LIFE ON EARTH:
Course aims:
• To understand the origins of the precursors of life on Earth à the elements, the solar system and
the planet Earth.
• To understand the theories for the origins of life on earth
• To understand the diversity, origins and development of life from the molecular through to
organismal level, including animals and plants.
• To understand the process of evolution and patterns of relatedness.
• To understand the link between the evolution of developmental processes and the evolution of
adult morphology.
Francisco Diego: Nick Lane: Julia Day
• Origins of the universe • The origins of life • Diversity of the fishes
• Origins of the elements • The origins, evolution and
• Origin of the solar system diversification of Goswami:
• Early history of the earth. eukaryotes. • The evolution of
vertebrates from fish
Sandy Knapp: Telford: to humans
• Chloroplasts, • The origins of the • Vertebrate fossils.
photosynthesis and the animals Richard Pearson:
origins of plants • The evolution of • The future of life on
• Evolution of plants major animal groups earth
• The evolution and • Modern ideas about • Human effects on
diversification of flowering animal evolution biodiversity
plants.
Lectures:
Lecture 1 à Introduction (Telford 1) à Oct 3
Lecture 2 à Cladistics (Telford 2) à Oct 5
Lecture 3 à Cosmological Origins (Francisco Diego - 1) à Oct 10
Lecture 4 à Cosmological Origins (Francisco Diego – 2) à Oct 12
Lecture 5 à Animal embryology and morphology (Telford 3) à Oct 17
Lecture 6 à Non-bilaterians (Telford 4) à Oct 19
Lecture 7 à Ecdysozoa (Telford 5) à Oct 24
Lecture 8 à Homology, Urbilateria and Mesozoa (Telford 6) à Oct 26
Lecture 9à Lophotrochozoa (Telford 7) à Oct 31
Lecture 10 à Origin of Life (Nick lane 1) à Nov 2
READING WEEK
Lecture 11 à Origin of eukaryotes (Nick lane 2) à Nov 14 (Wed)
Lecture 12 à Water to land (Julia Day) Nov 16
Lecture 13 à Vertebrate evolution – synapsids (Goswami 1) – Nov 21
Lecture 14 à Vertebrate evolution – cenozoic mammals (Goswami 2) – Nov 23
Lecture 15 à NHM Dinosaurs (Paul) – Nov 28
Lecture 16 à Deuterostomes (Telford 8) – Nov 30
Lecture 17 à Plants (Sandra Knapp 1) – Dec 5
Lecture 18 – Plants (Sandra Knapp 2) – Dec 7
Lecture 19 à Sixth Mass Extinction (Pearson 1) – Dec 12
Lecture 20 à Biodiversity in the Anthropocene (Pearson 2) – Dec 14
,Lecture 1 – Introduction:
Exam à 2 hour exam, Part 1 à 70 multiple choice questions covering all lectures. Part 2 à one long form
essays from choice of 5 or 6 questions – drawn from all lectures.
Negative marking.
Lecture 2 – Cladistics:
Aims:
Diversity of life
We want to explain:
• Pattern of relationships
• Diversity of body plans
An introduction to cladistics for reconstructing trees
• Cladistics
• Shared parsimony priniciple
• Shared derived characters
• Outgroup comparison
• Molecular phylogenies
• Gene sequences
• Other genetic characters.
Clade: group of organisms all related to each other.
Phylogenetic trees- used to explain extraordinary diversity- from single universal common ancestor. The
sharing of characters, similarity to universal genetic code. How is this explained?
1. History of change à looking at history books, telling us what happened à the pattern of change.
2. Mechanism of change/process. (i.e. the reasons behind (1) – the historical change). à process of
change
Monophyletic groups: groups with single common ancestor, all closely related to each other than any
other group. Also known as clades, have a single common ancestor (which is included in the group). The
group has all the descendants of the last common ancestor. E.g. mammals
Paraphyletic groups: group of organisms which contains a common ancestor, and some, but not all of the
descendants (doesn’t include all the descendants of the last common ancestor) e.g. reptiles
Polyphyletic groups: have more than one origin e.g. imaginary group of flying vertebrates including birds,
bats and pterodactyls. They may have similar characteristics, but don’t share a recent common ancestor
(they may be the result of convergence).
