(3) Unit 7 Topics 10 and 11 Packet

Species

A group able to interbreed and produce viable, fertile offspring.

Speciation

The formation of a new species, leading to diversity of life.

Allopatric Speciation

Speciation that occurs due to physical barriers dividing a population.

Founder Effect

A specific example of allopatric speciation where a small group separates from a larger population.

Sympatric Speciation

Speciation that occurs without geographic separation, often due to exploitation of a new niche.

Niche

The role or job an organism has in its habitat.

Polymorphism

The occurrence of two or more different phenotypes within a population.

Prezygotic Barriers

Mechanisms that prevent mating or fertilization before a zygote is formed.

Habitat Isolation

Prezygotic barrier where species occupy different habitats within the same area.

Temporal Isolation

Prezygotic barrier where species breed at different times.

Behavioral Isolation

Prezygotic barrier caused by unique behaviors that prevent mating.

Mechanical Isolation

Prezygotic barrier where reproductive anatomy does not allow for mating.

Gametic Isolation

Prezygotic barrier where the sperm and egg of different species cannot fuse due to incompatible proteins.

Postzygotic Barriers

Mechanisms that prevent hybrids from developing into viable, fertile adults.

Reduced Hybrid Viability

Postzygotic barrier where hybrid embryos do not develop properly.

Reduced Hybrid Fertility

Postzygotic barrier where hybrids develop but are sterile.

Hybrid Breakdown

Postzygotic barrier where hybrids are fertile, but their offspring are not.

Microevolution

Small-scale evolutionary changes within a single population.

Macroevolution

Large-scale evolutionary changes that result in the formation of new species.

Punctuated Equilibrium

Theory stating that evolution occurs in rapid bursts following long periods of stasis.

Gradualism

Theory stating that evolutionary changes occur slowly over time.

Divergent Evolution

Evolution where groups with a common ancestor evolve and accumulate differences.

Convergent Evolution

Evolution where different species develop similar traits due to similar environments.

Extinction

The termination of a species; currently, many scientists believe we are in a sixth mass extinction.