Genetic Biodiversity
Importance of Genetic Biodiversity:
- Individuals within a species often have very little variation within their DNA, as all members of the same species share DNA. However, different versions of genes, alleles, allow for different characteristics between organisms of the same species.
- Species with greater biodiversity are less likely to become extinct because they can adapt to sudden changes in the environment as some individuals will have a certain allele that aids survival, for example innate immunity.
- Mutation, creating a new allele, increasing genetic biodiversity.
- Interbreeding between populations from different regions, so a variety of alleles are distributed between the populations, called gene flow, increasing genetic biodiversity.
- Selective breeding means a minority is picked for desired characteristics, meaning a higher proportion of organisms within a species share the same allele, reducing genetic biodiversity.
- Captive breeding programmes where there is a small gene pool reducing genetic diversity.
- Cloning/asexual reproduction, where a new organism is genetically identical to its parent means there is no variation in genes across generations, reducing genetic biodiversity.
- Natural selection, where only organisms with characteristics beneficial to survival survive to reproduce and pass of their genes, meaning that a higher proportion of organisms within a species, reducing genetic biodiversity.
- Genetic bottleneck, where a few individuals in a population survive a sudden change or event, and this leaves the species with a small gene pool, reducing genetic biodiversity.
- Founder effect, where a small number of individuals start a new colony geographically isolated from the other, with the gene pool for this population being very small, and the subsequent generations having a high chance of having a previously uncommon allele.
- Genetic Drift, due to the randomisation of alleles being passed from parents to offspring, the frequency of occurence will vary, sometimes causing a gene to disappear completely.
Calculating Genetic Biodiversity:
Key Terms:
Polymorphic Gene: a gene with multiple variations.
Monomorphic Gene: a gene with only no different variations.
Loci: the position of a gene on a chromosome.
- Most genes are monomorphic, ensuring the basic structure of a species remains constant.
- The proportion of polymorphic genes can be calculated using the following formula:
- Proportion of polymorphic gene loci = Total number of Polymorphic Gene Loci ÷ Total number of all gene loci (x100%).
- The greater the proportion, the greater the genetic biodiversity within a species.
- Gel electrophoresis is a technique used to separate fragments of DNA based on their size. These fragments are placed in a gel and positive and negative electrodes cause DNA to move towards the negative electrode.
- This produces a 'banding pattern' which can be used to compare samples between individuals.