Evolutionsbiologie

1. Coccyx: base of spine; starts as seperate bones then fuse into lump; coccyx development controlled by genes homologous to tail genes in closely related species 2. Arrector pili muscle: base of hair follicles; makes hair stand, goose bumps; we're descendants from hairier ancestors 3. Appendix: vestigial form of a cecum. BUT 70% of primates have appendix despite having a cecum; may be a safe house for good gut bacteria in cases of bad diarrhea.

In 1801 Geroges Cuvier claimed that 23 species were extinct. Some of the species were so big, that it was very unlikely that they still lived wothout being discovered. Darwin claimed that extinct species were relatives of living organisms => Evidence for change over time

General pattern of correspondence between fossil and living forms from same region => Todays species decended with modifications from ancestors of the same region

Transitional Species => Evidence of transformation in progress; Ex: Archaeopteryx is a bird with modern feathers but dinosaur-like skeleton; Not necessarily on direct line dinosaurs => birds, but more likely on an extinct side branch; Birds are closely related to Maniraptors, extinct theropods like T-Rex, Velociraptor, ...

Similarity due to to the inheritance of traits of a common ancestor; Genetically and phenotypically defined; enables the use of model organisms as representative for a whole group of organisms; Ex: Vertebrate forelimbs are similar despite their different functions and apeearances

Similiar function but different design => Convergent evolution; Ex: Sharks and whales with similar streamlined shape, short fins and tail, but developed independently

Evidence that one species can split in two; Ex: Greenish warbler: Birds interbreed everywhere except in one specific region where they don't => splititng in two species

Special Creation: James Ussher, The Bible, Earth is 6000 years old, created by God on the 23rd October 4004 BC; Theory of Uniformitarianism: Hutton & Lyell, rocks and fossils, Earth is unimaginably old, gradual change of Earth

Superposition: Young rocks are deposited on top of old rocks; Original Horizontality: Tipping/Bending occured after deposition; Cross-cutting relationships: rocks that intrude into seams of other rocks must be younger than the host rocks; Faunal succession: Old fossils simpler than young ones, younger are more similar to present forms

=> Chronology of relative dates = geologic time scales

At beginning earth was molten => no radiometric dating; but we can use moon rocks/meteorites for dating => 4.6 bio. years. Initial parent-daughter ration muest be known Ex: Potassium-argon dating, No argon-40 in the beginning because gaseous would bubble out of liquid rock, but accumulates in solid rock and doesn't migrate

Life has evolved for at least 2.7 bio. years

Human have selectively bred desirable traits in plants and animals for millenia; Crop plants, garden plants, domestic animals; Darwin studied pigeon breeding; Ex: Different forms descending all from wild cabbage, varieties of the same species

Because artificial selection is a thing, same process must happen at different speed in nature; so Darwin formalized the process Natural Selection what lead to the pattern Descent with Modification

Evolutionary Change is a deductive implication of four postulates:

1. Individuals within populations are variable 2. Variations among individuals are partially passed from parent to offspring 3. Some individuals are more succesful at surviving and reproducing than others 4.Survival and reproduction of individuals are not random, they are tied to variation among individuals, the most favourable variations are being selected

1. Variation among individuals => white & yellow flowers 2. Some variation is heritable => Dominant allele S for white, recessive allele s for yellow 3. Do individuals vary in success? Yes, differnet number of bee visits 4. Is Reproduction nonrandom? Bees prefer white plants, slightly more seedproduction

Testing the prediciton: Did the population evolve? Yes, there were more white flowers

1. No variation in trait value among population; 2. Gradual adaption in all individuals due to continuous exercise 3. Inheritance of intermediate changes lead to longterm trend of adapted populations

Is NOT physiological acclimation; is NOT behavioral adjustment; A heritable trait that increases fitness relative to the absence of the trait

Darwinian fitness = relative reproductive success; Fitter = relatively more offspring; Survival of the fittest = Long-term survival of those individuals who have more offspring than other individuals; Alternative: fitter = better fit to the environment

Natural selection ... 1. acts on individuals, the consequences occur in populations 2. acts on phenotypes, evolution consists of allele frequency changes 3. is not forward looking: populations get adapted to conditions that were successful in the past, not to conditions that might occur in the future 4. is nonrandom but not progressive

