evo - devo i. background ii. core processes iii. weak linkage regulation - types of regulation...

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

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")

mutation in the transcription factor gene is called trans-regulation

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")

mutation in the transcription factor gene is called trans-regulation

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 cis-regulatory 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 cis-regulatory changes in a pleiotropic gene Nature 440:1050-1053.

yellow gene

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.)

"spotted wing"

enzyme for pigment production

- Prud'homme et al. 2006. Repeated morphological evolution through cis-regulatory 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 cis-regulatory 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 cis-regulatory 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 cis-regulatory changes in a pleiotropic gene Nature 440:1050-1053.

yellow gene

In D. tristis, the yellow gene is enhanced by a completely different, independently evolved CRE.

spotted wing

- Prud'homme et al. 2006. Repeated morphological evolution through cis-regulatory 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

I. Background

II. Core Processes

III. Weak Linkage Regulation

IV. Exploratory Behavior

V. Physiology and Evolution

- stress can reveal new phenotypes - "norm of reaction"

stress response phenotype

Evo - Devo

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

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

selection

Evo - Devo

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.)

- 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...

stress response phenotype

selection

initially an inefficient phenotypic stress response

now an efficient and genetically hardwired response.

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

Sources of Variation Agents of Change

Mutation

Recombination

Selection

Drift

Mutation

Migration

Non-Random Mating

VA

RIA

TIO

N

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

Sources of Variation Agents of Change

Mutation

Recombination

Selection

Drift

Mutation

Migration

Non-Random Mating

VA

RIA

TIO

N

P

HY

SIO

LO

GY

DE

VE

LO

PM

EN

T

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.