phylogenetics phylogenetic trees illustrate the evolutionary relationships among groups of...
TRANSCRIPT
Phylogenetics
• Phylogenetic trees illustrate theevolutionary relationships among groups of organisms, or among a family of related nucleic acid or protein sequences
Each branch represents a new species which inherits many (primitive) traits from the ancestor but also has a new (derived) trait which appear for the 1st time
Evolutionary trees depict clades. A clade is a group of organisms that includes an ancestor
and all descendents of that ancestor.
PhylogenyEvolutionary treePhylogenetic treeCladogram
Are synonymous
Tree terminology
a b c d
{a,b}
{a,b,c}
{a,b,c,d} root
Taxa
nodecluster
d is the outgroup of abc
Nodes represent the common ancestor
Parsimony
The principle of parsimony implies that we should prefer the phylogeny that requires the fewest evolutionary changes.
Which tree is demonstrating maximum parsimony?
Phylogeny forfour different taxa
orangutan Gorilla Pan H. sapien
Phylogenetic Systematics - Introduction
Start at the ROOT.
The root is the earliest point of time shown in this particular phylogeny…
orangutan Gorilla Pan H. sapien
roottime
Phylogenetic Systematics - Introduction
The root representsthe common ancestorto orangutans, gorilla,Pan and H. sapien.
orangutan Gorilla Pan H. sapien
roottime
Phylogenetic Systematics - Introduction
At some point this commonancestor split into two new species, one of which gave rise to orangutans and one which is the common ancestor to gorilla, Pan, and H. sapien.
orangutan Gorilla Pan H. sapien
roottimeora
nguta
nlin
eage
lineag
e
giv
es
rise
to g
ori
lla,
pan,
H. sa
pie
n
Phylogenetic Systematics - Introduction
The common ancestral lineage to Gorilla, Panand H. sapien eventuallysplits to form the lineagethat leads to modern gorillas and a lineage that will give rise to Pan and H. sapien.
orangutan Gorilla Pan H. sapien
roottimeora
nguta
nlin
eage
lineag
e
giv
es
rise
to g
ori
lla,
pan,
H. sa
pie
n
Phylogenetic Systematics - Introduction
The common ancestral lineage to Pan and H. sapien eventually splits to form the ancestors to chimpanzees and H. sapien.
orangutan Gorilla Pan H. sapien
roottimeora
nguta
nlin
eage
lineag
e
giv
es
rise
to g
ori
lla,
pan,
H. sa
pie
n
Phylogenetic Systematics - Introduction
orangutan Gorilla Pan H. sapien
roottimeora
nguta
nlin
eage
lineag
e
giv
es
rise
to g
ori
lla,
pan,
H. sa
pie
n
In summary, therehas been three splittingevents (circles) that leadto four taxa at the tips of the tree.
What is most closely related toGorillas?
Phylogenetic Systematics - Introduction
orangutan Gorilla Pan H. sapien
roottime
Gorillas share a morerecent commonancestor with Pan and H. sapien than with organutan.
most recentcommon ancestor togorilla, Pan,H. sapien.
Phylogenetic Systematics - Introduction
orangutan Gorilla Pan H. sapien
roottime
Pan and H. Sapien arecalled sister taxa becausethey are most closely relatedto each other than to any otherspecies.
Is there a sister taxon to theGorilla? most recent
common ancestor togorilla, Pan,H. sapien.
sister taxa
Phylogenetic Systematics - Introduction
Phylogenetic Systematics - Characters and Taxa
orangutan Gorilla Pan H. sapien
time
A phylogeny is a summary of both characters and taxa.
Characters diagnose branchesof a phylogeny.
upright posture
use of tools
reducedhairiness
bipedalcomplex language
orangutan Gorilla Pan H. sapien
time
Characters that allgroups in a phylogenyshare are plesiomorhies
Characters shared but derivedare called synapomorphies
Characters shared only in one tip taxon are autapomorphies upright posture
use of tools
reducedhairiness
bipedalcomplex language
Phylogenetic Systematics - Characters and Taxa
Homo sapiens 1 1 1
Pan paniscus 1 1 1
Gorilla gorilla 1 1 0
Pongo pygmaeus 1 0 0
Hylobates 0 0 0
1 2 3
1
2
3
MRP(Matrix Representation Parsimony)
23
A
ED
C
B
(11000)
(00100)
(01000)
(00110)
(11001)
m characters
n s
peci
es
Example
C1 C2 C3 C4 C5
A 1 1 0 0 0
B 0 0 1 0 0
C 1 1 0 0 1
D 0 0 1 1 0
E 0 1 0 0 0
Input: Possible output:
(00000)
(11000)
(01000)(00100)
C2
C3
zero-root
monophyletic taxon includes a group of organisms descended from a single ancestor
polyphyletic taxon is composed of unrelated organisms descended from more than one ancestor paraphyletic taxon, which includes an ancestor and a group of organisms descended from it
Classification based on physical and structural similarities
• Carolus Linnaeus (1707-1778)• Created binomial nomenclature (2 word naming system)• 1st word = Genus (genera if plural) = a group of similar species• 2nd word = specific epithet = Species • Scientific name = Genus + specific epithet e.g. Homo
sapiens
Rules for writing species names
1.Latin is the language of scientific names (Latin is no longer spoken, so it does not change)
2.Italicize in print and underline when hand written
3.1st letter of the genus is CAPITALIZED & 1st letter of specific epithet is lowercase
Canis lupus = Grey wolf
Canis latrans = Coyote
Cougar?
Puma?
Panther?
Catamount?
Mountain lion? Or…
Felis concolor?
• Domain Did• Kingdom Kinky• Phylum Phil• Class Come• Order Over• Family For• Genus Good• Species Sex
All Living Organisms are grouped into... 3 DOMAINS
• EUBACTERIA - true bacteria
• ARCHAEA - ancient prokaryotes
• EUCARYA - modern eukaryotes
Six Kingdoms
Eubacteria· Prokaryotic · True bacteria · RNA is simple · Have true cell walls· Unicellular
Archaebacteria· Prokaryotic · RNA more complex· Unicellular
Protista
· Eukoryotic
· Autotrophs and heterotrophs
· Lacks organs systems
· Lives in moist environments
· Unicellular or multicellular
Fungi
· Eukaryotic
· Heterotrophs
· Unicellular or multicellular
· Absorbs nutrients from organic material in its environment
· Unicellular or multicellular
Six KingdomsPlantae
· Eukaryotic
· Autotrophs
· Multicellular
· Photosynthetic
Animalia
· Eukaryotic
· Heterotrophs
· Multicellular