Module 7: Populations, Evolution, Inheritance Flashcards
species definition
group of organisms with similar characteristics that can interbreed to produce living fertile offspring
population definition
all of the individuals of a particular species in a particular place
community definition
all the population of different species in a particular place
habitat definition
the place where an organism lives
ecosystem definition
a mix of different communities and habitats and how they interact based on biotic and abiotic factors
ecological niche definition
organisms role/position in an ecosystem
in terms of its biotic and abiotic factors
why can two species not occupy the same niche
interspecific competition will take place for the limiting factors/resources (abiotic and biotic), better adapted species will outcompete the less adapted at the expense of the less adapted species.
competitive exclusion principle
how to sample a plant species over a large area
obtain a map of the area
divide the map into grids
select a large number of coordinates using a running mean
select a random set of coordinates using a random number generator
place a quadrat in each coordinate
measure abundance of the plant species in each quadrat and calculate frequency or percentage cover
calculate an average for the whole area
how to samples plant species along a path
use a transect
place tape along the path, count the number of plants touching the tape (line transect)
place tape along the path, at regular intervals along the tape place a quadrat and measure the abundance within the quadrat (belt transect)
how to sample animals species in an area
mark release recapture collect a sample of animals mark them using non-toxic marker release them after sufficient time for them to re-mix with the population recapture count the number in the second set and count the number of species that are marked number in sample 1 x number in sample 2 all divided by marked in sample 2
assumptions of mark release recapture
no births or deaths no immigration ort emmigration marked animals mix evenly with population mark is non-toxic mark doesn't come off large population
3 stages of population growth
slow/lag phase
rapid/log phase
stationary phase
lag phase
species becomes adapted to new environment
rapid phase
species are adapted
abundant resources
doubling with reproduction
birth rate > death rate
stationary phase
resources become limited
intraspecific competition
birth rate= death rate
abiotic definition
non-living factors
light, temperature, water, O2/CO2, minerals, pH, living space
biotic definition
living factors
predator, prey, mates, competition, disease
competition definition
where organisms compete for resources, both biotic and abiotic
2 types of competition
intraspecific
interspecific
intraspecific definition
occurs between organisms of the same species, only occurs when resources become limited, leads to natural selection and adaptation
interspecific definition
occurs between organisms of different species, can happen at any time even if resources aren’t limited
leads to formation of climax communities
predator prey relationships
prey increases more food for predator predator increases predators eat more of prey prey decreases less food for predator predator decreases less prey eaten prey increases in number
succession definition
how an ecosystem changes over time, change in species diversity and habitat diversity
what does succession rely on
the environment being made less hostile by present species via death and decomposition leading it to being outcompeted and replaced by larger better adapted species
2 types of succession
primary
secondary
primary succession definition
occurs on new land
secondary succession definition
occurs on previously colonised land that has become bare e.g. after a fire
process of primary succession
pioneer species colonies an inhospitable environment
the pioneer species improves a named condition because they are (list a feature)
over time the land erodes and soil will form, pioneer species are outcompeted by primary coloniser
primary coloniser will continue to improve named conditions
secondary coloniser will outcompete primary coloniser
climax community is reached
properties of succession
species diversity increases (peaks just before climax)
habitat diversity increases
environment becomes less hostile
food chains become more complex and biomass increases
primary succession vs secondary succession
secondary starts from small plants not pioneer species
so soil and nutrients are already present
secondary is faster
how can conservation prevent succession
used to prevent formation of woody forests
involves deforestation, burning trees, grazing and using pesticides
biodiversity definition
range and variety of genes, species and habitats within a particular region
species diversity definition
number of different species and the number of individuals of each species within a community
genetic diversity definition
variety of genes and allele frequency possessed by individuals that make up one species
ecosystem diversity
range of different habitats within a particular area
preservation definition
maintaining individuals, populationd and ecosystems in their current state without the exploitation of their natural resources
