Speciation Flashcards
4 types of fossils
Mould fossils - a fossilised impression is the substrate
Cast fossils - formed when a mole like ice or Amber is filled
body fossils - fossilised remains
Trace fossils - record what an animal was doing (footprints, excretion)
Why can’t scientists be sure about the origins of life
Soft bodied organisms leave no fossils
Any fossils left where wiped out by volcanic activity
What can be learnt from fossil record
Evidence of gradual change
The transition to land
From reptiles to mammals
Common ancestors
Definition of extinction
The permanent loss of all members of a species
Reasons of extinction
New predator New competitor New disease Catastrophic events Environmental changes
How do new species arise
Species becomes divided into different environments, due to random mutations and natural selection, different parts of species survive better in different locations. Eventually species becomes so adapted that when the 2 are brought back together they can’t successfully breed. Speciation
How do some population become isolated
Geographic isolation Isolation from man made barriers Isolation by distance, moving too far away Isolation after an event Isolation from separation
What role does genetic variation have in the formation of new species
Random mutations within a species can give an animal the competitive edge it needs versus other species, animals without this mutation may not be. As likely to survive and breed
What role does natural selection have in formation of a new species
Animals without the useful mutation are less likely to survive, breed and pass on the helpful gene
What is a fossil
The remains or impression of a prehistoric plant or animal embedded in rock and Preserved in petrified form
