Bio 101 Test 2 Flashcards
Evolution
Descent with modification, organisms evolve over time
What did Darwin observe while on his voyage that initiated his ideas about evolution?
Closely related species have different shapes and ecological roles.
Who was Darwin influenced by?
Georges-Louis Buffon, Erasmus Darwin, George Cuvier, Jean-Baptiste Lamarck, Charles Lyell, Thomas Malthus
Georges-Louis Buffon
proposed organisms change with migration
Erasmus Darwin
formulated one of the first formal theories on evolution
George Cuvier
established extinction as fact
Jean-Baptiste Lamarck
proposed evolution via inheritance of acquired characteristics
Charles Lyell
geologist who proposed uniformitarianism
Thomas Malthus
economist who recognized that populations grow faster than food production
Who else besides Darwin proposed evolution?
Erasmus Darwin-proposed one of the first theories
Jean-Baptiste Lamarck- proposed also an evolution theory
Lamarck’s theory of evolution
The giraffe neck theory
How does natural selection cause evolution?
Natural selection is the differential survival &/or reproduction of organisms whose genetic traits better adapt them to a particular environment.
What are the three conditions that must exist for natural selection to occur?
Variation exists for a trait
Variation results in differential fitness
Variation is inherited
Fitness
the genetic contribution of an individual to succeeding generations
Special types of selection
Artificial selection- selection occurs because of humans
Sexual selection- members of the same species
Which type of selection is responsible for divergence of a single species into two?
Disruptive Selection
Hardy-Weinberg equilibrium
Allows prediction of genotype frequencies
Hardy-Weinberg Equilibrium 5 Assumptions
No mutation takes place. No genes are transferred to or from other sources. Random mating is occurring. The population size is very large. No natural selection occurs.
Which of the five mechanisms of evolution are random?
Genetic Drift
Which of the five mechanisms of evolution always result in adaptation?
gene flow, mutation,
How to tell if a situation is HWE
If a population is in HWE, it is not evolving.
If a population is not in HWE, it is evolving.
Explain in words what q2, q, p, p2 and 2pq represent.
p2 = individuals homozygous for first allele 2pq = individuals heterozygous for both alleles q2 = individuals homozygous for second allele
How genetic drift results in evolution
Could just be a bug getting stepped on or eaten by a predator.
Compare and contrast the founder effect and the bottleneck effect.
Founder effect-When organisms go somewhere with no same species and with the alleles they have they procreate
Bottleneck effect- Drastic reduction in population
What effect does natural selection have on variation within a population?
Negative frequency-dependent natural selection
What effect do each of the 5 mechanisms of evolution have on variation within a population?
Mutation is the ultimate source of variation
Gene flow increases variation
Non random mating decreases variation
Genetic drift-population decreases while allele freq increases
Natural selection increases
How is variation maintained in populations
Changes in strength or direction of natural selection
Heterozygote advantage
What are two evolutionary mechanisms that can increase variation in a population?
Mutation, natural selection
Explain at least three reasons that evolution does not result in perfect organisms
Variation doesn’t exist
Pleiotropy when a single gene controls multiple traits
Gene interactions- when a trait is controlled by one or more gene
Environment changes, what’s needed to survive changed
If a population has no genetic variation, can it evolve?
No it cannot
What are some modern examples of evidence for evolution by natural (or artificial) selection?
Galapagos finches, domestication of silver foxes
What are the 4 types of evidence for evolution?
Fossil record
Anatomical/ morphological
Molecular
Biogeographical
What are the 3 types of anatomical evidence for evolution?
homologous structures
development
vestigial
What can we learn from the fossil record?
extinct species, paleontology
Differentiate between analogous and homologous structures. Which provide evidence for common ancestry?
Analogous- adaptions to a similar environment but from distantly related organisms
Homologous-structures with different appearances and functions that all derived from the same body part in a common ancestor
Convergent Evolution
Some plants and animals have similar appearance but are only distantly related
Macroevolution
major change, any evolutionary change at or above the level of species
Microevolution
small change, any evolutionary change under the level of species
What are two examples of macroevolution from class?
Evolution of dinosaurs
What is the biological species concept?
groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.”
How do we define a species?
A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding
How are organisms named and described/classified in biology?
Taxonomy
What are the mechanisms of reproductive isolation?
Prezygotic Prevent the formation of a zygote Mechanical Gametic Chromosomal Temporal Behavioral Ecological Geological
Postzygotic
Occur after formation of a zygote
Hybrid inviability
Hybrid infertility
How do these mechanisms of reproductive isolation contribute to speciation?
Cladogenesis- which can be Allopatric speciation involves geographical isolation
or Sympatric speciation does not involve geographical isolation
How does geography relate to speciation?
Given time, any two isolated populations will diverge because of genetic drift and/or natural selection
What are the two mechanisms by which geographically isolated populations diverge into new species?
Genetic drift and natural selection
What is polyploidy? How is it related to speciation?
cells of an organism have more than two paired sets of chromosomes
More common in plants (30-80% of flowering plants)
Occurs infrequently in fish, insects, and amphibian
How sympatric speciation occurs
evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region
How sympatric speciation occurs
evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region
What is character displacement and how does it relate to speciation?
selection acting to lessen resource competition or reproductive interactions causes sympatric species
What are the two models for the rate at which speciation occurs? How are they different from one another?
Gradualism is the traditional view
Punctuated equilibrium involves periods of stasis
What is adaptive radiation? How do new species arise in adaptive radiation?
is the rapid speciation of a single or a few species to fill many ecological niches. Key innovation Release from competition Colonization Extinctions Character displacement
What are the two types of extinction? How are they different from one another?
Background extinction - natural part of evolution
Mass extinction- catastrophic event
How does the rate of extinction compare to the rate of speciation in earth’s history?
The rate of extinction is faster
Does evolution always take a long time?
Not in all cases but most yes
