Friday Quiz Flashcards
Variation leads to
Natural selection
Morfitt phenotypes produced more ____
Offspring
What is allele frequency
Number of times an allele appears in a gene pool
Has nothing to do with whether an allele is dominant or recessive
What involves changes in allele frequency in a gene pool overtime
Evolution
Population does evolve true or false
True
Individuals do evolve true or false
False
Natural selection affects
Individuals
Survival/death effects
The whole population
What are the sources of variation
Mutations
Sexual recombination (meiosis)
Lateral gene transfer (bacteria use pili to pick up new genes)
How does natural selection affect phenotype
Natural selection on single gene traits—>allele frequency changes—>changes in phenotype
How does natural selection affect more than one gene trait
Natural selection on polygenetic trait affect the fitness levels of various phenotypes which leads to three possible types of selection
What is directional selection
Where individuals of one extreme have a higher fitness than those in the middle or other extreme
What is stabilizing selection
Where individuals in the middle have a higher fitness than either of the extremes
What is disruptive selection
Where individuals at both extremes have a higher fitness than those in the middle
What is speciation
Making new species
What is a species
Organisms that are able to reproduce and produce fertile offspring
What events caused the formation of a new species
Genetic changes
Environmental pressure
Biotic and abiotic factors
Isolating mechanisms
Define isolating mechanisms
Events that cause organisms to become reproductively isolated Drive the evolution of new species
Behavioral isolation
Depends on mating rituals that allow them to vary from other species. Changes in their behavior
Geographical isolation
Members of the population become separated from another population by geographical barriers that prevent the interchange of genes between the separated populations
For example two types of squirrels being separated by the Grand Canyon
Temporal isolation
Species breed/flowers – meet at different times
fireflies – often Breed at different times of night or flowers that bloom at different times of year
Agents of evolutionary change
Mutation Gene flow Nonrandom mating Generic drift Selection
Mutation
Causes novel traits to show up through a change in nucleotide sequence
Typically happens slowly. Mutations occur about 1 to 10 times for every hundred thousand cell divisions
Mutation rates are not affected by natural selection
Gene flow
Gene flow is the movement of alleles from one population to another
This will introduce new alleles to a population. If these do organisms can survive and reproduce, the gene pool of the population is changed.
Examples include bees pollinating flowers or most oceanic animals
Nonrandom mating
Some organisms will meet with organisms of a similar genotype, avoiding a random mating
What is inbreeding
A common form of nonrandom meeting. Inbreeding does not change the frequency of alleles, it creates more homozygous individuals.
What are examples of nonrandom meeting
Self fertilizing plants, or purebred domestic animals
Genetic drift
Random fluctuation of gene frequency for random chance
This random chance can radically change the gene frequencies in a population through Fenno Mena like the bottleneck effect and founder effect
What is the bottleneck effect
Happen when a drastic change occurs in a population leaving only a few survivors (natural disasters, disease, overhunting)
Offspring will resemble the survivors simply because those are the only jeans left
Founder affects
Occur when a few organisms from a species in habit a new area
Since they are the only representatives of their species the offspring will resemble the only jeans available
Natural selection
There is a variation in a population
More organisms are born and then will survive
Survival is not random
Advantageous traits must be heritable
Classification system
The grouping of organisms based upon their similarities
Classification is also known as
Taxonomy (the science of identifying, naming, and classifying organisms)
Evolutionary relationships in taxonomy
Based on three things: how Mollica structures, DNA evidence, embryological similarities
Cladistics
And approach to biological classification where organisms are grouped together based on whether or not they have one or more shared unique characteristics that come from the groups last Common ancestor and are not present in more distant ancestors
Cladograms
Branching diagrams that show how organisms are related based on shared, derived characteristics
Define gene pool
The set of all jeans, or genetic information, in any population, usually of a particular species