Differences in survival or reproduction can only occur among variants that already exist; But new traits can evolve due to natural selection; It's possbile due to mutations and recombination of alleles; Ex: Study on the oil content in corn kernels showed that mutation, recombination and selection produced a new phenotype

Mutation is random but natural selection ain't

Ex: Male mosquito fish, Females prefer males with larger anal fin, but these are slower an thus easier to prey upon => attractive but slow vs. unattractive but fast

Different eyes with different levels of complexity; But simpler eyes are not intermediate forms on the way to the more complex forms; They're contemporary adaptations to the problem of sensing light; But they could represent intermediate stages in evolution of the complex eyes in vertebrates

Complexity is not irreducible: snakes evolved from organisms with legs

Evolutionary history of a group of species; Phylogenetic tree is graphical summary; Evolutionary tree describes patterns and the timing of events that occured as species diversified

Grouping species by inherited similarity; BUT not all traits lead to correct phylogenies (homology vs. convergence)

Homology: Similarity due to inheritance of traits from common ancestor; Analogy: Similiarity due to convergent evoultion (Homoplasy); Plesiomorph: original trait => same as ancestor; Apomorph: derived trait => evolved between ancestor and current species; Synapomorph: similar trait across species beacuse it was modified in the common ancestor => momophyletic groups; Autapomorph: derived trait that is unique to a particular taxon

Monopyhletic groups: an ancestor and all his descendants, also known as clades or lineages

Synapomorphies are traits that are shared AND derived; All snyapomorphies are homologous traits, NOT vice versa; each branching of a tree involves at least one synapomorphy; Cladograms are built from synapomorphic analysis

Life, Domaine, Kingdom, Phylum (Stamm), Class, Order, Family, Genus, Species

Universal genetic code => Prokaryotes + Eukarya monophyletic; Cell walls made of peptidoglycan => Bacteria monophyletic; Nuclear envelope => Eukarya monophyletic

Outgroup Analysis: Compare lineages A-F with a closely related lineage G that is known from independent evidence to have diverged before synapomorphies shared by A-F arose => trait of G is ancestral

Evolutionary reversals: loss of synapomorphies in derived lineage => DNA sequence mutational reversals => wing loss on stick insects, lack of fruiting body in myxobacteria; Independent evolutionary convergence of similarities: camera eyes of octopuses and vertebrates, eyes on top of skulls in crocodiles and hippopotamuses, bat and bird wings, shark and whale body shape, body shape of snakes and legless lizards

1. Compare relationship across different traits: simliarities not in line with the majority of traits are likely homoplasies 2. Look closer, Ex: Octopus vs. vertebrate eyes: opoosite orientation of light-sensitive cells, movement of eyeball vs. lens to focus 3. Employ principle of parsimony

Cladistics (use of discrete characters); 1. Choose characters for comparative analysis: must vary across taxa, minimize chance of homoplasy, use deiverse and independent traits 2. Construct many trees and choose the best: Parsimony, Choose the tree that involves fewest character state changes across all characters 3. Evaluate quality of particular node calls, bootstrapping

Ditance Methods (Phenetics); Convert discrete character data into measure of overall distance, Ex: average degree of DNA sequence similarity

Cetaceae; Lack of posterior limbs; Whales evolved from ancestors that had hind limbs; First whales had hind limbs and resembled an extinct group of mammals; Phenotype (skeletal features), Genotype (DNA sqeuence); How closely related are hippos and whales?; No sister group, because whales don't have a pulley-shaped astralagus; BUT new paleontologist comes and claims earliest whales-like fossils had ankle bones similar to hippos; BUT other features were nonconsistent and the fossils may be nonwhale => inconclusive; Going molecular; Similarities in DNA sequence from whales and hippos are synapomorphies, same monophyletic group, Ex: Ear bone synapomorphies shared with whales => Current view: Whales are hippo sister group

Traditional calssification schemes based on grouping organisms by morphological similarities => Phenetic approach => Paraphyletic groups; schemes based on evolutionary relationships (phylogenetic/cladistic approach) give monophyletic groups

Possibility of dating events that are not in the fossil record; DNA changes in clocklike fashion, a lot of the muations are silent/neutral => not exposed to natural selection => random events govern evoultion => accumulation of neutral diversity according to mutation rate