Speciation

What is a species? A group of organisms that can interbreed (have kids with each other) and produce fertile offspring (kids that can also have kids).

What is speciation? The formation of new species.

How does speciation happen? New traits arise from random mutations. Two populations of the same species are separated from each other. Natural selection causes the two populations to change over time. After many generations, the populations become so different that they can no longer interbreed to produce fertile offspring (kids). When this happens, they are called different species.

Where does variation come from? New traits (like longer necks, different color eyes, etc) arise from random mutations in the DNA. Usually, mutations are harmful. But sometimes mutations are helpful, and natural selection makes these helpful mutations more common.

What are 2 ways populations can be separated? 1) Geographic isolation = when they live in different places 2) Reproductive isolation = when they are prevented from interbreeding (making babies) with each other. Example: if they have different mating seasons, or if they have different mating rituals, they are “reproductively isolated.”

What is gene flow? When new genes go into or out of a population, because individuals carrying those genes leave the population, or immigrate into the population. Example: Two populations of lizards live on 2 different islands. For many years, they evolve separately. Then, humans transport some lizards from one island to another.

What’s the difference between natural and artificial selection? Natural selection = nature determines which trait will make an individual more likely to survive and reproduce Artificial selection = humans determine which trait will make an individual more likely to survive and reproduce Example: In domesticated dogs, humans have chosen which ones are allowed to breed, based on whether or not they have certain traits.

Artificial Selection

Exit Ticket In order for a group of organisms to be considered the same species, what do they need to be able to do? Complete Sentence What is speciation? Complete Sentence True or false: if two species share homologous structures, this means that one species evolved from the other. Explain in a complete sentence.