Introduction to Evolution - a historical persepective
Evolutionary Biology (BI 25) Lecture Notes
History of Evolutionary Theory: Pre-history - 1650
Ancient Greeks
Search for Natural Explanations
Anaximander
Empedocles
Impact of Metaphysics
Plato
Essentialism, Eternal harmony, Soul, Supernatural Creation
Aristotle
Purpose for every organism, fixity of species, ladder of life (scala naturae)
St. Augstine
Creation According To Seminal Principles
Creation in 7 days - may not be 24 hr days
nature has the potential to produce and evolve
Middle Ages
Natural Theologians and Creationism
Bishop Usher
Protestant Reformation and Fundamentalism
History of Evolutionary Theory: Pre-history - 1650 and 1865-1925
Renaissance
Ray - catalogs/classifications of species of plants and birds
Linne
Linnean Hierarchy (Kingdom, Phylum, Class, Order ...)
Binomial epithet (genus species: Homo sapiens or Homo sapiens)
Physicists, Astronomers break with traditional beliefs (Galileo, Bacon, Descartes)
solar system debate - earth versus sun as center of the universe
Kant - first ideas about the Big Bang that created the solar system
1800's
Buffon - near the turn of the century
biogeography of mammals (predatory cats)
concept of species based on reproductive isolation (basis for modern species concept)
Cuvier
dilemma of fossils, previous ideas: fossils are examples of organisms growing out of rocks, killed off by the Great flood
fossils, extinction, catastrophism
Rise of Geology
Smith (principles of stratification), Lyell and Hutton - uniformitarianism
Lamarck - introduces concept of change through acquired inheritance, les sentiments interieur
Paley - last summary of creationism and natural theology
collected recent and extinct specimens of organisms from all over the world during voyages on the HMS Beagle
studied materials back in England - influenced by the fauna of the Galapagos islands - Galapagos Tortoise, Galapagos Mockingbird and Galapagos Finches
Galapagos Mockingbirds and Darwin
Influence on Darwin - different varieties/species/subspecies on different islands
Subspecies of Galapagos Mockingbird (courtesy of Dr. R. L. Curry, Villanova University)
Close Island relatives (courtesy of Dr. H. Rothman, RIT)
Hood Mockingbird
Chatham Mockingbird
Close mainland relatives
Probable ancestor - Long-tailed Mockingbird (courtesy of Dr. H. Rothman, RIT)
Giant Galapagos Tortoise and Darwin
English Governor, Nicholas Lawson claimed that he could 'pronounce with certainty from which island any tortoise had been brought' from the shape of its shell.
dome-shaped tortoises - domes is adaptation to pas through lush, thick vegetation of cloud forests on Isabela, and Santa Cruz (courtesy of Dr. J. Flanagan and or World Chelonian Trust)
intermediate tortoises - Wolf Volcano on Isabela and Santiago islands (courtesy of Dr. J. Flanagan and or World Chelonian Trust)
saddle-back tortoises - high front of carapace so they can raise their heads to feed on higher vegetation found on arid islands of Española, Pinzón, and Pinta (courtesy of Dr. J. Flanagan and or World Chelonian Trust)
Galapagos Finches and Darwin (courtesy of Dr. H. Rothman, RIT)
read Malthus' work on human populations and famine
noticed the results of artificial selection, sparked ideas about natural selection
Accumulated evidence for theory of evolution
geographic variation in species, comparative anatomy, comparative embryology, biogeography,
artificial selection, classic example of the use of scientific method and hypothetico-deductive method
1859 Linnean Society Meeting - co-authors famous paper on evolution by natural selection with Wallace
studied animals of Malaysia and surrounding archipelagos - Wallacea and Wallace's Line
read Malthus' work on human populations and famine while being struck with Malaria
1859 Linnean Society Meeting - co-authors famous paper on evolution by natural selection with Darwin
Mendel - working on studies of inheritance using peas, remained an unknown contribution until the early 1900s
Darwin-Wallace theory of evolution - basic tenets
evolution is change in populations over time
mechanism of change is natural selection, selects for most fit individuals and against less fit
natural selection can occur when
there is variation among individuals
some individuals are better fit/adapted to their environment than others
there are differences in productivity, some individuals leave more offspring behind in future generations than others
evolution is gradual, takes a long time, can't be observed in one person's lifetime
Emerging evidence - Discovery of Archaeopteryx by Von Meyer
Social Darwinism and influence on colonization by Europeans
History of Evolutionary Theory: 1865-1925 and 1926-1960
Early 1900's - leads to the New (neo-Darwinian) Synthesis
Mutationists
DeVries
Neo-Darwinian Synthesis - Everyone gets together and explains how evolution supports their ideas
Mathematicians
Hardy, Weinberg and the Hardy-Weinberg Equilibrium
Fisher, Haldane, Wright
Pearson and statistics
Geneticists - Fruit Fly Biologists
Morgan, Chetverikoff, Dobzhansky
Evolutionists
Mayr and speciation
Paleontologists - Simpson
Botanists - Stebbins
History of Evolutionary Theory: 1926-1960 and 1961-2003
Recent 1900's - leads to the "Unfinished Synthesis"
1953: Watson and Crick - discovery of DNA
Biochemical systematics
Immunology, Proteins, mtDNA, cl DNA, nuclear DNA
DNA-DNA hybridization
Nei and genetic distances
PCR and genetic sequencing
Debate over whether natural selection versus neutral evolution better explains change in populations and leads to speciation
Study of adaptation-using rigourous experimental testing versus idle-Darwininzing
Advances in paleontology - debate over punctuated versus gradual equilibrium
Study of ancient DNA - molecular paleontology
Hubble telescope and Big Bang
Advances in Embryology and Development, links with genetics (hox genes turn on and off developmental pathways)
New developments in systematics and theory of taxonomy
THE EVIDENCE FOR MICROEVOLUTION
Artificial selection
dogs, cats, horses, cattle, etc.
