Speciation Flashcards
What is a species?
A group of organisms able to interbreed and produce fertile offspring.
What are the three types of isolating barrier?
Geographical
Ecological
Reproductive
Explain the geographical isolating barrier.
Features such as rivers or mountain ranges isolate groups. Movement of land-masses by continental drift led to geographical isolation millions of years ago.
Explain the ecological isolating barrier.
Although groups are not geographically isolated from each other they may be isolated by such things as occupying different habitats or breeding areas, pH, salinity.
Explain the reproductive isolating barrier.
Breeding between groups within a population may not be possible because of differences in courtship behaviour, physical differences which prevent mating, or failure of gametes to fuse.
What is adaptive radiation?
A common pattern resulting from isolation and speciation.
What do fossils provide?
A record of organisms that lived a long time ago. They also provide evidence that animals and plants can change over long periods of time.
What are fossils?
Fossils are the preserved remains or traces of dead organisms.
What are fossils formed from?
Hard body parts, such as bones and shells, which do not decay easily or are replaced by other materials as they decay.
Parts of organisms which have not decayed. For example, dead animals and plants can be preserved in amber, peat bogs, tar pits or in ice.
Casts or impressions, such as foot prints or burrows. These become covered by layers of sediment, which eventually become rock.
What can scientists learn from studying fossils?
How much or how little organisms have changed as life developed on Earth.
Where are the fossils of complex organisms found?
In the newest rocks.
Where are the fossils of simple organisms found?
In the oldest rocks.
What are some of the factors that lead a species to become extinct?
New diseases
New predators
New, more successful competitors
Changes to the environment over geological time - such as a change in climate.
A single catastrophic event - such as a massive volcanic eruption or a collision between an asteroid and the Earth.
How do new species form?
As a result of isolation.
What is isolation?
Where two populations of a species become geographically separated.
