Current avenues of research:
How do new fins evolve?
Fishes have repeatedly evolved new appendicular systems. First, fins evolved on the midline, and later the paired fins evolved (pectoral and pelvic fins, which are homologous to our fore- and hindlimbs, respectively).
To understand how fins originate, we study the development and diversity of adipose fins. These are appendages that have evolved repeatedly in ray-finned fishes. Their repeated, independent evolution makes adipose fins a powerful system for testing hypotheses of how developmental systems evolve to generate new body parts.
Currently, we are exploring the developmental genetic basis of how adipose fins originated. There is also opportunity to tackle problems like how sexual dimorphism evolves and origin of proprioception in vertebrate appendages.
Relevant publications: #2, 3, 4, 5, 10 on Publications page.
How did fins evolve into limbs?
Limbs evolved from fins approximately 365 million years ago in early tetrapods. This fin-to-limb transition set the stage for the colonization of land by vertebrates, and significant research efforts have focused on understanding how this novel skeletal pattern originated.
To understand how fins evolved into limbs, we study both the paleontological record of tetrapodomorph fishes (like Tiktaalik roseae, left) and the evolution of fin skeletal patterning systems. Currently, we are analyzing fossils materials; there is opportunity to apply functional morphological approaches to these data to study Devonian fossils in Pennsylvania. We are also analyzing the how transcription factor and signaling genes regulate the development of fin rays.
Relevant publications: #9, 12, 13 on Publications page.
How do limbs diversify?
Once limbs originated, a five-fingered (pentadactyl) pattern stabilized. Among living tetrapods, limb diversity reflects variation on this theme.
To understand how limbs have diversified, we analyze how molecularity in the limb skeleton evolves. This work considers patterns of covariance among elements of the limb, which can arise from developmental phenomena and be selected upon for functional reasons. This research combines developmental genetic analyses (e.g., comparative transcriptomics) with analyses of morphological variation.
Relevant publications: #9, 11 on Publications page.
Why do we blink?
The water-to-land transition of vertebrates is marked by a suite of adaptations and functional innovations. A major, but overlooked, innovation is blinking, the occlusion of the eye by one or more membranes. In tetrapods, blinking functions to moisten, protect, and clean the eye. We have been studying how a second group of fishes, the mudskippers, have independently evolved the ability to blink.
Video to the left shows the blink of an Indian mudskipper. Video by Brett Aiello, collaborator on blinking research.
Relevant publication: #14 on Publications page
How does mammae number evolve?
Mammals are unique in providing their offspring with milk. Mammae, the structures that produce milk, are radically diverse. Mothers can have anywhere between 2 and 32 mammae from which to feed their offspring. Unfortunately, female reproductive biology is woefully understudied. Our lab seeking to establish mammae as an evolutionary developmental system for studying how patterning systems and canalization evolves.
To understand this diversity, we are analyzing how anatomical features coevolve with a mammal’s ecology and reproductive biology using comparative phylogenetic methods.
Relevant publications: #15 on Publications page.
