Final answer:
Sympatric speciation is a form of speciation that occurs without a geographic barrier. One mechanism, called disruptive selection, leads to the formation of two distinct populations within the same habitat. Disruptive selection occurs when individuals with extreme traits have higher fitness compared to individuals with intermediate traits.
Step-by-step explanation:
Sympatric speciation is a form of speciation that occurs without a geographic barrier. It involves the divergence of two or more populations within the same habitat. One mechanism of sympatric speciation is disruptive selection, which leads to the formation of two distinct populations with different traits.
Disruptive selection occurs when individuals with extreme traits have higher fitness compared to individuals with intermediate traits. This can happen when there are different niches or resources available in the same habitat. As a result, individuals with extreme traits are favored and have a higher chance of surviving and reproducing. Over time, this can lead to the formation of two distinct populations with different traits.
For example, imagine a population of birds that feed on different-sized seeds. If there are small and large seeds available, birds with small beaks may be more efficient at foraging for small seeds, while birds with large beaks may be more efficient at foraging for large seeds. This difference in beak size can lead to reproductive isolation, as the birds with small beaks prefer to mate with other birds with small beaks, and the birds with large beaks prefer to mate with other birds with large beaks. Eventually, this can lead to the formation of two separate populations with different beak sizes.