Biology 2900 Principles of Evolution and Systematics

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Biology 2900Principles of Evolutionand
Systematics

• Dr. David Innes
• Jennifer Gosse
• Valerie Power

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• Lecture Tues. Thurs 1030 - 1145 am
• IIC-2001
• Laboratory Mon Tues Wed Thr 200 - 500 pm
• SN-4110
• Labs. Week of January 7 11
• Organization of groups
• Group 1 Lab. Week of Jan. 14
• Download handout
• http//www.mun.ca/biology/dinnes/B2900/B29
  00.html

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Course Web Site

• http//www.mun.ca/biology/dinnes/B2900/B2900.htm
  l
• Course outline
• Lecture slides (pdf file)
• Lab. Information (new Lab. 1)
• Information, readings etc.
• Links to Evolution Web Page
• Midterm Test Thursday, Feb. 14, 2008

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Desire2Learn

• https//online.mun.ca/
• Login using MUN account
• 1. Course outline
• 2. Surveys i) student information
• ii) anonymous feedback
• 3. Internal email
• 4. online quizzes

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Goals

• Ask interesting questions about evolution
• Experiments and observations to answer ??
• Critically evaluate primary literature
• Contribute to the discussion of evolution between
  specialists and public
• Think like evolutionary biologists !!!!

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Evolution Thinking

• Why do organisms age and die ?
• What do fossils tell us about the evolutionary
  history of plants and animals?
• Why do some male spider sacrifice themselves
  during mating?

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Example
Sex and death in the Australian red-back spider
Sexual cannibalism How could
evolution have produced a behavior that reduces
the chance of survival ? (Research of
Dr. Andrade, U. of T.)
male
male
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Experimental Results

• Cannibalized males copulated longer and
  fertilized more eggs than those that survived
  copulation
• Females were more likely to reject subsequent
  suitors after consuming their first mate
• Empirical evidence for male copulatory
• suicide as an adaptive behavior

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Chapter 6 How to make love to a cannibal
Olivia Judson
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• Evolution
• a change in the properties of groups of
  organisms over the course of generations (ie.
  time) (Futuyma, 2005)

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• current life forms differ from those of previous
  times and yet are descended from them
• Descent with modification

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• The study of Evolution
• - how populations change in response to their
  environment
• - formation of new species
• The Study of Adaptation and Diversity

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• The Fact of Evolution
• - evidence from biology and geology
• - species have changed through time
• - descended with modification from common
  ancestors

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• The Fact of Evolution
• Evidence
• 1. relatedness of life forms
• 2. change through time
• 3. age of the earth

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• Relatedness of life forms

Morphology homology (vert. limb
bones) Molecular conserved structure and function
Cytochrome c Cellular respiration 3D structure
based on amino acid sequence
Tuna fish
Rice
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Darwin

• One of the most revolutionary ideas in the
  history of science
• All organic beings which
• have ever lived on this earth
• have descended from some
• one primordial form

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The Fact of Evolution

• A scientific theory is a mature, coherent body
  of interconnected statements, based on reasoning
  and evidence, that explains a variety of
  observations
• The fact of evolution is explained by
  evolutionary theory

Futuyma, 2005
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• The study of Evolution
• (Adaptation and Diversity)
• Where do living things come from ?
• Why are there so many different kinds of
  organisms ?
• How have organisms adapted so well to their
  environment ?

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• Darwin (Origin of Species)
• Existing species are the modified descendants of
  forms that existed previously
• (descended from common ancestors)
• But how ? ?Natural Selection
• Theory by C. R. Darwin and A. R. Wallace

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Artificial Selection

• The mechanism of evolution under domestication
• 1. Phenotypic Variation
• 2. Variation heritable
• 3. Selective breeding (non-random
• survival and reproduction)

C. Darwin (1868) The variation of animals and
plants under domestication
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C. Darwin (1883) The variation of animals and
plants under
domestication
http//www.esp.org/books/darwin/variation/facsimil
e/title3.html
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Dogs
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Domestic Cats
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Pigeons
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Cabbage
Brassica oleracea
Wild Cabbage
Kale
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Natural Selection

• Darwin realized that a process much like
• artificial selection happens in
  nature
• Why did it take so long to realize a connection
  between the power of artificial selection and the
  potential of natural selection for evolution?

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Phenotypic Variation in Natural Populations

• Phenotypic Variation among individuals within a
  wild species much more subtle

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Phenotypic Variation in Natural Populations
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Natural Selection

• The Theory of Evolution by Natural Selection
• Evolution is the logical outcome of 4 postulates

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Evolution by Natural Selection

• 1. Individuals within populations variable (Lab
  1)
• 2. Some variations inherited by offspring
• 3. Some individuals more successful at surviving
  and reproducing than others
• 4. Survival and reproduction not random tied to
  the variation among individuals

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• Individuals within populations variable
• - observed phenotypic variation
• 2. Some variations inherited by offspring
• - offspring resemble parents
  (mechanism?)

