Evolutionary Thought Timeline Chap 9 and 10

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Evolutionary Thought Timeline Chap 9 and 10

• Organisms
• Life Histories and Evolutionary Fitness

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Bit of review

• Convergent Evolution -

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Convergence
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Convergence
Theria
Eutheria
Metatheria
ancestor
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• Cactacea
• Euphorbacea

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Adaptation

• Pre-Darwinian idea
• Old School Adaptation

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a detour Very brief history of evolutionary
thought
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Evolutionary Thought Timeline

• Wallace
• Darwin

Mid-late 1800s
Process but not mechanism of inheritance Evoluti
on via natural selection Descent with
modification
New Ideas?
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Some problems constraining the development of
the theory

• Lack of knowledge on age of Earth
• Species are fixed constraint
• Lack of scientific methodology
• Separate creation constraint

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Major Tenets of Darwin and Wallace

• Evolution does occur
• Change is gradual
• Millions of species
• (fossil and extant) descended
• from a single ancestor
• Primary process called
• Natural Selection

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Features of Evolution via Natural Selection

• Population produces far more individuals than can
  survive.
• Population has variability in most features
• Features are heritable
• Certain variants incur relative reproductive
  advantage

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Variation in heritable traits
Elimination of certain variants
Reproduction of survivors
Result increases the frequency of certain
variants
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Gregor Mendel (1822-1884)

• Monk / Gardener
• Geneticist
• Experiments with Plant Hybrids (- peas)
• Provided mechanism of inheritance

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Theodosius Dobzhansky (1900-1975)

• Russian geneticist
• Lab evidence for natural selection (Drosophila)
• (previous research was field observation based)
• Architect of Modern Synthesis
• Integration of genetics and evolutionary theory
• Mutation raw material for natural selection
• Concerned with misuse of theory in society

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Ernst Mayr (1904-2005)

• German training medical student natural
  historian
• Architect of Modern Synthesis
• Integration of genetics and evolutionary theory
• Isolating mechanisms and population level
  evolution (Biological species concept)

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George Gaylord Simpson (1902-1984)

• Paleontologist
• Architect of Modern Synthesis
• Fossil record lends evidence to theory of Darwin
  and Wallace.
• Evolution is not on a predetermined, directed
  path.

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Adaptation

• Old School evolutionary process by which
  organisms become better suited to environment
• New School genetically determined
  characteristic that enhances the ability of an
  individual to cope with its environment.

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Velvet mite
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Life History Notes

• Mojave Desert
• Burrow in sand
• Main food source
• Grounded termites
• Termite fall-out
• Moderate temperatures
• 1st sunny day after a rain (gt8mm)

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Daily Migration
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yes
Breed
Find Mate?
?
yes
Emerge from burrow
?
yes
Termite fall-out?
no
Favorable Conditions?
Lay eggs
Stay in burrow
no
no
Burrow
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The cost of making a wrong decision.

• Emerge at wrong time
• No food can lead to death
• No mate can lead to reduced RO
• No herd effect can lead to death via predation

Those variations of the population become
rare IOW Big cost to making wrong decision.
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Migrant birds

• Migration is energy demanding
• Staging areas to fatten up.
• If no, then fail.
• The bad weather versus predator avoidance
  trade-off
• Bad weather
• Fatten-up to survive until better conditions
• Predator avoidance
• Requires maneuverability proportional to lean
  body mass.
• The choice
• Fatten up? Payoff prior to bad weather or season.
• Remain lean? Payoff during times of high
  predation risk.

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Features of Evolution via Natural Selection

• Population produces far more individuals than can
  survive.
• Population has variability in most features
• Features are heritable
• Certain variants incur relative reproductive
  advantage
• Fitness is one component of big picture

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Fitness

• Fitness
• Generic
• Genetic
• Genotype
• Phenotype

VP VG VE VGxE
Variation in population
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Natural Selection acts here random?

• VP VG VE VGxE

Alleles different genetic information for
same gene A type produces Enzyme A B type
produces Enzyme B O type produces no enzyme
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B
A
Alleles genetic variability in the
population Allelic variation arises from MUTATION
DNA ? RNA ? Protein
Central Dogma
m
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Mutation

• Stochastic changes in genetic material
• Caused by
• Internal
• Misrepair of DNA
• Misreading of DNA by RNA
• External (Environmental)
• http//www.evol.nw.ru/labs/lab38/spirov/hazard/mut
  agen_lst.html
• Radiation (UV)
• Most are harmful or neutral
• Provides palette for Natural Selection

Not-random
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Select
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Citrus Scale in California
1 example of selection leading to evolution
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Evolution of sexual preference in Drosophila
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Back to VP

• Even though there is variability in the
  phenotype, there is still only a particular range
  of environmental conditions that any given
  organism (or population) can occupy
• Organism unit of natural selection
• Activity Performance Space
• Population unit of evolution
• Distribution

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• Thermo-tolerance graph (warm-blooded orgs)
• Activity Performance Space (Resource
  utilization curve) the optimum environmental
  conditions

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Desert Iguana
Regulation of temp
Time spent at each location varies throughout year
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Microhabitat selection favors optimum
conditions -
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Cactus Wren
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Figure 9.8
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Figure 9.7
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Downy Woodpecker Picoides pubescens BBS Summer
Distribution Map, 1994 - 2003
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Red-cockaded Woodpecker Picoides borealis BBS
Summer Distribution Map, 1994 - 2003
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Figure 9.9
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Acclimation across species
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Two porcelain crab species in N. Pacific
Petrolisthes cinctipes
P. eriomerus
Other crabs
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Coverage
P.c. P.e.
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• P.c. can handle being out of water longer
• They dont shift to anaerobic respiration as soon

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• PC can recover
• from cold temps

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Added respiratory anatomy