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MECHANISM of DARWINIAN NATURAL SELECTION. 1. Variation exists in the population 2. Competition for survival, most animals dying before reproducing 3. Survival of those most fit for the environment 4. Offspring are from the survivors 5. Offspring inherit the genes that made their parents

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slide1

MECHANISM of DARWINIAN NATURAL SELECTION

1. Variation exists in the population

2. Competition for survival, most animals dying

before reproducing

3. Survival of those most fit for the environment

4. Offspring are from the survivors

5. Offspring inherit the genes that made their parents

fit for the environment.

slide2

DIVERSITY EXISTS WITHIN POPULATION

Homo sapiens subgraduensis

slide4

DEATH IS NOT RANDOM; IT IS SELECTIVE

Changes in finch beak morphology during drought of 1976/1977

slide6

THE MODERN SYNTHESIS

“Evolution is a change in the genetic composition of populations.

The study of the mechanisms of evolution falls within the province

of population genetics.”

--Theodosius Dobzhansky. 1951

slide7

CHARLES DARWIN

ON THE ORIGIN OF SPECIES

1859

“Community of embryonic

structure reveals community

of descent.”

“Embryology rises greatly in interest, when we look at the embryo as a picture, more or less obscured, of the progenitor, either in its class or larval state, of all the members of the same great class.”

slide8

HOMOLOGY

“The same organ in all its

varieties of form”

Serial Homology

Derived forms within

the same organism

Special Homology

Derived forms between

different species

Versus

Analogy

Sir Richard Owen

Forms similar due to

same function

slide10

KARL ERNST von BAER:

“The general features of a large group of animals

appear earlier in development than do the specialized

features of a smaller group…The early embryo is never like a lower animal, but only like its early embryo.”

slide11

DARWIN (1874):

“Thus, if we may rely on embryology, ever the safest guide in classification, it seems that we have at last gained a clue to the source whence the Vertebrata were

derived.”

AGGASIZ (1874):

“One could hardly open a scientific Journal or any

popular essay onNatural History without meeting some allusion to the Ascidians as our ancestors.”

slide12

THEOLOGICALLY TRAINED PASSENGERS

ABOARD HMS BEAGLE

Charles Darwin, 22

Cambridge University, 1830

York Minster, ca. 27

Church Missionary Society, 1830

slide13

EVIDENCE of COMMON DESCENT:

1. Material evidence

Biblical Archeology

Paleontology

Fossil Archeopterix showing feather

imprints and a reptilian body

Herod’s Palace, Israel

slide14

EVIDENCE for COMMON DESCENT:

2. VESTIGIAL APPARATUS

“Old Testament” Stories

Unused structures

Would the aortic archhave been

independently created in fish and

In mammals?

Would the story of Ahab been

independently created in Judaism

and in Christianity?

slide15

CLADOGRAM ( partial) of VERTEBRATES:

DESCENT WITH MODIFICATION

slide17

TWO CLADOGRAMS of WESTERN RELIGION BASED on DIFFERENT SYNAPOMORPHIES

Synapomorphy of papal

primacy: Protestantism splits

from Orthodoxy

Synapomorphies of liturgy

and ritual: Protestantism

splits from Catholicism

slide18

INDEPENDENT EVIDENCE for COMMON DESCENT:

3. Historical Records

Religious textual documentation

Biological genetic documentation

slide19

GENETIC EVIDENCE for DESCENT WTH MODIFICATION

MOLECULAR SYNAPOMORPHIES

Phylogenetic tree made from interspersed DNA elements. Four transposon

insertions, at loci 4-7, define a clade of whales and hippos.

slide20

Ernst Haeckel

“ONTOGENY RECAPITULATES

PHYLOGENY””HY

slide21

ONTOGENY RECAPITULATES

PHYLOGENY:

Correspondence

Terminal addition

Truncation

ONTOGENY

PHYLOGENY

slide23

Evolution is based on Haeckel’s diagrams about as much as Christianity is based on

Titian’s paintings.

HAECKEL’S CRIMES WERE FAR WORSE:

“The lower races…are physiologically nearer the mammals--apes and dogs--than to the

civilized European. We must, therefore, assign a totally different value to their lives.”

