Evolution & Classification

Theory by Darwin: organisms change → explains diversity of life Theory: accepted hypothesis with lots of evidence; explains and predicts something Evolution is the cumulative change in characteristics of a population Postulate (basis for reasoning) 1) populations tend to produce more young than can be supported by the environment (expect death) 2) there is a struggle for survival and variation among individuals within population 3) there is a greater survivable and reproductive success of individuals with favorable heritable variations (natural selection) 4) population characteristics can change over time Variations: random fertilizations, mutation, crossing over in prophase 1, independent assortment in metaphase 1, conjugation and transformation in prokaryotes

Antibiotic resistance in bacteria (antibiotics stop bacteria reproduction): Observations: after an antibiotic is introduced, resistant bacteria appear in a few years, in each species the proportion of infections caused by the resistant strain increases Explanation: conjugation passes resistant gene between bacteria (tb can be resistant to 9/12), unnecessary use of antibiotics as precaution in humans and farm animals, bacteria reproduce rapidly, populations often large → increased chance of mutation Peppered moth color: Peppered (gray) form and melanic (black) form Before industrial revolution: mainly gray → tree trunks darkened → mostly black Efforts to decrease air pollution → light trunks → more peppered Can’t say 100% that it’s natural selection because we don’t know it birds see them camaflouged

Daphne Major (Galapagos Island): 13 unique finch species across islands, descended from 1 species, island is small so you can track individual birds, little emi/immigration Tracked medium ground finches 1977 drought → no vegetation → need big beaks for seeds >80% died, average beak of next generation 4% higher 1983 rain → vines → drought → need small beak Beak size swung smaller 1983-1985

Fossils (all start in water): Absolute (direct age) and relative (depth) dating techniques Past organisms differ from present ones, have gone extinct Evolutionary change within groups of organisms: extinct trilobites change place/angle of head spines, whales went from land to ocean mammal Comparative biochemistry: Sequence genomes → closer relatives share more DNA Cytochrome C protein shared by all ancient aerobic organisms (common ancestor) Comparative anatomy: Homologous structures: variations of a structural theme from a common ancestor, different functions (pentadactyl arm in human, cat, whale, bat) * analogous structures are same function different structure (wings) Vestigial structure: Remnants of structures that had a function for ancestors but don’t now (whale femur and pelvis, snake leg bones) Selective breeding (artificial selection) Done by humans with domesticated animals (dairy cows bred for straighter backs and taller legs for milking machines, dog subspecies)

Sexual selection: traits that maximize reproductive success (peacock plumage) Divergence: accumulation of differences between groups that lead to new species; usually via geographic or physical isolation Adaptive radiation: rapid speciation from a single recent ancestor (many new species like Daphne Major) Gradualism: slow but continuous evolutionary change; intermediate changes must have an advantage for the organism

Classification benefits: predictions about new organisms, find pattens and group things, global system for discussion and study, shows evolutionary links Biased and flawed because it’s a construct Heirarchal system: Domain (bacteria, archaea, eukarya) Supergroup/ kingdom (prokaryotae - bacteria, protoctista - Protozoa and algae, fungi - and mold, plantae, animalia) Phylum, class, order, family, genus, species

Pea plant: Eukarya, Plantae, Angiospermae, Dicotyledoneae, Rosales, Papilionaceae, Pisum, sativum Human: Eukarya, Animalia, Chordata, Mammalia, Primates, Hominidae, Homo, sapiens

Nuclear envelope: bacteria no, archaea no, eukarya yes Membrane-bound organelles: bacteria no, archaea no, eukarya yes RNA polymerase: bacteria 1 kind, archaea several, eukarya several Introns in genes: bacteria rare, archaea some, eukarya present Response to antibiotics: bacteria don’t grow, archaea none, eukarya none Plasmid: bacteria yes, archaea yes, eukarya no Growth >100°c: bacteria no, archaea some, eukarya no

Names are approved by an international committee Genus capitalized, species lowercase Italics or underlined After the binomial name, use the abbreviated genus Earliest published name after 1753 is correct

Classification in which the genus and higher levels of taxa contain species evolved from 1 ancestral species Can expect organisms with a common ancestor to inherit similar characteristics Advantage: easier to identify species or key out a new one, allows predictions within a group (useful thing in 1 plant may be found in others) Challenge: convergent evolution (appear similar but are unrelated) or adaptive radiation (closely related but appear different), especially for physical traits Can use biochemical evidence to decipher Changes over time: now we use DNA and protein sequencing and embryonic development, not just observable physical characteristics

All organisms use DNA or RNA and the same 20 amino acids Similar biochemistry indicates similar origin Cladistics: new term for phylogeny Clade: group of organisms with a common ancestor Cladograms (phylogenic trees): tree showing groups of clades Node: branching point on tree; hypothetical ancestral species that split Computers do most of the work in parsimony (simplest explanation that fits evidence) Molecular clocks: length in line of cladogram represents the number of mutations since branching → long line is more evolutionary difference since mutations are slow Indicates time since divergence

Adaptive landscape: graph showing trait frequency Peaks are the most fit / frequent versions of a trait, valleys are least Selective episodes: Stabilizing (more variation to less, more pointy curve) Directional (moved left or right) Disruptive (two peaks with few frequencies at the prior peak)

Porifera: aquatic colony of cells Platyhelminthes: bilateral symmetry, flat worm Annelid: bilateral symmetry, cylindrical segmented worm Mollusk: bilateral symmetry, shell, no legs, soft body Coelenterate / Cnidaria: radial symmetry, tenticles / sting, no organs Echinoderms: radial symmetry, spiney skin, watervascular system Chordate (sub-phylum vertebrate with endoskeleton or protochordate without): bilateral symmetry, spinal chord, heart

Prokaryota, protist, animal, plant, fungi

Bryophyta (moss): no roots, stems, leaves Filicinophyta (fern); has roots, stems, leaves, reproduces by spores Coniferophyta (conifer): has roots, stems, leaves, reproduces by seeds, has cones Angiospermophyta (flowering): has roots, stems, leaves, reproduces by seeds, has flowers

Fish: scales, gills, no limbs, fins Mammals: skin with hair, lungs with alveoli, tetrapod with pentadactyl limbs, 4 legs Amphibians: skin permeable to water and gas, simple lungs, tetrapod with pentadactyl limbs, 4 legs as adults Reptiles: impermeable scales, lungs with large surface area, tetrapod with pentadactyl limbs, 4 legs Birds: feathers, lungs with para-bronchial tubes, tetrapod with pentadactyl limbs, 2 legs and 2 wings