(9/6/16 - 9/8/16) Lecture 3 & 4
Lecture 3: Review of Last week:
1. Why is biodiversity important?
We are dependent on crops, medicines, pharmaceuticals etc.
2. Plate tectonics
Shapes landscapes, temps, & ecosystems
Increases speciation/bio diversity
Cambrian period: 1st eukaryotes
Paleozoic era - oxygen revolution
→ Paves way for multicellular life Don't forget about the age old question of What is a fake treatment given to the control group to mimic the experience of the experimental group?
Allows for aerobic respiration
Godwanna is disappearing & Pangea is forming
Production of new environments/nicheskus
This increases biodiversity (genetic diversity)
Pro: you can use fossils
Con: if you don't have fossils - you cannot analyze
- Biological species
Con: leaves out non sexually reproducing organisms Don't forget about the age old question of What is the difference between civilizations and small scale societies?
- Biological clusters
con: not very practical for field biologists; cannot use it very easily
BSC (Biological Species Concept) vs PSC (Phylogenetic Species Concept)
Defines species as groups of interbreeding populations that are reproductively isolated
Species is a population/set of pop characterized by one or more shared/derived characteristics. Don't forget about the age old question of Who suggested that radiant energy is only emitted or absorbed in discrete quantities like small packages?
Hypothesis about patterns of Cannot be applied to allopatric populations
relationships among species BSC
Can only be applied to sexual species
- Phylogeny: evolutionary history of a group
I Darwin was (one of the) first creators of a tree
Can be applied to both sexual & asexual species
Systematics: If you want to learn more check out What is catering sales manager (csm)?
*** Biologists used to just use morphological traits to classify
We now have more tools to classify (DNA)
z organisms share a lot of traits 1. Composed of 1 or more cells 2. Carry out metabolism 3. Transfer energy via ATP 4. DNA as genetic code
Reconstruction & study of evolutionary relationships
- Phylogenetic tree → may or may not have time scale If you want to learn more check out Transformation is initiated by the recipient. the donor is not involved because it is dead. this is often how bacteria acquire antibacterial resistance. why?
Graphical representation of ancestry (pictured hypothesis of patterns/relations)
- Sister Taxa
• How are phylogenetic trees constructed?
u Rates of evolution may vary
ools to construct:
1. Comparative anatomy 2. Comparative embryology 3. Fossil record If you want to learn more check out What are the some type of investigation?
4. biogeography 5. Molecular analysis Phylogenetic research is "dominated" by methods: Cladistics -
Analysis of shared & derived traits
- Use of Parsimony: hypothesis that uses the least amount of assumptions
Ancestral (Shared) vs. Derived characteristics —
"recent" trait Mammals --> hair (more recent trait)
"informative trait" Mammals --> lungs
(also present in
reptiles) Cladistics terminology:
• Plesiomorphy: ancestral characteristic Symplesiomorphies: shared ancestral states
• Apomorphy: derived characteristic
• Homoplasy: trait that could have come from convergent evolution
Cladistics: analysis of derived & shared traits in a group
Ancestral vs. Derived:
• Plesiomorphy = original ancestral trait
Shared plesiomorphy = symplesiomorphies
Apomorphy = derived characteristic
Shared apomorphy = synapomorphies
Homoplasy = does not tell us much about how animals are related; a trait that is not shared due to ancestry (convergent evolution)
Clade = aunts, uncles, cousins
→ = 1 clade
You, siblings, & parents
= 1 clade
OR the whole family = 1 clade
Outgroup = the comparison group to the rest of the clade; has the least amount of
1 common ancestor & all descendants
Some, but not all descendants of a common ancestor
Does not include most recent ancestor
Notes/Discussion from the reading:
"Gregory, T. R., 2008. Understanding Evolutionary Trees. Evolution Education & Outreach, 1(2):121-137"
1. 2 points when it comes to phylogenetic literacy
a. It is critical to understand modern evolutionary concepts
b. It is in sufficiently common 2. There are no mainlines/hierarchies in phylogeny
Humans are not on top 3. Reading across the tips:
The order f the tips (on a tree) mean nothing. (make sure to pay attention to branching though. 4. Sibling vs. ancestor
chimps & humans; we didn't evolve from chimps & they aren't our ancestors - however we are related.
Molecular clocks - use proteins to make assumptions about substitutions & mutations
this allows us to se the latest ancestral divergence.