Genetics Flashcards
What are the 6 ways genetic tools can help environmental biology
Resolving taxonomic uncertainty to identify species (turtles)
Rescue populations from inbreeding
Manage captive breeding individuals
The role of sex in ecology or captive breeding
Identify pathogens
Forensics can be used to solve wildlife crimes
What are the principles of genetic tools?
- Use a site/locus on the genome that differs at the level you need to understand/ identify (level of polymorphism)
- Generate suffcient DNA at that site/locus
- Sequence the DNA at the site of interest
What is a marker loci?
A ‘gene’ sequence located at the sequence-specific site in a genome. Can be coding or non-coding DNA
Whats the difference between coding and non-coding DNA
Coding DNA is less variable: useful for comparing between species (e.g mitochondrial enzyme genes like cyctochrome b
Non-coding DNA is highly variable : useful for comparing between populations or individuals as it allows for hidden mutations (e.g microsatellites showing high variation between individuals)
What are the 5 core ‘ingredients’ required to set up a PCR.
The DNA template that needs to be copied
DNA nucleotides to produce the new chains
Primers to bind to each end of the DNA that needs to be copied
Taq polymerase to add on the new bases
A buffer to ensure the conditions remain optimal
Describe a PCR
DNA is denatured at 94 Celsius and the strands separate.
Temp. lowered to 54 celsius to allow synthetic primers to anneal
Temp raised back up to optimal temp 72 for taq to allow extension and DNA reforms at the locus of interest
What is phyletic speciation
It is the process of gradual change in a single population.
What is divergent speciation
the divergence of one species into two or more descendant species
What is extinction
The end of an evolutionary lineage (population, Species, Genus, Family)
If extinction rates are currently exceeding speciation rates , what is the result?
Loss of biodiversity
How are individual and population phenotypes struggling?
REDUCED POPULATION SIZES
CONSTRAINED POPULATION MOBILITY
INCREASED ENVIRONMENTAL STRESS
What does phenotypic expression depend on?
dominance and heterozygosity within the alleles
Why is genetic diversity good? 2 reasons
Genetic variation / heterozygosity allows adaptability to environmental stress / change = evolutionary potential
prevents expression of deleterious homozygous recessive genes which prevents inbreeding depression
How is genetic variability maintained
Through recombination and sexual reproduction
What are the consequences of a highly inbred population
reduced heterozygosity /increased probabability of parents sharinf identical alleles
Why is reduced heterozygosity bad
It increases the chance of parents sharing common alleles which will increase the expression of genes in their homozygous form
Why are homozygous genes bad
Homozygous genes persisit in the genome with low expressions so they are rarely selected against so tend to code of sub=perfect phenotypic traits
Examples of deleterious homozygosity
Cystic fibrosis
sickle cell anaemia
red green coour blind
What is fitness`
is a measure of survival and reproductive success in the natural environment
What are the consequences of inbreeding
is a measure of survival and reproductive success in the natural environment
= Inbreeding depression of fitness
How does inbreeding depression manifest?
Infertility Abnormal sperm Reduced clutch size/hatching success Embryonic mortality Offspring survival Disease susceptibility General survival under extreme selection Local extinction
Example of inbreeding not reducing fitness
Current population of black robins descended from 1 breeding female with a bottlenecked population of 5 birds. The descendants show no minisatellite DNA variation but overall their survival rate is normal
What is heterosis
improved or increased function of any biological quality in a hybrid offspring.
What is outbreeding depression
When very genetically different organisms breed. Can occur when local adaptations are disrupted within a species, or when newly-formed species are hybridised
Example of inbreeding depression
Deer mice Jimenez et al. 1994
captured in wild, then inbred or not in lab
n=367 inbred and n=419 non-inbred released
inbred survived at rate only equal to 56% of non-inbred
inbred lost weight after release, non-inbred maintained weight
How can outbreeding depression manifest
Intermediate genotypes are not adapted to either parental habitat.
Breakdown of biochemical or physiological compatibility.
How can molecular makers help in conservation policy
mitochondrial DNA analyses was used to determine the species status for the Kemp Ridley sea turtle and the olive Ridley sea turtle. Scientists were unsure of their relatedness, but analyses showed that their mtDNA was distinct enough to be considered for separate protection under the US Endangered species act
What is introgession?
It is the movement of a gene (gene flow) from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species
Example of how genetic tools can help with the issue of introgression
Enzyme and mitochondrial data indicated that the cut throat salmon was hybridising with non native salmon which is contributing to their population decline and native populations become isolated from each other. Introgessed populations were removed by conservation efforts to encourage native individuals to breed with each other
Limitations to genetic monitoring
added expense, particularly with non-invasive samples, owing to the need to repeat genetic analyses to reduce genotyping errors
genotyping errors, if not adequately controlled, impede accurate estimates of many metrics e.g multifold overestimates in abundance
genetic monitoring efforts that rely on non-invasive samples are more vulnerable than are traditional monitoring to fraud
What is genetic monitoring
he use of molecular markers to (i) identify individuals, species or populations, or (ii) to quantify changes in population genetic metrics (such as effective population size, genetic diversity and population size) over time.
example of genetic monitoring used fraudulently
Controversy over a lynx survey done in the U.S. rub pads were used to to collect lynx fur and sent to a lab for DNA analysis. There is some evidence to say that some of the presented data came from captive lynxes and not wild ones. It is easier to plant a spurious genetic sample than a live individual Dalton 2002
Example of using molecular markers to define population viability
Mircosatellites were used to measure genetic diversity after a significant bottleneck in koalas
Limitations to RAPD markers
the least informative of all known DNA markers; rarely detect heterozygosity
Very sensitive to reaction conditions so results are often laboratory dependent cus enxyme reaction
Amplification products are not always reproduce-able
Co migration can occur
What is RAPD
RAPD is a modification of the PCR in which a single, short and arbitrary oligonucleotide primer, able to anneal and prime at multiple locations throughout the genome, can produce a spectrum of amplification products that are characteristics of the template DNA
What can RAPD be used for
gene mapping, population genetics, molecular
evolutionary genetics, and plant and animal breeding
Example of saving an inbred population
An isolated population of adders in Sweden nearly went extinct due to inbreeding depression; a high proportion of offspring were stillborn or deformed. 20 males were introduced into the area for 4 mating seasons before being returned. In the following years the adder population grew rapidly and DNA analysis showed increased genetic variability
What does RAPD stand for
Random amplified polymorphic DNA
