Tiger sharks live in warm temperate and tropical waters throughout our oceans and travel huge distances. Andrea uses genetics to asses which populations are interbreeding and how genetically diverse they are.
Currently, I live in sunny southern Florida about three kilometres from the beach. But this wasn’t always the case. I grew up in Toronto, Canada, almost as far from the ocean as you can get – and yet still very close to water. In those days I lived about three kilometres away from Lake Ontario, one of the five Great Lakes of North America. If you haven’t seen the Great Lakes, you are missing out. They have that name for a reason – they are just enormous! The shoreline runs as far as you can see, and when you look...
The key objective of this project is to examine the genetic connectivity of tiger sharks Galeocerdo cuvier across their global distribution. After using a suite of genetic tools, to examine the broad-scale connectivity and gene flow of tiger sharks, I will adopt a new, high-throughput, cutting-edge approach called genotyping by sequencing to tease out fine-scale differences in the tiger shark’s genetic population structure.
Understanding the genetic population structure of a species is essential for its proper management and conservation. If populations of tiger sharks are connected across broad ocean-basin scales, then they need to be managed on a similar geographic scale. This would require the cooperation and efforts of multiple government agencies across many countries. Conversely, if tiger sharks are made up of small isolated groups of animals, then each of these groups needs to be managed independently to ensure their conservation, health and persistence.
Tiger sharks occupy warm-temperate and tropical waters across a global distribution. As generalist predators, tiger sharks consume a huge variety of prey, including sea birds, sea snakes, dugongs and even some smaller shark species. Unlike many other species of sharks, tiger sharks reside in coastal, pelagic and coral reef habitats. Combined, the tiger shark’s cosmopolitan distribution and wide-ranging diet make them extremely important members of marine ecosystems. Given their key role in aquatic communities, understanding how populations are connected is essential not only to managing tiger sharks, but also to understanding the dynamics of the ecosystems they inhabit. Currently, little if anything is known about how tiger sharks are genetically connected globally, and recent work has shown that some regional declines in abundance have occurred, underscoring the immediate need for this work.
The main goal of this work is to identify in high detail the current global genetic population structure and connectivity of tiger sharks using a next-generation, high-throughput genetic approach. Specific objectives are to determine:
John is developing a set of targeted ‘capture panels’ that focus DNA sequencing efforts on specific regions of the cownose ray genome that can be used to identify related individuals. These panels will facilitate construction of a close-kin mark-recapture model to estimate abundance of cownose rays along the US East Coast.
To find out which shark species occur in Puerto Rican waters, Glorimar is using genetics and getting samples from fish markets. She also relies on the assistance of local fishers. Filling this fundamental knowledge gap will help to assess local consumption of sharks and build up the community’s understanding of how sharks function in the marine ecosystem.
To really understand how vulnerable sharks are to fishing in localised areas, we need to know the genetic variation across large areas. Dominic is investigating this in blacktip sharks, one of the dominant shark species caught in US Atlantic and Gulf of Mexico fisheries, to understand population connectivity across the Caribbean Sea and between these regions.