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Key concepts for today – Part 2:
Diversity of the biosphere –
- The biosphere is a hierarchy, but the levels are nested.
- Emergent properties arise at each level of organization.
- Biologists like to find order and define relationships.
Evolution – how diversity arose
- A blind watchmaker of nature, evolution happens by tinkering,
= engineering.
- It’s all about being fit.
LIFE’S HIERARCHY
Bacteria biosphere
Eucarya BACTERIA/ARCHAEA
ecosystem
community
population
organism
[cell]
molecule
atom
EUKARYA
Archaea LIFE’S HIERARCHY
Bacteria biosphere
Eucarya BACTERIA/ARCHAEA
EUKARYA
Single-celled
ecosystem
community
population
organism
[cell]
organelle
molecule
atom
Archaea LIFE’S HIERARCHY
Bacteria biosphere
Archaea Eucarya BACTERIA/ARCHAEA
EUKARYA
Single-celled
Multicellular
(plants/animals/fungi)
ecosystem
community
population
organism
[cell]
organelle
molecule
atom
organ
tissue
organ
system
LIFE’S HIERARCHY
Bacteria biosphere
Archaea Eucarya BACTERIA/ARCHAEA
EUKARYA
Single-celled
Multicellular
(plants/animals/fungi)
ecosystem
community
population
organism
[cell]
organelle
molecule
atom
organ
tissue
organ
system
LIFE’S HIERARCHY
Bacteria biosphere
Archaea Eucarya BACTERIA/ARCHAEA
EUKARYA
ecosystem
community
population
NESTED – an animal
is both a organism
and a composite!
Organism
[cell]
organelle
molecule
atom
organ
tissue
organ
system
Emergent Properties – properties of one level are not additive,
i.e., equal to the sum of their components – new properties and
rules emerge that could not have been predicted from full
understanding of the lower level – WHOLE GREATER THAN
SUM OF PARTS
biosphere
ecosystem
community
population
organ system
organ
tissue
cell
organelle
molecule
atom
In your readings:
Cohen (your reader) Math & Biology
Davies (PDF, Bi1 Website] Emergent biological principles and the computational
properties of the universe.
Emergent Properties
Emergent properties of
bacterial community affect
host health
Host’s body selects for
specific microbes
RELATIONSHIPS
Limits of RESOLUTION
BC– eyes –
Aristotle
ANIMALS/PLANTS
Late 1700s
Magnifying lenses (microbes) –
all
about
seeing
Anton van Leeuwenhoek
ANIMALS/PLANTS/MICROBES
Better microscopes – (organelles) –
5 kingdoms – taught [~1960s-2000]
ANIMALS/PLANTS/FUNGI/PROTISTS/’MONERA’
[Bacteria/Archaea]
RELATIONSHIPS
Limits of RESOLUTION
BC– eyes –
Aristotle
ANIMALS/PLANTS
Late 1700s
Magnifying lenses (microbes) –
all
about
seeing
Anton van Leeuwenhoek
ANIMALS/PLANTS/MICROBES
Better microscopes – (organelles) –
5 kingdoms – taught [~1960s-2000]
ANIMALS/PLANTS/FUNGI/PROTISTS/’MONERA’
[Bacteria/Archaea]
Sequencing of hereditary molecules
3 domains – taught [~1990 – present]
Bacteria Eucarya Archaea ARE WE DONE – have we finally discovered the essence? Maybe not
Bacteria Archaea Eucarya Each time biologists are sure they had the final picture
-  STAY OPEN!
THE DNA IS NOT STATIC! IT NATURALLY
MOVES AROUND and
WE’RE BEGINNING TO MOVE IT AROUND.
[END OF Bi1 – Myles Jackson, NYU – ethics in
modern biology
How did the diversity of the biological world arise?
EVOLUTION – the ‘glue’ that joins all of biology - A theme that will run through Bi1
Charles Darwin
1809-1882
Voyage of the Beagle
Charles Darwin
1809-1882
Voyage of the Beagle
From Darwin’s journal
Divergence of the
Galapagos finches
From Darwin’s journal
Divergence of the
Galapagos finches
UTube video – possible idea for your writing assignment:
http://www.youtube.com/watch?v=_UZ5u5sN1WQ
Published
November 1859
the foundation of
evolutionary biology
How did the diversity of the biological world arise?
WHAT IS EVOLUTION:
The change in genetic [DNA] composition
(blueprint) of a population over generations
Basis – genetic variation, differences in the
blueprint, in fitness
Fitness (ω) = capacity of a particular
genetic makeup (= genotype) to leave
offspring to the next generation
ω
abs = Nafter
Nbefore
Absolute fitness (ω) of a genotype is defined as the
ratio between the number of individuals with that
genotype after selection to those before selection. ω > 1, genotype representation in the population increases
ω < 1, genotype representation in the population decreases
How did the diversity of the biological world arise?
MECHANISMS:
1.  Changes in the genome
Genetic drift – chance creates novelty
random changes that accumulate
Horizontal gene transfer – transfer of large pieces of DNA
from one organism to another
2. Natural Selection – individuals with more advantageous traits
at a given time have higher fitness [not acquired within a
generation]
Change in the genome
Frequency of changes in DNA:
Error rate in DNA replication: 1 in 50 x 106
DNA damage: >1000 lesions/cell during this lecture
HGT: variable – rise on antibiotic resistance
Evolution through laboratory experiment
DESIGN
Frances Arnold
Chemical Engineering
Darwin was all about natural selection
His precepts:
1.  Life had a common beginning.
It’s written on your genome (sum of all of your genes)
Humans:
23,600 genes
Graphics by N Glasser
Darwin was all about natural selection
His precepts:
1.  Life had a common beginning.
2. Random variation arises by chance (genetic drift)
3. Selection from the environment (abiotic, biotic) for favorable traits
(natural selection)
4.  Cumulative over time – new forms
5.  Gradual change
Punctuated equilibruim – Steven J Gould
Long periods of stability and short episodes of change
species 3
evolution
species 2
species 1
Rapid changes in the environment
time
KEY INNOVATION – [e.g., development of electricity – light bulb, airplane, computer]
in biology, trait that enables a group of organisms to diversify;
e.g., hardened forewing of beetles
KEY INNOVATION – e.g., hardened forewings (elytra) of beetles
Vortex field contour during one
cycle of hind wing flapping
Le et al. (2010) Numerical investigation of the aerodynamic characteristics
of a hovering Coleopteran [beetle] insect.
Key concepts for today:
Principles of biology – Key concepts that structure the course
Diversity of the biosphere –
Evolution – how diversity arose
Syllabus