Macroevolution Unit

Logo for the Marine Macroevolution Unit, featuring the early jawless fish Sacabambaspis and the Okinawa prefectural fish, the Gurukun (Caesio diagramma)

The Macroevolution Unit (PI: Lauren Sallan) investigates how environmental change, global events, ecological interactions and key traits shaped aquatic biodiversity on timescales outside human observation (macroevolution). We seek to determine the origins of major groups and key ecosystems (marine and freshwater) as well as understand how species respond to big challenges – living or environmental, regional or global, gradual or sudden. 

Our work synthesizes approaches and discoveries spanning a broad range of scientific areas relevant to major questions about the past, present, and future of marine biodiversity. We undertake computational analyses of newly-constructed biodiversity databases for fishes (half of standing vertebrate diversity), early vertebrates (half of vertebrate evolutionary history) and marine ecosystems. We work at scales ranging from local to global, from communities to phyla and from the present day to the last 600 million years. We also undertake detailed investigations of biodiversity at the species level, investigating various forms and features from developmental, biomechanical, genomic, and ecological angles. We use methods from fields as varied as community ecology, fluid dynamics, phylogenetics, and mechanical engineering (to name a few). 

Paleontology is a thriving science at the intersection of other multiple fields and technologies. There is no bigger data than the fossil record, and we mine very bit of it. We use CAT scans, we use isotopes, we use genomes, we use mathematical simulations, and all kinds of analytics.

Our current areas of interest include how crisis and opportunity (e.g. the “Big Five” mass extinctions, Ice Ages and Global Warming) shaped fish biodiversity, the origins of major animal groups past and present (e.g. ray-finned fishes, sharks, jawed vertebrates, reef fishes), and the construction of major ecosystems (e.g. the Indo-Pacific Biodiversity Hotspot). Our projects range in scope from the functional value and evolvability of “key innovations”, to the unequal impacts of extinctions and global crises, to the influence of new, “invasive” predators on the construction of marine ecosystems, to the timing and triggers of diversification and “failure” (e.g. persistence at low diversity).

Illustration of fish

The MMU Logo (painted by John Megahan) features two fishes that represent the scope of our research interests in terms of groups, timespan, and traits. Sacabambaspis (left) was one of the earliest jawless fishes with bone (armor). This fish was common in shallow marine waters throughout the Southern Hemisphere 465-460 million years ago. Caesio diagramma (right), a.k.a Gurukun (グルクン Okinawan), Takasago (タカサゴ standard Japanese), Banana Fish or Double-lined Fusilier (English), is the prefectural fish of Okinawa. This fish is very common in Indo-Pacific coral reefs, and is used in a variety of Okinawan dishes. Sacabambaspis and the Gurukun are roughly the same adult size (25 cm), and have similar ecologies, suction feeding on zooplankton.