Unit 3 & 4: What Is Evolution? & Mendelian Inheritance Flashcards
Why is studying evolution so important?
In order to make predictions of what will happen, we must understand and study what has happened.
What causes variability among species?
The events of evolution lead to diversity among species.
What interaction does biological diversity reflect?
The forms that preceded them and the ongoing process of change.
What is our definition of evolution?
Change in allele frequencies (genotype) in a population over time.
T/F = Evolution is a theory for the origin of life.
F = Evolution is an explanation for how life has changed since its origin.
T/F = Selection can only operate on the available variations in a population.
T = Evolution does not give species traits needed for survival.
T/F = Bad genes may be maintained by mutation, gene flow, or the late effect onset.
T = Evolution does not progress species toward perfection by removing bad genes.
T/F = Variation from mutation is random but selection favors beneficial traits.
T = Life does not evolve only by random chance.
T/F = Evolution does not affect humans.
F = Humans continue to adapt.
T/F = Species are clear and easy to recognize.
F = Simple view of species as groups that can interbreed doesn’t always apply.
T/F = Usually slow but can also occur in rapid bursts.
T = Evolution is not slow and gradual.
What 4 elements can we use to study evolution?
- ) Genetics or inheritance
- ) Allele frequencies or genotype
- ) The large scale changes overtime - paleobiology
- ) Morphology or investigating evolutionary patterns and growth
What was the main finding of Cuvier?
He observed fossils and found that those organisms that once lived and left these bones behind no longer exist.
What was the main finding of Lyell?
The changes that occur of the landforms that were formed occurs very slowly and since the change is slow the Earth must be very old.
What was the main finding of Lamarckism?
The idea that the acquired traits of an organism are heritable and are passed on.
What did Malthus find?
Survival of the fittest - because the number of people is growing at a faster rate then the amount of food being made thus there is competition.
What is the relationship of the increase of food resources and population growth on a graph?
The amount of people increases geometrically or at a faster rate than the amount of food which increases arithmetically or less fast.
Why is the food resource increasing?
The food resources are increasing because the production of food continues to increase since the amount of people synthesizing the food resources are increasing thus the amount of food will increasing.
What is transmutation?
The belief that species change over time.
What 3 elements are required for natural selection?
- ) Variations
- ) Difference in fitness
- ) Inheritance
What is the fitness difference?
The variation of the phenotype results in a difference in reproductive success.
What is variation?
This is the difference of the phenotype of the organism.
What is inheritance?
This is the process of passing these variations on from one generation to the next.
What are Darwin’s 4 postulates?
- ) Individuals within a species vary
- ) Some variation is heritable
- ) More offspring are produced that can survive and reproduce
- ) Survival and reproduction is not random but related to the phenotypic variation
Why are only some variations heritable?
Not all phenotypic variation can be passed on from one generation to the next because if you look at acquired traits that an organism gains those are not passed on from one generation to the next.
What did Wallace discover?
Wallace came up with the theory of natural selection without knowing that Darwin was exploring the same idea.
What are Darwin’s main ideas?
The mechanism that leads to the biological evolution that changes in species over time.
What is natural selection?
This is the mechanism that leads to the evolution of species over time.
What is adaptive radiation?
A process in which organisms diversity rapidly from an ancestral species to produce new forms.
What is the differentiation that occurs in the islands?
The species that are isolated on the islands are able to evolve and differentiate from their neighbouring species over time, and new species will not be arriving.
What is the differentiation that occurs in the mainland?
There is very little gene flow between the mainland and the species in the islands.
What is the genotype?
The particular combination of alleles present in a given organism is the genotype.
What is the phenotype?
The expression of a trait in an individual.
What is blending inheritance?
Where the offspring has traits that are an intermediate of its parents.
What is Lamarck’s Theory?
Favourable traits acquired by the parents are passed on to offspring.
What happens to blending inheritance over time?
Over time if blending variation will be reduced and traits will be lost.
What did Mendel do?
Mendel observed the phenotypes of the pea plants that he was selectively crossing through the use of true breeding.
What 3 distinctions was Mendel observing?
