown, H. Huang and J.G. Larson. 2014. BAMMtools: an R package for the analysis of evolutionary dynamics on phylogenetic trees. Methods in Ecology and Evolution 5: 701-707.
Mason, N.A., P.O. Title, C. Cicero, K.J. Burns and R.C.K. Bowie. 2014. Genetic variation among western populations of Horned Lark (Eremophila alpestris) indicates recent colonization of the Channel Islands, mainland-bound dispersal, and post-glacial range shifts. The Auk 131: 162-174.