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Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
- Types of Regulation
Enhancer - upstream activation
sequence. Binding site for
transcription factor.
Mutation here is cis-regulation
(within the operational "cistron")
Evo - Devo
I. Background
II. Core Processes
mutation in the
transcription factor gene is
called trans-regulation
III. Weak Linkage Regulation
- Types of Regulation
Enhancer - upstream activation
sequence. Binding site for
transcription factor.
Mutation here is cis-regulation
(within the operational "cistron")
Evo - Devo
I. Background
II. Core Processes
mutation in the
transcription factor gene is
called trans-regulation
III. Weak Linkage Regulation
- Types of Regulation
Enhancer - upstream activation
sequence. Binding site for
transcription factor.
Mutation here is cis-regulation
(within the operational "cistron")
Each type modulates
activity about 50% of the
time...
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
- NOVELTY
Mutations may make an enhancer
available to a different transcription
factor... and now that gene is 'on' in a
new tissue and can be used for a new
function. Crystallins in eye lens are
homologous to heat-shock proteins;
but when they are expressed in the
eye, they are used in a completely
different process.
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
- NOVELTY
OR, an entirely new binding site can
evolve - they are typically quite short
(6-10 bases) so they will arise
frequently by random
mutation...selection can then favor new
regulatory pathways....
KEEP THE OLD, but GAIN NEW
(sound familiar???)
- Prud'homme et al. 2006. Repeated morphological evolution through cisregulatory changes in a pleiotropic gene Nature 440:1050-1053.
a–c, The wing spots on
male flies of the
Drosophila genus.
Drosophila tristis (a)
and D. elegans (b)
have wing spots that
have arisen during
convergent evolution.
Drosophila gunungcola
(c) instead evolved
from a spotted
ancestor. d, Males
wave their wings to
display the spots during
elaborate courtship
dances. (Photographs
courtesy of B.
Prud'homme and S.
Carroll.)
- Prud'homme et al. 2006. Repeated morphological evolution through cisregulatory changes in a pleiotropic gene Nature 440:1050-1053.
yellow gene
enzyme for pigment
production
"spotted wing"
In their previous research, they
found that spotted members of
both spotted clades had same cis
regulatory element (CRE). So,
they hypothesized that all
members of the clade were
descended from a spotted
ancestor (99% chance ancestor
was spotted - fig.)
- Prud'homme et al. 2006. Repeated morphological evolution through cisregulatory changes in a pleiotropic gene Nature 440:1050-1053.
yellow gene
LOSS of the spot within this clade
(an example of convergent
evolution AND reversion) occurred
by different mutations in same
CRE.
- Prud'homme et al. 2006. Repeated morphological evolution through cisregulatory changes in a pleiotropic gene Nature 440:1050-1053.
yellow gene
LOSS of the spot within this clade
(an example of convergent
evolution AND reversion) occurred
by different mutations in same
CRE.
Importantly, yellow is still on
elsewhere. This is a pleiotropic
gene that has many effects.
- Prud'homme et al. 2006. Repeated morphological evolution through cisregulatory changes in a pleiotropic gene Nature 440:1050-1053.
yellow gene
LOSS of the spot within this clade
(an example of convergent
evolution AND reversion) occurred
by different mutations in same
CRE.
Importantly, yellow is still on
elsewhere. This is a pleiotropic
gene that has many effects.
Shutting it "off" by a mutation in the
gene would cripple it's activity
throughout the organism. Here,
through cis regulation, it's
expression is modulated in only
one tissue (wing).
- Prud'homme et al. 2006. Repeated morphological evolution through cisregulatory changes in a pleiotropic gene Nature 440:1050-1053.
yellow gene
spotted wing
In D. tristis, the yellow gene is
enhanced by a completely different,
independently evolved CRE.
- Prud'homme et al. 2006. Repeated morphological evolution through cisregulatory changes in a pleiotropic gene Nature 440:1050-1053.
Two gains and two losses are due
to independent changes in the
regulation of the yellow gene.
The developmental 'scaffold' for
forming spots exists... subsequent
evolution of enhancement can form
a new anatomical trait, which can
be rapidly selected for by sexual
selection.
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
- HETEROCHRONY
- paedomorphism
- peramorphism
- allometry
All simply changes in the developmental rates
of different structures or processes.
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
- environmental cues affect cell activity - production of growth factors
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
- environmental cues affect cell activity - production of growth factors
- hypoxia - stimulates cell to produce endothelial growth factor
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
- environmental cues affect cell activity - production of growth factors
- hypoxia - stimulates cell to produce endothelial growth factor
- neighboring vascular tissue grows towards the source of growth factor
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
- environmental cues affect cell activity - production of growth factors
- hypoxia - stimulates cell to produce endothelial growth factor
- neighboring vascular tissue grows towards the source of growth factor
- and BINGO... now you have vascular tissue and hypoxia is corrected
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
- environmental cues affect cell activity - production of growth factors
- hypoxia - stimulates cell to produce endothelial growth factor
- neighboring vascular tissue grows towards the source of growth factor
- and BINGO... now you have vascular tissue and hypoxia is corrected
- Nerves and vessels grow in response to local signals... the pattern is not
hardwired.
