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ZZZ AS level: Biology > Genetic Diversity > Flashcards

Flashcards in Genetic Diversity Deck (22)
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1
Q

What is genetic diversity?

A

total number of different alleles in a population

2
Q

what is a population?

A

a group of individuals that occupy the same place and can interbreed

3
Q

what is allele frequency?

A

how often a particular allele occurs within a population

4
Q

what is a gene pool?

A

total number of alleles of a particular population (at a specific time)

5
Q

what is the advantage of genetic diversity?

A

the greater the diversity, the greater the number of different alleles that all species possess

  • Therefore they are more likely to survive and adapt to environmental change
  • they have a wider range of alleles - wider range of characteristivcs
  • higher probability that an individual posesses desriable characteristic for new conditions
6
Q

name five factors that increase genetic diversity

A
  • random mutation
  • genetic recombination
  • independent assortment
  • immigration
  • outbreeding
7
Q

name six factors that decrease genetic diversity

A
  • inbreeding
  • reduced gene pool
  • small population
  • selective breeding
  • genetic bottleneck
  • founder effect
8
Q

what is selective breeding?

A
  • humans artificially choosing desirable characteristics and using them as breeding stock
9
Q

what is the consequence of selective breeding?

A
  • reduced variety of alleles at desired number
  • reduced genetic diversity
  • unable to adapt to sudden environmental change
10
Q

how does natural selection work?

A
  • random mutation causes genetic variation
  • mutation can either be harmful or beneficial
  • individiual with advantageous characteristivs would survive an environmental selection pressure
  • survive and reproduce
  • pass on beneficial allele to offspring
  • over many generations, the frequency of the advantageous allele increases and becomes more common
11
Q

what are genetic bottlenecks?

A
  • original population contains many different alleles
  • sudden population reduction due to natural disaster for example
  • only one group has allele which benefits their survival and only they live
  • this group reproduces and a population is created of individuals with reduced genetic diversity, since there are fewer different alleles
12
Q

what are the problems with bottlenecks?

A
  • less variation - as alleles are lost from gene pool
  • not representative of original population
  • some alleles are overrepresented among population so some may be eliminated completely
13
Q

give an example of a genetic bottleneck

A
  • northern elephant seal
  • over hunting in late 1800s reduced population
  • surviving seals repopulated - new population has reduced genetic diversity
14
Q

name a type of genetic bottleneck

A

founder effect

15
Q

what is the founder effect?

A
  • few individuals from a population form a new colony in a new habitat
  • since there is a small number of individuals, there is a small number of different alleles in the gene pool
  • allele frequency of the new colony is different to allele frequency of original population
  • new colony more susceptible to genetic disorder due to lack of new alleles introduced into the population
16
Q

name an example of a human population who have suffered from founder effect

A

old order amish population

- colonists escaped persecution to settle in pennsylvania

17
Q

what is selection?

A

processs by which organisms that are better adapted to environment survive and breed

18
Q

name three ways in which an organism may be better suited to the environment

A
  • anatomical
  • physiological
  • physical
19
Q

what are polygenes?

A

characteristics that are influenced by more than one gene`

20
Q

what are three types of selection

A
  • directional
  • stabilizing
  • (disruptive)
21
Q

what is directional selection?

A

population mean favours one extreme

22
Q

what is stabilizing selection?

A

population mean moves towards average