Meeting Abstract

P3.29  Saturday, Jan. 5  Cichlid brain diversity develops at the boundaries SYLVESTER, JB*; VAN STAADEN , MJ; FRASER, GJ; STREELMAN, JT; Georgia Institute of Technology; Bowling Green State University; Georgia Institute of Technology; Georgia Institute of Technology gth644s@mail.gatech.edu

Cichlid brain diversity develops at the boundaries Jonathan B. Sylvester, Moira van Staaden, Gareth J. Fraser, J. Todd Streelman Primary Author E-mail: gth644s@mail.gatech.edu The cichlids of Lake Malawi have undergone rapid diversification in the past million years. For this reason, they represent a great system for studying the processes of differentiation that lead to speciation and morphological novelty. Malawi cichlids exhibit a wide range of phenotypes in all morphological characters, such as dentition and jaws. Their brains are highly variable as well, although these have been less studied. Variation has been observed in four major structures of the brain: the optic tectum, telencephalon, cerebellum, and hypothalamus. We first demonstrated significant differences among adults of multiple species in the volume of the four structures. Next, we used whole-mount in situ hybridization with gene markers for the three major developing regions of the brain, the forebrain, midbrain, and hindbrain, and their boundaries. Cichlid embryonic brains exhibit variation in the expression of patterning genes between species in the forebrain, which develops into the telencephalon and hypothalamus, and the midbrain-hindbrain boundary, which separates the optic tectum and cerebellum. These data suggest that developmental adjustments in gene deployment during the establishment of regional boundaries, promotes a vast diversity of brain morphology among Malawi cichlids.