Exam 1 Flashcards
What is evolution?
A change in allele frequencies in a population over time.
________ evolve, not _________.
populations, individuals
_________ must exist in the population before selection.
Variation
Does evolution happen across generations or within a generation?
Across generations
True or False: Selection is random.
False, selection is not random
What are the four ways in which evolution can happen?
- Mutation
- Random events leading to genetic drift
- Movement such as migration that changes gene flow
- Adaptive Evolution
What is adaptive evolution?
Natural Selection, such as sexual selection
What three things are not evolution?
- Individual Development
- Ecosystem Change
- Cultural Evolution
What is an example of individual development?
A tadpole grows into a frog (NOT EVOLUTION)
What is an example of Ecosystem Change?
Trees growing in a plot of land over time (NOT EVOLUTION)
What is an example of Cultural evolution?
One japanese macaque learns how to do a certain skill. Others see it do this skill and learn it to. Then, the entire population of macaques is doing it.
What is the purpose of studying evolution?
Evolution is the central unifying theory of modern biology.
What are the six reasons to study evolution?
- To understand the diversity of life
- Conservation biology
- Fisheries Management
- Agriculture
- Medicine
- Forensics and Paternity Analysis
What scientist is Essentialism attributed to?
Aristotle
What is essentialism?
The idea that the physical world and its life forms are fixed, and that all members of a class share unchanging properties that define the class
What is Scala Naturae?
The great chain of being in which life is arranged hierarchically
Who is attributed with Scala Naturae and Binomial nomenclature?
Carolus Linnaeus
What was George-Louis Leclerc’s idea?
- there are differences in related species based on the environment they live in
- organisms must somehow change after migrating to suit the new environment
What is Jean-Baptiste Lamarck attributed with?
- First scientific treatment of evolution
- Transformism
- Inheritance of acquired characters
What is Transformism?
- Lamarck’s idea
- The idea that lineages persist forever, but change in form
- There is some mechanism of internal force that causes transformation
- There is no extinction or branching of lineages
What is inheritance of acquired characters?
- Lamarck’s idea for how individuals change
- If the change is beneficial, parents transmit acquired characters to offspring
- giraffe’s neck example
Who was Georges Cuvier?
- Lamarck’s biggest critic
- Favored essentialism
- Believed in Correlation of Parts
- First to firmly establish extinction
What is Correlation of Parts?
The idea that organisms are so integrated in form and function that any change would lead to death. Also called irreducible complexity.
What idea is James Hutton attributed with?
Gradualism
What is gradualism?
Earth’s physical features gradually changed due to slow geological processes
What idea is Charle’s Lyell attributed with?
Uniformitarianism
What is uniformitarianism?
Historical changes result from uniform geological processes that still occur today
-Replaced geological catastrophism
What are two implications of earth’s history?
- Earth is very old and is always slowly changing
2. The past can inform the present, and vice-versa
Who proposed natural selection?
Darwin
What is the outcome of evolution?
Descent with modification through natural selection
What was Darwin’s job title?
Naturalist
What book did Darwin write explaining natural selection?
The Origin of Species
What four things led to Darwin’s ideas about evolution?
- Modern species resemble fossils
- Domesticated animals can be made to vary through artificial selection
- The creatures he saw varied from island to island
- organisms may have complex modifications that are necessary for their survival
What is the observation that is made between domesticated and wild species?
Domesticated species show much more variation due to artificial selection
What is the common opinion among animal and plant breeders regarding domestic varieties?
Domestic varieties arose from wild ancestors that had the same or similar characteristics as the domesticated variety
What was Darwin’s big idea about wild species?
They also undergo selection, just as domesticated species undergo artificial selection. Rather than accumulating large modifications over several generations, they accumulate tiny changes over a long period of time.
What was John Gould’s opinion on the Galapagos finches?
The finches belonged to the same family even though they all looked different
What was the biggest difference between the Galapagos finches?
The size and shape of their beaks
The 13 species of finches found on the Galapagos compromise the same number of feeding types as….
9 families of birds in South America
Thomas Robert Malthus came up with the idea of “natural” checks on population growth. Today, this is known as..
carrying capacity
What is the Malthusian Dilemma?
At the point where population size outstrips resource production, there are only two alternatives: find a way to expand the resource pool or die.
How does the Malthusian Dilemma apply to finches, and what is the reproductive consequence?
- In periods of drought, soft seeds are depleted, leaving only hard seeds. Only finches with beaks capable of breaking the hard seeds survive. Unfavorable finches die and the population adjusts in size to fit the resource pool.
- Favorable beak morphologies are passed on, leading to morphological differences in a population.
According to Darwin, what four things must happen for natural selection to take place (Darwin’s four postulates of natural selection) ?
- Variation
- Inheritance (variations are passed to offspring)
- Differential Survival (more offspring are produced than can survive)
- Extinction
What are the four things besides natural selection that Darwin proposes?
- Common Descent
- Gradualness of change over time
- Population differentiation
- Natural Selection
What is common descent?
- All living things are part of a community of descent
- Organisms that have a more recent common ancestor are more similar than those that are more distantly related
What is gradualness of change over time?
Differences of organisms have accumulated in small increments over time
What is population differentiation?
