Guppies, Guppies Everywhere!

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How do different populations adapt to their environment? Let’s explore this concept through guppy speciation.

Guppies (Poecilia reticulata) are one of those species of fish that are all over the place. Walk into just about any pet store with live fish for sale. You’ll probably find a display of guppies. Go snorkeling in a freshwater stream somewhere near the Equator. You may find guppies there, too. Take a close look at one of Rio de Janeiro’s sewers. You’ll find that guppies even live there quite happily!

Wild and domestic guppies/guppys vivant dans la nature et des guppys vivant en aquarium
Wild guppies on the left and domesticated guppies on the right (Sources: Per Harald Olsen [CC BY 3.0] via Wikimedia Commons [Left] and isoft via iStockphotos [Right]).

But even though these are the same species of fish, they may have very different traits. For example, they might have different breeding patterns or different diets. Let’s look at how and why this happens.

What are some examples of local adaptation in guppies?

Guppies are abundant and widespread. There’s a lot of them, and they live in many different places and environments. Guppies in different environments need specific characteristics, or traits, to live in those environments.

The development of these differences is a process that ecologists call local adaptation. In this process, populations adapt to their environment in a way that will let them survive. These adaptations may eventually limit breeding between populations. In other words, these adaptations may lead to speciation, the formation of new species.

For example, some guppies coexist with (live in the same streams as) their predators. Others do not. Ecologists (scientists who study interactions between organisms and their environment) have found that these two categories of guppies have different traits (2).

One guppy predator is a type of fish called the cichlid. Some cichlids that live alongside guppies have features that make them fierce predators. For example, they have long bodies that let them swim quickly. They also have strong, fast-moving jaws that can help them catch more prey.

Pike Cichlid (Cichlidae Crenicichla): a voracious guppy predator
Pike Cichlid (Cichlidae Crenicichla): a voracious guppy predator (Source: Clinton & Charles Robertson from RAF Lakenheath, UK & San Marcos, TX, USA & UK [CC BY 2.0] via Wikimedia Commons).

With cichlids around, individual guppies are less likely to survive to adulthood. Guppies that coexist with cichlids have strategies to make sure at least some of their offspring survive. They start reproducing earlier, produce many offspring and reproduce often. Ecologists call animals like this r-strategists. This reproductive strategy often occurs in environments with heavy predation.  

How do different guppies impact their environment?

Guppies that coexist with cichlids also impact their environment differently than those that do not. That’s because these two categories of guppy have different diets. Guppies that coexist with cichlids usually do not live near many other guppies. This way, they do not have to compete with other guppies for food. These guppies get access to the best quality food, like midges and other invertebrates

Meanwhile, guppies that don't coexist with cichlids live at much higher densities. They have to compete for food with many other guppies, so they cannot be picky! They have a much broader diet that includes microorganisms and decomposing (rotting) organisms.

This is really important. It means that predator-prey interactions can change the traits of a population, and vice versa. In other words, ecological processes (the flow of matter and energy) and evolutionary processes affect each other. Biologists used to think that evolutionary processes took thousands of years and ecological processes happened much more quickly. Discovering that the two processes affect each other was an exciting breakthrough!

Starting Points

Connecting and Relating

  • Can you name any different species of a type of fish? (e.g., Pacific salmon versus Atlantic salmon.) How do these species differ? Do they live in the same environment?
  • Have you owned guppies or other fish? Do you know what variety of guppy  you had?

Connecting and Relating

  • Can you name any different species of a type of fish? (e.g., Pacific salmon versus Atlantic salmon.) How do these species differ? Do they live in the same environment?
  • Have you owned guppies or other fish? Do you know what variety of guppy  you had?

Relating Science and Technology to Society and the Environment

  • Since there are guppies all over the world with adaptations based on the ecosystem in which they live, what do you think might happen if guppies from a different ecosystem were brought in and added to an existing ecosystem? Explain.

Relating Science and Technology to Society and the Environment

  • Since there are guppies all over the world with adaptations based on the ecosystem in which they live, what do you think might happen if guppies from a different ecosystem were brought in and added to an existing ecosystem? Explain.

