Chapter 6 (Evolution)

Evolution

gradual changing of one species into another; indifferent to whether the change is helpful/harmful

Paleontology

branch of science concerned with fossils

How do species change into new ones?

• Darwin’s work (The Origin of Species by means of natural selection0 based on research on the Galapagos Islands

• Variation among individuals affects the probability of survivial/reproduction and passing on distinct traits

Natural selection

Process where traits become more/less common based on reproduction voer time

adaptations

traits which increase the probability of the organism surviving

• Ex. I buy a keruieg to survive college

fitness

How well a spiecies/memeber of a species “fits” into its niche

• Ex. a polar bear is very good at being a polar bear. A koala bear would suck at being a polar bear

Homology

Features which are based on common ancestry

• Ex. the “arm” limb on animals

  • Flippers, fins, arms, wings

Homoplasy

Similar features which evolved sepratly/ did NOT come from a common ancestor

• Any different characteristic (broader)

• Ex. we have similar eyes to squids

Analogy

strucutres/traits that have similar function but different evolution/anatomy

• Specifically have a different function

• Ex. insects have wings, birds have wings, unrelated to one another

Conserved genes

genes that remain unchanged across species

• vary from species to species; generally, there are broad genetic similarities across organisms

• Ex. Pretty much everything requires air

Taxomony

classification system of organisms (hierarchical structure), older method

• looks at similarities/ top-down order

Phylogeny

The evolutionary history of a species; this is what we mainly use now

• looks at history/relationships

“DNA Clock” concept

DNA seems to change at a similar rate regardless of species, so DNA can serve as a clock to tell how long ago two species diverged from one another

Extra evolution info

• evolution is not Linear/goal oriented

• successful characteristics depend on selective pressures (these change over time)

• there is no “primitive” or “advanced” evolution; there is just how well we fit into our niche

Darwin’s 4 observations

1. reproduction increases population unless factors limit it

2. individuals in a species are not identical

3. some variation among individuals is due to inheritance

4. not all offspring survive to reproduce

Jesus fucking christ

Bilateral symmetry

the idea the left and right side are mirror images of one another