Evolution Flashcards
What does the theory of special creation believe?
That all species are independent (all unrelated to each other), life on earth is young (6000 years), species are incapable of change (made perfect)
Living organisms were instantaneously created by a supernatural being
What are the two components of scientific theories?
Pattern component: statement that summarizes a series of observations
Process component: mechanism that produces that pattern or set of observations
What did Plato think about organisms? What is his thinking called?
Every organism was an example of a perfect essence made by God and that they were unchanging and that variations between species were unimportant and misleading
Typological thinking
What did Aristotle think about organisms?
He ordered them into a linear scheme called the Great Chain of Being (scale of nature), he thought that species were fixed types organized into a sequence based on increasing size and complexity
What was Lamarck’s theory of evolution?
Species change through time by inheriting acquired characteristics, phenotypes would be passed down (giraffe neck example)
Based on scale of nature
What is population thinking?
Variations among individuals in a population is not unimportant but was the key to understanding the nature of species
Why was the theory of evolution by natural selection revolutionary?
Overturned the idea that species don’t change, replaced typological thinking with population thinking, it was scientific (had a mechanism to account for change through time and made predictions that could be tested)
What did Darwin repeatedly describe evolution as? What does this mean?
Descent with modification
Species that lived in the past are the ancestors of the species existing today
What predictions are made by the pattern component of the theory of evolution by natural selection?
Species change through time and species have common ancestors
What is a fossil?
Any trace of an organism that lived in the past
Range from bones, branches, shells, tracks, impressions, and dung
What is a fossil record? What did this support?
Consists of all fossils that have been found on earth and described in a scientific literature
The hypothesis that species have changed through time
What are extant species? What are extinct species?
Species that are living today
Species that no longer exist
What is uniformitarianism? Who proposed it? How did he reach this conclusion?
Idea that geological processes occurring today are similar to what occurred in the past
James Hutton
Travelled around Europe and measured patterns and rates of rock formation and erosion
What are sedimentary rocks? What did they make Hutton realize?
Rocks that form from sand or mud or other materials that were deposited at beaches or river mouths
They take a long time to form so for the massive rock formations to form then the earth must be very old (older than 6000)
Who popularized Hurton’s ideas? What did he do?
Charles Lyell
Placed fossils in a younger to older sequence using their relative position in layers of sedimentary rock
What is radioactive decay?
Steady rate at which the unstable parent atoms are converted into stable daughter atoms
What is radiometric dating based on?
Observed decay of parent to daughter atoms
The ratio of parent to daughter atoms present in newly formed rocks
The ratio of parent to daughter atoms present in a particular rock sample
What did advocates of the theory of special creation argue extinct species fossils were? What did Darwin interpret them as?
Victims of the flood from Noah’s ark
Evidence that species are not static, because of species have gone extinct that the species living on earth has changed over time
What is the law of succession?
Striking resemblance between fossils and living species found in the same area
What is a transitional feature? Example?
Trait in a fossil species that in intermediate between older (ancestral) and newer (derived) species
Fossils documenting a gradual change from fins to limbs
What are vestigial traits? Examples?
Reduced or incompletely developed structure that has no or reduced function but is clearly similar to functioning organs/structures in closely related species
Whales and snakes have hip and leg bones that do not help them move, ostriches have wings but can’t fly, blind fish still have eye sockets
Does correlation always equal causation?
No
For a hypothesis to be useful it must?
Clearly establish mutually exclusive alternative explanations for a phenomenon, generate testable predictions, able to be tested empirically
What is the difference between a theory and hypothesis?
Hypothesis: proposed explanation that leads to testable prediction
Theory: evidence-based overarching
explanations for a general class of
phenomenon (many testable hypotheses related to it), supported by large body of evidence, fits observations not used in formulating the theory
What is the difference between microevolution and macroevolution?
micro: change in genetic characteristics (allele frequency) of a population over time
macro: descent of different species from a common ancestor over a very long time
What is an allele?
variant form of a gene
What is genetic variation?
number and relative frequency of alleles in a particular population
What is a mutation?
change in a genetic sequence, introduces new alleles
What is evolution?
change in allele frequencies in a population over time
What is genotype vs phenotype?
genetic makeup vs the visible expression of genes
Why is variation important for evolution?
all organisms would have the same fitness so natural selection and therefore evolution wouldn’t occur
When do mutations occur?
randomly, happen whether or not they are useful to an organism
Can individuals with different genotypes exhibit the same phenotype?
yes because if an allele is dominant then that corresponding phenotype will show when an individual is homozygous dominant or heterozygous
What is the product rule?
the individual probabilities of two or more independent events occurring are multiplied together
What is the sum rule?
the individual probabilities of two or more different events that produce the same outcome are added together
What is allele frequency vs genotype frequency?
allele: relative abundance of alleles in a population (B or b)
genotype: percentage of individuals in a population with each genotype (BB, Bb, bb)
What will the frequency of the dominant and recessive alleles add up to?
F(B) + F(b) = 1
F(B) is frequency of dominant allele
F(b) is frequency of recessive allele
What does it mean if there is only one allele for the gene of interest?
One allele is fixed and the other was lost
What are null models? When do we use them?
Predict what we’d see if a particular factor has no impact
In observational studies where there is no suitable control group
What is the equation for hardy-weinberg equilibrium? What do the variables represent?
p^2 + 2pq + q^2 = 1
Frequency of homozygous dominant genotype is p^2
Frequency of homozygous recessive genotype is q^2
Frequency of heterozygous genotype is 2pq
What are some limitations on Hardy-Weinberg equilibrium?
Only works for diploid sexually reproducing populations
Why is Hardy-Weinberg equilibrium useful?
Predicts allele and genotype frequency if evolution doesn’t occur so it gives us a baseline to compare to and see if and how a population is evolving
What biological process results in adaptation?
natural selection
Why isn’t inbreeding considered an evolutionary mechanism?
it does not change allele frequencies
If the nucleotide variability of a gene is 0%, what is the genetic variability and the number of alleles?
0% and 1 allele
What is macroevolution?
evolutionary changes that create new species and groups of species
What is a molecular clock?
A mechanism to estimate the timeline of evolution based on constant rates of change in certain genes.
What is homoplasious?
traits that result from ways other than inheriting from a common ancestor
What would prevent a gene or phenotype directly associated with said gene from being a reliable molecular clock?
natural selection
What can gene duplications provide?
the raw material used to produce morphological innovations, free from prior selection pressures
What are some possible outcomes of gene duplication when its not deleterious? What outcomes can result in evolution of new traits?
- they retain the original function and provide additional amounts of the same product
- may retain original function but the expression pattern changes (new tissues/development timing)
- they gain mutations and the protein product is altered
- mutations prevent expression, makes a pseudogene
2 and 3 could
What is adaptive radiation?
evolutionary process that produces new species from a single, rapidly diversifying lineage
What is an example of adaptive radiation?
A population of birds becomes stranded on an island archipelago
What is a homeotic mutant?
An individual with a structure located in the wrong place
Why was the Cambrian explosion important?
It resulted in an explosion of ecological diversity and morphological change among animals
What group is classified as homo sapiens?
cro-magnons
What is true of the out of africa hypothesis?
Homo sapiens have a common ancestor with Neanderthal and Homo erectus from Africa, but did not interbreed with them
