Biodiversity Flashcards
What is biodiversity
The variety of living organisms that we find in a region is called the biodiversity
rich biodiversity - rainforest
relatively low biodiversity - arctic
species richness
Species richness is a measure of the number of different species in
a community.
What is habitat, genetic species diversity
The degree of biodiversity can be assessed at 3 levels
Habitat (ecosystem) biodiversity, species and genetic
Habitat biodiversity - refers to all of the different habitats that we find in an area e.g. woodlands, meadows, sand dunes and streams
Rich habitat diversity - lots of different habitats /contain a greater range of species
Species biodiversity tells us about the species living in a certain area. This has 2 parts
The species richness counts the number of different species present
Population sizes
The species evenness compared how many individuals of each species there are in a community
Areas can have a greater species evenness - if population of species are more balanced
Genetic biodiversity considers the variety of genes and alleles within a species
This depends on the different species and alleles present
Alleles present in difffeent genes leads to different phenotypes
Important for survival of species
Species with a greater level of genetic biodiversity can better adapt to environmental change
What is a community
The populations of living organisms in a habitat
Genetic biodiversity - gene pool
Describe the factors that can increase and decrease genetic biodiversity
In any population of organisms there are only 2 ways genetic biodiversity can increase
A random mutations can take place, creating new alleles
Secondly, migration between populations can transfer alleles
If an organism migrated into an existing population
This individual may have different alleles
When interbreeding takes place, these alleles can now enter the population’s gene pool
This process is called gene flow
It can decrease
As a result of natural selection, individuals with advantageous alleles are more likely to survive and reproduce than individuals with less advantageous alleles
Over time, the less advantageous alleles become less common in the population
So natural selection can reduce genetic biodiversity
Selective breeding/artificial selection
Humans select individuals in a population for breeding
That is because those individuals have alleles which are seen as advantageous
Individuals without the desired alleles are not allowed to breed, so over time, these alleles disappear from the population
Hunting can reduce the genetic biodiversity of a wild species
Cloning plants (cuttings of plants)
Genetic bottleneck - when the gene pool is severely reduced
Founder effect - a small number of individuals move, forming an isolated population with limited genetic biodiversity
Genetic biodiversity can change due to random chance - genetic drift
E.g. some individuals within a population may not reproduce
If these individuals are the only ones with a certain allele, then that allele will be lost
This is most likely to happen when a population is small and has low genetic diversity e.g. after a genetic bottleneck has taken place
describe random and non-random sampling
in random sampling - the areas that we take samples from are selected by using random numbers
these random numbers can determine the coordinates on a map
because the area is not chosen by a human, random sampling reduces the chance of sampling bias
if a human chose the area - it may not be typical of the whole habitat
This would reduce the reliability of the sample
3 type - non-random
opportunistic sampling
stratified sampling
systematic
Genetic diversity within, or between species, can be made by
comparing:
Genetic diversity within, or between species, can be made by
comparing:
* the frequency of measurable or observable characteristics
* the base sequence of DNA
* the base sequence of mRNA
* the amino acid sequence of the proteins encoded by DNA
and mRNA.
An index of diversity
An index of diversity describes the relationship between the
number of species in a community and the number of individuals in
each species.
index of diversity equation
d =N (N − 1)/Σn (n − 1)
where N = total number of organisms of all species
and n = total number of organisms of each species.
