Natural Selection in Guppies – How it Works?

In this article, I’ll go over a few key findings of natural selection guppies and how they evolved to reach the present stage. In the wild, guppies are very adaptable to new environments and threats. One of their key defenses is the ability to reproduce endlessly, hence their nickname “million fish.”

To better raise guppies, you should understand what makes them tick, how they react to environmental stimuli and how they behave. With this knowledge, you’ll know what habitat to build for them, and how to better care for them. Guppies aren’t too different from other Atlantic fish species, fortunately.

Let’s begin with their natural habitat and move on from there!

Natural Habitat of Guppies

Where there’s tropical waters, you’ll find guppies roaming around, mating and surviving in large packs. Around the Caribbean Islands, near Tobago and Trinidad, there are scores of guppy fish. They’re also present in South America, around Brazil, Guyana, and Venezuela. But these are just the places where you can find guppies naturally.

Throughout the years, people have brought them to most continents except for Antarctica. To find guppies, you only have to look for small ponds or bodies of slowly moving water. Streams or bodies of fast-moving water will not contain guppies because they can’t survive in these environments. Though, slow rivers or even stationary bodies of water are prime locations for guppies.

In terms of water composition, guppies prefer saline waters. While other tropical fish prefer fresh water, guppies do just as fine in fresh and saline water habitats. Still, the salinity shouldn’t reach the level of marine water because that’ll mess with the guppies’ health.

The water also needs to be warm, at about 72-79° Fahrenheit, and the same goes for aquarium water. Keep your guppies tucked in warm water and they’ll thrive! Make sure the pH of the water is between 6.5 and 8 for best results, as well. I’ve written other articles on the pH level requirements for guppies, so you’re welcome to read that article.

It contains valuable information about increasing or decreasing the pH level of the guppies’ aquarium water, depending on their needs.

Guppies’ Natural Predators

Small fish like guppies are always threatened by bigger and meaner fish. It’s not surprising that killifish, birds, and cichlids are the guppies’ natural predators in the wild. These are the most notable ones that I’ve been able to find. They’re not the only ones, though. Think of it this way – any carnivore fish that’s larger and stronger than guppies will hunt and eat them.

To survive these encounters, guppies have developed a pack mentality. They gather around in large schools for extra protection, and to intimidate would-be predators. They only do this where predators are known to stalk in large numbers. But over the years, they’ve developed an innate sense of dangerous areas and they quickly around to deter predators from approaching.

What Do Guppies Eat in the Wild?

Guppies eat what they find. They’re not exactly scavengers but they invade the habitats of other fish without a second thought. They can eat:

• Plant fragments
• Invertebrates
• Aquatic insect larvae
• Diatoms
• Mineral particles
• Algae

It might look that their diet is varied but generally, guppies only eat algae. It’s the easiest to find and offers a ton of nutrients, vitamins, and minerals. Guppies are also known as aquarium cleaners because they eat all the accumulated algae and other wastage in the tank.

Of course, this isn’t true for all guppies. Depending on their natural habitat, other guppies may have a different main diet. Take the Trinidad guppies, for instance. They generally eat invertebrates instead of algae. The waters around Trinidad are filled with invertebrates, which suits guppies just fine. It’s a staple diet for them.

The more abundant a food source is, the more likely it is for guppies to start eating that specific food. But this isn’t always the rule. Sometimes, guppies will choose food sources that are more nutritional and offer more vitamins, proteins, and minerals. For instance, guppies may still choose to eat invertebrates even if they’re harder to find than algae.

If you compare two populations of guppies, one that mainly eats algae and one whose diet mainly consists of invertebrates, you’ll find that the latter is healthier, stronger, and better adapted to their environment. That’s because invertebrates are a better diet than algae. They offer more nutrients which help the guppies develop faster.

Lastly, guppies may choose to alter their diet if they have competitors eating that same food source. So, for instance, if another fish species starts competing for invertebrates, guppies may choose to change their diet to algae to avoid conflicts. Guppies are a soft and puny species!

So, guppies often change their diet based on environmental factors.

How Does Natural Selection Influence Evolution?

Natural selection manifests in various ways, including what I said earlier. Diet choices, predators, all these can influence the evolution of guppies. If they eat different things or live in different environments, guppy populations may start looking and behaving differently from other guppy populations a couple hundred miles away.

The presence of predators may lead to guppies developing specific colors to hide from said predators. They’ll also start behaving differently based on how those predators move in the environment. Guppies may become more skittish or braver depending on these factors.

But, one thing is true – if a guppy population doesn’t adapt to its environment, it’ll die quickly. Just like with every other wild animal out there, strong individuals thrive and spread their genes, while the weak die. Natural selection is a wonderful evolutionary mechanism that ensures animal populations stay adapted to their environment.

What Makes Guppies Adapt So Quickly?

“Quickly” is a relative term when it comes to natural selection, adaptation to the environment, and evolution. Nothing happens quickly. It happens on a grand scale, over many generations. Guppies aren’t any different from other animals in this respect. To survive, they need to adapt, and that’s what they do. It’s nothing conscious but rather their instincts kick in.

Many studies show that, if moved to new environments, guppies will start adapting and improve their survival chances. For instance, when moved to areas with fewer predators, guppies start giving birth to fewer guppy fry. With fewer predators around, fewer guppies die from being eaten, so the overall guppy population doesn’t need to compensate too much for this risk.

On the other hand, if moved to an area with more predators, guppies will do the opposite. They’ll start giving birth to more guppy fry to compensate for the rising number of dying guppies. The species needs to stay alive, that’s the final goal of any animal.

Wrap Up

Watching guppies adapt to their environment is fascinating. If you place aggressive fish in the tank, many guppies will become stressed and perhaps die, but in time, they’ll adapt to this as well. Perhaps they’ll crowd together and intimidate the aggressive fish or they’ll learn to hide better. They’ll give a wide berth to that fish, maybe.

I recommend keeping these things into account if you plan on buying guppies for your home aquarium. Knowing how they behave in certain environments, what they eat, about their natural predators, and how they survive, will help you take better care of them.

If you have more questions, leave them below!