Chapter 8 Flashcards
Population
groups of organisms of the same species living in a particular geographic region and have the potential to interbreed; can be as small as a lake test tube
how many influences did darwin have and who were they?
five; george cornte de buffon, george culvier, jean baptiste lamarack, charles lyell
Which of darwin’s influences had the most inspiration on him?
charles lyell in his boook principles of geology, that geological forces had shaped the earth and were continuing to do so, producing mountains and valleys, cliffs and canyons, through gradual, but relentless change
give two examples of observations that helped chip away at the idea of a relatively young and unchanging earth
- buffon: earth is much older than previously believed
- cuvier’s fossil evidence had occurred
- lamarack: living species change over time
- lyell: geological forces gradually shaped the earth continue to do so
Darwin originally studied __ but then changed to __ bc ___
medicine, ministry, he hated surgery and his farther insisted it
which boook did darwin take with him on the beagle?
lyell’s principles of geolgy
traits
any characteristic or feature of an organism such as red petal color in a flower, body size, beak shape, feather color
What two important, unexpected patterns did Darwin notice on his voyage that led him to develop his theory of evolution?
1) Galapagos finches; he originally assumed they were the same species with different physical characteristics but however,, he later discovered that they were all separate species. assumed that over time, the island species had separated an diverged from the original mainland population
2) Similarity between fossils of extinct species (glyptodonts) and living species (armadillos) in the same areas. deducted that the two organisms resembled one another because the glyptodont was an ancient relative of the armadillo
Who is alfred russel wallace?
he too independently identified the process of evolution by natural selection
Change to the changed statement after Darwin’s publishing:
-all organisms were put on earth by a creator at the same time
organisms change over time
Change to the changed statement after Darwin’s publishing:
-organisms are fixed: no additions, no subtractions
some organisms have gone extinct
Change to the changed statement after Darwin’s publishing:
-earth is about 6,000 years old
earth is more than 6,000 years old
Change to the changed statement after Darwin’s publiChange to the changed statement after Darwin’s publishing:
- shing:
- earth is mostly unchanging
the geology of earth isn’t constant, but always changing
What finally prompted darwin to publish his theory of natural selection as the means of evolution after it sat idle for over 15 years?
alfred russel wallace independently arrived at the same theory, so darwin needed to publish his work to get credit for developing the theory
Do individuals evolve?
NO, the proportions of the alleles in a population do
Four evolutionary mechanisms:
four ways evolution can occur?
1) mutation
2) genetic drift
3) migration
4) natural selection
mutation
alteration of the base pair sequence in the dna of an individual’s gamete-producing cells that changes an allele’s frequency
genetic drift
random change in allele frequencies, unrelated to any allele’s influence on reproductive success
migration
change in allele frequencies caused by individuals moving into or out of a population
natural selection
change in allele frequencies that occur when individual with one version of a heritable trait have greater reproductive success than individuals with a different version of the trait
evolution
change in characteristics of a population over time
natural selection
way evolution can occur
what does “mutations are random” mean?
1) can’t predict which individuals will have which mutations
2) can’t predict whether the consequences of a mutation will be benign, harmful, or useful
all variation –the raw material for natural selection – must initially come from mutation
n/a
why do mutations occur
can be caused by high energy radiation or chemicals in the environment and can also appear spontaneously
what’s the only way alleles can be crated within a population?
Mutation
fixation
no more genetic variability; frequency of an allele is 100%
two types of genetic drift
founder effect and population bottleneck effect
founder effect
small numbers of individuals leave a population and become the founding members of a new, isolated population; may have different allele frequencies than the original population, and if so, evolution has occurred
population bottleneck efect
when a famine, disease, or rapid environmental change causes the deaths of a large proportion of individuals in a population. bc the pop is quickly reduced to a small fraction of its original size, this reduction is bottleneck
ex of founder effect
extra fingers/toes in amish population
ex of bottleneck effect
only 12 cheetahs surviving the bottleneck and having no variation
migration (aka gene flow)
change in allele frequencies of a population due to the movement of some individuals from one population to another
migration vs founder effect
individuals migrate to a new habitat previously unpopulated by that species
three conditions for natural selection
1) must be variation for the trait within a population
2) variation must be heritable (capable of being passed to offspring)
3 diffrerential reproductive success: )individuals w one version of the trait must produce more offspring than those with a different version of the trait
heritability/inheritance
transmission of traits from parents to children through genetic information
differential reproductive success
within a variable population, those whose traits are most suited for survival and reproduction will often times have more offspring
sexual selection
natural selection favors traits that give an advantage to individuals of one sex in attracting mating partners ex ornaments (increasing status/appeal) or fighting behavior
how can we predict genotypes and phenotypes?
by knowing the frequency of each allele in a population
Which conditions must be present for Hardy-Weinberg equilibrium to hold true?
random mating and evolution is not occurring
The origin of all genetic variation is:
mutation
In a given population, a few individuals may, by random chance, leave behind more descendants than other individuals. Thus, the genes of the following generation will have a higher proportion of the alleles of the “lucky” individuals. Which of the following concepts is this example representative of?
genetic drift
fitness
measure of an individual’s reproduction with a particular phenotype compared w the reproductive output of individuals of the same species w alternative phenotypes
3 factors to fitness
1) fitness is measured relative to other genotypes or phenotypes in the population
2) depends on environment that organism lives in
3) depends on reproductive success compared to others in the population
Who has greater fitness: a world-class bodybuilder with a single child, or an overweight, middle-aged accountant with four children?
accountant with four children
adaptation
organisms become better matched to their environment AND to the specific features that make an organism more fit
adaptation occurs as a result to what
natural selection
what are the three reasons that we can’t be perfectly adapted to our environment?
1) environments can change quickly and more rapidly than natural selection can adapt
2) mutation doesn’t produce all possible alleles
3) there isn’t always a single, optimum adaption for a given environment
