Darrin Hulsey's Lab

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	Morphological convergence provides strong evidence that evolution is adaptive. However, putatively convergent morphology is often examined in two dimensions with no explicit model of function. In this study, we investigated structural and mechanical similarities of the lower pharyngeal jaw (LPJ) in cichlid fish that have evolved the ability to crush hard-shelled molluscs. Using a novel phylogeny, we demonstrated molluscivory has been gained and/or been lost numerous times in Heroine cichlids. Within this comparative framework, we produced three-dimensional computed tomography (CT) scans for LPJs of both morphotypes in the trophically polymorphic Herichthys minckleyi and six evolutionarily independent pairs of closely related species. Like H. minckleyi, these species exhibit divergence between a molluscivore and a nonmolluscivore. Using the CT scans, we generated finite element models of papilliform H. minckleyi LPJs to determine where stress would concentrate in a jaw not modified to crush molluscs. Then, we examined whether stress in the papilliform LPJ predicted structural modifications in molariform H. minckleyi and other molluscivorous species. Despite potential constraints, stresses imposed during prey processing explain 40% of LPJ variation in mollusc crushing species. The structural and mechanical analyses also suggest divergence found in polymorphic species could provide the substrate for trophic differences found in reproductively isolated cichlids.
	Here is a video of an Orconectes australis specimen jumping in its tank in response to an outside stimulus, in this case an water stream. This species is a freshwater crayfish that inhabits rivers and creeks in Tennessee and Alabama.
	Here is a slow motion video of a Danio rerio specimen exercising evasion maneuvers. They are native inhabitants of streams, canals, ditches, ponds, and slow-moving bodies of water in the Himalayas. They are commonly known as Zebrafish.
	This is a slow motion video of a Caquetaia kraussi feeding on a small fish in a tank. It inhabits river basins in Colombia and Venezuela. They are commonly known as a Mojarra.
	Here is a video of a Cichlasoma festae specimen feeding on a smaller fish in a tank. They are normally located in Pacific drainages from South American rivers. It is commonly known as a festae.
	Here is a slow motion video of a Cichlasoma grammodes specimen feeding on a small fish in a tank. They are indigenous to rivers from Mexico to Guatemala. They are commonly known as Chiapa de Corzo cichlids or a Sieve cichlids.
	Here is a slow motion video of a Nandopsis tetracanthus specimen eating a minnow in a tank. This species is located in the fast-flowing rivers and lakes of Cuba. It is commonly known as a Cuban cichlid.
	Here is a slow motion video of a Parachromis dovii specimen feeding on a small fish in a tank. This fish can be found in the rivers of Costa Rica and Honduras. It is commonly known as a Guapote.
	Here is a video of a Parachromis friedrichsthalii specimen eating a small fish in a tank. This species is indigenous to the Atlantic slope rivers of Mexico, Belize, Guatemala, and Honduras. It is commonly known as a Yellowjacket or Monarch cichlid.
	Here is a slow motion video of a Parachromis managuensis specimen feeding on a small fish in a tank. They are indigenous to water bodies on the Atlantic slop of Central America from Honduras to Costa Rica. They are commonly known as Jaguar guapote.