Topic 4.1 Flashcards
Biodiversity
Variety of living organisms in an area
Species diversity
Number of different species (species richness) and the abundance of each species in an area (species abundance)
Genetic diversity
Variation of alleles within a species
Endemism
When a species is unique to a single place (isn’t naturally found anywhere else in the world)
-> endemic species are very vulnerable to extinction due to their limited range
Variety of life
Natural selection leading to adaptation and evolution has increased biodiversity on earth over time, but human activities are reducing species diversity
-> some of these human activities include:
. Hunting
. Deforestation
. Climate change
. Agriculture
. Overexploitation
Hábitat
Place where an organisms live
-> it is important to measure species adversity in order to compare different habitats or to study how a habitat has changed over time
Measuring species diversity: 2 ways
- Calculate species richness -> count number of different species in an area
- Calculate species abundance -> count number of different species and the number of individuals in each species and then use index of diversity (D)
Sampling
- Choose area to sample randomly -> makes results more reliable (less bias)
- Count number of individuals of each species in sample area
. For plants: use a quadrant
. For flying insects: use a sweep net
. For ground insects: use a pitfall trap
. For aquatic animals: use a net - Repeat the process as many times as possible -> makes results more representative of whole habitat
- Use results to estimate total number of individuals or total number of different species (species richness) in the habitats studied
Genetic diversity within a species:
Individuals of the same species vary because they have different alleles, so genetic diversity within a species refers to the variety of alleles in the gene pool
Genetic diversity within a species: gene pool
Complete set of alleles in a species (or population) - the greater the gene pool, the greater the genetic diversity
-> its importante to measure genetic diversity to investigate how populations of the same species show different diversity or to show how the genetic diversity of a population change over time
Measuring genetic diversity: phenotype
The larger the number of different phenotypes within a species, the greater the genetic diversity (greater variety in alleles present in species)
Measuring genetic diversity: genotype
The larger the number of different alleles present within a species, the greater the genetic diversity.
-> to look at similarities and differences of alleles within a species you can sequence DNA of individuals of the same species
Heterozygosity index
Heterozygotes are individuals that have two different alleles at a particular locus, and a higher proportion of heterozygotes in a population means that the population has a greater genetic diversity
-> this proportion of heterozygotes in the population can be found with the heterozygosity index (H)
Niche
Role of a species within its habitat -> each species will have its own niche
-> this includes:
. It’s interactions with other living organisms
. It’s interactions with the non-living environment
-> if two species try to occupy the same niche they will compete with each other, and one species will be more successful than the other until only one of the species is left
Adaptation
Features which increase the organisms chances of survival and reproduction
-> these features include
. Behavioural adaptations
. Physiological adaptations
. Anatomical adaptations
- Adaptations become more common in populations of species because of evolution by natural selctio
Organism adaptations to their niche: behavioural adaptations
Ways an organism acts that increase its chances of survival
Examples:
-> possums ‘play dead’ to avoid being detected by predators and attract prey
-> scorpions dance before mating to attract the best partner of species
Organism adaptations to their niche: physiological adaptations
Processes inside an organisms body that increase its chances of survival
Example:
-> brown bears hibernate in winter to slow down their metabolism to conserve energy as there’s less prey available
Organism adaptations to their niche: anatomical adaptations
Structural features of an organisms body that increase its chances of survival
Example:
-> whales have thick layer of blubber to keep them warm in cold water where they can catch prey
Evolution: mutations
These can introduce new alleles into a population causing individuals within a population to show their variation in their phenotypes
-> some of these alleles determine phenotypes that can make the individual more likely to survive
Evolution: selection pressure
These are changes in the environment that create struggle for survival
Evolution: competition
Individuals without advantageous allies don’t survive so there’s fewer individuals and less competition for resources
Evolution: survival and reproduction
Individuals with better adaptations are more likely to survive, reproduce and pass on their advantageous alleles to offspring
Evolution: over time
Number of individuals with advantageous alleles increase
Evolution: over generations
Evolution happens as frequency of the advantageous alleles in the population increases and the favourable adaptations become more common
Speciation
Development of new species
-> species: group of similar organisms that can reproduce to give fertile offspring
-> speciation occurs when populations of the same species become reproductively isolated due to random mutations or geographical isolation which prevent individuals from successfully breeding together
Random mutations
Random mutations can produce new alleles, new phenotypes, and so the following changes
- seasonal changes
- mechanical changes
- behavioural changes
Random mutations: seasonal changes
Individuals from the same population develop different flowering or mating seasons (become sexually active at different times of the year)
Random mutations: mechanical changes
Structural changes to the genitalia in some individuals prevent them from successfully mating with main population
Random mutations: behavioural changes
Group of individuals develop courtship rituals that aren’t attractive to main population
Geographical isolation
- Population is divided by a physical barrier
- There’s different conditions and selection pressures on either side of the barrier
- Natural selection takes place due to the different environments on either side to make advantageous characteristics more common
-> Different characteristics will be advantageous so allele frequencies will change in each population
-> Mutations will take place independently in each population changing the allele frequencies - Different allele frequencies will make the populations more genetically distinct and will lead to different phenotype frequencies arising on each side
- New species is formed eventually as they aren’t able to reproduce with one another to produce fertile
offspring
Allele frequency
How often an allele occurs in a population
-> The frequency of an allele in a population changes over time due to gene mutations and this leads to evolution
-> Hardy-Weinberg equations can be used to calculate allele frequencies and to see if a population has changed over time
Hardy-Weinberg principle
Predicts that the frequencies of alleles in a population won’t change from one generation to the next
-> this is only true under certain conditions:
. Large population
. No immigration
. No mutations
. No natural selection
. Random mating
-> if allele frequencies do change in a large population then immigration, emigration, mutations or natural selection have happened
Hardy-Weinberg equations
P + q = 1
(P: frequency of dominant allele)
(Q: frequency of recessive allele)
P^2 + 2pq + q^2 = 1
(P^2: frequency of homozygous dominant genotype)
(2pq: frequency of heterozygous genotype)
(Q^2: frequency of homozygous recessive genotype)
