Thursday, October 29 2009 Writing assignment: http://www.nytimes.com/2009/02/10/science/10essa.html?_r=1&scp=1&sq=darwin%20must%20die&st=cse (Darwinism must die) And three excerpts from scientists about their favorite quotes from “Origin of Species” Then, discuss the beneficial and detrimental aspects of focusing on Darwin’s work. And, discuss whether you would have liked him as a person.

Evolution is a theory that unites many areas of research: Classification Behavior Morphology Physiology Genetics Biogeography Paleontology

Scientific theory Video clip from AMNH on theories http://www.amnh.org/exhibitions/darwin/evolution/theory.php

How does evolution work? Each organism contains DNA, which carries the genetic code. When DNA replication happens (via RNA), mistakes can occur in the copying process. These mistakes or other modifications of the DNA are mutations. Most mutations have no outward effect on appearance, but some do. Most mutations are unfavorable for the individual.

How does evolution work? (continued) If the individual with a mutation is able to reproduce, that mutation may be (but not necessarily) passed on. If the mutation causes an advantage in terms of survival, even very slight, that mutation may wind up in greater abundance in the next generation. This concept is called fitness. Thus, while mutations are usually harmful for an individual, some may be beneficial for a species.

Fitness Fitness describes the number of alleles (a version of a gene) that occur in the next generation. Fitness includes survival and reproduction. Inclusive fitness involves the survival and reproduction of near relatives. This idea is used because although an individual might not reproduce, the allele might survive if siblings do.

How does evolution work? While mutations are usually harmful for an individual, some may be beneficial for a species. In fact, given the major changes in the Earth over geological times, mutations are necessary for survival of life.

Evolutionary relationships and the diversity of life How do we classify life on Earth? How do we determine the patterns of relatedness between species? What evidence is used to determine these patterns? Where do we see uncertainty in the data?

Six components of Darwin’s idea Evolution Gradualism Speciation Common ancestry Natural selection Nonselective mechanisms of evolutionary change

Common ancestor of birds and dinosaurs Common ancestor of humans and dinosaurs

Consider four butterflies connected to their parents offspring parents

future Individuals past Population

Lineage-branching Speciation Population Lineage/ Species What happened here? Phylogeny Lineage-branching Speciation

Most speciation (the production of new species) is due to geographical barriers

Representation of phylogenies B C A B C A simplified representation The True History

When reading a phylogeny: 1) It is tree-like, not ladder like 2) There is no “advancement”

3) For any speciation event on a phylogeny, the choice of which lineage goes left and which goes right is arbitrary:

Humans didn’t evolve from chimps, they share a common ancestor that was neither chimp nor human

Relatedness = How recent is the common ancestry You are more closely related to your first cousins than to your second cousins because you share a more recent common ancestor grandparents vs. great-grandparents You are more closely related to a chimpanzee than to a worm because you share a more recent common ancestor ≈ 6 Million years ago vs. ≈ 600 Mill. years ago

Is a newt more closely related to a fish or a human? Lizard Mouse Human Note one can add all sorts of info onto trees. Character changes, biogeography, chemical features, time, etc. Is a newt more closely related to a fish or a human?

Why might you go wrong? If you look “along” the top Fish Newt Lizard Mouse Human Note one can add all sorts of info onto trees. Character changes, biogeography, chemical features, time, etc. Is a newt more closely related to a fish or a human?

But this is not how evolution happened Fish Newt Lizard Mouse Human But this is not how evolution happened All these species are alive today: A living fish is not an ancestor of a newt The order “along the top” can change without changing the content of the tree

Which of the following is different? A B C D E A B D E C A B D E C A B E D C A B C D

Why are phylogenies useful? They provide the basis for biological classification They allow us to infer the evolutionary history of traits (when, where, and why they evolved)

How can we use a tree to make inferences about character evolution? Suggests one change from yellow to red Parsimony: pick the mapping that involves fewest changes

By parsimony, where did flower color change?

Sometimes more than one change must have taken place Suggests that red-flower in the two groups are not really the “same” or homologous

Cobert report Ken Miller http://www.colbertnation.com/the-colbert-report-videos/181409/january-12-2006/kenneth-miller Also http://www.colbertnation.com/the-colbert-report-videos/173859/june-16-2008/kenneth-miller