Evolution Textbook notes:
Biological Evolution: Any change in the inherited traits of a population that occurs from
one generation to the next.
- Evolution is a process by which populations of organisms change over time.
- Whales and dolphins are known as Cetaceans.
They develop in the uterus, forming a placenta
Born alive and drink milk
Descended from mammals that lived on land
Lineage: A chain of ancestors and their descendents.
Natural Selection: A mechanism that can lead to evolution, where differential survival
and reproduction of individuals causes some genetic types to replace (outcompete)
Convergent Evolution: The independent origin of similar traits in separate lineages.
Homologous: Characteristics are similar in two or more species because they are
inherited from a common ancestor.
Synapomorphy: Derived form of a trait that is shared by a group of related species (ex:
one that evolved in the immediate common ancestor of the group ans was inherited by
all its descendants)
- The mammalian middle ear is an air-filled cavity enclosed in a hollow shell known as
- The inner wall of the ectotympanic is the Involucrum. - Eocene period, was from 56 to 34 million years ago.
- Pakicetus is the fossil found in Pakistan; meaning " whale of Pakistan" , and was 50
million years old.
- Ambulocetus meaning "walking whale".
- Darwin argued that life evolved like a branching tree with new lineages splitting off
from old ones.
Phylogeny: A visual representation of the evolutionary history of populations, genes, or
- Scientists can get clues about the origin of cetaceans also from looking at the
individual atoms inside the animal. (ex. could tell if they drank fresh or salt water)
- Mutations had developed which put a stop to the growth of the limb buds in cetaceans.
- Scientists have concluded that whales had lost their teeth and had developed pleats
instead; much like how they lost their limbs.
- Whales were hunted for their oil and baleen (oil for lamps and baleen for corset strays)
- Whale and fish lineages, evolving independently, converged on body forms that are
- Ambulocetus was a fossil whale that had legs. The animal had traits that were
intermediate btwn modern whales and their terrestrial ancestors.
- The chemistry of fos