This gradually leads to a different distribution of species based on geographical areas. Over time, diversification within one species can go deep enough to create several other species originating from the same ancestor. As it spreads, the particular individuals gradually adjust, specializing to live in slightly different environments, with slightly different food resources and landscapes. As a population of one species grows, it needs to spread to other habitats in order to simply feed itself. But Darwin was probably unaware of that while making this observation.Īnother important factor for a species’ survival is diversification. This is certainly an important point to the ongoing feminist debate. Consequently, they have an important say in how the species evolves! The latter, conversely, get to decide which characteristics they value the most in their mates. As Darwin notes, male are the ones who have to adjust their traits to the liking of the females. Interestingly, the competition in this realm happens mainly between males. That’s why being attractive to the potential sexual partner is also a key factor in natural selection. Other important mechanisms in play are sexual selection and diversification.Ī very well-adapted individual, whose genes enable it to thrive in their current environment may still not manage to pass those genes on if it fails to mate. But they’re not the only factor which decides about how natural selection will shape the species. Lesson 2: Evolution uses sexual selection and diversification as important factors to decide what genes are passed on. This ensures that the most adaptive traits are passed down to the offspring – and so, the next generations always evolve to be better suited for survival than their ancestors. The more a specific trait is useful for survival, the more the possessor of that trait is likely to breed. However, rather than picking the trait variations based on some arbitrary aesthetic principles (like with pigeon breeding), nature chooses those traits which support the species survival. We can acknowledge that, in the process of natural selection, nature acts as an “invisible breeder” of the species. According to that rule, parents’ genes are passed down to their offspring – but always with some modification and mixing with their partner’s genes. This process is possible thanks to the rule of descent with modification. After they mate and produce offspring, she will again pick the longest-necked pigeons from among them and breed them again.Īfter repeating this process for many generations, the breeder will eventually get pigeons with significantly longer necks than those in the first bunch. What she will do is select a couple of pigeons from a bunch with longer necks. Let’s assume a pigeon keeper wants to obtain a breed of pigeons with long necks. Various breeds of dogs or pigeons, for example, are the product of human selection. If you want to save this summary for later, download the free PDF and read it whenever you want.ĭownload PDF Lesson 1: To understand natural selection, it may help to look at human selection first.īefore we proceed to explore the laws of natural selection, let’s look at human-induced breeding of certain animals. Without further ado, let’s try and at least touch upon the main ideas of Darwin’s theory.
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