- ) True breeding strains - these are good phenotypes.
- ) Focused on single traits at a time.
- ) Quantitative findings were a result of counting the progeny.
What is P1?
This is the parental generation.
What is F1?
This is the progeny or daughter generation.
What is the difference between dominant and recessive protein production?
Dominant alleles code for functional proteins while recessive alleles do not code for functional proteins.
What is a monohybrid cross?
- ) Single character trait cross
- ) Using true breeding varieties all offspring have the same phenotype
- ) P Generation: Cross 2 varieties with a different phenotype.
- ) F1 Generation: F1 filials are self fertilized (2 of the same progeny are fertilized)
- ) F2 Generation: Both the phenotype of the parental generations arose.
What was special about the monohybrid cross?
If the cross was only blending inheritance we would not see rise of both phenotypes.
What are homozygous alleles?
The 2 alleles are the same therefore producing only one type of gametes.
What are heterozygous alleles?
The 2 alleles are different therefore producing only multiple types of gametes.
What are independent events?
These are events that occur in succession and the probability of one does not impact the other.
What is the product rule?
The individual probabilities of independent events are multiplied.
What are mutually exclusive events?
The individual probabilities of independent events do not overlap in probability.
What is the sum rule?
The probability that one or the other or 2 mutually exclusive events will occur is the sum of the individual probabilities.
What is true breeding?
This is when 2 parents produce offspring that all have the same phenotype.
Why use homozygous recessive for a test cross?
Once you know the homozygous recessive phenotype you know if you have had a heterozygous or homozygous genotype for the parent.
How are alleles transmitted to the gametes?
Alleles are transmitted to the gametes via chromosomes that are passed on to the cells through meiosis specifically in anaphase where the alleles are separated.
What is Mendelian inheritance?
This is when the dominant traits mask the recessive traits.
What is incomplete dominance?
This is when one allele is not completely dominant over the other allele and both alleles are present through a mixing of the phenotype.
What is codominance?
This is when both alleles are expressed and both are competing for dominance thus they do not mix.
What is Cr?
This allele is responsible for making the functional enzyme that produces the red pigment.
What is Cw?
This allele is responsible for making the nonfunctional enzyme.
What is a population?
An interbreeding group of organisms that are restricted to a specific geographical area.
What is the null hypothesis for evolution?
If the evolution is change in allele frequencies over time then the null hypothesis is that there is no change in allele frequencies over time.
If these factors occur then the allele frequencies do not change and there is no genetic diversity what are these factors?
- No mutation
- No migration
- A large population
- Genotypes do not differ in fitness = no selection
- Mating is random
What is the Hardy-Weinberg Principle?
The alleles are present in breeding in the proportions p and q which remains constant since there are no mutations, no gene flow, and random mating.
What is population genetics?
This is a shift from looking at the individual to looking at the population.
When/why do we use the sum rule to calculate the allele frequency?
The sum rule is used to calculate the allele frequency of the dominant allele because both homozygous dominant and heterozygous must be taken into account.
What is the problem with taking the square root of the P^2?
- ) It assumes that the population is in HWE
2. ) It does not account for the dominant alleles in the heterozygous genotype
Why do you multiply by 0.5 when calculating the allele frequency?
The 0.5 accounts for the half of the alleles that includes the dominant alleles.
How do you test whether a population is in HWE?
- ) Calculate the allele frequencies p and q
- ) Use allele frequencies to calculate the genotype
- ) Calculate the expected numbers under HWE
- ) Compare observed to expected using the Chi-square Test
Why do you divide by 2n to find the allele frequency of an allele in a sample of individuals?
Divide by 2 because there are 2 alleles per individual.
How do you find the degree of freedom?
Genotypes - #Alleles
How do you know if selection is taking place?
- ) Individuals with a species vary.
- ) Some variation is heritable.
- ) More offspring are produced than can survive.
- ) Survival and reproduction is not random but related to phenotypic variation.
What is drift?
This is a random change that occurs during natural selection which impacts the reproductive success and genes although it is independent of phenotypes.
What is genetic drift?
The impact on the hereditary material and reproductive success due to random changes that are not reliant on phenotypic variation.
