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Concepts in Evolution – Fall 2010
Contact Information
Karl Kjer, Associate Professor, Ecology Evolution, and Natural Resources
Office: 121 Blake Hall. Phone: 732-932-9880
The best way to contact Kjer is through E-mail; [email protected]
If you ever want to meet, (and I encourage you to do so), just send me an E-mail and come over. I
much prefer that to meetings that are scheduled long in advance.
Broad overview
Welcome to “Concepts in Evolution”, and possibly, to graduate school. This course is
designed to bring all the graduate students in DEENR to the same starting point in terms of what
every scientist needs to know about evolution. I want you to get to know one another, and see some
of the habitats that New Jersey has to offer. Before breaking down the subject matter, I think we
should consider the objectives in broader terms.
Broad Objective 1: Evolution is a basic underlying principle in biology:
Evolution explains why things look the way they do, why they act the way they do, and
why they are where they are. But saying so, doesn’t make it so. We need examples, and
explanations. Ostriches, Emus, and Rheas look alike because they share a common ancestor that
looked like them… a long time ago, on Gondwanaland. Spiny plants in the old world and the new
world look alike because they live in the same habitat, and have converged on the same water-saving
design. Common ancestry and convergence explain a lot of things, but you need a phylogeny in
order to tell them apart. Why do birds lay eggs? “Because their ancestors did” is not the typical
answer you get from ecology students, but it is an answer we all need to be exposed to. Their
ancestors were therapod dinosaurs, whose ancestors developed a hard-shelled egg long before birds
evolved. Where on the tree of life was “hard-shelled eggs” a new innovation, and for which taxa is
it an ancestral character? We need to be able to recognize the difference between innovation and
ancestry, because they have very different implications.
Broad Objective 2: Making the switch from students to scientists
I also think that one of the general goals of this class is to shift from being stars in the
classroom (which you ALL were) to being star scientists. Phylogenetics and population genetics
offers an excellent introduction to moving away from memorizing facts to evaluating evidence. The
“conclusions” generated from population genetics are only as good as the assumptions that go into
the analysis (What are the assumptions of Hardy-Weinberg, and how realistic are they?) We can
never repeat the experiment that led to life on earth, so we can never “know” a phylogeny is “true”.
This means that phylogenies cannot simply be lifted out of papers and used as “facts” Stop
thinking about “facts”; science has little place for facts. Evidence must be understood, and
evaluated, and this means that scientists must understand the details of analytical assumptions.
Recognizing the dependence of science on our analytical assumptions is something new to most
students. This is why I think it is important to maintain the level of detail in explaining how
evolutionary inferences are made. You may not make cladograms for a living, but you are all
headed down a path of evaluating evidence, and it is hoped that this kind of critical thinking will
cross over into whatever field you pursue.
Resources
The course reading materials will be presented on the Rutgers eCompanion website;
http://rutgersonline.net/
Please check the eCompanion site before every class for readings. Follow the links, and enjoy
yourself.
The Compleat Cladist Wiley, Siegel-Causey, Brooks and Funk
University of Kansas special publication 19 (Available under “Doc Sharing” in eCompanion)
(not required, see also reading list)
The tree of life Lecointre and Le Guyader, Belknap press, 2006
eCompanion Website
The course is organized on the eCompanion website. Text files are extensively hyperlinked, and I
expect you to explore the subject material on your own for each topic, using the text file on the
website as a resource. There is an example of the text file for the first day at the end of this syllabus.
Reading materials will be posted on the "doc sharing" portion of the website. I will post your scores
within one day of each quiz, so you can track your standing at any time on the website.
Evaluation
There will be no exams this year. But before you sigh in relief, I expect you to study
(perhaps more than you would for three exams). Instead of exams, the first 10 minutes of every
class period will be dedicated to a short quiz. Two areas will be covered; one on the current days
reading assignment, generally in lesser detail, and the second about previous material (probably the
previous period, but sometimes about earlier material). Each of the two parts is worth 3 points. One
point will be given for saying anything at all that is reasonable (Do NOT leave it blank, because you
can probably get a point for saying something). Two points for getting something right, but missing
something. Full credit for a correct answer. There will be no makeup, although extra credit may be
arranged to make up for up to 3 absences. Those arriving late to class will not be given extra time to
complete the quiz. These quizzes will allow the instructors to monitor student understanding. I ask
that students communicate with us about how this system is working for them, so that I can make it
better. I also expect that daily evaluations will encourage students to come to class prepared, having
read the assigned materials in advance.
