Speciation Flashcards
What are fossils?
They are the remains of organism from many years ago, which are found in rocks
What are the various ways in which fossils are formed?
From the hard parts of animals that do not decay easily
From parts of organism that have not decayed because one or more of the conditions needed for decay are absent
When parts of the organisms are replaced by other materials as they decay
As preserved traces of organisms, e.g. footprints, burrows and rootlet traces
Why are scientist not sure when life began?
Because many early forms of life were soft-bodied, which means that they have left little trace behind
What aces there were have been mainly destroyed by geological activity
What can we learn from fossils?
How much or how little different organisms have changed as life developed on Earth
How can extinction occur?
New predators may wipe out snout species if the prey is not sufficiently well-adapted to cope
New infectious diseases could arise which kill off the whole species
Competition which another better adapted species e.g. for food, may cause a gradual decline in the less successful specie
Why may mass extinction of a huge number of species occur?
Climate change, such as an ice age
Volcanic eruption
Asteroid impacts
Define the term of species
A group of living organisms consisting of similar individuals capable of exchanging genes of interbreed
How may new species arise?
This is known as speciation; the formation of a new species from a pre-existing one. This often occurs when some organism are isolated (usually occur due to geographical isolation). As time goes by genetic vacation begin to occur between the organism, due to the new living conditions. Natural selection will then select the different characteristics needed to survive in the are. Different mutations may also take place I’m the original group. Eventually , sufficient differences will evolve in each population as that they can no longer interbreed to produce offspring
What do fossils provide?
Evidence for early forms of life
