Lecture 3-population And Evolution Flashcards
Who came up with the idea of evolution
Charles Darwin
Where did he discover it
He discovered it on an Galapagos island - there was finches
There beak was different to adapt to the area they were at
What is natural selection in finches
Originated from one mainland seed eating finch
The birds were a bit different to the bird on mainland
What is variation
Caused by random mutations resulting in new alleles
These may be advantageous for survival
New better adapted organism have better chance of survival
What allows natural selection
Genes - hair colour , tongue rolling ,PTC
Alleles - brown , blonde , ginger etc, yes or no , bitter taste / not
What is genetic diversity
Number of different allele of genes in a species or population
-Is a factor enabling natural selection to occur
-Random mutations in the dna can result in new allele of a gene
Gene flow /migration - can increase genetic diversity
What is adaptation
Natural selection leads to organisms becoming better adapted to their environment
What features help organisms to survive
Behavioural
Physiological
Anatomical
What are genetic bottlenecks
Causes big reduction in a population
Eg. If there is a war they will be less people so it’s a genetic bottleneck
What is founder effect
Few organisms from a population start a new colony and there are only a small number of different alleles in the initial gene pool
What are the different types of natural selection
- Directional selection - individuals with alllels for a single extreme phenotype are more likely to survive and reproduce
- Stabilising selection - individuals with alleles with characteristics towards middle of the range are more likely to survive , occurs when environment isn’t changing
- Disruptive selection - where individuals with alleles for extreme phenotype are more likely to survive and reproduce
What are phylogenetic trees
Represent the relationship between organisms
What is speciation
Development of new species from an existing species due to reproductive isolation
Two types of speciation
- Geographical isolation - caused by physical barrier
2.sympatric speciation - when random mutations within a population prevent individuals that carry the mutation from breeding with other members of the population that don’t have a mutation
Other examples of reproductive isolation
Seasonal - different flowering or mating season
Mechanical
Behavioural
What is genetic drift
Instead of environmental factors affecting which individuals survive , breed and pass on their alleles , chances dictates which alleles are passed on
Example : giraffes
Explain how evolution can occur through natural selection
Through genetic variation etc
