3.2 Natural Selection Flashcards
(15 cards)
Evolution
1) All organisms show variation due to mutations
2) If conditions change then some organisms will be better suited to the new environment than others
3) Competition- Those who are better suited will survive
4) Survivors will reproduce + pass on desired alleles to the next generation
Niche
The role of an organism in the ecosystem, based on the adaptations which they have
Anatomical Adaptations
The form + structure of an organism
Physiological Adaptations
The way the body of an organism works
Behavioural Adaptations
Changes to the programmed or instinctive behaviours
Speciation
Formation of a new species
Requires 2 populations of the same species to become reproductively isolated
Types of Speciation
Allopatric- Geographical Isolation
Sympatric- Changes in the reproductive mechanism
Allopatric Speciation
Geographical Isolation
Ecological Isolation
Seasonal Isolation
Geographical Isolation
A physical barrier that separates individuals from an original population
Ecological Isolation
2 populations inhibit the same region, but develop preferences for different parts of the habitat
Seasonal Isolation
Timing of sexual receptiveness drifts away from the norm of the group
Sympatric Speciation
Behavioural Isolation
Mechanical Isolation
Behavioural Isolation
Changes in the mating pattern
Some animals don’t recognise each other as mates
Mechanical Isolation
A mutation occurs that changes the genitalia of animals
Speciation Stages
1)A population becomes separated into 2 groups that are reproductively isolated
No gene flow between the groups
2) Natural selection favours different characteristics for each group
3) Allele frequencies in the 2 groups will change in different ways
4) Eventually the 2 populations won’t be able to interbreed
They will be 2 different species