“He (Jesus) is generally regarded as being purely Jewish. Yet the characteristics

Which distinguish his high and noble personality and which give distinct impress to his religion are certainly not Semitical. They are the features of the higher Arian race.”

--The Riddle of the World, 1899

slide24

THE DEMISE of EVOLUTIONARY MORPHOLOGY…

“It is difficult, even if possible, to say whether the differences or the resemblances have a greater zoological value (because we have no clearly defined standard of zoological value).”

-A. Sedgwick, 1894.

“Haeckel’s “incautious generalization” has “done more to delay

the progress of sound phylogeny than any other modern speculation.”

-E. S. Goodrich, 1924

…AND THE EXODUS TO GENETICS

"Morphology having been explored in its minutest corners, we turned elsewhere...The geneticist is the successor of the morphologist."

-W. Bateson, 1894

slide25

EXORCISING THE GHOST of ERNST HAECKEL from BIOLOGY:

Stephen J. Gould, Ontogeny and Phylogeny, 1977.

Confusion of von Baer with Haeckel. Von Baer established

commonality of embryonic forms. Haeckel believed that

embryos of later organisms

past through adult stages of

primitive organisms.

2. Darwin used von Baer, not Haeckel. However, Haeckel became popular and eclipsed the Darwinian/von Baer view.

slide26

FRANÇOIS JACOB: EVOLUTION AS TINKERING

with REGULATORY GENES in the EMBRYO

“Small changes modifying the distribution in time and space of the same structures are sufficient to affect deeply the form, the functioning, and the behavior of the final product--the adult animal. It is always a matter of using the same elements, of adjusting them here or there, of arranging various combinations to produce new objects of increasing complexity. It is always a matter of tinkering.”

slide27

RICHARD B. GOLDSCHMIDT:

Evolution consists of inherited changes of development

Functional biology = anatomy, gene expression

Development =d[Functional biology]/dt

Evolution = d[Development]/dt

slide28

PAX6/Eyeless Expression in

Insect and Mouse Eye Primordia

slide29

HOMOLOGOUS GENES for ANALOGOUS TRAITS

Mouse Pax 6 instructs fly compound eye formation in antenna

slide32

MUTATIONS IN

REGULATORY GENES CAN GIVE THE PROTEINS NEW

PROPERTIES: UBX

ACQUIRES THE ABILITY to REPRESS

DISTAL-LESS in the

INSECT CLADE

R. Galant and S. B. Carroll,

2002. Nature 415:910.

Ronschaugen, M. et al.

2002. Nature 415: 914.

.

slide33

HOW THE DUCK GOT ITS WEBBED FEET

Merino et al., 1999. Dev. Biol. 200: 35 - 45.

Chick

Hindlimb

Duck

Hindlimb

Gremlin

Apoptosis

Newborn

BMP

slide34

HOW THE DUCK GOT ITS WEBBED FEET. II.

Experimental Manipulation of Chick Feet

Chick Hindlimb Treated

with Gremlin-Containing Bead in Interdigital Space

Untreated

Chick Hindlimb

slide35

ORIGIN OF FEATHERS FROM SCALES

Through Repetition of SHH-BMP Interactions

(Harris, M., et al., 2002)

slide36

GIS MODELING of TOOTH DEVELOPMENT:

FINE RESOLUTION of MORPHOGENETIC CHANGE

(Jernvall et al., 2000)

slide37

GENE EXPRESSION PATTERNS PREDICT

MORPHOLOGICAL CHANGES BETWEEN SPECIES

slide38

MATHEMATICAL MODELING of TOOTH EVOLUTION BY ANALYSIS

of GENE EXPRESSION CHANGES

(A. Salazar-Ciudad and J. Jernvall, 2002)

slide39

Developmental Mechanisms for

Phylogeny

Shigeru Kuratani et al. 2001. Phil. Trans. Roy. Soc. London B 356: 1615-1632

slide40

Population Genetics

Developmental Genetics

Variation within

population

Variation between populations

Genes in adults competing for

reproductive success

Genes in embryonic

and larval organisms

building structures

Arrival of the fittest

Survival of the fittest

Natural selection

Phylogeny

A NEW EVOLUTIONARY SYNTHESIS

EXPLAINING BIODIVERSITY