Genetic diversity, species and taxonomy Flashcards
What happens in Meiosis 1?
Homologous chromosomes pair up and chromatids wrap around one another. Crossing over occurs here. Homologous pairs separate, halving chromosome number.
What happens in Meiosis 2?
Pairs of sister chromatids that make up each chromosome separated. 4 haploid cells which are genetically different formed.
What is crossing over?
Homologous pairs come together and pair up. Twist around each other and alleles exchange.
Genetic variation occurs due to…
Crossing over, Independent segregation of chromosomes, random fertilisation
How does independent segregation lead to genetic variation…
Each homologous pair is made up of one maternal and one paternal chromosome. When the pairs are separated in meiosis 1, it’s random which chromosome from the pair ends up in which cell.
How does random fertilisation lead to genetic variation…
Sperm colliding with egg is a completely random process
Species meaning
A group of organisms which can divide to produce fertile offspring
What is the founder effect?
When a few individuals from population colonise new region. Carry only small fraction of alleles of population. Eventually form a separate species.
What is a genetic bottleneck?
When there’s an event which leads to few survivors which possess small variety of alleles. When they breed, their genetic diversity remains restricted. Less likely to adapt to changes in the environment.
Genetic diversity meaning
variety of genes possessed by the individuals that make up any one species
Species diversity meaning
number of different species and number of individuals of each species
Species richness meaning
number of species in an area
