Genetic diversity, selection and adaption Flashcards
What is genetic diversity?
the total number of different alleles in a population
Why is a greater genetic diversity a positive thing?
the greater the genetic diversity, the more likely that some individuals in a population will survive an environmental change
Natural selection can’t happen without…
genetic diversity
How can we measure genetic diversity?
-the frequency of measurable/observable characteristics
-the base sequence of DNA or RNA
-the amino acid sequence of proteins
What is the gene pool?
the total information from all the genes and alleles of the breeding individuals in a population at a particular time
Describe and explain the 3 conditions for evolution
variation- must be differences between the individuals in a population
heredity- the differences between the individuals must be heritable
means of selection- there must be a pressure that selects some variables for the next generation at the expense of others
What is the template to use for every question about natural selection?
-variation in (characteristic) due to a random mutation in a gene
-those with (characteristic) will (benefit of characteristic) so won’t be harmed by the (selective pressure)
-those with the advantageous allele for (characteristic) will survive and reproduce and have increased reproductive success
-more offspring will inherit the beneficial allele of (characteristic)
-there is an increased frequency of the beneficial allele in future generations
What does selection do?
causes some traits to survive and spread, while losing others
What does selective pressure do?
determines which traits of an organism are successful
What is stabilising selection, with an example?
-where individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
-it occurs when the environment is stable and reduces the range of possible characteristics
-tends to eliminate the phenotypes at the extremes
-mean/mode/median are unaltered
-range/standard deviation are reduced
AN EXAMPLE IS HUMAN BABY WEIGHT
What is standard deviation?
the variation of data around the mean
What is directional selection, and an example?
selection pressure towards one extreme phenotype, moves the mode to the direction of this phenotype.
AN EXAMPLE IS ANTIBIOTIC RESISTANT BACTERIA
What are the two types of variation?
continuous and discontinuous
What is continuous variation?
things you can measure, like height/weight
What is discontinuous variation?
things you don’t measure, but you count, and only have a fixed number of options for like eye colour/blood group