Thus, phylogenetic tree: series of monophyletic groups (clades)- representing the evolutionary
relationships among organisms.
,Ingroup: essentially a monophyletic group/clade
Outgroup: groups that are outside clade you’re interested in (not a member of the clade/monophyletic
group) à
e.g. dinosaur and frogs are both outgroups relative to the ingroup of
mammals.
Sistergroup: special kind of outgroup à the closest outgroup to the clade we
are looking at. Essentially two sister groups form a monophyletic group e.g.
dinosaur not frog, is the sistergroup to mammals.
Two types of trees:
• Cladogram: represents only branching pattern, doesn’t show how much change occurred along
branches
• Phylogram: shows information with the branch lengths as well – telling you how much
evolution/change occurred along these branches.
Cladogram Phylogram
Principle for mapping characters on a tree:
• Occam’s razor à which uses the principle of parsimony. i.e what is the simplest theory that
explains the observation we have?
• The principle of parsimony: tells us to choose from a set of otherwise equivalent models, the
simplest one (requiring the fewest assumptions).
• Determining when a character evolved is based on the principle of parsimony.
• The other thing that can be done with this principle- trying to work out which tree is most
probable/the right tree. How do we choose between 2
equally apparent well supported tree?
• We need to know the character present in the ancestor-
to do this, use principle of parsimony. à need to look at
a more primitive animal.
• A characteristic shared with a more primitive animal
must be the primitive state. i.e. adding a frog to this
tree- which is cold blooded and has 5 toes, it shows that these were already there in the animals-
more parsimonious to suggest that cold blood was a primitive state and also having 5 toes ß this is
what was the primitive state.
• Have to do 2 trees for the two characteristics. First tree for the blood à frog, dinosaur, then
rabbits, then horses. Also for the toes- frogs, dinosaurs, rabbits then horses à this in total requires
, 2 changes to have occurred. In contrast to another scenario- which means that a total of 3 changes
occurred- most parsimonious explanation is the first one.
Because the toe character- having 1 or 5 toes- in
both cases, the cost/change = 1. Single change in
ancestory of the horse- this is called an
uninformative character. But, the other
character- is an informative character. One
character was useful and the other wasn’t
because having evolved warm blood is a novel
(new) change.
These shared-derived characters: characters derived (meaning new)- are derived from something
primitive.
So there’s a primitive state and a derived state. à e.g. cold blood is primitive, but warm blood is a derived
state.
Apomorphy: A new/novel (derived) character is called an apomorphy.
When an apomorphy is shared between other members- it’s called a synapomorphies à These are
informative- a character allowing us to prefer one tree over others.
Primitive character à also called pleisiomorphy
Shared primitive character à called symplesiomorphies.
Shared primitive characters are uninformative.
Shared primitive characters- bad characters for defining groups- they support paraphyletic groups. i.e.
reptiles share primitive characters- but creating a group based on this- is wrong. E.g. basing it off the fact
that you have scales, and are cold blooded (primitive state) à there are some problems:
• The truth is that Birds are more closely related to crocodiles than lizards are to crocodiles.
• They have lost the primitive character – e.g. archosauria. Birds have lost the reptilian
characteristics. à they are still reptiles, but lost scales and became warm blooded.
• Crocs and birds share derived characteristics e.g. extra hole in skull.
Looking at the same thing with apes à if we group apes as separate from humans because they are hairy-
this is wrong. Humans are more closely related to chimps (apes) and chimps are more closely related to us.
We get lots of characters that don’t agree- some which evolve twice in related groups- or some disappear.
Convergent evolution: Characters can appear in unrelated groups- independently of each other, causing us
to reconstruct tree wrong.
So far, demonstration of morphological characters- but we can also look at genome (non-morphological
character)
• Mammals – 3 billion nucleotides in genome- similar numbers in other mammals- looking at genetic
sequences we share- which constantly change and the changes inherited à resource of characters.
• Can also be interpreted in same way à using principle of parsimony.