- Changes in a species happen at the level of individuals
- There is no sudden origin of a new species or transformation of individuals
What is Natural Selection?
Population differentiation caused by differential reproductive success of individuals bearing particular traits
Who was Alfred Russel Wallace?
- Wrote a paper on natural selection and sent it to Darwin
- This encouraged Darwin to write the Origin of Species
What was Darwin’s main flaw in his ideas about the mechanism of natural selection?
Lacked a mechanism for heredity
What theory of inheritance did Darwin favor?
Blending
What is adaptive radiation?
Evolution into a wide variety of types suited for a certain way of living; caused by the accumulation of differences over time
Without _______, there can be no evolution.
Variation
Does natural selection have a goal?
No
What is polymorphism and what type of variation is it?
- Multiple forms within a species, such as color variation in lizards that determines behavior
- Discrete variation
- You either have the characteristic or you don’t
What is continuous variation?
- Variation that has no distinct categories, such as height or beak depth in galapagos finches
- Due to different alleles of genes
- Has a complete range of measurements
What two things influence variation?
Environment and genotype
What mechanism for inheritance did Darwin favor?
Pangenesis- all cell lines contribute to gamets
What were the four parts to Gregor Mendel’s theory of heredity?
- Genes are preserved during development
- Genes are passed unaltered to offspring
- An organism can “carry” a gene without expressing the phenotype
- The phenotype may be intermediate, but genes do not blend
Blending claimed that rare variants would blend out of the population. What did Mendelian genetics say about this?
Rare variants will persist and become established in the population
What three concepts of genetics did Mendel contribute?
- Dominance
- Law of Segregation
- Law of Independent Assortment
What is simple dominance?
When two unlike alleles are present in an individual, one factor is dominant and its trait is preferentially expresed
What is the law of segregation?
- The two alleles of a gene segregate randomly into gametes and combine randomly to form the next generation
What is the Law of Independent Assortment?
Characteristics are inherited independently of each other
What did Reginald C. Punnett do?
- Combined Mendel’s laws with statistics
- Considered the “father” of genetics as a scientific discipline
- Creator of the punnett square as a method to visualize allele combinations
What did William Bateson do?
- Promoted Mendel’s laws of inheritance
- Translated Mendel’s work into English
What is a testcross?
A cross of an unknown genotype with the homozygous recessive genotype to find the genotype of the unknown
_________ is the ultimate source of all heritable variation.
-Mutation
What do point mutations do?
Alter single nucleotides
What are three contributors to genetic variation?
- Mutation
- Unequal crossing over
- Recombination
What is unequal crossing over?
Parts of a chromosome switch places. The parts that switch are in unequal amounts.
What is recombination?
Shuffles existing variation into new combinations that lead to greater phenotypic variation
Does mutation, crossing-over, and recombination result in adaptation?
No, they are random with respect to adaptation.
Mutation acts on existing genes, modifying or generating ____________
New alleles
What controls mutation rate?
Nothing, mutations happen due to random processes. However, the spread of the mutation may not be random.
What is codominance, and what is an example of codominance?
- Both alleles are expressed
- Blood type
What is Incomplete Dominance, and what is an example?
- Alleles are blended together, none being dominant
- A red and white flower reproduce to form a pink flower
What is pleiotropy?
-A single gene has multiple phenotypic effect
What is epistasis?
Two genes contribute to one phenotype
What are polygenic traits?
Several genes interact to form the phenotype (Ex. at least three genes control eye color)
What determines the degree to which genetic potential is realized?
Environment
What are maternal effects?
Special case of environmental effects that can be attributed to the mother, such as the environment of the womb or post birth maternal care
What is a common garden experiment?
-Offspring are raised under identical conditions to determine if a phenotype is environmentally or genetically determined
What is cross fostering?
- Offspring are reared by parents other than their own
- Helps determine if a phenotype or behavior is environmentally or genetically determined
Phenotype = ________ + _________
Genotype + environment
What is heritability?
The proportion of variation that can be attributed to genotype (the amount of variation due to genes)
When environmental variation is low, heritability is ________ .
High
Can heritability change without a change in genes?
yes, heritability can change due to environmental change because environment affects gene expression
Reproductive potential and reproductive effor greatly ______ requirements of reproductive replacement.
Exceed
What governs reproductive output and affects competitive ability?
Genotype
Determining which organisms survive has to do with what?
- Interactions with other organisms
- Interactions with the environment
What allows us to derive frequencies of alleles, genotypes, and phenotypes when particular conditions are met?
Hardy-Weinberg Equation
What equation is used to determine allele frequencies?
p + q = 1
What equation is used to determine genotype frequencies?
p^2 + 2pq + q^2 = 1
Hardy-Weinberg takes known _________ to predict _________.
allele frequencies, genotype frequencies
What are the five assumptions for Hardy-Weinberg equilibrium?
- Mating is random
- No natural selection
- No net mutation
- Large population
- Closed population
In the absence of selection, genotype frequencies go into _______________.
Hardy-Weinberg Equilibrium
If a population is not in Hardy-Weinberg equilbrium, what does this mean?
One of the five assumptions is violated and evolution is occuring
What does random mutation generate?
A new allele