conservation definition
allowing ecosystems to evolve naturally without resources being overused
how to conserve an area
active human management
in situ
ex situ
in situ
whole ecosystems and landscapes
within habitat
monitoring succession
ex situ
outside natural habitat
individual endangered species in zoos
which stage of succession do you manage
mid succession
not dominated by one species
not very hostile
can support multiple species/habitats/food sources as there is a higher biodiversity
evolution definition
change in allele frequency in a population
2 types of evolution
adaptation and speciation
adaptation definition
species adapting to changes in its environment, driven by natural selection, where most of the individuals in the species will have the favourable allele/characteristic for that environment
process of adaptation
variation in species population
new allele arises due to random mutation
environment applies a selection pressure on the population
those with favourable characteristics/alleles survive at the expense of those less well adapted
ones that survive will reproduce to pass on their favourable alleles
if this happens for many generations then that characteristic will become most common
favourable allele becomes more frequent
3 types of selection
stabilising
directional
disruptive
stabilising selection
when environment favours individuals with the most common characteristic
at the expense of the extremes (favoured against)
most common will increase in proportion
range (standard deviation) will decrease
e.g. birth weight
directional selection
when the environment favours one of the extremes causes curve to shift to the right mean favoured against overtime this will become most common e.g. antibiotic resistance
disruptive selection
when the environment changes between both extreme conditions
individuals on both extremes are favoured at different times and increase in number
the middle/average will decrease in number
e.g. fur length
Speciation definition
Process by which new species arise from existing species
2 types of speciation
Allopatric
Sympatric
Allopatric speciation
Speciation driven by geographical isolation
Describe allopatric speciation
Start with a population of species
variation in population
Population separated into different groups by geographical isolation
Each group exposed to different enironments/selection pressures
Each group undergoes different directional selections
Each group changes so much in genetic diversity that they can’t interbreed with each other to produce living fertile offspring= different species
Changes include different courtship behaviours or incompatible gametes
Sympatric speciation
Speciation occuring in the same geographical area driven by random mutation
Inheritance definition
Offspring inheriting a combination of alleles ( paternal and maternal) for each gene which will help determine characteristics
gene definition
Section of DNA that codes for a protein
Allele definition
Version of a gene
Dominant allele definition
Allele that is always expressed if present
Recessive allele definition
Allele that is only expressed if 2 are present
Genotype definition
Genetic makeup of an organism, combination of alleles for a particular gene
Phenotype definition
Expressed/observed characteristic
Continuous then determined by genotype and environment
Discontinuous then only genotype
Homozygous definition
Having 2 of the same alleles
Heterozygous definition
Having 2 different alleles
Monohybrid inheritance
Inheritance dealing with one characteristic
Examples of monohybrid inheritance
Dominant/recessive
Codominant
Multiple allele
Sex linkage
Expected ratio monohybrid dominant/recessive
3:1 dominant to recessive
Why are observed ratios different from expected ratios
Random fertilisation of gametes
Small sample size
Mutation
Selection
How can 2 parents with dominant characteristic have offspring with recessive characteristic
If both are heterozygotes
25% chance of homozygous recessive
What is co-dominance
When 2 different dominant alleles are inherited both will be expressed in the phenotype
What are multiple alleles
Gene has more than 2 alleles
Blood group
Alleles for blood group
I^A, I^B, I^O I^A gives A antigen I^B gives B antigen I^O gives no antigen I^A and I^B are codominant I^O is recessive
Genotypes/phenotypes for blood group A
I^A I^A
I^A I^O
4 blood groups
A
B
AB
O
Genotype/phenotype for group B
I^B I^B
I^B I^O
Genotypes/phenotypes for group AB
I^A I^B
Genotype/phenotype for blood group O
I^O I^O
Who can receive blood from whom
A from A and O
B from B and O
AB from A, B, AB and O
O only from O
What is dihybrid inheritance
Inheritance with two characteristics
Examples of dihybrid inheritance
Dominant/recessive
Autosomal linkage
Epistasis
Expected ratio dihybrid dominant/recessive
9 DD
3 DR
3 RD
1 RR
What does hardy weinberg principle calculate
Frequency of allele in a population
What does HWP assume
That frequency wont change over time based on: Isolated population Large population Random mating No mutation No selection
HWP
p= frequency of dominant allele q= frequency of recessive allele p+q= 1, all population p^2 homo dominant 2pq hetero q^2 homo recessive p^2 +2pq dominant p^2 + 2pq + q^2= 1
