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Developmental Biology and Evolution 佟佟 佟佟佟佟佟佟佟佟佟佟佟
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Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Dec 31, 2015

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Page 1: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Developmental Biology and Evolution

佟超浙江大学生命科学研究院

Page 2: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Outline

• Overview• Preconditions for evolution• Deep homology• Mechanisms of evolutionary changes• Developmental constrains on evolution• Selectable epigenetic variation• Summary

Page 3: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

What is Evolution ?

Page 4: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

What is Evolution ?

Evolution is the change in the inherited characteristics

of biological populations over successive generations. Evolutionary processes give rise to diversity at every level of biological organization, including species, individual organisms and molecules such as DNA and proteins.

Page 5: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

• Descent from a common ancestor

• Natural selection

• At the different level

What is Evolution ?

Page 6: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Timeline of evolution theory

1735 biological classification

1809Lamarckism

18580n the origin of species

1865Mendel's laws

1896Weismannism“germ cells vsSomatic cells”

population genetics

1953DNA structure

Page 7: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Galapagos

Page 8: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Summary of Darwin’s theory

Every species is fertile enough that if all offspring survived to reproduce the population would grow (fact).

Despite periodic fluctuations, populations remain roughly the same size (fact).

Resources such as food are limited and are relatively stable over time (fact).A struggle for survival ensues (inference).

Individuals in a population vary significantly from one another (fact).Much of this variation is inheritable (fact).

Individuals less suited to the environment are less likely to survive and less likely to reproduce; individuals more suited to the environment are more likely to survive and more likely to reproduce and leave their inheritable traits to future generations, which produces the process of natural selection (inference).

This slowly effected process results in populations changing to adapt to their environments, and ultimately, these variations accumulate over time to form new species (inference).

Ernst Mayr 

Page 9: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Why we need to understand evolution?

"nothing in biology makes sense except in the light of evolution"

Theodosius Dobzhansky

Page 10: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Basics of Biology

• Theory of evolution

• Mendelian inheritance

• The central dogma of molecular biology

Page 11: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

How “far” away they are

Page 12: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

How “close” they are

Page 13: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

How does evolution work

• Preconditions for evolution: The developmental structure of genome

• Modularity• Molecular parsimony The small tool kit

Page 14: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Modularity: Divergence through dissociation

Page 15: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Modularity: Divergence through dissociation

• Apterous

Page 16: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Molecular parsimony: gene duplication and divergence

• Some “tool kit” genes play the same roles in all animals

• Gene duplication provides opportunities for divergence.

• Paralogues• Orthologues

Page 17: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Molecular parsimony: gene duplication and divergence

Page 18: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Deep Homology

Page 19: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Mechanisms of evolutionary change

Evolution works with what it has:

• Change in location (Heterotopy)• Change in time (Heterchrony)• Change in amount (Heterometry)• Change in kind (Heterotypy)

Page 20: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Heterotopy

Fgf8

BMP

apoptosis

Page 21: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Heterotopy

Fgf10 attract ribs to enter the dermis

BMP induce the bone formation

Page 22: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Heterchrony

Page 23: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Heterometry

• Darwin’s finches

Page 24: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Heterometry

Page 25: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Heterotypy• Why insects have only six legs?

Page 26: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Developmental constraints on Evolution

• Physical constraints

• Morphogenetic constraints

• Phyletic constraints

Page 27: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Physical constraints

Page 28: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Morphogenetic constraints

Page 29: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Phyletic constraints

Page 30: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Selectable epigenetic variation:Environment cues

• Somatic cells VS germ cells What is wrong with lamarck?• Epialleles• Symbiont variation• Genetic assimilation

Page 31: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Epialleles

Page 32: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Symbiont variation

Interaction with an expected population of symbionts could result in phenotypic plasticity.

When symbionts are transmitted through the germ line, the symbionts provide a second system of inheritance.

Page 33: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Symbiont variation

Page 34: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Genetic assimilation

• The environment could both “induce” and “select” a phenotype.

• Genetic assimilation happens both in labs and in nature.

• Fixation of environment induced phenotypes 1. The phenotype is not random. 2. The phenotype already exists in a large

portion of population

Page 35: Developmental Biology and Evolution 佟超 浙江大学生命科学研究院.

Summary• Variation-modularity, molecular parsimony, and

duplication- enable changes in development without destroy the organism.

• Four modes of genetic changes act during development to produce new and large variation in morphology.

• Epigenetic inheritance provide selectable variations and aid their propagation through a population.