Reproductive Isolation in Evolution

Reproductive Barriers

• Hybrid inviability is the term used to describe the phenomenon where hybrid embryos die.
• Premating barriers, such as differences in behavior, habitat, or morphology, prevent mating or fertilization in different species before the formation of a zygote.

Hybrid Offspring

• Hybrid sterility or hybrid inviability is the term for the offspring of hybrids that are weak or infertile.

Postzygotic Reproductive Barriers

• Hybrid sterility or hybrid inviability prevents the development of fertile adults.

Plant Reproductive Barriers

• Structural isolation in plants prevents cross-pollination, ensuring that different species do not mate.

Gamete Incompatibility

• The male and female gametes of red and purple sea urchins fail to unite due to differences in their reproductive cells.

Failure of Hybrid Development

• When hybrid zygotes fail to develop or reach sexual maturity, it is known as hybrid inviability.

Structural Isolation

• The primary effect of structural differences in genitalia or flowers is to prevent copulation between different species.

Biological Species Concept

• A species is defined as a group of interbreeding populations that are reproductively isolated from other groups.
• Barriers to gene flow in the biological species concept prevent the exchange of genes between different species.

Prezygotic Reproductive Barriers

• One type of reproductive barrier is the prezygotic barrier, which prevents mating or fertilization in the biological species concept.
• An example of a prezygotic reproductive barrier is the difference in flowering times between two plant species, preventing them from cross-pollinating.

This quiz covers the concept of reproductive isolation in evolution, focusing on how structural differences in genitalia or flowers prevent copulation or pollen transfer between different species. It also discusses how plant species have flower structures adapted to specific pollinators, with examples provided.