Biodiversity and natural selection Flashcards
what is biodiversity
Biodiversity is the measure of the variety of living organisms in an area.
How can biodiversity be measured
By species richness and genetic diversity
what is species richness
the number of different species in a habitat
what is genetic diversity
a measure of the genetic variation in a specific species
In other words, the number of alleles in a gene pool
what does the species diversity index measure
measures species richness and evenness.
used to compare biodiversity in different habitats
what is the formula for species diversity index
D= N(N-1) divided by En(n-1)
N- total number of organisms of all species
n-total number of organisms of each species
D- diversity index
E- the sum of
The higher the diversity index, the higher the biodiversity of that area.
what does the heterozygosity index measure
it measures genetic diversity
formula for heterozygosity index
number of heterozygotes divided by total number of individuals in the population
what are endemic species
species only found in one geographical region(e.g an island)
what is a niche
role of the species within the community
and the way an organism exploits its environment
species which share the same niche compete with each other for resources
all species in a community have different niches
the better adapted species will outcompete the other(natural selection)
3 types of adaptations of organisms to their environment
behavioural
physiological
anatomical
what are anatomical adaptations
any physical structures that helps an organism to survive or reproduce
e.g. thick layer of blubber for insulation
what are physiological adaptations
any biochemical processes which helps it to survive or reproduce
e.g. produces venom
what are behavioural adaptations
any action/behaviour by an organism which will help it survive or reproduce
what is a gene pool
the total number of different alleles in a population
a larger gene pool means there is more genetic variation within the pop
what is natural selection
better adapted organisms to their environment are more likely to survive and pass on the advantageous alleles to future generations
what is evolution
the frequency of alleles in a gene pool changes over time as a result of natural selection
5 step process of natural selection
1- a population has some naturally occurring genetic variation with new alleles created through mutations.
2-a change in the environment causes a change in the selection pressures acting on the population
3-an allele which was previously of no particular advantage now becomes favourable
4-organisms with this allele are more likely to survive and reproduce (pass on advantageous allele)to their offspring
5-their offspring are more likely to have the advantageous allele and so it’s allele frequency will increase in the population
what is the hardy-weinberg equation used for
used to estimate the frequency of alleles in a population and to monitor changes in allele frequency
formulas for hardy weinberg equation
p + q=1
p^2 + 2pq + q^2 =1
p-the frequency of the dominant allele
q-the frequency of the recessive allele
p^2-frequency of AA(homozygous dominant)
2pq-frequency of Aa(heterozygous)
q^2-frequency of aa(homozygous recessive)
what are the conditions of the hardy weinberg equation
-no mutations
-random mating
-large pop
-isolated pop
-no selection pressure(stable gene pool)
what is allopatric speciation
-when populations are geographically isolated from each other
-prevents the groups from mating with each other
-so the populations become reproductively isolated
-meaning that there will be accumulation of diff genetic info in pops, potentially forming new species
sympatric speciation
when 2 pop become reproductively isolated in the same environment without any geographic barrier
what will geographic isolation lead to(a type of allopatric speciation)
no gene flow between 2 groups/ causes change in allele frequencies/leads to reproductive isolation and eventually speciation
list 5 types of sympatric speciation
-temporal isolation
-behavioural isolation
-mechanical isolation
-ecological isolation
-hybrid inviability
what are drosophila
they are a type of fruit fly and are invertebrates(so no ethical guideline needed)
