BIo darwin'

scientific theory

A _____is an explanatory model supported by a large body of evidence. Unlike everyday “theory,” it isn’t a guess. Examples: Cell Theory, Atomic Theory, Gravity, Evolution.

Evolution

___is the change in the genetic makeup of a population over many generations. Individuals do not evolve—populations do. Driven by natural selection.

Natural Selection

Differential reproductive success due to interactions with the environment. It causes changes in allele frequencies in a population.

Gene Pool

The total of all genes in a population. Populations may contain many alleles; individuals can only have two. Evolution = change in gene frequencies.

Why is perspective important when viewing mutations?

Mutations must be viewed from the organism’s perspective. Example: antibiotic resistance is beneficial for bacteria.

Artificial Selection

Humans choose which individuals reproduce to get desired traits. Leads to domestication (dogs, Brassica oleracea).

What are consequences of Artificial Selection?

Reduced genetic diversity, unintended linked trait effects (e.g., white strawberries, stress-sensitive pigs).

What are fossils?

Preserved remains or activities of organisms. Hard parts common; impressions and whole-body fossils rare. Fossilization is extremely rare; microfossils most abundant.

What did Cuvier contribute?

Founded paleontology; identified extinct species; strata relationships; catastrophism; relative dating (deeper = older).

What did Lyell contribute?

Supported Uniformitarianism—Earth changes gradually via constant processes. Implies Earth is extremely old.

What did Buffon propose?

Anatomy changes over time; noted non-functional structures (pig toes). Suggested species were once more perfect.

What did Linnaeus and Erasmus Darwin propose?

Linnaeus: classification + species change. Erasmus Darwin: all life evolved from a single source.

What did Malthus propose?

Populations grow geometrically; resources grow arithmetically → competition → selective pressure.

What were Lamarck’s ideas?

Use and disuse, felt needs, inheritance of acquired traits (incorrect). Correct: species evolve and adapt over time.

What was Darwin’s voyage?

Sailed on HMS Beagle (1831–1836). Naturalist. Published Origin of Species in 1859.

What were Darwin’s 2 major points?

1. Species change gradually from ancient ancestors. 2. Natural selection drives this change.

What observations did Darwin take from Malthus?

More young born than survive; populations stable; survival non-random → adapted individuals survive.

What are Darwin’s 5 Postulates?

1. More born than survive. 2. Variation exists. 3. Some traits give survival advantage. 4. Traits are heritable. 5. Long time spans allow change.

What are homologous features?

Structures with common origin, different function (e.g., flippers vs. hands). Evidence seen in embryos.

What are analogous features?

Structures that have similar function but different origin (e.g., wings of birds, bats, insects).

What are vestigial features?

Non-functioning structures homologous to functioning ones (e.g., whale hip bones, dog dew claws).

Who was Wallace?

Independently developed natural selection. Presented findings with Darwin in 1858.

What were criticisms of Darwin’s theory?

Earth too young, missing fossils, church opposition, blending inheritance problem (solved by Mendel).

How old is the Earth?

Kelvin estimated 15–400 million years (wrong). Modern value: ~4.5 billion years.

What is radiometric dating?

Uses radioactive decay and half-lives to determine age. Examples: C-14 (100–100k yrs), U-235 (10 million–4.5 billion yrs).

What did Mendel contribute?

Foundations of genetics through pea experiments.

What did Morgan contribute?

Showed genes are on chromosomes; discovered sex-linked traits.

What did Dobzhansky contribute?

Helped create modern evolutionary synthesis; defined evolution as allele frequency change. Famous quote.

What is punctuated equilibrium?

Gould & Eldridge: species stay in stasis long periods, with bursts of rapid evolution. Complements gradualism.

What two things vary widely in a population?

Populations have a wide range of phenotypes and genotypes.

What does natural selection cause in terms of reproductive success?

Some individuals produce more offspring than others, increasing the frequency of their traits in the population.