Phylogeny [phylo = tribe, family; gen = creation, birth] taxonomy: classifying and naming organisms...
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Transcript of Phylogeny [phylo = tribe, family; gen = creation, birth] taxonomy: classifying and naming organisms...
Phylogeny [phylo = tribe, family; gen = creation, birth]
taxonomy: classifying and naming organisms
taxon, taxa (pl.): classification unit (e.g. genus, order)
systematics: taxonomy based on phylogeny
cladistics: modern approach to systematics
clade: group of spp. with common ancestor
Biological diversity and classification
Biol 121, Fall 2010, Tom Buckley 01 Sep 10
Biological diversity and classification
Reminders:
1. print out the lab handout from WebCT
and bring it to lab
2. bring your textbook to lab
Hierarchy of classification
Species:Pantherapardus
Genus: Panthera
Family: Felidae
Order: Carnivora
Class: Mammalia
Phylum: Chordata
Kingdom: Animalia
ArchaeaDomain: EukaryaBacteria
Domain
Kingdom
Phylum/Division
Class
Order
Family
Genus
Species
Kids Prefer Cheese Over Fried Green Spinach King Phillip came over for great spaghetti.Keeping Precious Creatures Organized
For Grumpy Scientists
Phylogenetic trees
concepts:
common ancestors
sister taxa
trees show sequence,not time
what is sister taxon
of Panthera pardus?
monophyletic group: last common ancestor and all of its descendants(a.k.a. clade)
polyphyletic group: does not include last common ancestor
paraphyletic group: includes last common ancestor, but not all descendants
Phylogenetic trees
Classification
Carolus Linnaeus (1707-1778)
binomial nomenclature
Homo sapiens L.
genus(always capitalised)
(abbreviated after first use)specific epithet
(never capitalised)
authority
species name (italics or underlined){
Nomenclature... which is valid?
Humans are members of the species sapiens.
Humans are members of the species Homo sapiens.
Humans are members of the species Homo sapiens.
Humans are members of the species H. sapiens.
Humans are members of the species Homo Sapiens.
Bison bison
Marmota marmotahttp://en.wikipedia.org/wiki/List_of_tautonyms
How phylogenies are inferred
homology: similarity due to shared ancestry
cf. analogy: similarity due to something else
either coincidenceor convergent evolution
e.g. opposable thumbs in orangutans and humans
e.g. wings in bats and birds
Convergence: cacti vs euphorbs
Convergence: cacti vs euphorbs
Convergence: Equisetum vs Casuarina (diverged 400 MYA)
examples: http://evolution.berkeley.edu/evolibrary/search/topicbrowse2.php?topic_id=55
How phylogenies are inferred
homology: similarity due to shared ancestry
cf. analogy: similarity due to something else
analogies are also called homoplasies
How phylogenies are inferred
homology: similarity due to shared ancestry
phenotypic: based on anatomy, morphology, physiology
molecular: based on DNA sequences
How phylogenies are inferred
shared ancestral characters
shared derived characters
= homologies
conifers
flowering plants
vascularseedless plant
Q: is vascular tissue homologous or analogous in conifers & flowering plants?
vascular seed plant
= analogies
How phylogenies are inferred
outgroup vs ingroup
(e.g. ferns are an outgroup of seed plants)
conifers
flowering plants
seed plants
vascularseedless plant
vascular seed plant
seedsevolved
here
ferns
Deducing phylogenies by parsimony
somegene
Ancestor
"ancestral sequence" = A outgroup?
ingroup?
fewest assumptions, simplest story
AA
C
C
AC
A
C
AC
C
AAC A
# of mutations: 1 2 2
somegene
Ancestor
"ancestral sequence" = A
Deducing phylogenies by parsimony
tree based on genetic data:
Induction or deduction?
birds & crocs share traits:
e.g., 4-chamber heart
shared trait:
more likely ancestral
than derived
Q: where is common ancestor of birds and crocs?
1
2
3
4
Q: when did 4-chambered heart likely evolve?
did dinosaurs have
4-chambered hearts?
YES, PROBABLY
element
number of protons (atomic #)
electronic structure
chemical behaviour
Fossil dating
Isotopes: different # of neutrons
Carbon-12 (12C)Carbon-14 (14C)
6 protons6 neutrons
6 protons8 neutrons
element
chemical behaviour
Radiometriccosmic rays(neutrons)
14N
14CO2
12CO2 12C
14N
14C12C
14N
14C12C
14N
14C
14C
12C
isotopes
Dating fossils
2 Kingdoms: animals
plants (incl. protists, prokaryotes, fungi)
Phylogenies keep changing
5 Kingdoms: prokaryotes
protists
fungi
animals
plants
3 Domains: Archaea
Bacteria
Eukarya
Many Kingdoms...
Domains
Q: are multicellular organisms monophyletic?
red boxes:non-colonial,multicellularorganisms
monophyletic group: last common ancestor and all of its descendants