Unit 2- Evolution Flashcards
Define evolution
Evolution is the change over time in the proportion by differing in one or more inherited traits
Where does variation come from
Variation comes from a result of a mutation
What is genetic drift
Genetic drift occurs when trance events cause unpredictable fluctuations in an allele frequency from one generation to the next
What can cause genetic drift
Disease
Abiotic factors
Isolation
Natural disasters
It’s genetic drift random or a nonrandom process
Random
What is the founder affect
Do you found affect occurs when a few members of a population or isolated from a larger population
What is a population bottleneck
When a population is reduced for at least one generation
Does genetic drift have a great effect on smaller or larger populations
Smaller
Explain the key stages in the process of natural selection
- too many offspring for the environment to sustain them all
-  individuals struggle for survival until reproductive age
- Better adapted individuals survive reproduce and pass on favourable alleles to offspring
- Less adapted die and do not pass on alleles
Define sexual selection
Sexual selection is a nonrandom process in the increase of the frequency of alleles that make mating more likely
What is the difference between intersexual an intra sexual selection
Intersexual selection is between individuals of different sexes
Intersexual selection is within the same sex
What is the difference between natural and sexual selection
Sexual selection only selects for alleles to give increased reproductive chances these may have a negative impact on survival
List of the assumptions of the hardy Weinberg equilibrium
No selection No mutation No migration Large population Random mating
Define fitness
But this is an indication of an individual’s ability to survive
Explain the difference between absolute and relative fitness
Relative fitness is the ratio of surviving offspring of one genotype compared with other genotypes
Absolute fitness is the ratio of frequencies in a particular gene of types before and after selection
What is the value for absolute fitness that would represent a stable genotype
One
What is the value for absolute fitness that would represent a decreasing genotype
Less than one
What is the value for absolute fitness that would represent an increasing genotype
Greater than one
What is a selection pressure
A selection pressure is an instrumental factor that influences which individuals pass on their alleles
List for biotics selection pressures
Disease
Predation
Paratism
Competition 
List for abiotic selection pressures
PH Light Salinity Humidity Temperature
Define co-evolution
Co evolution is the frequency seen in pairs of species that have Symbiotic interactions
List the stages of the process of co evolution
- Individuals of the species A may have a trait that is an advantage and there is interactions with species B
- Proportion of individuals in species A with beneficial to rate increases
- Some individuals of the species B have a trait that now give them an advantage
- Proportion of individuals in species B which have the beneficial trait increases
What does the red Queen hypothesis state
That in a co evolutionary relationship change in the traits of one species can act as a selection pressure on other species
What is symbiosis
A co-evolved intimate relationship between members of two different species
Describe three Sim biotic relationship is and there affect on each other
Mutualism is when both organisms benefit
Commensalism is when one benefits and one remains neutral
Paratism is when one organism benefits while the other is harmed
