Are you interested in mammals? Do you want to study evolution? We are looking for a Master student to work with an exciting project on bats using image analysis, morphometrics, evolutionary genetics, and advanced statistical tools.
Phyllostomidae (New World leaf-nosed bats) represents one of the largest and most ecologically diverse mammalian families, having evolved in the New World over the last 30 million years. These bats have been highly successful in exploiting a wide range of ecological resources, and their pronounced morphological diversity provides an exceptional opportunity to understand how evolutionary processes shape the evolutionary potential of ecologically important traits. While cranial evolution in this group has been extensively studied, much less is known about how evolutionary processes shape the diversification of the mandible, a structure that plays a central role in feeding performance.
Evolutionary quantitative genetics predicts that phenotypic covariance among traits can bias both the direction, pace, and amount of evolutionary change. In particular, evolutionary divergence is expected to occur preferentially along directions of greatest phenotypic variation, often referred to as lines of least evolutionary resistance (LLR). When morphological divergence is aligned with these directions, evolution may proceed more rapidly, whereas divergence away from the LLR may be more constrained. Understanding whether and how mandible evolution follows these predictions remains a key open question.
The New World leaf-nosed bats provide an ideal system to address this problem. Their repeated dietary transitions including insectivory, frugivory, nectarivory, omnivory, and sanguivory are associated with substantial variation in mandible form and function. The available dataset of two-dimensional mandible images, representing all subfamilies and feeding strategies of phyllostomids, allows explicit testing of whether patterns of phenotypic covariation influence both the direction and the tempo of mandible evolution across a macroevolutionary radiation.
In this Master’s project, we will use comparative quantitative genetic approaches and phylogenetic comparative methods to investigate how phenotypic covariance shapes the evolutionary trajectory of mandible morphology in phyllostomid bats. Using existing mandible imaging datasets and a phylogenetic framework, the project will reconstruct evolutionary divergence along branches of the phylogeny and quantify both the orientation and magnitude of morphological change.
Specifically, the project will test whether (i) mandible evolution occurs preferentially along the major axis of phenotypic variation, (ii) evolutionary divergence aligned with this axis is associated with greater amounts and faster rates of morphological change. Together, these analyses will evaluate the role of phenotypic covariance in shaping the long-term evolutionary dynamics of a functionally important structure in a remarkably diverse clade.
This project will include:
- digitization of two-dimensional mandible data across phyllostomid species,
- estimation of phenotypic covariance structure and major axes of variation,
- reconstruction of evolutionary divergence vectors and rates using phylogenetic comparative methods in R, and
- interpretation of results in the context of evolutionary quantitative genetics.
Through this project, the student will gain experience in multivariate statistics, phylogenetic comparative methods, and evolutionary quantitative genetics, while contributing to a broader understanding of how phenotypic variation shapes evolutionary trajectories across macroevolutionary timescales.
Length of the project: 60 credits master’s thesis
Start day: Flexible but preferably Autumn
If interested, please contact Daniela M. Rossoni (daniela.rossoni@biol.lu.se, main supervisor) and Masahito Tsuboi (masahito.tsuboi@biol.lu.se) for further details of the project.
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