As a university focused on using research for the upliftment of its community, The University of the West Indies, St Augustine (UWI STA), the premier tertiary institution in the region, producing world-class scholars, believes science should be accessible to the public. We are pleased to present our media series, UWI Scientists Speak. Today, we hear from Dr Amy Deacon and Professor Indar Ramnarine from the Faculty of Science and Technology about their research on the Trinidad Guppy.
Often referred to locally as a lowly ‘drain fish’, many are surprised to learn that a species that is found in almost every stream, pond and drain in Trinidad is, in fact, a global celebrity. Not only are guppies sought after by aquarists, who enjoy the colour they bring to the aquarium, but they are also utilised by scientists, who have been studying this species since the 1940s to help answer some of the biggest questions facing biology.
What is a guppy?
At just 3cm long, guppies (seven-colours or millions) are Trinidad and Tobago’s (T&T’s) smallest freshwater fish. Males are adorned with spots and stripes of orange, black and iridescent yellows, blues and greens. Every male is different, and females select a mate according to who is brightest, healthiest or most unique. Females give birth to live babies, not eggs. They also store sperm, which means that just one female in a pond can generate more than a hundred guppies in just a few months.
How the guppy
got its name
In 1866, Robert Lechmere Guppy caught a guppy in the St Ann’s River and sent it to the British Museum, where it was named ‘guppii’ in his honour. However, it was soon discovered that the same species had already been described from Venezuela, so the ‘guppii’ was lost. However, in the early 1900s, Mr Guppy’s son began exporting fish for the aquarium trade, and it is likely at this point that the family name ‘guppy’ was popularised internationally.
History of the science of guppies
While descendants of Guppy’s guppy were being selectively bred in Europe and North America to become increasingly colourful and fan-tailed, in the 1940s, the humble wild populations in Trinidad caught the attention of scientists.
Soon, the Northern Range had become known as a “natural laboratory” where profound discoveries would be made. Most famously, how evolution by natural selection can take place in guppies within just a few generations. These days, if you pick up any textbook on evolutionary biology, you will find “Trinidadian guppy” in the index and pages devoted to work that took place here in the streams of the Northern Range.
These days, guppy research has broadened to include genomics, mate choice, memory, disease, ecosystem function, nutrient cycling, invasive species and social networks. Work-based in the Department of Life Sciences has included research relevant to many of these themes, in particular invasive species and social networks.
Guppies as an invasive species
While guppies are found naturally in Trinidad and Tobago, they have been transported around the globe by humans. Initially kept as aquarium fish or added to outdoor water tanks to control mosquitoes, guppies inevitably escape into natural water bodies, where they can have a negative ecological impact. Populations are now established in over 70 countries across every continent except Antarctica. This makes guppies unusual, as most species are unable to thrive outside of their natural range due to differences in predators, food or climate. By studying guppies here in Trinidad, we can begin to understand what makes a successful invader and how we can prevent other species with similar traits from being given the opportunity to establish.
The social lives of guppies
Guppies are highly social and often form large shoals. There are several reasons for spending time in large groups, perhaps the most important being protection from predators, who find it harder to target a group than an individual. However, it is becoming clear that guppy group behaviour is more sophisticated than we first gave it credit for. Just like we have networks of contacts in real life and on social media, guppies’ lives can be considered part of a social network of connections with other guppies. By studying guppy networks, we are learning more about social behaviour in other species, including our own.
Potential for more research
Guppies are a part of our country’s natural heritage and have placed Trinidad and Tobago on the map in the world of science. Scientists visit the country every year solely to work with this species. There is still great potential for discovering more using guppies, not just in terms of the “blue sky” research of evolution and behaviour, but also in the real world, for example, by helping us predict and manage invasive species.
When Lechmere Guppy caught that specimen near his home in 1866, he could never have predicted that more than 150 years later, scientists would still be studying this fascinating little fish!