Course aims:
• To understand the origins of the precursors of life on Earth à the elements, the solar system and
the planet Earth.
• To understand the theories for the origins of life on earth
• To understand the diversity, origins and development of life from the molecular through to
organismal level, including animals and plants.
• To understand the process of evolution and patterns of relatedness.
• To understand the link between the evolution of developmental processes and the evolution of
adult morphology.
Francisco Diego: Nick Lane: Julia Day
• Origins of the universe • The origins of life • Diversity of the fishes
• Origins of the elements • The origins, evolution and
• Origin of the solar system diversification of Goswami:
• Early history of the earth. eukaryotes. • The evolution of
vertebrates from fish
Sandy Knapp: Telford: to humans
• Chloroplasts, • The origins of the • Vertebrate fossils.
photosynthesis and the animals Richard Pearson:
origins of plants • The evolution of • The future of life on
• Evolution of plants major animal groups earth
• The evolution and • Modern ideas about • Human effects on
diversification of flowering animal evolution biodiversity
plants.
Lectures:
Lecture 1 à Introduction (Telford 1) à Oct 3
Lecture 2 à Cladistics (Telford 2) à Oct 5
Lecture 3 à Cosmological Origins (Francisco Diego - 1) à Oct 10
Lecture 4 à Cosmological Origins (Francisco Diego – 2) à Oct 12
Lecture 5 à Animal embryology and morphology (Telford 3) à Oct 17
Lecture 6 à Non-bilaterians (Telford 4) à Oct 19
Lecture 7 à Ecdysozoa (Telford 5) à Oct 24
Lecture 8 à Homology, Urbilateria and Mesozoa (Telford 6) à Oct 26
Lecture 9à Lophotrochozoa (Telford 7) à Oct 31
Lecture 10 à Origin of Life (Nick lane 1) à Nov 2
READING WEEK
Lecture 11 à Origin of eukaryotes (Nick lane 2) à Nov 14 (Wed)
Lecture 12 à Water to land (Julia Day) Nov 16
Lecture 13 à Vertebrate evolution – synapsids (Goswami 1) – Nov 21
Lecture 14 à Vertebrate evolution – cenozoic mammals (Goswami 2) – Nov 23
Lecture 15 à NHM Dinosaurs (Paul) – Nov 28
Lecture 16 à Deuterostomes (Telford 8) – Nov 30
Lecture 17 à Plants (Sandra Knapp 1) – Dec 5
Lecture 18 – Plants (Sandra Knapp 2) – Dec 7
Lecture 19 à Sixth Mass Extinction (Pearson 1) – Dec 12
Lecture 20 à Biodiversity in the Anthropocene (Pearson 2) – Dec 14
,Lecture 1 – Introduction:
Exam à 2 hour exam, Part 1 à 70 multiple choice questions covering all lectures. Part 2 à one long form
essays from choice of 5 or 6 questions – drawn from all lectures.
Negative marking.
Lecture 2 – Cladistics:
Aims:
Diversity of life
We want to explain:
• Pattern of relationships
• Diversity of body plans
An introduction to cladistics for reconstructing trees
• Cladistics
• Shared parsimony priniciple
• Shared derived characters
• Outgroup comparison
• Molecular phylogenies
• Gene sequences
• Other genetic characters.
Clade: group of organisms all related to each other.
Phylogenetic trees- used to explain extraordinary diversity- from single universal common ancestor. The
sharing of characters, similarity to universal genetic code. How is this explained?
1. History of change à looking at history books, telling us what happened à the pattern of change.
2. Mechanism of change/process. (i.e. the reasons behind (1) – the historical change). à process of
change
Monophyletic groups: groups with single common ancestor, all closely related to each other than any
other group. Also known as clades, have a single common ancestor (which is included in the group). The
group has all the descendants of the last common ancestor. E.g. mammals
Paraphyletic groups: group of organisms which contains a common ancestor, and some, but not all of the
descendants (doesn’t include all the descendants of the last common ancestor) e.g. reptiles
Polyphyletic groups: have more than one origin e.g. imaginary group of flying vertebrates including birds,
bats and pterodactyls. They may have similar characteristics, but don’t share a recent common ancestor
(they may be the result of convergence).
