When genes are added to a community via emmigration (genomes moving in) or immigration (genomes moving out)

When the number and type of alleles available in a gene pool decreases due to chance, often some catastrophic event.

The term for when unrelated organisms evolve in similar directions because they have to solve the same ecological challenges. For example, dolphins and sharks both live in the water. Consequently, though they are not closely related species, both are torpedo shaped, with dorsal fins. Both have mouths full of teeth because they both eat fish, etc.

The term for when a single ancestor species splits into groups that adapt to different environments and evolve into different species. For example, Darwin's idea about the Galapagos finches: one species was blown onto the islands, different islands had different seeds available, birds that could eat the available food survived. Eventually, they became the various species of finches found on the islands.

Structures that have a similar function but different structure.

Structures that have a similar structure but different function.

When males compete to overpower another male and thereby gain control of the herd (rams charging one another)

When males compete for the attention of/ selection by the females (bird of paradise dance)