Molecular ecology.1 Flashcards
What do molecular genetic markers allow us to do?
To look at differences in species’ DNA which is not clearly shown by their phenotype
Name a few examples of phenotypic variations within a population
eye colour and skin colour
How has genetic variation lead to adaptation?
through a process of having a genetic variation being segregated, the force of natural selection has lead to selecting among the variants in populations to make them better adapted to their environment
What is the short term importance of genetics?
avoiding inbreeding, fitness decrease affecting population survival
What is the long term importance of genetics?
adaptation to changing conditions affecting species survival
What is fst/fixation index?
A measure of population differentiation due to genetic structures estimated from genetic polymorphism
What does it mean when the fst equals 0?
the populations are very similar, no genetic variation from within compared to between
What does effective population (Ne) represent?
the average number of individuals in a population which are assumed to contribute genes to the next population
What factors decrease effective population (Ne)?
- uneven sex, different numbers of males and females,
- variance in family size
- fluctuating population sizes
- barriers to gene flow
What is inbreeding?
breeding among relatives
What is the relationship between inbreeding and Ne?
inbreeding tends to decrease Ne because of less genetic variation within the population ratios
What are the 4 main factors effecting genetic variation?
- selection
- gene flow
- mutation
- genetic drift
Define gene flow?
the exchange of genes between populations
Is gene flow migration?
No because it must involve the exchange of genes
Define genetic drift
the change in allele frequency from one generation to the next caused by random sampling of alleles
How does genetic drift change a population?
it changes the genetic structure of that population but no change in genetic diversity
What is natural selection?
non- random differential survival due to heritable differences among organisms in their ability to survive and reproduce in the environment
change in allele frequencies over time
Describe Darwin’s theory on natural selection
- advantageous mutations
- natural selection acts to preserve and accumulate minor advantageous genetic mutations
Describe the Kimura-neutral theory on natural selection
all mutations are neutral therefore genetic drift plays a major role
new alleles may become more common within new population
they may decline and disappear or become fixed
Describe the Ohta-Nearly Neutral theory
most mutations are neutral and teh advantageous mutations are rare
the deletiourous mutations are purged out of the population by selection
What are mutations?
mistakes in replication of our genes and the transmission into the following generation
What is the significance of mutations?
if mutations are occurring, its continuously giving new variants in the populations
Name two factors that decrease genetic variation
natural selection and genetic drift
Name two factors which increase genetic variation
gene flow and mutation
What are allozymes
Variant forms of an enzyme specified by an allelic gene.
What are restriction enzymes?
An enzyme that can recognize specific nucleotide sequences in DNA then cuts the DNA at a specific (restriction) site
What are single-nucleotide polymorphisms? (SNPs)
most simple form and most common source of genetic polymorphism in the genome
- A singe base in the DNA differs from the usual base at that position
What does it mean when FST =1?
no gene flow between the population
What does it mean when FST =0?
no sub division between these populations, they are acting the same
What is transcriptome?
the full range of functional RNAs or genes expressed by an organism
What are metabolites?
- small molecular weight organic and inorganic biochemicals
- the building blocks for larger biochemical proteins, RNA, DNA