Other assignments may be given for credit.
Grading
94-100%
A
90-93%
A87-89%
B+
84-86%
B
80-83%
B77-79%
C+
74-76%
C
70-73%
C64-69%
D
60-63%
DYou can monitor your grades on the eCompanion website.
Field Trips
One of the most important objectives of this course is to introduce you to your classmates.
You will be together through all the years of your graduate education, and many of you will
collaborate with one-another for the rest of your lives. Look around; these people will be your
colleagues, and your friends. A good way to get to know people is to spend some time in the field
with them.
The second objective of our field trips is to show you around to various ecosystems in New
Jersey, and to some of the field stations and resources available to you. Not all of you have decided
upon a research project, and I hope to get you thinking about that.
Field trips will be on Fridays in September, and one trip in November. I have reserved vans
for transportation. We will leave from the parking lot in front of DEENR. Once a time has been set,
we leave at that time, so please don’t be late. There are always people who can’t make some of
these trips for one reason or another. Don’t panic; we can find a way to make it up, but please
come if you can.
Sep. 3
Sep. 10-11
Sep. 17
Hutcheson Forest: Morning only, back by noon for orientation picnic.
Stokes State Forest, overnight camping
Tuckerton Salt Marsh: 8-5
Sep 24
Pine Barrens: 8-5
Early Nov (to be arranged)
Philadelphia Academy: 8-5
Concepts in Evolution – Fall 2010 Schedule
Any of these dates are subject to change.
09-01-10
Kjer - Class: Introduction, Darwin and Natural Selection
09-03-10 Kjer/Tartaglia
Field: Hutcheson Memorial Forest (all morning)
09-08-10
09-10-10
Kjer
Kjer
Class: Cladistics and trees; Lab: Morphological matrix
Field: Stokes State Forest (overnight)
09-15-10
09-17-10
Struwe Class: Tree of Life: Life begins - overview of Bacteria, Archea
Kjer/Turnure Field: Rutgers Marine Field Station
09-22-10
09-24-10
Kjer - Class: Tree of Life: Metazoa
Kjer/D. Ehrenfeld - Field: Pine Barrens (all day)
09-29-10
10-01-10
Kjer Kjer -
Class: Tree of Life: Vertebrates
Class: Tree of Life: Plants
10-06-10
Kjer -
Class: Species Concepts; Lab: Butterfly exercises
10-08-10
Kjer -
Class: Species Barcoding; Seminar by Damon Little, 12:30 in 237 Foran
10-13-10
10-15-10
Kjer Kjer -
Class: Speciation
Class: Biogeography ; Lab: Exercises, DIVA analysis
10-20-10
10-22-10
Kjer Kjer -
Class: Sex in plants
Class: Phylogenetic Data; Lab: PCR in Blake 129
10-27-10
129
10-29-10
Kjer -
Class: Properties of molecular data, and Homoplasy; Lab: PCR in Blake
11-03-10
11-05-10
Fonseca
Fonseca
11-10-10
11-12-10
Fonseca
Fonseca
Green - Class: Introduction to Bayesian statistics
11-17-10
Kjer 11-19-10
Kjer Essay due, 11-20
11-24-10
No class -
Population Genetics
Nomenclature and support indices
Museum trip (Acad Nat Sci, Philadelphia) – all day
Thanksgiving Week
11-25-10 is thanksgiving
11-26-10 No class - Thanksgiving Week
12-01-10
12-03-10
Kjer
Maximum Likelihood; Lab: Phylogenetic software
Jordan Adaptation and behavior
12-08-10 Kjer 12-10-10 Kjer -
PAUP
Class: Bayesian phylogenetics
Creationism
Concepts in Evolution – Fall 2010 Syllabus
We will be breaking the subject into three areas; The “tree of life”, population genetics
(patterns of relationship WITH geneflow), and phylogenetics (patterns of diversity in absence of
geneflow). Other areas we will explore will depend on the expertise and interests of our guest
speakers.
