Natural Selection in Chickens

Evolutionary processes have been cited as the reason for the different characteristics of living organisms. The most important of these processes is natural selection.

Charles Darwin noted that as herders shaped their herds by picking animals with the best traits to breed, so too nature could shape organisms by choosing those with the best qualities to survive. According to Darwin, the ability to survive and reproduce is not based on a random population sample but on specific variants suited to an environment.

Natural selection is an evolution mechanism. It states that organisms that are more suited to an environment are more likely to survive then pass their genes to another generation.

As such, a species will transform and diverge with time as genetic mutations that are beneficial to the survival of an organism are passed to other organisms through reproduction. You might assume this phenomenon only applies to man and large organisms.

However, here are tidbits that will help you understand natural selection in chickens to transform your poultry-keeping venture.

Understanding Natural Selection

Natural selection entails all selection processes occurring because of the ability of an organism to adapt to its environment. This is the main process that allows living things to adapt to their surroundings to boost their odds of survival and increase their numbers through breeding.

Natural selection is among the mechanisms of evolution, together with migration, mutation, and genetic drift. It is caused by changes in an environment and an organism’s genotype rather than happening intentionally.

While the genotype changes that increase the odds of an organism’s survival are passed to the next generation, those that are less advantageous are lost as generations increase. Natural selection can follow differences in mating success, fertility, survival, and other elements of the life cycle.

Conversely, artificial selection entails selective breeding by an external entity, often humans, to enhance some desirable features in an organism. The breeder, in this case, selects specific desirable characteristics in animals or plants and then breeds them to get offspring with the desired trait. Unlike natural selection, this is a man-made process.

Natural selection is a slow process occurring in wild populations, while artificial selection is rapid and occurs in domestic or reared populations.

Furthermore, while natural selection results in evolution, artificial selection does not. Natural selection preserves and increases a population’s variation by driving the reproduction and survival of organisms with beneficial traits.

This leads to genetic diversity, which is the combined differences in the DNA of organisms that comprise a species. Genetic diversity increases the odds of a species’ survival and adaptation.

Natural Selection in the Wild

Life in the wild generally means freedom for animals. However, it also means a greater risk of disease and predation. As such, in the wild, natural selection will primarily focus on traits that boost the odds of survival for an animal by protecting it from disease and predators.

The domesticated fowl descended from the red junglefowl over 9500 years ago. Junglefowl still exists in robust numbers, with several adaptations for their life in the wild.

In the wild, chickens use the left eye to perceive new stimuli and the right for small details like food. With this trait, the bird can divide its attention between searching for food and protecting itself from predators.

The hens have colorful, plumages that allow them to camouflage when looking after chicks and eggs. Wild chickens also fly to relatively high places to roost and escape ground predators.

In recent years, some interbreeding has happened between wild and tame chickens. Though it seems harmless, remember that chickens do not have much genetic diversity. Mixing wild and domesticated chicken populations further reduces their genetic diversity instead of adding o it.

The genetic adaptations from years of natural selection in wild chickens will be lost when interbred. This means losing the diversity that can support the introduction of relevant adaptations for domestic chickens.

Not preserving wild populations also leads to the easy spread of diseases because the genetic diversity that can confer some resistance is lost.

Natural Selection in Domestic Chickens

You might not think that natural selection might be occurring right in your backyard among your chickens, but it is. One study on beak sizes and bird feeders confirmed how human activity affects bird evolution.

The researchers noted that birds got longer beaks to reach for the bird seed in feeders compared to the same species feeding from the ground. The phenotype for long beaks to adapt to feeding from bird feeders was passed to offspring, thus changing the species.

You can slowly and unintentionally change the genetic makeup of your chickens’ lineage by your environment. For instance, encouraging free-ranging means your birds will develop strong beaks to scour the ground and be vigilant to avoid predators.

Nonetheless, it is important to maintain the genetic diversity of your flock by avoiding habits that will change its entire genetic makeup. Having a flock with no genetic diversity puts it at risk because the birds are susceptible to the same predators and diseases.

This means your flock can be easily wiped out.

The Role of the Breeder

The breeder’s role in natural selection is positively manipulating an environment so that chickens adopt the right characteristic to help them survive.

In so doing, subsequent generations are born with desirable traits that help them thrive in specific environments. There are two types of breeding a breeder can pick from; selective and non-selective breeding.

Selective breeding happens when you choose the animals to breed and when they should breed. You will pick desirable characteristics in parents that you want an offspring to inherit before breeding an animal.

For instance, if you want a superior egg-laying chicken, it is prudent to breed two exceptional layers. Repeated selective breeding over several generations will get you an exceptional layer as the egg-laying gene becomes stronger.

In non-selective breeding, the choice of when to breed and with whom is left to nature. The genetic changes witnessed in this case are driven by environmental elements limiting reproduction and survival, like harsh weather and predation.

Breeding so that you can pass the best possible characteristics to your offspring and adapt them to certain elements in an environment ensures you harness the highest benefits from poultry keeping as you get superior chicken breeds.

The Impact of Artificial Selection

In artificial selection, you will choose the desirable characteristics you need in your chickens to decide which animals will breed. While this might seem failsafe, the seemingly desirable genes you select for breeding might not necessarily convey greater benefits than natural selection would.

In fact, artificial selection might cause some undesirable traits to persist in a species. Since the chickens are artificially selected rather than allowing natural selection to take its course, you might end up with chickens that are not adapted to certain drawbacks in their environments.

You can breed two types of chickens: heritage and commercial chickens. While commercial birds are bred for one purpose, heritage chickens are bred for multiple uses. For instance, you can keep commercial chicken for meat or eggs, while heritage chickens can be for meat and eggs.

Heritage breeds can be expensive to buy and rear since they live longer and need more care. However, adding them to your flock will benefit you in terms of conservation and biodiversity since most heritage chicken breeds are endangered.

Balancing natural and artificial selection in your flock is essential since this guarantees that your birds are well-adapted to their environments and have desirable traits that benefit your poultry farming.

Genetic Conservation of Chicken Breeds

Conservation genetics entails the application of genetics to understand and then reduce the risks to which a population is exposed. Its primary goal is to prevent the extinction of a species. You can preserve desirable genetics in your chickens by inbreeding or outbreeding.

Inbreeding is mating your chicken with others in the same breed or flock, while outbreeding entails mating your chicken with one from another breed or flock.

While outbreeding results in offspring that are superior to their parents, the offspring in inbreeding are similar to their parents. Lastly, inbreeding is meant to maintain homozygosity so that you have pure breeds, while outbreeding produces hybrids.

The genetic diversity caused by outbreeding is a means of helping your flock adapt to its environment and gain superior genes that boost their benefits for you.


Breeding of chickens is essential when you want to maintain a flock. Nonetheless, you should pay attention to the traits you desire in your birds so that you maximize the odds of getting these traits when the birds mate.

From the above information, you know what to expect when you hear of natural selection in chickens and how this will benefit your poultry keeping. With the right approaches, you can manipulate the genetic makeup of your flock and offspring to maximize your benefits and guarantee the survival of your birds when breeding them.

However, it is prudent to involve a vet when breeding your chickens to ensure it is done right.

avatar James
Hey, I'm James, a hardworking homesteader for more than 30 years. I enjoy the feeling of accomplishment that comes from tending my flock. I've raised chickens and ducks for eggs and meat for many years. I also have experience with other poultry too. Learn more

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