Copy of *(GSN) AP Bio Chapter 15 Group Notes: Darwin and Evolution

Darwin’s Trip:

1. Started: December 1831, HMS Beagle
2. His unpaid job as a 22 year old naturalist: collect and record the geological and biological diversity he saw during the 5 year voyage
3. Darwin:
   1. was going to go to med school but could not stomach it - went to school to be a clergyman
   2. had a strong interest in natural science and interned with a botanist and geologist
4. His viewpoint began changing throughout the journey - several other scientists --- him before, during and after his journey

Historical Viewpoints of Evolution:

1. Linnaeus (1707-78) - -binomial nomenclature-, classified all known plants, special creation with fixity of species/scala naturae
2. LeClerc (1707-88) - 44 volume history of all known plants and animals, speculated on influences of environment, migration, etc
3. Erasmus Darwin (1731-1802) - Charles’ grandfather, physician/naturalist, possibility of evolution, looked at vestigial structures (anatomical structures that apparently functioned in an ancestor but have since lost their function - tail bone)
4. Cuvier (1769-1832) - comparative -anatomy- for classification, founded -paleontology--, fixity of species/special creation, believed in -catastrophism-- (catastrophes with repopulation gives appearance of evolution)
5. Lamarck (1744-1829) -
   1. -First- to offer hypothesis of how evolution -- --- occurred
   2. incorrectly proposed the idea of “inheritance of -aquired-- characteristics”. That an organism could acquire adaptations during its lifetime that it passed to offspring - think giraffe necks
   3. Use and disuse: idea that the parts of the body that are used extensively become larger and stronger and visa versa
6. Hutton’s theory published in Lyell’s (1797-1875) book, Principles of Geology, discussed the idea that the earth is -old.- (Darwin had the book on his journey)
   1. slow gradual geologic change - erosion, dirt, sedimentary layers, rock
   2. “uniformitarianism” - uniform rate of change in geology
7. Thomas Malthus (1766-1834) -
   1. socioeconomist who published, An Essay on the Principle of Population, proposed that the size of human population is limited only by the quantity of resources.
   2. Famine, war, epidemics comes from overstretching those limited resources.
   3. Darwin used these ideas after his voyage to develop the mechanism of natural selection when he applied this to animals and competition for resources, to support the theory of evolution

Darwin did NOT agree with uniformitarianism.

Observations of Change over Time:

1. If given enough time (Hutton/Lyell) - older earth, species could - change-- over time
2. Evidence:
   1. marine seashells inland and on raised beaches
   2. bones of extinct organisms - that were similar to extant (living) organisms

For the shell example, water levels decreased and shells were found in the land/ground by Darwin, helped form his theory

Biogeographical Observations:

1. Defined: study of the -geographic distribution-- --- of organisms throughout the world
2. Evidence:
   1. similar environments seemed to produce -similar-- organisms regardless of location
   2. Galapagos island species varied slightly from mainland and island to island - think tortoise variations
   3. Finch variations

Natural Selection and Adaptations: By 1842 - Darwin came up with the mechanism of Natural Selection, however did not publish until Alfred Wallace, in 1958, sent him a similar idea.

The idea of Natural Selection:

1. Organisms Have --Heritable- Variation:
   1. essential to natural selection
   2. can be helpful or harmful
   3. to be an -adaptation - it must be heritable
   4. Darwin could not state cause of variations - no -genetics- yet
2. Organisms -Compete-- for Resources: applied Malthus’ ideas, overproduction potential, competition etc
3. Organisms Differ in -Reproductive-- Success:
   1. Differential reproductive success - ability to have more offspring as a result of acquiring -more resources- --
   2. Fitness: reproductive success of an -individual-- relative to other members of a population
4. Organisms Become Adapted:
   1. Adaptation: any evolved trait that helps an organism be more --suited- to its environment
   2. Convergent Evolution: when –unrelated- organisms living in similar environments display -similar-- characteristics

Parallel selection: when two or more different species that are related, develop the same characteristic even though it is not found in their common ancestor.

Convergent>

<Convergent evolution

Parallel evolution^

Observations of Selection:

1. Artificial Selection: -Humans-- select which traits are valued - think dog breeding
2. Common ancestry and derived characteristics: a species of wild mustard is the parent plant of Chinese cabbage, brussels sprouts and kohlrabi
3. Beak depth and weather
4. Industrial -melanism-
5. Antibiotic -Resistance

industrial melanism^

antibiotic resistance, our experiment! ^

Fossil Evidence:

1. Fossil defined: remains and -traces-- of past life or any other direct evidence of past life - includes bones, footprints etc.
2. Must be at least 10,000 years old
3. Transitional Fossils: resemble -two-- groups that are currently classified separately - often times represent the intermediate. Think Archaeopteryx - birds/dinosaurs, whales with hindlimb reductions, Equus - horse history

I want you to look for two patterns for every piece of evidence:

1. Homologies - same, which = common ancestor

2. Change - change over time, from what to what

Biogeographical Evidence:

1. provide evidence that variability in a single, ancestral population can lead to adaptation to --environments --- through the forces of natural selection - driven by competition
2. Examples: South America didn’t have rabbits but a species similar to a rabbit filled the niche, finches, where/when continents were joined there were similar species but after separated more continent specific species like marsupials
3. Endemic species: found at a --particular- geographic location and --NOWHERE- else. Example: marine iguanas are endemic to the Galapagos.

Anatomical Evidence:

1. homologous structures: similar -anatomy-- due to common ancestry but may have different functions - think vertebrate forelimbs. (analogous is similar function and not evidence)
2. vestigial structures: --?- of structures that served important function in the organism's ancestors, anatomy traces evolutionary history. think - vestigial eyes in cave salamander and whale hindlimbs
3. -developmental-- structures/embryological homologies: all vertebrates have a postanal tail and paired pharyngeal pouches (become gills in fish)

Same anatomy (bones) = same DNA = common ancestor.

Convergent evolution would be like bird wings and bee wings. They both have wings to help them fly (solving problem in the same way) but the structures to create those wings are different!

Biochemical Evidence/Molecular homologies:

1. almost all living organisms use: -ATP, DNA, and specific enzymes. --
2. same triplet code for the same -20-- amino acids
3. similar --introns-
4. high degree of similarity in amino acids for cytochrome c (part of ETC in mitochondria)

Developmental Biology Evidence:

1. similar set of -regulatory-- gene for development
2. Homeobox (Hox) genes orchestrate development in all animals
3. influenced significantly by timing and duration of expression

Criticisms of Evolution:

1. Evolution is a theory about how life originated - no, it's about how --life EMERGED-- following the origin of life
2. There are no transitional fossils - no, there are many, but scientists would predict that not all would be found because they have to be a type of tissue that can be -?--, then be preserved and then be -found--
3. Evolution proposes that life chance as a result of random events or change - no, chance is only --part- of the story, so is mutation and ---natural selection ---
4. Evolution is not observable or testable; thus it is not science - no, there are genes that code for more than one trait, several studies show how traits in populations -changing-- in response to environmental changes.