using Genetic Technology
Conservation
NZ black robin - down to just 7 in the 1970s now there are over 300.
They have been saved from extinction. But have they? What are the consequences of such a small Gene Pool?
Inbreeding depression - depresses the success of the offspring by an increase in recessive alleles and a lack of diverse alleles
Lack of diversity of alleles
Reduction in the Number of alleles within the gene pool (the population that is interacting) reduces as some are not passed on due to random chance in a small population - this reduces the genetic diversity within the population - thus the population is less likely to survive any environmental change
Increased homozygous recessive - due to small population, heterozygous individuals are more likely to breed with other heterozygous individuals (their relatives) rather than homozygous dominant individuals (thus non-related) - thus more homozygous recessive individuals will be born
The black robins eggs now have very weak egg shells thus reduced survival
Are there ways to reduce inbreeding? Increase genetic diversity? And make the species Fitter?
These small populations are genetic bottlenecks caused by habitat loss by humans clearing the NZ forests for farms. As well as by introduced pests such as stoats, rats and cats
The smaller the population, the greater the risk of extinction
Sadly in New Zealand we have multiple species at risk of extinction as outlined in the article below
One way to address this is to introduce some breeding members from other populations - if there are any - this is Gene Flow - as new alleles flow into the bottlenecked population from outside populations
If no other population can be found - such as with the robins - then you need to use Gene Techniques
You can use DNA Fingerprinting to look at how related each member in the population is to each other. You can then pair up those that are the most Unrelated to each other (the most distantly related)
You can also use DNA sequencing to look for carriers of particular detrimental recessive alleles and prevent those carriers from breeding (if you can remove them from the gene pool without causing extinction) OR just stop them from breeding with each other
DNA Fingerprinting in Conservation
DNA Fingerprinting = Relatedness in a group
Microsatellites aka Short Tandem Repeats - GTAGTAGTAGTAGTAGTA
Highly repetitive - high risk of replication mistake during gamete formation during meiosis
Non-coding, so mistakes don't matter
Take blood sample
Copy a location on a chromosome (locus) using PCR till you have a few million copies.
Cut this area up into fragments with Restriction Enzymes
Run through Gel Electrophoresis
Distance fragments move based on size
Each individual will have a unique pattern of fragments in the gel
The more similar their pattern is - the more related
The more different their pattern is - the less related
Options: Breed those that are LESS related
DNA Sequencing in Conservation
DNA Sequencing = Individual and Individual Alleles
Used to find out if an individual is Homozygous Dominant or Heterozygous
In other words, to find out if an individual is carrying a particular recessive allele
Take blood sample
Use PCR to copy the are where the Gene of interest is
Include fluorescent nucleotides with all the normal nucleotides
Whenever a fluorescent nucleotide is added, this is where that fragment will end
Once several million copies are made, run through Gel Electrophoresis
The smallest pieces will travel the furthest
Now you can read the sequence based on size of fragment and the fluorescent colour of the end nucleotide
The recessive allele will have a specific sequence
If this sequence is detected, then the individual is a carrier and is thus heterozygous
If they are heterozygous you have two options
1. remove from the breeding stock - so they no longer have offspring
2. only breed them with Homozygous dominant individuals - however, their children have a 50% chance of being heterozygous
Humans
DNA Fingerprinting in Humans - Paternity
DNA Fingerprinting = Relatedness in a group
DNA fingerprinting is used as a quick way to see if the father actually is the father
This is done because some of his microsatellites would have been inherited by the child
DNA Fingerprinting in Humans - Crime
DNA Fingerprinting = Crime
Because each person has unique microsatellites / short tandem repeats the pattern that is made when these fragments are run through a gel are unique to that person, like a 'fingerprint'
In the case to the side - they used the blood samples from 5000 people to find the killer
DNA Sequencing in Humans
DNA Sequencing = Individual person and Individual Alleles
DNA sequence is to see if a person carries a specific Recessive allele
This will be done by a Genetic Counsellor who can then discuss and explain their results the consequences and their options
This is done if there is a history of a recessive disease in one of the family trees.
The person and their partner can have DNA sequencing conducted to see if they carry the recessive allele
Options
Both are homozygous dominant - can breed
One is Homozygous dominant, the other is Heterozygous - can breed
Both are Heterozygous - in this case they can:
do IVF
risk a natural conception with a 25% chance of Homozygous Recessive child
stay together and have no children
breakup and find new partners
Ethics
Genetic Information
Genetic testing is not too expensive, and some companies say it is a good idea to have it done. But is it?
There are things you may want to know, but some things you may not want to know - sometimes "ignorance is bliss"
Also, what happens if your information is sold or stolen from data centers?