Evolution by Natural Selection
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Evolution by Natural Selection

• 3. Some individuals more successful at surviving
  and reproducing than others
• - enormous reproductive potential
• Aphid ?
  524 billion/yr
• House fly ?
  191 x 1018 in 5 months
• Thomas Malthus' Essays on
  Population
• http//personal.clt.bellsouth.net/t/a/tarab
  yl/malthus.htm

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Evolution by Natural Selection

• 4. Survival and reproduction not random tied to
  the variation among individuals

Two phenotypes white, yellow
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Natural Selection

• If the 4 postulates true, then the composition of
  the population changes from one generation to the
  next
• Natural Selection produces decent with
  modification (Evolution)

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• Fitness
• Ability of an individual to survive and reproduce
  in its environment
• Adaptation
• Traits that increase fitness relative to
  individuals without the traits

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Adaptation

• PBS Webpage
• http//www.pbs.org/wgbh/evolution/library/01/index
  .html

Praying Mantis
Praying Mantis leaf mimic
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• Implications and consequences of NS
• -natural mechanism for evolution
• -descent from common ancestor ? order
• -natural classification ? hierarchical
• -all living things related ? phylogeny
• -humans evolved
• Darwin-Wallace Theory of NS testable

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• Can natural selection lead to evolutionary change
  ?
• Model systems to test natural selection
• Galapagos Finches - P. R. Grant

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Galapagos Islands
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• Galapagos Finches
• - 13 closely related species
• differ in beak morphology
• Variation associated with food eaten
• http//www.youtube.com/watch?vv16aG5Ve0q0

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Geospiza fortis
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(No Transcript)
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• Test of 4 postulates
• Geospiza fortis on the island of
• Daphne major
• 1. Are populations variable ?
• 2. Variation heritable ?
• 3. Only some offspring live to reproduce ?
• 4. Survival and reproduction nonrandom ?

If 1, 2, 3, 4, true ? evolution by natural
selection
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• 1. Variation in Bill Depth

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2. Heritability of Bill Depth
Fig 9.20
Offspring Bill Depth (mm)
1978 1976
VP VG VE H2 VG / VP 0.90
Midparent Bill Depth (mm)
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Seed abundance
Pop. Size
Large Hard
Seeds
3. Not all individuals survived. 4. Was survival
nonrandom with respect to bill size ?
Small Soft
1977 drought
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Before drought
After drought (survivors)
4. Survival nonrandom with respect to bill size.
Beak Depth (mm)
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Natural Selection

• 1. Large amount of variation in bill depth
  (phenotypic)
• 2. Much of variation heritable (genetic)
• 3. Drought resulted in decreased survival
• (due to change in food resource)
• - only some individuals survived to
  reproduce
• 4. Survival and reproduction non-random with
  respect to bill
• depth (birds with larger bills
  favoured)

Did the population evolve?
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Natural Selection

• Did the population
• evolve?
• Yes!!!
• Evolutionary change also evident in
  parent-offspring regression

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Bill Depth Parent Offspring regression
Fig 9.20
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1978 1976
Offspring Bill Depth (mm)
Midparent Bill Depth (mm)
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Natural Selection

• Large amount of variation in bill depth
  (phenotypic)
• Much of variation heritable (genetic)
• Drought resulted in decreased survival and
  reproduction
• (due to change in food resource)
• - only some individuals survived and
  reproduced
• Survival and reproduction non-random with
  respect to bill
• depth (birds with larger bills
  favoured)

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Natural Selection

• Finches with a larger, deeper bill had an
• advantage (directional selection)
• Drought resulted in only larger, harder seeds
• Wet years abundant small, soft seed
• smaller bills favoured
• Natural Selection is Dynamic

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Beak Size
Natural Selection Dynamic 30 years of data
Beak Shape
95 CI for 1973 data
Body Size
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• Features of Natural Selection
• 1. Acts on indiv., consequences in pop.
• 2. Evolution consists of changes in gene
  frequencies

Gen. 1
Freq.
Gen. 2
Phenotype (ie. Size)
If Heritability 0
If Heritability gt 0
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• Features of Natural Selection
• 3. NS not forward looking
• 4. NS acts on existing traits
• 5. NS directed, not random
• 6. Fitness not circular (Survival of the
  fittest)
• 7. NS acts on individuals not groups

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• Features of Natural Selection
• Components of fitness
• - survival
• - reproduction
• More offspring produced than can survive
• (Potential for exponential population growth)

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Examples of Natural Selection
Fig. 13.3 Soapberry bug
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Examples of Natural Selection
Fig. 13.3 Soapberry bug
Native host plant
Introduced host plant
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Natural Selection

• molecular/morphological change over
• very short time intervals
• small changes
• can small changes over short time
• intervals lead to larger changes over
• longer time intervals ?

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• Changes
• Microevolution to Macroevolution
• Requires very long periods of time

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• Age of the Earth
• - about 4.6 billion years ago
• - first evidence of life 3.8 billion years ago
• - over long periods of time, small changes become
  large

Fig. 3.12 60 year corn oil selection experiment
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• Origin of New Species?
• - Physical isolation (dispersal and colonization)
• - Divergent natural selection (diff.
  environments)
• Natural selection can explain - adaptation
• 
  - diversity

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• Problems that concerned Darwin
• 1. Source of variation ? mutation
• 2. Inheritance ? Mendel
• 3. Age of the earth ? radioisotopes

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• Modern Synthesis
• Synthesis of variability, inheritance and time
• 1932 - 1953
• - botany, systematics, population genetics,
  paleontology

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Evolution by Natural Selection

• Complexity in nature
• - how random changes can lead to order ?
• - how can complex structures evolve through the
  gradual accumulation of small changes ?

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• The Eye
• Evolution of a Complex Structure
• - each step had to increase fitness
• - are there diverse forms of eyes, some more
  complex than others ?

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Mollusc Eyes
Pigment spot
Pigment cup
abalone
octopus
Marine snail
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Evolution of the eye

• http//www.pbs.org/wgbh/evolution/library/01/1/l_0
  11_01.html

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Evolution by Natural Selection

• Observed diversity of life
• Organisms adapted to their environment
• The fact of evolution
• NS a mechanism for explaining
• observations
• Natural Selection in Humans ?