Earth 7 Essay

Submitted By Babyizzie12Y
Words: 625
Pages: 3

Species: a group of viably interbreeding organisms
Lineage: a species through time
Speciation: when lineages split
One lineage splits into two and so on
Change of species over time
NOT Darwin’s idea
Lamarck’s ideas on evolution were already well known in Darwin’s day
Darwin’s most important ideas:
Common Descent with Modification
Natural Selection
Common Descent with Modification:
All living organisms are related, descending from a single common ancestor.
Diversity is the result of the bifurcation of lineages
Similarity is the result of close ancestry
Things are all related and the differences tell whether how close or far related.
Evolution is a process
Natural Selection is just one mechanism explaining that process
Natural Selection follows from three observations:
1. Variation in Species
Source of genetic variation: sexual reproduction, changes in DNA
2. Differential Survival and Reproduction
Often brutal in nature
Artificial Selection: Analogous
3. Heritability of Variation

Earths Age
Radioactivity not discovered until 1896
First absolute ages published in 1907
Earth rocks/minerals, moon rocks, and meteorites all suggest that the Earth and solar system formed 4.8 billion years ago

Nested Hierarchies
History of Humans is not History of Life
First seriously explored by Buffon. Popularized by Hutton and Lyell
Many species have gone extinct
Overwhelming evidence provided by Cuvier in 1796
Common descent with modification and Natural Selection
Darwin’s “On the Origin of Species” 1859
Linnean Hierarchy
Genus- Homo
Species- Homo Sapiens

Node: where one lineage divides into two. Any time a split occurs
Cladograms also called a tree or phylogeny
Taxa: (Taxons) any name you give to an organisms. (such as ‘birds’, ‘Tetrapods’)
Higher Taxa: groups that include many species ( Animalia, ect.)
Species: “Binomial nomenclature”
Genus: Tyrannosaurus
Species: Rex

How to read a tree:
Sister groups: Always go down to the last node and then up from there
Closest relative and sister group are the same thing
Try to only apply scientific names at nodes

How do we figure out relationships?
Backbones, four limbs, feathers, (characteristics, etc)
Types of characters: physical features, behavioral features..
Homologous: similar due to inheritance. Homologs have same structures inherited from a common ancestor
Convergent: similar but not due to inheritance (wings)

Homologous: character that inherited from a common ancestor.
Convergent: Wings are convergent in butterflies and birds. Independent characters.
Cladogram 1- midterm 1
Cladogram 2 3 4 – final
VERY IMPORTANT: Groups are defined by the…