Calculating genetic diversity 11.5 Flashcards
why is it important to maintain genetic biodiversity
All members of the species share the same genes. However, they may have different versions of some of these genes (alleles).
Species that contain greater genetic biodiversity are likely to be able to adapt to changes in their environment, and hence are less likely to become extinct. This is because there is likely to be some organisms within the species that carry an advantageous allele, which enable them to survive in the altered conditions
What are some factors that can affect genetic biodiversity (increase in genetic biodiversity)
- mutations in the DNA of an organism, creating a new allele
- interbreeding between different populations. (gene flow)
What is meant by gene flow
when an individual migrates from one population and breeds with a member of another population, alleles are transferred between the 2 populations.
What are some factors that could decrease genetic biodiversity
- selective breeding
- captive breeding
- artificial cloning
- natural selection
- genetic bottle necks
- genetic drift
- the founder effect
How can selective breeding decrease genetic biodiversity
Only a few individuals within a population are selected for their advantageous characteristics and bred. For example the breeding of pedigree animals or of human food crops
How can captive breeding decrease genetic biodiversity
Captive breeding programmes in zoos and conservation centres, where only a small number of captive individuals of a species are available for breeding. Often wild populations is endangered or extinct
How can rare breeds decrease genetic biodiversity
- if the population of an organism drops then alleles may be lost from organisms, resulting in reduced biodiveristy
How can natural selection decrease genetic biodiveristy
Species will evolve to contain primarily the alleles which code for advantageous characteristics. Overtime, alleles coding for less advantageous characteristics will be lost from a population, or only remain in a few individuals
How can genetic bottle necks cause a decrease in genetic biodiveristy
This is where only a few individuals within a population survive an event or change, thus reducing the ‘gene pool’. Only the alleles of the surviving members of the population are available to be passed on to offspring
How can the founder effect cause a decrease in genetic biodiversity
This is where a small number of individuals create a new colony, geographically isolated from the original. The gene pool for this new population is small
How can genetic drift cause a decrease in genetic biodiveristy
due to the random nature of alleles being passed on from parent to their offspring, the frequency of occurrence of an allele will vary. In some cases, the existence of a particular allele can disappear from a population altogether. Genetic drift is more pronounced in populations with a low genetic biodiversity
What are polymorphic genes
Genes that have more than one allele
What are monomorphic genes
Genes with only 1 allele
What is a way we can quantify genetic biodiversity
by measuring polymorphism
Are there more poly or mono morphic genes and why would this be
Most genes are not polymorphic. This ensures that the basic structure of individuals within a species remains consistent
what formula is used to measure the proportion of polymorphic genes loci