The “Units” on the eCompanion site have little real meaning, other than to break the
materials up in chronological order.
Unit 1: Introduction
09-01-10
Kjer - Introduction, Darwin and Natural Selection
History of Evolution: Linnaeus, Lamarck, Darwin and Natural Selection, the modern synthesis.
We study history for two reasons.
First, if I am having a chat with a colleague, and I find out that she has never heard of
Linnaeus, and that she doesn’t know that Darwin sailed on the Beagle, I have a diminished opinion
of her as a scientist. I’m not talking about posturing; this is a matter of cultural literacy. There are
just things you need to know.
Second; (and this is far more important) studying how these people figured out what they did
gives us insights into our own careers. Darwin was subject to the norms and constraints of his
world’s view. So are we. How are we to discover new things, if we only accept what is already
“known”? How do current concepts enhance or inhibit new ideas? How do revolutionary ideas
come to pass? You may not be the next Charles Darwin, but you might be. And even if it is not
your destiny to revolutionize the world as we know it, the things you discover are important, and
they will develop over time the same way these huge ideas did. We can learn from history.
09-03-10 Field: Hutcheson Memorial Forest (all morning) We will meet there at 9:30, so check the
website below for directions.
http://rci.rutgers.edu/~hmforest/
09-08-10
Kjer - Cladistics and trees
Cladistics: Homology, Apomorphy, Plesiomorphy, character, monophyly, paraphyly, sister taxon,
synapomorphy, clade …
Tree thinking is a skill that seems intuitive to professional systematists, but must be taught to
newcomers (and generally is not taught, except in a class like this one). The objectives of this
lecture is to introduce the basic terms of cladistics, and to teach how we interpret the information
found in a phylogenetic tree. This is important because phylogenetic trees convey an enormous
amount of information, and studies have shown that most college biology majors are unable to
interpret them. Many important concepts of evolution can be symbolized with these branching
diagrams.
Lab: Morphological matrix
We will be given a box of insects. Break into teams of three, and construct a data matrix, with
which we will infer a phylogeny, using PAUP.
09-10-10 Kjer - Field: Stokes State Forest (overnight)
http://www.state.nj.us/dep/parksandforests/parks/stokes.html
Unit 2: The Tree of Life
The tree of life: Life is monophyletic. How are the different forms related to one another? What
are the characteristics shared through common ancestry of the major groups of life, and when did
they occur on this one grand history? (Cladograms for these lectures are available in eCompanion)
09-15-10
Kjer - Tree of Life: Life begins - overview of Bacteria, Archea
Broad overview- Most of the genetic diversity of life is prokaryotic. Woese’s three superkingdoms
are Archaea, Prokaryota, and Eukaryota. So how are the non-eukaryotes different, and what
roles do they play? Lots of bacteria and germs in this lecture.
Eukaryotes (except Metazoa and green plants, which are covered later): fungi, slime molds, ciliates,
golden algae and many other small creatures.
09-17-10
(Turnure) Field: Rutgers University Marine Field Station
http://marine.rutgers.edu/rumfs/RUMFSpersonnel.htm
09-22-10
Kjer - Tree of Life: Metazoa
Metazoa- These are multicellular animals, from cnidarians, poriforans and echinoderms, all the way
up to annelids (Ha!, I bet you thought I would say Humans, but that betrays your underlying
misconceptions about evolution... yeah, vertebrates are part of that group too, but only a tiny twig on
the tree)
09-24-10
(Ehrenfeld)
Field: Pine Barrens (all day)
http://marine.rutgers.edu/pinelands/index.htm
09-29-10 Kjer - Tree of Life: Vertebrates
Vertebrates- “Fish”, Amphibians, Archosaurs, Mammals, Birds... Did you know that you are a
fish? Details here.
