Advancing marine wildlife conservation through genetics

Ray species play a vital role in marine ecosystems. Yet, they are often overlooked in conservation efforts due to a lack of data and public awareness of their ecological importance.  

To help address this, a researcher at the Roslin Institute and the Royal (Dick) School of Veterinary Studies is using genetic techniques to inform the management and protection of cownose rays, which are found in oceans around the world, and include some critically endangered species.

Understanding the genetic diversity and population structure of cownose rays across their entire range will aid in identifying groups that may need specific conservation management strategies.

Insights from this research could influence conservation policies for other marine species facing similar challenges.

Genetic mapping

The research team’s ongoing global study on cownose rays seeks to address critical gaps in understanding the animals’ geographic distribution and population structure, particularly in under-researched regions such as the Pacific Ocean.

Helen Weber, PhD student in the Conservation Science Group at the Roslin Institute, hopes to reveal whether different ray populations are genetically connected across oceans.

The researcher also aims to investigate potential hybridisation between species to clarify the evolutionary history of cownose rays, and identify groups that require tailored management strategies to ensure their survival. 

Cownose rays may interbreed due to habitat overlap, for example where one species inhabits an estuary and another the river feeding into it. This overlap during mating, combined with their recent evolutionary divergence, raises important questions about species boundaries. 

If these rays, which are physically indistinguishable but genetically distinct, can interbreed, they may form a species complex rather than separate species. 

Understanding their evolutionary history helps inform conservation strategies, as genetic diversity and geographic boundaries influence a population’s resilience to environmental changes, the researcher explains.

Genetic analysis

To achieve these goals, the researcher will use tried-and-true methods such as mitochondrial DNA analysis, which traces genetic information passed down from mothers to distinguish between closely related species and explore long-term evolutionary trends. 

In addition, advanced techniques such as whole mitogenome and genome sequencing will offer an in-depth view of genetic information. 

Conservation breakthrough

Previous studies carried out by Weber during their Master’s degree at the University of Southern Mississippi revealed that the critically endangered Brazilian cownose ray - once thought to be confined to southern Brazil - inhabits waters as far north as the United States. 

This discovery has important implications for conservation, they explain. As there are no clear physical differences between the endangered Brazilian cownose rays and the closely related American cownose rays, researchers turned to genetic analysis to distinguish between the two species.

Genetic evidence supported that these species co-occur in North and South American waters, leading to upcoming legislative changes in the US, which will grant protections for both species.

“Our discovery was a pivotal step in stopping harmful practices such as the cownose ray hunting competitions once held on the east coast of the United States, where the species was wrongly blamed for declining oyster populations.” – Helen Weber, PhD student

Biodiversity focus

Currently, there are significant uncertainties about the number of distinct cownose ray species, with estimates ranging from five to nine. 

Genetic data will help clarify these ambiguities, providing a standardised framework for species identification, the team explains.

As the threats facing marine wildlife continue to grow, this project highlights the importance of a science-driven approach to safeguarding biodiversity and ensuring the health of marine ecosystems.