Ichthyology seminars

Neil Shubin investigates the origins of vertebrate teeth and bone through fossils, comparative anatomy and modern imaging. Evidence from early jawless fishes places related tissues in external armour and suggests an initial sensory role for tooth-like structures. The lecture also considers the early appearance of tissue remodelling and other familiar skeletal properties.

Neil Shubin explores evidence that walking-like movements evolved in aquatic animals before vertebrates colonised land. Fossil anatomy and living fishes challenge a simple land-first explanation for limbs and joints. Underwater treadmills, behavioural experiments and robots help test why walking can be energetically useful even in water.

Neil Shubin connects human anatomy to the deep evolutionary history of animal bodies. Fossils, developmental mechanisms and comparisons with living species reveal inherited patterns in limbs, nerves, muscles and organ systems. The lecture also considers how research on fishes contributes to understanding human biology and disease.

Freshwater fish assemblages reflect millions of years of geographic isolation, producing unusually strong regional endemism. This seminar traces how tectonic history shaped those regions and how human transport and local extinctions now disrupt them. It examines the social drivers and ecological consequences of introductions, the resulting reorganization of global fish distributions, and the lasting effects of changes imposed within only a few decades.

Many animals are highly visual. They view their world through photoreceptors sensitive to different wavelengths of light. Animal survival and optimal behavioral performance may select for varying photoreceptor sensitivities depending on animal habitat or visual tasks. Our goal is to understand what drives visual diversity from both an evolutionary and molecular perspective. The group of more than 2000 cichlid fish species are an ideal system for examining such diversity. Cichlid are a colorful group of fresh water fishes. They have undergone adaptive radiation throughout Africa and the new world and occur in rivers and lakes that vary in water clarity. They are also behaviorally complex, having diverse behaviors for foraging, mate choice and even parental care. As a result, cichlids have highly diverse visual systems with cone sensitivities shifting by 30-90 nm between species. Although this group has seven cone opsin genes, individual species differ in which subset of the cone opsins they express. Some species show developmental shifts in opsin expression, switching from shorter to longer wavelength opsins through ontogeny. Other species modify that developmental program to express just one of the sets, causing the large sensitivity differences. Cichlids are therefore natural mutants for opsin expression. We have used cichlid diversity to explore the relationship between visual sensitivities and ecology. We have also exploited the genomic power of the cichlid system to identify genes and mutations that cause opsin expression shifts. Ultimately, our goal is to learn how different cichlid species see the world and whether differences matter. Behavioral experiments suggest they do indeed use color vision to survive and thrive. Cichlids therefore are a unique model for exploring how visual systems evolve in a changing world.