Evolution & Classification Flashcards
What is evolution and its 4 postulates?
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
Describe natural selection in antibiotic resistant bacteria and the peppered moth
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
Describe Darwin’s finches and the selective episodes
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
What are the 5 main evidence types for evolution?
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)
Define evolution vocab: sexual selection, divergence, adaptive radiation, gradualism
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
Why classify? What is the heirarchal system?
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
What are the classifications of the pea plant and the human?
Pea plant: Eukarya, Plantae, Angiospermae, Dicotyledoneae, Rosales, Papilionaceae, Pisum, sativum
Human: Eukarya, Animalia, Chordata, Mammalia, Primates, Hominidae, Homo, sapiens
What are key differences between the 3 domains?
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
What are the binomial nomenclature rules?
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
What is natural classification? pros and cons?
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
What are cladograms and molecular clocks?
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
What is an adaptive landscape? Selective episodes?
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)
What are the names and characteristics of the 8 animal phyla we learned about?
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
Name the 5 kingdoms
Prokaryota, protist, animal, plant, fungi
What are the 4 plant phyla and characteristics?
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
