Species- a group of living organisms, such as animals or plants that can interbreed or exchange genes and the largest unit inwhic gene flow
Speciation: when one species becomes two or more, due to evolution
How does speciation occurs?
For speciation to occur the population should be isolated. Once the population has been isolated then it would evolve independently.
Speciation can occur in two ways :
Allopatric Speciation- This is geographic separation ( other country)
Sympatric Speciation-This population still lives in the same area. (same country)
Reproductive Isolation- when two groups of animals live close enough to one another to interact, but not able to interbreed.
Prezygotic- Preventing mating between different species
Exmaples of Prezygotic Isolation
Ecological- species occur in the same region but occupy different habitats thus rarely encountering each other.
Temporal- species do not mate because they are active at different time of the day or seasons.
Behavioral- unique behavioral patterns and rituals.
Mechanical- mating is attempted but physically unable.
Postzygotic Isolation - Mechanisms that reduce gene flows after fertilization between closely related species.This means the animals mated but no offspring came along because the offspring is a hybrid and is not sterile, viable.
Hybrid Species- also known as cross breed, two animals or plants of different breeds. mating.
Examples of Postygotic Isolation
Gametic- sperms of one species may not be able to fertilize the eggs of another species.
Geographic- Separation of two population of the same species.
Prezygotic prevent hybrid from
- Reduced hybrid viability- Two different species interact in ways that will hinder the hybrids development or survival.
- Reduced hybrid fertility- when hybrids are sterile
- Hybrid breakdown- when hybrid reproduce but their offspring can't
Native: Species which colonized Bermuda naturally without humans help. Most arrived long before human settlement and are found in other countries too.
Introduced: A species which is not found naturally in Bermuda, but has been brought her either accidentally or intentionally by humans, animals, wind or water.
Endemic: a species that can be found in Bermuda and nowhere else.
Invasive: An introduced self-propagating species which has a tendency to spread rapidly, overwhelming the native and endemic species and/or causing economic damage.