biodiversity Flashcards
biodiversity definition
the variation that exists within and between all forms of life
why is biodiversity important
it helps the resilience of ecosystems as it allows organisms to resist + cope with changes in their environment
3 main types of biodiversity
habitat diversity
species diversity
genetic diversity
habitat diversity definition
the number and range of different ecosystems and habitats
how dies habitat diversity contribute to biodiversity
if there is a large range of different habitats within an area, that area is more likely to have a high biodiversity
e.g. a coral reef = very complex with many microhabitats
vs the desert = similar conditions throughout area
species diversity definition
the number of species in an area and their relative abundance
what 2 factors make up species diversity
species richness and species evenness
species richness definition
the total number of species in 1 ecosystem
species evenness definition
the evenness of abundance of each species in an ecosystem
how does species diversity contribute to biodiversity
high species richness + high species evenness = high species diversity = higher biodiversity
how does species diversity relate to the stability of an ecosystem
ecosystems with high species diversity tend to be more stable as they are more resilient to changes in their environment
genetic diversity definition
the genetic variation within a species
gene pool definition
all the alleles for all genes in a species
how does genetic diversity relate to the stability of an ecosystem
- some genes within a species have different alleles
- this leads to genetic diversity within a species
- this allows for better adaptation to environmental changes + selection pressures
give 2 biotic selection pressures
- new predators
- pathogens / disease
give 3 abiotic selecton pressures
- changing temperatures
- changing rainfall
- changing humidity
loci definition
the specific position of a particular gene on a certain chromosome
what are the some causes + consequences of low genetic diversity
low genetic diversity may occur in small isolated populations or as a result of inbreeding
it can cause a high proportion of homozygous individuals which reduces genetic diversity
it also means genetic diseases caused by recessive alleles become more common
give 3 ways to measure genetic diversity
- measuring the proportion of polymorphic gene loci
- measuring the proportion of the population that is heterozygous for any specific gene locus
- measuring allele richness
polymorphic loci definition
a loci/genes with 2 or more alleles
how can genetic diversity be assessed
through examining phenotypes - for some genes, the expression of different alleles produces observable differences
or through examining DNA sequences / proteins of alleles
give the formula for calculating the proportion of polymorphic gene loci
P = proportion of polymorphic gene loci =
(no. polymorphic gene loci) / (total no. gene loci examined)
give 1 limitation of using the formula for calculating the proportion of polymorphic gene loci to calculate genetic diversity
- it doesn’t illustrate the alle richness of a species as the no. of alleles for each gene locus are not the same
outline the 2 other ways genetic diversity could be assessed
- comparing the amino acid sequences of proteins / alloenzymes, and how they may function differently
- comparing DNA sequences, as genetic code is degenerate, this is more effective than comparing amino acid sequences, as the sequence could be the same but the base sequence could be different
alloenzyme definition
slightly different forms of the same protein, coded for by different alleles
give 1 method of measuring levels of biodiversity + a limitation of this method
identifying + cataloguing all organisms in an ecosystem, this allows a species list to be built, showing the species living in an ecosystem and their population sizes
- this may only be possible where species are very large or where the area is very small, in large complex ecosystems e.g. rainforest this isn’t feasible
give 1 method of measuring biodiversity that is more applicable to larger or more complex ecosystsems
sampling - taking different samples of the area + using them to estimate the total number of species
what is the simpsons index + the formula
a formula used for measuring species diversity as it takes into account both species evenness and species richness
D = 1 - (Σ(n/N)^2)
D = simpsons index
n = total number individuals for 1 species
N = total number individuals for all species
what does the D (simpsons index) value tell you
D can fall between 1 and 0
near 0 = low biodiversity
near 1 = high biodiversity
sampling definition
a method of investigating abundance + distribution of species populations
what are the 2 types of sampling
random
non random