2.2 Evolution Flashcards
What is Evolution?
Evolution is the change over time in the proportion of individuals in a population differing in one or more trait
What are selection pressures?
These are environmental conditions that can influence which individuals in a population can pass on their alleles
What happens when there are strong selection pressures?
The rate of evolution can be rapid
What are examples of biotic selection pressures?
Competition, predication, disease and parasitism
What are examples of abiotic selection pressures?
Changes in temperate, light, humidity, pH and solidity
What is an example of Random Evolution?
Genetic drift
What are examples of Non-Random evolution?
Natural selection and sexual selection
What is Natural Selection
This acts on the genetic variation within populations. This non-random process increases the frequency of alleles that improve the survival chance of an organism and decreases the frequency of deleterious alleles
What causes variation?
Mutations
What is a Selective advantage?
When an organism has an advantage on selective pressures based on the traits they have
What is Sexual selection?
It is a form of natural selection, where the increase in allele frequency is determined through the selection of mating partners
What is Male-male rivalry?
Large size or weaponry increased access to females through conflict
What is female choice?
Female choice involves females assessing the fitness of males
What is genetic drift?
This leads to variation in the relative frequency of different genotypes in a population, when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
What is a population bottleneck?
An event that drastically reduces the size of a population for at least one generation which can be caused by environmental disaster, overhunting or habitat destruction
What does population bottleneck cause?
Reduced genetic diversity and it reduces the gene pool
What is the founder effect?
This occurs through the isolation of a few members of a population from a larger population. The gene pool of the new population is not representative of that in the original gene pool
What is the Hardy Weinberg principle?
This states that in the absence of evolutionary influences, allele and genotype frequencies in a population will remain constant over the generations
What are 5 conditions for maintaining the HW principle?
-No section
-No mutation
-No migration
-Large population
-Random mating
Define the term fitness?
The measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species. Fitness can be defined in absolute or relative terms
What is Absolute fitness?
The ratio of frequency of a particular genotype from one generation to the next
What is the equation for Absolute fitness?
Frequency of a particular genotype after selection / Frequency of a particular genotype before selection
What is Relative fitness?
The ratio of surviving offspring of one genotype compared with other genotypes
How do you calculate Relative fitness?
Number of offspring per individual of a particular genotype / Number of surviving offspring per individual of the most successful genotypes
What is Co-evolution?
The process by which two or more species evolve in response to selection pressures imposed by each other.
What is a Symbiosis relationship?
This is a co-evolved relationship between members of two different species
What is Mutualism? (+/+)
Both organisms in the interaction are interdependent on each other for resources or other services. They both gain something from the relationship
What is Commensalism? (+/0)
Only one of the organisms benefits but the interaction does not negatively affect the other organism
What is Parasitism? (+/-)
The parasite benefits in terms of energy or nutrients and the host is harmed as a result of the loss of these resources
What does the Red Queen Hypothesis state?
In a co-evolutionary relationship, change in the traits of one species can act as a selection pressure on the other species