10-01-10 Kjer - Class: Tree of Life: Plants
Green Plants – nearly everything with chlorophyll on Earth, from green algae to mosses and
orchids, and the reason why we have lots of oxygen to breath
Unit 3: Species
10-06-10
Kjer - Species Concepts;
The recognition of species as things we can name goes all the way back to when your
parents pointed to a picture of a duck, and said “duck...quack quack...” What did they mean,
and why do all cultures teach this to infants? Are species real? How do we define them? It
turns out that this seemingly simple question has bothered scientists for centuries, and we
still struggle with it. One of the main objectives of this lecture will be to introduce the idea
that defining species is an extremely difficult process.
1. The biological species concept. Strengths, weaknesses, and practitioners.
2. The phylogenetic species concept. Strengths, weaknesses, and practitioners.
3. Besides these two, the students should recognize phenetic species concepts, and
current applications of phenetics.
Lab: Butterfly exercises; Given a box of butterflies, we will make species identifications
10-08-10
Kjer - Barcoding. Collecting a short sequence of DNA, in order to identify species.
What are its promises, and limitations. Kjer will talk about his experience with the Barcode of Life
initiative in Guelph
Damon Little will give a seminar on plant barcoding at 12:30 in 237 Foran
10-13-10 Kjer - Speciation and nomenclature
Speciation. How do populations subdivide into new species? What are the barriers to gene flow?
Speciation in terms of distribution.
10-15-10
Kjer -
Biogeography ; Lab: Exercises, DIVA analysis
10-20-10
Kjer - Sex in Plants. We all know a bit about birds and bees, but what about plants?
They are really different when it comes to sex.
Unit 5: Phylogenetics
How did the patterns of diversity come about, and how are these patterns inferred?
10-22-10 Kjer - Phylogenetic Data;
Phylogenetic data
What are allozymes, RFLPs, DNA…? What makes for a good dataset, and how do these differ with
time scales, and the questions you are exploring
Lab: PCR in Blake 129. Polymerase chain reaction (PCR) has become such a central part of
molecular lab techniques, I think we should all have done it, at least once.
10-27-10 Kjer - Homoplasy and support; Lab: PCR in Blake 129. Part 2; Horizontal agarose gel
electrophoresis to see if the PCR worked.
10-29-10 Bayesian statistics is taking over. Ed Green is a real expert, and he will be introducing
it. Bayesian methods are currently the dominant means of generating phylogenies. Pay close
attention to MCMC, AIC, priors, and posteriors.
Unit 4: Population Genetics
How do genes (traits) move within species, and what does this tell us? Dina Fonseca will supply
details to come
11-03-10 Fonseca
11-05-10 Fonseca
11-10-10
11-12-10
11-17-10
Kjer - Nomenclature
What is a Holotype, Paratype and other terms?
How are species described, and who describes them?
What is a biological museum and what is it used for
Tree support
Given that we never “know the truth”, how do we evaluate phylogenetic hypotheses? This is
particularly important for ecologists or others, who may wish to use phylogenetic hypotheses for
interpreting their work, but are not constructing trees themselves. What do bootstraps, jack-knife
values, and decay indices mean?
11-19-10
Kjer -
Museum trip (Acad Nat Sci, Philadelphia) – all day
http://www.ansp.org/research/index.php
11-24-10
11-26-10
No class No class -
Thanksgiving Week
Thanksgiving Week
12-01-10
Kjer - Maximum Likelihood, PAUP, Parsimony;
M.L. What is likelihood, and how does it work?
Parsimony. What is the principle of parsimony (in the broadest sense), and how is it applied
as an optimality criterion for inferring phylogeny? What are its strengths, and weaknesses,
and who are its practitioners?
Lab: Working exercises with phylogenetic software, from the data matrix produced earlier.
12-03-10
Jordan -
Adaptation and behavior
12-08-10 Kjer Kjer - Maximum Likelihood and Bayesian phylogenetics
Correction methods, models, and Likelihood.
What kind of trees are hard to recover with parsimony, and how can models be used to correct for
things like long branch attraction, nucleotide compositional bias, and among-site rate variation.
12-10-10 Kjer - Creationism. There are powerful forces involved with the politics of this issue,
and by powerful forces, I don’t mean God. We used to be able to ignore this issue, because it was so
deeply rooted in ignorance. Now it is a battle for hearts and minds, with huge consequences.
