Chapter 22
What are the four evolutionary evidences?
Direct observation, homology, fossil record, & biogeography
What are the five conditions required for a population to remain in Hardy-Weinberg equilibrium?
No mutations
Large population size
No gene flow
No natural selection
Random mating
What is the difference between micro & macroevolution?
Changes in allele frequencies over time
Broad pattern of evolution above the species level
What are the characteristics of life?
Order, reproduction, growth & development, energy utilization, response to environment, homeostasis, & evolutionary adaptation
What’s the difference between stratigraphy and radiometry, and what are the pros and cons of both methods?
Stratigraphy: determines fossil’s relative age by its position in sedimentary rock layers; easily establishes evolutionary sequence; only yields order of events not exact age
Radiometry: uses isotopic half-lives to calculate a fossil’s absolute numerical age; highly accurate numerical age; not suitable for sedimentary rocks
Who are all of Darwin’s predecessors and what theories are they associated with?
Lamarck: Use & Disuse; Inheritance of Acquired Traits
Cuvier: Paleontology
Hutton & Lyell: Gradualism; Geologists
Malthus: Exponential Population Growth
What are the two Hardy-Weinberg formulas, and what information do they gather?
p + q = 1; p^2 + 2pq + q^2 = 1
allele frequency; genotype frequency
What are the two kinds of reproductive barriers, and what are all the isolation types under each barrier?
Prezygotic: habitat, temporal, behavioral, mechanical, & gametic
Postzygotic: reduced hybrid viability & fertility, hybrid breakdown
What are the steps and materials needed for abiogenesis?
Synthesis simple organic compounds -> polymer synthesis & formation -> polymers packaged into protocells & aggregation to form protocells -> origin of self-replicating molecules
Water, simple gasses, carbon & mineral catalysts, heat/energy source
Plant Species A has 2n=6 chromosomes, and Plant Species B has 2n=4 chromosomes. They interbreed to produce a hybrid plant that is sterile. A cell division error occurs in this hybrid that doubles its total number of chromosomes, producing a fertile new plant species.
Is this new fertile species an autopolyploid or an allopolyploid? How many total chromosomes does the new fertile plant have in its cells?
Allopolyploid; 10
What did Darwin and Wallace identify through their research?
Natural selection as a means to drive change and diversification
What is genetic drift, and what are two examples of it?
change in allele frequency due to randomness/chance rather than natural selection
bottleneck & founder effect
When closely related species meet in a hybrid zone, what are the three possible evolutionary outcomes over time regarding reproductive barriers?
Reinforcement: strengthening of barriers
Fusion: weakening of barriers
Stability: continued production of hybrids
A sample of a fossil was formed 1.8 million years ago. A mass spectrometer measures that 12.5% (1/8) of the original parent isotope remains in the crystals. Based on this measurement, what is the half-life of the parent isotope?
17,190 years old
In an unbanded Lake Erie water snake population on an isolated island where unbanded camouflage is strongly favored, banded snakes continuously appear every generation despite heavy predation. Evaluate why natural selection fails to eliminate the unfavored band allele from the island.
Ongoing gene flow from the mainland populations continuously reintroduces the banded allele to the island gene pool faster than natural selection can eliminate it.
Provide an example for all four of the evolutionary evidences, including subcategories.
Direct Observation: Case Studies & Artificial Selection
Homology: Comparative Anatomy, Embryology, & Biochemistry
Fossil Record
Biogeography
If the frequency of homozygous recessive individuals in a population is 0.09, what is the frequency of heterozygous individuals under Hardy-Weinberg equilibrium?
0.42
What is the fundamental difference between allopatric speciation and sympatric speciation regarding the physical location of the diverging populations?
Allopatric speciation: geographically separated populations
Sympatric speciation: same geographic area
Volcanic rock surrounding a newly uncovered fossil contains a radioactive parent isotope and its stable daughter product. Chemical analysis shows that the ratio of parent isotope to daughter isotope is 1:15. If the parent isotope has a half-life of 1.25 billion years, how old is the rock layer?
5.0 billion years old
Humans produced distinct vegetables like broccoli and cabbage through artificial selection from a single wild mustard plant by targeting specific anatomical structures. Explain the key difference in the selective agent driving artificial selection versus natural selection.
artificial selection: humans intentionally choose desirable traits to breed
natural selection: environmental forces determine reproductive success based on survival value
In the Florida soapberry bug study, how and why did the average beak length change after the introduction of the non-native goldenrain tree?
The beak length decreased because the introduced goldenrain tree’s fruit is thinner than the native balloon vine fruit, selecting for shorter beaks.
How is having a large population size and genetic drift related? Give an example.
Large population size helps prevent genetic drift as the species is less likely to be affected
How does allopolyploidy and autopolyploidy differ in where their chromosomes are derived from, and who are they able to mate with?
Autopolyploidy: all extra chromosomes derived from a single species; themselves
Allopolyploidy: all extra chromosomes derived from the hybridization of two different species; only other hybrids, not able to reproduce with parent species
A sample of volcanic ash sandwiching a fossil was formed 1.8 million years ago. A mass spectrometer measures that 12.5% (1/8) of the original parent isotope remains in the crystals. Based on this measurement, what is the half-life of the parent isotope?
600,000 years old
A researcher argues that natural selection should eventually engineer a "perfect" predator capable of swimming infinitely fast, living indefinitely, and out-competing all rivals. Formulate an evolutionary argument refuting this claim by applying the four evolutionary constraints on adaptation.
Selection can only modify existing ancestral anatomical structures, not create optimal adaptations from scratch
Every adaptation involves an energy/functional compromise
Selection is strictly limited to whatever alleles exist within the available gene pool and cannot invent beneficial mutations on demand
Selective pressures and ecological conditions continuously shift over time, turning previously adaptive traits into neutral or disadvantageous ones