Evolution Flashcards
What is biodiversity?
Consequence of evolution
What is species diversity?
Number of different species within an ecosystem
What is genetic diversity?
Range of genetic characteristics within a single species
Genetic variation can occur when:
Variation in offspring: genetic material from both parents combine, the offsprings have genes of a random mix
Mutations: when there is an incorrect code within the gene, thus coding for something different
Lamarckian theory:
Acquire characteristics:organism acquire characteristics during its lifetime to adapt environment- changes then can be passed i.
E.g. giraffes have stretched their necks to reach food, trait has been passed to their offsprings to result to our current giraffes with long necks
Darwin’s finches:
- birds found on the Galapagos
- 13 finches in total on island with different beak sizes and shapes , representing a different species
Finches diagram:
Small cute beak: only ate fruits and seeds from trees on the ground
Mid beak: ate both fruits and larger insects in trees or the surface
Long beak: ate insects within the soil e.g. worms
Tortoises diagram:
Dry island tortoises has higher border to allow for head mobility to access food since
Enviro: shrubs and small trees
Dense vegetation tortoises: lower border therefore is tougher allowing to push through habitat
Enviro: dense vegetation
Darwin’s theory of evolution:
Species change overtime
As they change they diverge and create other species
Some species become extinct
What symbol did he refer to as evolution?
A tree of life, as all organism come from a common ancestor and over time they change and begin to diverge away from this ancestor
What is the Wallace line?
Imaginary line dividing the fauna of Australia and Asia. This is because there was drastic difference between the fauna on either side of line.
Nothing close to kangaroo in Asia
Natural selection:
- is a principle mechanism for evolution
1) variation in population
2) selective pressures e.g. predation, environment
3) individuals with favourable characteristics will survive and pass this trait to their offspring
4) over many generations, majority of the populations now has the favourable characteristic
How is there variation in population?
Due to genetic differences, all gene differences are stored in a gene pool a collection of all alleles for the population.
Gene differences arise from mutations and random reproduction.
Allele frequency:
Frequency of an allele
What is selective pressures?
Is the change in the environment that will affect the survival of some individuals in a population. + drives evolution
E.g.