Example of Website Content: Please follow the hyperlinks to fully explore the topic.
Introduction and History- Concepts in Evolution
Please spend some time on the web reading about the history of evolutionary thought. Here are some good starting sites
http://evolru.rutgers.edu/index.html
http://evolution.berkeley.edu/
Systematics ...classification and naming of organisms AKA Taxonomy. Used to be interchangeable synonyms. What is the
difference? ...connotation. Systematics ...modern ... includes phylogenetics, Taxonomy can be limited to classification outside of a
phylogenetic framework.
Alpha taxonomy is species description
The dominant philosophy of systematists today accept that classification is linked to relationships, so taxonomy too may be
relationship oriented.. And this is where systematics has become linked and perhaps synonymous with phylogenetics.
Phylogenetics is the study of the relationships among organisms.
Evolution=change through generations:
Darwin called it "descent with modification"
Four stages:
1. Pre-Darwin
2. Darwin's theory: evolution through (1859)
3. Natural selection rejected (c.1880-1920)
4. The modern synthesis (1920s-1950s)
You should all be able to put events and influences in order.
Pre Darwin: Species fixitiy, but people were not stupid...
Carl von Linné or Carolus Linneaus- (1707-1778) http://www.ucmp.berkeley.edu/history/linnaeus.html
A physician; all doctors studied plant taxonomy. An essentialist, set out the system of binomial nomenclature we use today. An
essentialist believes that each species is given it’s unchanging “essence” from God, and it is this essence that is passed on from
generation to generation.
Strong essentialist
Set up binomial nomenclature
Still used today
How many here would submit themselves to 18th c surgery?
Essentialist?
When things work, you don’t need to get all the pieces right
Turns out that Linnaeus was sorting things based on Characters
As opposed to grand schemes of organization
Characters are heritable- like genes
Characters are subject to natural selection
Buffon- (1707-1788)
http://www.ucmp.berkeley.edu/history/buffon2.html
Each species has an unchanging internal mold, but species within a genus share the same mold, which was inherited from a common
ancestor
The earth is 60-70,000 years old. He noticed Lamarck’s potential, and supported him.
There were challenges to the world views of unchanging essentialism:
Erasmus Darwin
How many of you believe that the writings of Darwin’s Grandfather had no influence on him?
Jean-Babtist Lamarck (1744-1829)-Philosophie Zoologique (1809)
http://www.ucmp.berkeley.edu/history/lamarck.html
Lamarck argued that species DO change over time.
http://evolution.berkeley.edu/evolibrary/article/0_0_0/history_09
Mechanism similar to what we now label as "transformism". Darwin gets the credit, while we make a joke of Lamarck.
Transformism: preprogrammed "logical" chain of events
Fig. 1.1
Lineages persist indefinitely, changing from one form to another. Did not branch or become extinct. Change is a result of "internal
forces". These internal forces are of unknown mechanism, causing organisms to give rise to offspring that are slightly different. After
many generations, these slight differences may become significant enough so that we would recognize a new species. Lamarck's
second mechanism is what he is remembered for today: the inheritance of acquired characteristics. These characteristics can be
acquired through diet, accidents, diseases or muscular activity. Environment changes, causing use and disuse of organs or parts-use
produces a nervous fluid that promotes growth; change as a result of a changing environment
Example: a giraffe stretches to reach the tasty leaves, and as a result, its neck becomes longer (can happen: think of lip plates or neck
rings in humans). The neck-stretcher then gives birth to a giraffe with a slightly longer neck (can't happen: think of same human
examples). Lamarck talked about the process being driven by some sort of "striving", and described animals as "wishing", or
"willing" change upon themselves. He believed in the ancient age of the earth, and that change was gradual, through use or disuse.