Exploring Concepts

  • What is a local adaptation?  
  • What adaptations did the guppies have that lived with the cichlids develop to help them survive? Explain.
  • What is the difference between an ecological process and an evolutionary process?
  • What other animals are r-strategists? Why does this strategy make sense given their environments? (This may take some additional research.)

Exploring Concepts

  • What is a local adaptation?  
  • What adaptations did the guppies have that lived with the cichlids develop to help them survive? Explain.
  • What is the difference between an ecological process and an evolutionary process?
  • What other animals are r-strategists? Why does this strategy make sense given their environments? (This may take some additional research.)

Nature of Science/Nature of Technology

  • How has the observation of these guppy predator-prey interactions influenced scientific thinking about evolutionary processes? Explain.

Nature of Science/Nature of Technology

  • How has the observation of these guppy predator-prey interactions influenced scientific thinking about evolutionary processes? Explain.

Teaching Suggestions

  • This article, and the connecting resources, can be used in Biology to support teaching and learning related to adaptation of organisms, populations, speciation, and trophic levels. This article can help students deepen their understanding of the connections between adaptations and predator-prey relationships within ecosystems. Concepts introduced include traits, populations, speciation, local adaptation, coexist, ecologist, reproductive strategy and ecological processes.
  • After reading the article, teachers could have students complete the Concept Definition Web learning strategy (individually or as partners) to help them develop a deeper understanding of the concept of local adaptations. Download ready-to-use reproducibles using the Concept Definition Web learning strategy for this article in [Google doc] and [PDF] formats.

Teaching Suggestions

  • This article, and the connecting resources, can be used in Biology to support teaching and learning related to adaptation of organisms, populations, speciation, and trophic levels. This article can help students deepen their understanding of the connections between adaptations and predator-prey relationships within ecosystems. Concepts introduced include traits, populations, speciation, local adaptation, coexist, ecologist, reproductive strategy and ecological processes.
  • After reading the article, teachers could have students complete the Concept Definition Web learning strategy (individually or as partners) to help them develop a deeper understanding of the concept of local adaptations. Download ready-to-use reproducibles using the Concept Definition Web learning strategy for this article in [Google doc] and [PDF] formats.

Additional Resources

Additional Resources

Learn more

The Guppy Project

An extensive website about a group of scientists working on what guppies show about adaptation including videos and profiles of each scientist

Variation in a species (2009)

A video lecture (19:51 min.) from Khan Academy with on-screen diagrams on how and why mutation and sexual reproduction cause variation in species.

Ecology - Rules for living on Earth (2012)

A video (10:25 min.) from CrashCourse that explains at a basic level how the environment affects biology

References

Arbour, J. H., & López-Fernández, H. (2013). Ecological variation in South American geophagine cichlids arose during an early burst of adaptive morphological and functional evolution. Proceedings of the Royal Society B: Biological Sciences, 280(1763). DOI: 10.1098/rspb.2013.0849 

Bassar, R. D., Marshall, M. C., López-Sepulcre, A., Zandonà, E., Auer, S. K., Travis, J., … Reznick, D. N. (2010). Local adaptation in Trinidadian guppies alters ecosystem processes.  Proceedings of the National Academy of Sciences, 107(8), 3616–3621. DOI: 10.1073/pnas.0908023107

Des Roches, S., Post, D. M., Turley, N. E., Bailey, J. K., Hendry, A. P., Kinnison, M. T., … Palkovacs, E. P. (2017). The ecological importance of intraspecific variation. Nature Ecology & Evolution, 2(1), 57–64. DOI: 10.1038/s41559-017-0402-5

Reznick, D., Bryga, H., & Endler, J. (1990). Experimentally induced life-history evolution in a natural population. Nature, 346(6282), 357-359. DOI:10.1038/346357a0

Travis, J., Reznick, D., Bassar, R. D., López-Sepulcre, A., Ferriere, R., & Coulson, T. (2014). Do Eco-Evo Feedbacks Help Us Understand Nature? Answers From Studies of the Trinidadian Guppy. In Eco-Evolutionary Dynamics, 50, 1–40. DOI: 10.1016/b978-0-12-801374-8.00001-3