Function, ecology and macroevolution of the mammalian masticatory system

Background: The masticatory apparatus of mammals is a model system for understanding how extrinsic ecological and environmental factors interact with anatomy and physiology to shape phenotypic diversity. However, most studies have focused on macroevolutionary and ecological patterns in bony morphology. Relatively few studies have simultaneously assessed patterns of disparity and convergence in muscle morphology and function, thereby limiting our understanding of adaptations and constraints in the masticatory system.

Objectives: The aim of this project is to carry out an integrated analysis of hard (bone) and soft tissue (muscle) evolution in the mammalian masticatory system to determine the relative nature and timing of adaptive changes in these tissues across evolutionary shifts in trophic ecology. Our specific objectives are therefore to:

OBJ1: Determine patterns of skull shape evolution across a taxonomically and ecologically diverse range of extant and extinct mammals.
OBJ2: Determine patterns of muscle evolution and their correlation with ecological diversity in extant mammals.
OBJ3: Combine data from OBJ1&2 to generate predictions of muscle evolution in lineages of extinct mammals that record evolutionary shifts in trophic ecology.
OBJ4: Map predictions of mechanical performance or fitness metrics for the masticatory system generated from biomechanical models on to an evolutionary landscape to analyse the relationship between morphological, functional and ecological diversity in the mammalian masticatory system.

Novelty: Existing integrated studies of hard and soft tissue evolution are restricted to specific subgroups with limited taxonomic and ecological breadth. We will exploit this gap in understanding by combining cutting-edge biomechanical techniques with evolutionary landscape analysis approach for the first time.

Timeliness: The works follows two recent studies by Bates and Cox that demonstrate fundamental limitations in current macroevolutionary studies of functional morphology. Bates/Cox have already assembled soft tissue data and Goswami the CT data sets that will underpin the study.

The masticatory apparatus of mammals is a model system for understanding how extrinsic ecological and environmental factors interact with anatomy and physiology to shape phenotypic diversity. However, most studies have focused on macroevolutionary and ecological patterns in bony morphology. Relatively few studies have simultaneously assessed patterns of disparity and convergence in muscle morphology and function, thereby limiting our understanding of adaptations and constraints in the masticatory system.

The aim of this project is to carry out an integrated analysis of hard (bone) and soft tissue (muscle) evolution in the mammalian masticatory system to determine the relative nature and timing of adaptive changes in these tissues across evolutionary shifts in trophic ecology. Our specific objectives are therefore to:

OBJ1: Determine patterns of skull shape evolution across a taxonomically and ecologically diverse range of extant and extinct mammals.
OBJ2: Determine patterns of muscle evolution and their correlation with ecological diversity in extant mammals.
OBJ3: Combine data from OBJ1&2 to generate predictions of muscle evolution in lineages of extinct mammals that record evolutionary shifts in trophic ecology.
OBJ4: Map predictions of mechanical performance or fitness metrics for the masticatory system generated from biomechanical models on to an 'evolutionary landscape' to analyse the relationship between morphological, functional and ecological diversity in the mammalian masticatory system.

Existing integrated studies of hard and soft tissue evolution are restricted to specific subgroups with limited taxonomic and ecological breadth. We will exploit this gap in understanding by combining cutting-edge biomechanical techniques with 'evolutionary landscape analysis' approach for the first time.