Sum up: Lamarck thought that acquired characters could be inherited. This is an ancient idea: Plato discussed it. But now called
"Lamarckian inheritance"
Lamarck was not a popular man, and there were those who enjoyed putting him down. One of these was Georges Cuvier (17691832).
http://www.ucmp.berkeley.edu/history/cuvier.html
Cuvier's school looked at fundamental and unalterable body plans. The plan was so exquisite, that any change would destroy the
whole. Cuvier was a paleontologist who could reconstruct entire body plans from a single bone fragment. He proved extinctions,
http://evolution.berkeley.edu/evolibrary/article/0_0_0/history_08
comparing fossil elephant teeth from Italy to those of extant African, Indian and fossil Siberian, mocking the idea that there could be
elephants we don’t know about. Animals could go extinct, but could not change. Cats don’t change; look at the Egyptian mummies
he said! Cuvier noticed that the deeper you looked in the rocks, the less the fossils looked like living animals.
But think about extinction in context of unexplored regions
Jefferson thought that Lewis & Clark might encounter mammoths. Why not?
Richard Owen (1804-1892)
http://www.ucmp.berkeley.edu/history/owen.html
studied under Cuvier, and became Britain's leading anatomist. Most biologists in the first half of the 19th century accepted the
Cuvier/Owen view of unchangeable species, each of which had a separate origin, but could become extinct.
Malthus; 1798 published “An Essay on the principle of population”
http://www.econlib.org/LIBRARY/Malthus/malPop.html
Both Darwin and Wallace independently cited this work as influencing their theory
Lyall; 1830 publishes “Principles of Geography”,
http://www.esp.org/books/lyell/principles/facsimile/title3.html
which discusses the age of the earth
Darwin takes it with him on the Beagle.
2. Darwin (1809-1882)
Changed everything, and he knew it. He worried about it, and planned how he would release his findings over 20 years.
Charles’s grandfather, Erasmus Darwin (1731-1802)
http://www.ucmp.berkeley.edu/history/Edarwin.html
had to have been an influence, although most of the material I read about Darwin downplays this connection. But look at what he
said:
"The final course of this contest among males seems to be, that the strongest and most active animal should propagate the species
which should thus be improved".
Organic life beneath the shoreless waves
Was born and nurs'd in ocean's pearly caves;
First forms minute, unseen by spheric glass,
Move on the mud, or pierce the watery mass;
These, as successive generations bloom,
New powers acquire and larger limbs assume;
Whence countless groups of vegetation spring,
And breathing realms of fin and feet and wing.
Erasmus Darwin. The Temple of Nature. 1802.
Charles Darwin studied to be a surgeon, left, and then graduated from Cambridge divinity school and then traveled on the
Beagle http://www.dropbears.com/l/links/beagle.htm as a naturalist from 1831-1836. Soon settled in the
English countryside, where he lived as a life of independent means. Son of a doctor, and son -in-law of a successful businessman
http://www.nndb.com/people/821/000049674/.
On the Galapagos, Charles Darwin noted: "The distribution of tenants of this archipelago would not be nearly so wonderful,
if for instance, one island has a mocking-thrush and a second island some other quite distinct species... But it is the circumstance that
several of the islands possess their own species of tortoise, mocking-thrush, finches, and numerous plants, these species having the
same general habits, occupying analogous situations, and obviously filling the same place in the natural economy of this archipelago,
that strikes me with wonder."
Darwin had his theory in 1839, fully 20 years before the publication of “Origin”!
In 1844 he left his wife instructions to publish his notes if he died.
He recognized the importance of timing. For one thing, he was a nobody, and needed some credibility. He gained some rccognition
with the publication of “The Voyage of the Beagle” in 1845. Enter the barnacles, which he studied from 1846-1854. The revolutions
in Europe of the 1840s were on all wealthy people minds. Just 50 years earlier, just having money meant the guillotine in France.
Entitled gentlemen did not want to rock the boat.
_______________________________________________________________________
Historic hint: When I think "independent means", I think about the value of time. Many of Darwin’s contemporaries were chained to
various assignments on poverty wages (like TAs). Graduate students need to think about how valuable time is, and how you should
not feel like you are wasting time if you are just THINKING about your science. Also, be willing to reject in your mind those things
that don't make sense, even if they are established "world views"
_______________________________________________________________________
Important period to us is when he returned and looked over his collection of Galapagos birds, he wished he had recorded which island
they had come from, because they were different. Quite a mistake today, but in his time, it was not unusual to label things as "South
America". What he had thought was a single species of finch was actually many, and it did not take any great leap of the imagination
to hypothesize that they had come from a single species. They had changed! The next step was WHY? Darwin's notebooks survive,
and they record his struggle with the question. Examined Lamarckism, but rejected it because it did not explain WHY. He needed to
describe a mechanism for ADAPTATION. Not only why things change but how they are well adapted for life. In 1838, he thought
that slight modifications that were favorable to the survival of an organism would result in that organism leaving more descendants,
and that this would lead to the formation of new species. This was his working theory for the next 20 years!
