Molecular Evolution

Morphology You can classify the evolutionary relationships between species by examining their features Much of the Tree of Life was developed by observing phenotypes and then inferring relationships based on species that have the most similar phenotypes

The Root

Eukaryotes

Animals

Eyes

Paralog or Homolog You might conclude that eye development occurred through different paths for humans and flies since the morphology is so different Mutations in the Pax-6 gene cause small eye in mice, knockouts have no eyes The Pax-6 homolog in flies (eyeless-ey) has 94% amino acid identity with small eye

Knockouts You can knockout the Pax-6 gene in the fly and you get a fly with no eyes. You can put the mouse Pax-6 gene into a fly with the fly version of Pax-6 knocked out and you get eyes again. You can put mouse Pax-6 on other regions of the fly body and get extra eyes

Ectopic eyes

Sequence Data Many detailed phylogenetic relationships can only be inferred using dna The two eye genes descend from a common ancestor to both flies and humans The gene wasn’t changed because it is important to survival

Evolution Mutations that confer an advantage will tend to dominate in a population When separated, populations will eventually lose the ability to mate and their population will differentiate from other populations You can determine the evolutionary distance by looking at the number of mutations in a common gene

ribosomal RNA sequences 18s produces the small ribosome that is used by all eukaryotic organisms We can compare it across all of life Barcode

Lineages Mitochondrial DNA comes only from the mother (sperm don’t have mitochondria) Y chromosome comes only from the father and doesn’t recombine with other chromosomes Mitochondrial Eve is the common ancestor (or group of ancestors) that originated mitochondrial dna Mutations can occur that don’t impact the fitness, but are single nucleotide polymorphisms

Age of a species You can determine the age of a species by noting how much variation there is in a species Two chimpanzees are times more different than each other than 2 humans Humans are a recent species that hasn’t had the chance to accumulate much diversity Small populations tend to lose mutations (genetic drift)

Mutiny on the Bounty Fletcher Christian shipwrecked on Pitcairn island Almost everyone now has the last name of Christian 7 types of mitochondrial DNA in Western Europe, so there were 7 women that were the ancestors of all western European women By molecular clock you can estimate that about 150,000 years ago there was a woman that all of our mitochondria came from

Finland 70% of finish men have a SNP on the Y chromosome that is unheard of in other European countries 2 million men in Finland all descend from a common male ancestor that didn’t interbreed much with other countries Modern european humans descend from a group of about 20 people that migrated recently from africa

American Indians Y chromosome is largely european Mitochondria is largely native You can explain a lot of human history by looking at DNA

Molecular Geneology

Example for Surname: Anders Genetics show what the name does not intuitively show

Discovering Previously-Unknown Relationships G Generations F SorensenEDCBSorensonA

Coalescence Two individuals theoretically share all their ancestors at a very recent point in time Individual 1 Individual 2 Unique Ancestors Unique Ancestors Common Ancestors

Cohen Cohen in Hebrew means high priest, and Cohens are always the son of a Cohen (no adoption) Cohens are supposed to be descendents from Aaron Cohens are 4% of people in Israel Select 100 Sefardi Cohen's from Spain, north africa, Iraq etc Select 100 Ashkenazi Cohen’s from Europe 70% of Cohens have the same Y chromosome polymorphisms, where only 15% of the general population does Over 3000 years, Cohen’s have almost all descended from one ancestor

LEMBA Tribe in Africa that are rumored to have the ruling class descended from Jews Almost all of the ruling caste have the Cohen polymorphisms None of the other caste members have the mutation

Young Species Because humans are such a young species with a small number of SNPs, we can associate the SNPs with characteristics