What is the difference between a large and small sample?
Genetic drift causes a change in allele frequency due to chance “sampling error” in finite populations the smaller the population the more significant the change.
What is fixation?
This is the elimination of an allele from a population and it is more likely to take place in smaller populations because during the random mating the allele will steadily become rare.
What is the bottleneck effect?
This is an example of genetic drift where a population is decimated due to extreme natural disasters and the remaining population is a random assortment of the population.
What is the founder effect?
This is another example of genetic drift where a small subset of the main population breaks off and establishes its own new colony.
What are the similarities between the bottleneck and founder effect?
- ) Offspring carry only a small sample of the original population’s genetic variation.
- ) They have important implications for conservation biology.
- ) Some alleles may be rare or missing from the resulting population.
- ) Some alleles might be much more common compared to the original population.
- ) They are an example of genetic drift.
What is phylogeny?
This is when the human populations are closely related to the neighbours.
What is population divergence?
The change in allele frequencies due to genetic drift.
What are the similarities between the bottleneck and founder effect?
1.) The main difference is that in the founder effect a small subset of the main population breaks off and establishes its own new colony and this does not occur in the bottleneck effect.
What is inbreeding?
Mating among relatives.
What is outbreeding?
Mating with individuals more distantly related.
What is assortative meeting?
Individuals with similar genotypes/phenotypes mate with one another more frequently than would be expected under a random mating pattern.
What are the 3 patterns of natural selection?
- ) Directional stabilizing
- ) Stabilizing selection (balancing selection)
- ) Disruptive selection
What is directional selection?
Individuals of one extreme phenotype is favoured.
What is stabilizing selection?
Individuals with intermediate phenotype is favoured, extreme phenotypes selected against.
What is disruptive selection?
Both extreme phenotypes favoured; intermediate phenotypes selected against.
What is viability selection?
The differences in survival.
What is fecundity selection?
The differences in reproductive success.
What are the male gametes?
Males produces energetically cheap, abundant, and more motile sperm.
What are the female gametes?
Females produces energetically expensive, fewer, and less motile eggs.
What is sexual dimorphism?
Systematic differences in traits between the genders within a species.
What are the 2 aspects of sexual selection?
- ) Intrasexual selection is fitness where there are differences resulting in differing abilities of a single gender within a species so males competing with each other for the female.
- ) Intersexual selection is fitness where there are differences due to preferred or non random mating.
What is speciation?
When new species arise due to the formation of biodiversity.
What causes genetic divergence?
- ) Genetic drift
- ) Founder effect & bottleneck effect
- ) Mutation
- ) Differential selection
What are prezygotic mechanisms?
These are mechanisms or barriers that prevent 2 gametes from combining/fertilizing and forming the zygote.
What are postzygotic mechanisms?
These are mechanisms or barriers that prevent the development or growth of the zygote.
What are the 3 outcomes of postzygotic mechanisms?
- ) Individuals can readily hybridize
- ) Individuals do not hybridize at all
- ) Individuals hybridize but offspring have reduced fitness
What are the 2 modes of speciation?
- ) Allopatric speciation
2. ) Sympatric speciation
What is vicariance?
These are factors that can separate parts of a species for prolonged amounts of time.
What is allopatric speciation?
This is speciation that occurs as a result of the physical barriers that divide the geographic ranges.
What is sympatric speciation?
There is no geographic barrier to gene flow.
What is autoploidization?
Reproductive isolation they can only reproduce with other autoploids.
What is polyploidization?
They have an increasing number of chromosomes.
What is the species concept?
This is a framework to address how to organize the discrete clusters of variation in nature.
What is the advantage of the species concept?
Easy to use.
What is the disadvantage of the species concept?
No clear genetic or evolutionary justification.
What are the major categories?
- ) Morphological - Individuals that look alike
2. ) Reproductive - Ability to produce offspring
What is the Biological Species Concept?
These are species or groups that are reproductively isolated from other such groups.
What is the advantage of BSC?
Clear justification of evolution.
What is the disadvantage of BSC?
May be difficult to distinguish in the field.