Then in 1858 he heard of the work of another traveling British naturalist, Alfred Russel Wallace,
http://rjohara.net/teaching/uncg/freshman-104w-1-letters
who had come up with the same idea independently. But it was too late for Wallace to get much credit, because by that time Darwin
was 20 years into building support for his theory. On the Origin of Species (1859) was written as “an abstract” of this work.
http://www.zoo.uib.no/classics/
3. Rejecting Darwin
Many biologists immediately accepted evolution, (species change....obviously, BUT...) but natural selection had a harder
time. They saw evolution as a progression up a ladder, and not as a bush. Of course, Homo sapiens was at the pinnacle of the ladder.
This was not natural selection. People didn't like natural selection. If natural selection where accepted, most believed that there must
be something more. One objection was that it lacked a theory of heredity. All theories of heredity at the time are now known to be
wrong. Darwin preferred a "blending" theory, in which offspring blend their parents attributes. But natural selection COULD NOT
WORK if attributes were blended. (Black + white=grey).
Why "blending" cannot work
This was a sophisticated rejection, but then as now the principle rejections came from 2 rather silly sources.
1. Evolution as Darwin proposed it was random (God was cut out of it)
2. There were gaps in the utility of new structures
What good is a proto-wing? Wouldn’t a wing that doesn’t quite work yet be more likely to lead to an animal’s extinction? Defenders
of Darwin explained some sort of directed mechanism in which there was some tendency for the development of wings, even though
they carried no advantage in the early stages. Lamarckian inheritance was the most accepted mechanism of directed inheritance, and
Darwin accepted the idea that acquired characters could be inherited. One of the few things that Darwin was wrong about. If only he
had read Mendel.
Mendel http://mendel.imp.ac.at/mendeljsp/biography/biography.jsp
1865; observed ratios, 3:1 ratios indicated dominant and recessive traits from unaltered genes. Traits are not blended. His work was
ignored. Why read the work of some untrained monk working with peas? Naturalists didn’t work with statistics. Mendel sent one of
his papers to Darwin, who didn’t read it. (would you? http://www.mendelweb.org/Mendel.html ) Even Darwin
observed the 3:1 ratio in snapdragon flower color, but made nothing of it. Historic hint: Crosslinks matter! Read and understand
work outside your field.
4. The modern Synthesis: Neo-Darwinism
http://evolution.berkeley.edu/evolibrary/article/_0_0/history_19
Darwin's missing mechanism was Mendelian genetics. Mendel's work was basically lost to science until the early part of this century,
and by the 20's, Mendelian research was hot.
Most of the genetic research did not deal with evolutionary biology directly. Around 1920 and a little before, Ronald A. Fisher
(1890-1962) http://www-history.mcs.st-andrews.ac.uk/Mathematicians/Fisher.html, J. Haldane
(1892-1964) and Sewall Write (1889-1988) independently showed that natural selection could operate within Mendelian genetics
(these were young guys...I hate them). Fisher, Haldane and Write are best known for their summarizing works in books and long
papers written around 1930. http://students.washington.edu/gw0/modernsynthesis/
Remember how originally natural selection was "proved" wrong because it could not operate under the contemporary theories of
inheritance? Now Darwin's critics had little to criticize. There is nothing else needed to explain evolution through natural selection:
no external unknown drives, or organisms willing themselves to change. No need to invoke the inheritance of acquired characteristics.
It was taxonomists that were at the very center of the modern synthesis, perhaps the most unifying principle in all of biology. And
taxonomists have given us our current concept of the species. Why are taxonomists still taking a back seat to the lab-coat crowd?