Chapter 25 – Phylogeny and Systematics Phylon = tribe Geny = genesis Phylogeny=Evolutionary History of a Species/Genus (branch order, branch length) Systematics – studying biodiversity in an evolutionary context (involves the se of fossil record) Taxonomy - classifying organisms
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Chapter 25 – Phylogeny and Systematics Phylon = tribe Geny = genesis Phylogeny=Evolutionary History of a Species/Genus (branch order, branch length) Systematics.
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Chapter 25 – Phylogeny and Systematics
Phylon = tribeGeny = genesis
Phylogeny=Evolutionary History of a Species/Genus (branch order, branch length)
Systematics – studying biodiversity in an evolutionary context (involves the se of fossil record)
Taxonomy - classifying organisms
Fossil record—the order of fossils within layers (strata) of sedimentary rock. (helps determine order of events in history, age of rocks, how environments were in history). Hard parts like bones and shells leave fossils - so record is incomplete.
FOSSIL GUESSING GAME
How are fossils formed?
Sedimentary rocks form from layers of sand and silt that settle to the bottom of seas and swamps.
As deposits pile up, they compress older sediments below them into rock.
The bodies of dead organisms settle along with the sediments, but only a tiny fraction are preserved as fossils.
Sedimentary rocks are made from layers of minerals that settle out of water.
Sand forms sandstone.
Mud forms shale.
When pieces of organisms settle along with the inorganic material, they can be preserved as fossils.
Petrified Trees – 190 million years old!
Leaf with intact chlorophyll – 40 million years old!
Dinosaur footprints – 150 million years old!
Summary:Most parts of dead organisms decay quickly, but mineral-rich parts can remain as fossils.
ex. shells, teeth, bones
Fossils that retain organic (soft) material are rare - a cast is made of the soft parts.
Many fossils are imprints left by organisms that have since decayed.
Paleontologists can determine relative ages of fossils bylooking at what’s found in each layer.
Index fossils are fossils that are found at different locations.
They can help to correlate the fossil record from multiple locations + serve as guides to the age of rocks they are found in.
Relative Dating:The geological time scale consists of eras, periods, and epochs. Date a fossil based on where it is found in a rock strata = relative dating.New eras are marked by a distinct change in the types offossils found.
Binomial classification—genus and species (Linneaus System)
(Domain)KingdomPhylumClassOrderFamilyGenusSpecies
Taxonomic unit/ Taxa
Cladogram
A phylogenetic diagram - cladogram
Classification parallels phylogeny.
Monophyletic—includes most recent common ancestor and all its descendentsPolyphyletic—members come from 2 or more ancestors; does not include the most recent common ancestorParaphyletic— includes the most recent ancestor, but not all its descendents
Homology—likeness from shared ancestry; ex. forelimbs of mammals
Analogy—likeness due to convergent evolution; ex. wings of birds and insects
In developing phylogenetic trees, we should use only homologies.
Daa
•A cladogram presents the chronological sequence of branching during the evolutionary history of a set of organisms.
An outgroup is a species that is kind of related to the species being studied, but not as much as the other species studied are related to each other.
Cladistic analysis--classifies organisms
according to the order that branches arose along a phylogenetic tree
Each branch point is defined by homologies that are unique to the species on that branch.
Molecular Biology Comparisons Amino acid sequence DNA and RNA sequences
DNA-DNA hybridization—extent of H-bonding between DNA of 2 different species restriction maps
comparison of restriction fragments DNA/RNA sequencing
Molecular Clocks – UCCP CD
Classification based on protein and DNA similarities