Thus, phylogenetic tree: series of monophyletic groups (clades)- representing the evolutionary
relationships among organisms.
,Ingroup: essentially a monophyletic group/clade
Outgroup: groups that are outside clade you’re interested in (not a member of the clade/monophyletic
group) à
e.g. dinosaur and frogs are both outgroups relative to the ingroup of
mammals.
Sistergroup: special kind of outgroup à the closest outgroup to the clade we
are looking at. Essentially two sister groups form a monophyletic group e.g.
dinosaur not frog, is the sistergroup to mammals.
Two types of trees:
• Cladogram: represents only branching pattern, doesn’t show how much change occurred along
branches
• Phylogram: shows information with the branch lengths as well – telling you how much
evolution/change occurred along these branches.
Cladogram Phylogram
Principle for mapping characters on a tree:
• Occam’s razor à which uses the principle of parsimony. i.e what is the simplest theory that
explains the observation we have?
• The principle of parsimony: tells us to choose from a set of otherwise equivalent models, the
simplest one (requiring the fewest assumptions).
• Determining when a character evolved is based on the principle of parsimony.
• The other thing that can be done with this principle- trying to work out which tree is most
probable/the right tree. How do we choose between 2
equally apparent well supported tree?
• We need to know the character present in the ancestor-
to do this, use principle of parsimony. à need to look at
a more primitive animal.
• A characteristic shared with a more primitive animal
must be the primitive state. i.e. adding a frog to this
tree- which is cold blooded and has 5 toes, it shows that these were already there in the animals-
more parsimonious to suggest that cold blood was a primitive state and also having 5 toes ß this is
what was the primitive state.
• Have to do 2 trees for the two characteristics. First tree for the blood à frog, dinosaur, then
rabbits, then horses. Also for the toes- frogs, dinosaurs, rabbits then horses à this in total requires
, 2 changes to have occurred. In contrast to another scenario- which means that a total of 3 changes
occurred- most parsimonious explanation is the first one.
Because the toe character- having 1 or 5 toes- in
both cases, the cost/change = 1. Single change in
ancestory of the horse- this is called an
uninformative character. But, the other
character- is an informative character. One
character was useful and the other wasn’t
because having evolved warm blood is a novel
(new) change.
These shared-derived characters: characters derived (meaning new)- are derived from something
primitive.
So there’s a primitive state and a derived state. à e.g. cold blood is primitive, but warm blood is a derived
state.
Apomorphy: A new/novel (derived) character is called an apomorphy.
When an apomorphy is shared between other members- it’s called a synapomorphies à These are
informative- a character allowing us to prefer one tree over others.
Primitive character à also called pleisiomorphy
Shared primitive character à called symplesiomorphies.
Shared primitive characters are uninformative.
Shared primitive characters- bad characters for defining groups- they support paraphyletic groups. i.e.
reptiles share primitive characters- but creating a group based on this- is wrong. E.g. basing it off the fact
that you have scales, and are cold blooded (primitive state) à there are some problems:
• The truth is that Birds are more closely related to crocodiles than lizards are to crocodiles.
• They have lost the primitive character – e.g. archosauria. Birds have lost the reptilian
characteristics. à they are still reptiles, but lost scales and became warm blooded.
• Crocs and birds share derived characteristics e.g. extra hole in skull.
Looking at the same thing with apes à if we group apes as separate from humans because they are hairy-
this is wrong. Humans are more closely related to chimps (apes) and chimps are more closely related to us.
We get lots of characters that don’t agree- some which evolve twice in related groups- or some disappear.
Convergent evolution: Characters can appear in unrelated groups- independently of each other, causing us
to reconstruct tree wrong.
So far, demonstration of morphological characters- but we can also look at genome (non-morphological
character)
• Mammals – 3 billion nucleotides in genome- similar numbers in other mammals- looking at genetic
sequences we share- which constantly change and the changes inherited à resource of characters.
• Can also be interpreted in same way à using principle of parsimony.
