1) A species is a group of organisms that can interbreed and produce fertile offspring. This is known as the biological species concept. 2) Speciation is the process by which new species arise from existing species. It occurs through anagenesis, where a population accumulates traits over time to form a new species, or cladogenesis, where a new species branches off from an ancestral species. 3) Speciation increases biodiversity by splitting ancestral species into multiple descendant species over time.

1. BIODIVERSITAS S P E S I E S

4. The biological species concept is based on inter-fertility, rather than physical similarity.

5. Biological species concept: "a species is a group of actually or potentially interbreeding individuals who are reproductively isolated from other such groups." It suggested a critical test of species-hood: two individuals belong to the same species if their gametes can unite with each other under natural conditions to produce fertile offspring. This concept also emphasized that a species is an evolutionary unit. Members share genes with other members of their species, and not with members of other species. Although this definition clearly is attractive, it has problems. Can you test it on museum specimens or fossil data? Can it explain the existence of species in a line of descent, such as the well-known lineage of fossil horses? Obviously not.

8. Speciation results in the splitting of an ancestral species into two (or more) descendent species. This process is the source of biological diversity.