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
- environmental cues affect cell activity - production of growth factors
- hypoxia - stimulates cell to produce endothelial growth factor
- neighboring vascular tissue grows towards the source of growth factor
- and BINGO... now you have vascular tissue and hypoxia is corrected
- Nerves and vessels grow in response to local signals... the pattern is not
hardwired.
- So, if bone growth changes, muscles cell growth responds, and correct
ennervation and vascularization occurs on this new platform.
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
V. Physiology and Evolution
Evo - Devo
stress response
phenotype
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
V. Physiology and Evolution
- stress can reveal new phenotypes - "norm of reaction"
Evo - Devo
stress response
phenotype
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
V. Physiology and Evolution
- stress can reveal new phenotypes - "norm of reaction"
- (cloned plants raised in different environments will look different,
as a result of different physiological responses and gene action.)
stress response
phenotype
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
selection
IV. Exploratory Behavior
V. Physiology and Evolution
- stress can reveal new phenotypes - "norm of reaction"
- (cloned plants raised in different environments will look different,
as a result of different physiological responses and gene action.)
- Initially, this response is phenotypic and probably suboptimal in
integration. However, mutations that stabilize this phenotype (create it with
greater integration) would be selected for (If more integration means greater
energetic efficiency at achieving that phenotype, and more energy to divert
to reproduction).
stress response
phenotype
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
V. Physiology and Evolution
selection
initially an inefficient
phenotypic stress
response
now an efficient and
genetically hardwired
response.
- stress can reveal new phenotypes - "norm of reaction"
- (cloned plants raised in different environments will look different,
as a result of different physiological responses and gene action.)
- Initially, this response is phenotypic and probably suboptimal in
integration. However, mutations that stabilize this phenotype (create it with
greater integration) would be selected for (If more integration means greater
energetic efficiency at achieving that phenotype, and more energy to divert
to reproduction).
- So the phenotype might not change, but it shifts from a
physiological stress response to a genetically encoded norm. Subsequent
stress expresses new variation...
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
V. Physiology and Evolution
VI. The Role of Physiology and Development in Evolution
Mutation
Recombination
Agents of Change
VARIATION
Sources of Variation
Selection
Drift
Mutation
Migration
Non-Random Mating
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
V. Physiology and Evolution
VI. The Role of Physiology and Development in Evolution
VARIATION
Recombination
DEVELOPMENT
Mutation
Agents of Change
PHYSIOLOGY
Sources of Variation
Selection
Drift
Mutation
Migration
Non-Random Mating
Evo - Devo
I. Background
II. Core Processes
III. Weak Linkage Regulation
IV. Exploratory Behavior
V. Physiology and Evolution
VI. The Role of Physiology and Development in Evolution
VII. Example - Darwin's Finches
VII. Example - Darwin's Finches
- two genes interact in a co-ordinated way to determine beak
dimensions (Abzhanov et al. 2006. Nature 442:563-567).
VII. Example - Darwin's Finches
- two genes interact in a co-ordinated way to determine beak
dimensions (Abzhanov et al. 2006. Nature 442:563-567).
- BMP4 is a highly conserved signaling molecule in all metazoa; it is "bone
morphogen protein" that stimulates collegen production and subsequent
production of cartilage and bone.
VII. Example - Darwin's Finches
- two genes interact in a co-ordinated way to determine beak
dimensions (Abzhanov et al. 2006. Nature 442:563-567).
- BMP4 is a highly conserved signaling molecule in all metazoa; it is "bone
morphogen protein" that stimulates collegen production and subsequent
production of cartilage and bone.
- The timing and amount of BMP4 varies during development of finches;
VII. Example - Darwin's Finches
- two genes interact in a co-ordinated way to determine beak
dimensions (Abzhanov et al. 2006. Nature 442:563-567).
- BMP4 is a highly conserved signaling molecule in all metazoa; it is "bone
morphogen protein" that stimulates collegen production and subsequent
production of cartilage and bone.
- The timing and amount of BMP4 varies during development of finches;
- Large Ground Finch produces more, and produces it earlier, than other
species.
VII. Example - Darwin's Finches
- two genes interact in a co-ordinated way to determine beak
dimensions (Abzhanov et al. 2006. Nature 442:563-567).
- BMP4 is a highly conserved signaling molecule in all metazoa; it is "bone
morphogen protein" that stimulates collegen production and subsequent
production of cartilage and bone.
- The timing and amount of BMP4 varies during development of finches;
- Large Ground Finch produces more, and produces it earlier, than other
species.
- And a second, Calmodulin, is expressed more in long pointed beaks. CaM
modulates calcium signalling in cells
VII. Example - Darwin's Finches
- two genes interact in a co-ordinated way to determine beak
dimensions (Abzhanov et al. 2006. Nature 442:563-567).
VII. Example - Darwin's Finches
- two genes interact in a co-ordinated way to determine beak
dimensions (Abzhanov et al. 2006. Nature 442:563-567).
Used a virus to insert an up
regulator of CaM into the
beak of growing chick
embryos. This is a kinase
that increases absorption
of CaM.
Caused beak elongation.
VII. Example - Darwin's Finches
- so, if you remember, allometry like this is a common source of
adaptive variation that may often be involved in adaptive radiations.
- This variation is in the developmental timing of action of the same
structural genes.