Genetic Biodiversity
- alleles - different versions of the same gene
- genetic diversity—number of different alleles that exist in a species
- species with a greater genetic diversity will better adapt to their environment and be more resistant to to environmental change and therefore less likely to become extinct
# Factors affecting genetic biodiversity
- to increase biodiversity the number of alleles within a species must increase. This can happen via:
- mutations
- gene flow: interbreeding between different populations leads to alleles crossing between distinct groups
- genetic diversity can also decrease, this can happen via:
- selective breeding: selected characteristics are bred for
- captive breeding programmes: only a small number of individuals (and therefore alleles) available for breeding.
- rare breeds: difficult to maintain high numbers of individuals but also meet requirements for that rare breed
- artificial cloning: eg tissue cultures or cuttings in plants
- natural selection: species evolve to only have beneficial alleles so less advantageous ones are lost
- genetic bottlenecks: when only a few individuals survive environmental change such as a disease meaning the gene pool is reduced
- founder effect: when a small number of individuals create a new colony and are isolated from the original population
- genetic drift: due to random nature of which alleles do/don’t get passed on during sexual reproduction
# Measuring genetic biodiversity
polymorphic genes: genes that have more than one allele
monomorphic genes: a single allele exists
locus/loci: position of a gene/genes on a chromosome
the proportion of genes that are polymorphic can be calculated by:
- (number of polymorphic gene loci/ total number of loci) x 100
the greater the proportion of polymorphic loci, the greater the genetic diversity