Defining Species Flashcards
What’s the morphological species concept?
The idea that organisms are classified based on their appearance, the observable phenotypes.
What problems are there with the morphological species concept?
Some species are morphologically very similar, and there can be morphological variation (I.e. Diversity) within a single species.
How can we know if morphologically different (or even similar) organisms are the same species?
Through reproductive isolation.
What is the Biologically Species concept?
Reproductive isolation, the idea that there are barriers to prevent reproduction in order to prevent interbreeding between species.
What are the two main types of reproductive barriers?
Prezygotic reproductive barriers and postzygotic reproductive barriers.
What does “Prezygotic Reproductive Barrier” mean?
Barriers that prevent mating or fertilization.
What does “Postzygotic Reproductive Barriers” mean?
Barriers that prevent development of fertile adults.
What types of Prezygotic Reproductive Barriers are there?
- Habitat Isolation
- Temporal Isolation
- Behavioral Isolation
- Mechanical Isolation
- Gamete Isolation
What is Habitat Isolation?
A Prezygotic reproductive barrier where the species may occupy different habitats, so they do not have any contact with each other and as such mating does not take place.
What is Temporal Isolation?
A type of Prezygotic reproductive barrier where the species have different mating or flowering seasons or times of the day, or become sexually mature at different times of the year. These differences reduce the encounters for interbreeding.
What is Behavioral Isolation?
A Prezygotic reproductive barrier where there is little or no sexual attraction between males and females of different species due to differences in behavior or physiology. They may use different songs/scents/techniques to attract mates.
What is Mechanical Isolation?
A Prezygotic reproductive barrier where there is structural differences in genitalia or flowers to prevent copulation or pollen transfer between two different species. Many plant species have flower structures that are adapted to specific pollinators, and as such cross pollination cannot happen.
What is Gamete Isolation?
A Prezygotic reproductive barrier where male and female gamete die before uniting, or just fail to unite.
What types of Postzygotic Reproductive Barriers are there?
- Hybrid Inviability
- Hybrid Sterility
- Hybrid Breakdown
What is Hybrid Inviability?
A type of Postzygotic reproductive barrier where the hybrid zygotes fail to develop or to reach sexual maturity.
