The developmental bases of morphological variation

Among Anolis lizards

The Evolution and Development of the Vertebrate Diversity

“Evolution is the control of development by ecology.” Leigh Van Valen (1976)


Studying the relationship between the variation generating mechanisms of development and the variation sorting mechanisms of selection promises to create a seamless understanding of the evolutionary process underlying animal diversity. My research program focuses on understanding the developmental bases of morphological adaptation and diversity from two distinct, but complimentary approaches. On one hand, I work from patterns of diversity downwards to carefully reconstruct how changes in development relate to changes in phenotype over the history of a group. This line of research focuses on understanding the developmental bases of Anolis lizard diversity, a textbook example of adaptive diversification. On the other hand, my research expands outward from detailed analyses of development in the mouse model system to comparative analyses among species with distinct anatomies. In this line of research I am studying the molecular regulation of plantar dermal appendages and asking how these networks have been modified in different amniote lineages en route to novel phenotypes.

Evolution of skeletal growth mechanisms

There are nearly 400 species of Anolis lizards. Years of ecological and evolutionary study have made them one of the premiere model systems for studies of diversification.  My research program adds another chapter to this story - an understanding of the developmental and molecular bases of morphological diversity. I have studied limb, toe pads, and skull proportions and I am developing new techniques to develop Anolis into a system suitable for laboratory experimentation.  Integrating my novel developmental data with information on the ecology and evolution of anoles allows me to test long standing hypotheses regarding mechanisms of diversification. See my publications page for more details on this research.

Bone and cartilage are tissues common to all vertebrates, shared due to common ancestry. Despite this common evolutionary origin, the developmental basis of these tissues have changed over time. Were these changes associated with major transitions in ecology, life history, or morphology? Perhaps some of these modifications occurred to accommodate faster rates of skeletal growth or other changes in physiology? Perhaps they are simply byproducts of of change associated with other processes? My research aims to, first, determine the precise differences in skeletal development associated with major lineages of tetrapods. As this picture develops I would like to know why these changes have evolved. I am currently developing research programs examining variation in long bone growth and facial outgrowth mechanisms.


Department of Molecular Genetics and Microbiology

University of Florida

P.O. Box 103610

2033 Mowry Rd

Gainesville, FL 32610


th.sanger[AT]ufl.edu

Development and diversification of amniote dermal appendages

My newest area of research focuses on the development of skin and its appendages. Skin appendages such as hair, feathers,  andectodermal glands are extremely diverse yet all through similar developmental mechanisms. The plantar dermal appendages (plantar pads and sweat glands) are particularly poorly studied and vary widely in size, shape, number among species using different forms of locomotion. I am using transgenic mice to finely dissect the developmental regulation of these micro-organs which I will use as a model that can be tested among species. Stay tuned for updates on this area of research.