Some Genetic Variation Maintained by Natural Selection
Sickle-Cell Anemia
Disease affects shape of hemoglobin molecule
Causes red blood cells to assume irregular, elongated shapes
Molecules form long, fibrous clumps that deform blood cell
Sickle-cell trait
Heterozygous, Ss individuals
Produce few sickle-shaped cells
Frequency of recessive allele in various populations - geographic distribution
Recessive allele maintained at unusually high levels
Heterozygotes less susceptible to malaria
Heterozygous women more fertile than homozygotes
Environment acts to maintain allele frequency
Selective force in Africa is presence of malaria
Maintenance of allele has adaptive value in Africa
No such selective force in US black population
Selection acts to eliminate allele in US
Peppered Moths and Industrial MelanismLead ToleranceEuropean moth that rests on trees during daytime
Prior to 1850 most had light-colored wings
After 1850 most had dark-colored wings
Possess dominant allele
Allele rare in populations until then
Observed dark tree trunks in industrial areas
Dark moths less conspicuous on their surfaces
Air pollution killed light-colored lichens
Kettlewell hypothesis: birds ate moths on trees
More dark moths survived in polluted areas
More light moths survived in unpolluted areas
Trends reversing due to pollution controls
Bent grasses grow on lead mine refuse
Soils contain toxic chemicals
Few plants survive conditions
Comparison of plants in pasture and mine refuse areas
Mine plants in pasture soil survived but grew slowly
Mine plants in mine soil grew well
Most pasture plants in mine soil grew poorly if at all
Few exceptions that grew well
Were of same ancestral stock as mine plants
Genetic predisposition to lead tolerance
Population change is rapid when environment demands it
Adaptation
Documented cases of adaptation exist as indicated above
More medical examples
Darwinian medicine - antibiotic resistance (microorganisms, strains of the AIDS virus)
Environment dictates direction and extent of change
THE EVIDENCE FOR MACROEVOLUTION
The Fossil Record
Discovery of Archaeopteryx
Subsequent discoveries of bipedal ancestors
Formation of fossils
Imprints of dead organismsOrganisms buried in sediment
Calcium in bone and hard tissue is mineralized
Fossil bonesExample of sedimentary rocks - Grand Canyon and other Canyons of the western US
Date of rocks reflects age of fossils
Dating in Darwin`s day solely by relative position
Recent dating uses more accurate techniques
Measure rate of radioisotope decay
Example - radioisotopes and half-lives
Rate constant over time, not affected by temperature or pressure
Fossils arranged from oldest to youngest
Provide evidence of progressive evolutionary change
Examples
Hoofed mammals
Horse evolution
Human evolution
The Molecular Record
Progressive evolutionary change implies a change within DNA
Result from accumulation of genetic changes
Distant relatives have greater number of differences
Comparison of DNA sequences between organisms
Greater time since divergence associated with more nucleotide changes
Example: cytochrome c
Example: hemoglobin
Phylogenetic tree
Pattern of genetic descent
Determined by comparing nucleotide sequences
Often similar to relationships predicted by anatomy
Homology
Structures derived from common form, but functions are variable
Example: forelimbs of mammals
Development
Evolutionary history reflected in development of embryo
Embryo exhibits characteristics of its ancestors` embryos
Example: human development
Possess fish-like gill slits early in development
Exhibit tail, its vestige becomes coccyx
Possess fine fur during fifth month
Example:Other Vertebrate embryo comparisons
Vestigial Structures
Structures with no apparent function resembling those of presumed ancestors
Examples
Human ear muscles
Whale pelvic bone
Four-footed "missing link" whales
Human vermiform appendix
Convergent Evolution - Unlikely that similarities result from coincidence
Community level
Different areas may possess very distantly related communities with similar appearance
Species level
Pleiosaur - fusiform shape
Example: forms of Australian marsupials
Examples: albinism and blindness in cave-dwelling organisms
Systematics and Classification and Comparative Anatomy
Patterns of imilarities among organisms and their classification strongly suggests evolutionary origins
Patterns of Distribution
Continent - Island
Organisms on islands most closely resemble forms on nearest continent
Forms not identical, but diverged over time
Example: Galapagos Finches, Hawaiian Honeycreepers
Continent
Biogeographic realms
Blackboard at Saint Anselm College
Trademark and Disclaimers
Parts of this presentation were adapted from Raven, P., G. Johnson. 1997. Biology (4th ed.). New York, McGraw-Hill Compannies.
Evidence for Micro- and Macroevoution
http://www.mhe.com/biosci/genbio/rjbiology/ELOs/ELO21.html
Copyright © 2001 Jay Pitocchelli. All rights reserved. The contents of this page are the intellectual property of Dr. Jay Pitocchelli for distribution to students enrolled in Evolutionary Biology BI 25 at Saint Anselm College. These pages may not be copied, photocopied, reproduced, translated, or published in any electronic or machine-readable form in whole or in part without prior written approval of Jay Pitocchelli. Students enrolled in Evolutionary Biology BI 25 at Saint Anselm College have permission to print this material for their lecture notes.
