Evolution Test 3
phenotypic differences in species used to define the species (morpho=form)
traits can distinguish populations based on phylogeny if the populations have been isolated in terms of gene flow and have diverged
species are named on the basis of statistically significant differences in traits
if a population does not hybridize regularly in nature or offspring do not survive they are considered reproductively isolated
identified using song or other "coded" non physical characteristic
Three stages of speciation
- divergence of traits
- reproductive isolation
Allopatric vs. sympatric speciation
Allopatric speciation occurs when there is a physical barrier between the two species such as the panama canal rising up. Sympatric speciation is when two species share a geographical area but are reproductively isolated because of polyploidy.
a founding event: when a part of the group travels to a new area
an existing area is split by a physical barrier such as a mountain
Panama Canal: support for vicariance
The canal closed and a land bridge formed. They sampled snapping shrimp on either side of the canal that used to live together. The shrimp lived on the levels in the water. Shrimp on either side that lived on the deepest level had a higher genetic divergence than ones living higher up because the canal closed from the bottom up. Species on either side were closer in genetics to the species living on the other side than to species on their own side.
The last common ancestor which is not the very first living thing (noah not adam)
How RNA world solved the chicken and the egg problem because it contains genetic material yet is also a catalyst for its own replication in the form of ribozomes
because it contains genetic material yet is also a catalyst for its own replication in the form of ribozomes
- How could RNA be created in an abiotic environment
- How could RNA evolve into DNA
Is RNA the origin of life?
Probably not but it did proceed complex life but was not the first organisms to :live"
The Murchison Meteorite
The materials for life could have come from starts because they found many amino acids on a meteorite that fell over Australia
He boiled water and ran the vapor through a mixture of gases believed to make up the atmosphere. Some organic molecules were created. This is being questioned because the gases he used were not the ones that really made up our atmosphere at the time.
Was not a reducing atmosphere
All the ingredients to create life were found on earth.
- Formation of building blocks (nucleotides or amino acids)
- polymerization to form marcomolecules
- marcomolecules would have directed formation of other structures
First complex organism: 540 million years ago
540 million years ago