More Theories...

LAMARCK: Inherited Acquired Characteristics Structural variations are due to

functional needs – “to use or disuse” Use of a structure increases its size. Failure to use it decreases its size These variations (now referred to as

“acquired characteristics” are inherited.

There is no supporting evidence in modern biology to support Lamarck’s idea

LAMARCK: Inherited Acquired Characteristics

A) Theory of need = production of new organ or appendage results from a need

B) The Theory of Use or Disuse = organs remain active as long as they are used, but disappear gradually with disuse

C) Theory of Inherited Acquired Characteristics = all that has been acquired by the individual is also inherited by his progeny in the next generation

LAMARCK: Inherited Acquired Characteristics

LAMARCK: Inherited Acquired Characteristics

The Theory of Natural Selection

The Theory of Evolution states that the present species have descended, with modifications, from species that existed in the past.

Species are not fixed, unchanging things, but are constantly evolving.

Evolution is therefore the constant change that has occurred in our world since its beginning to the present time

Dutch Botanist who studied the plant, Evening Primrose.

Observed that out of 50 000 individuals, 800 showed variations which were not inherited, and that mutations had occurred

HUGO DeVRIES: Theory of Mutation (1901)

HUGO DeVRIES: Theory of Mutation (1901)

Evolution has taken place through the accumulation of fortuitous variations

Due to the appearance of a series of changes in the germ-plasm

These may be pronounced or minor, but they are not equivalent to individual variations

HUGO DeVRIES: Theory of Mutation (1901)evening primrose plants

Coelocanth

Evidence Supporting Evolution

EVIDENCE SUPPORTING EVOLUTION: MISSING LINKS

Impossible to completely piece together the evolutionary history of some organisms

There are gaps in the fossil record called” “missing links” For many years there was no connection between birds &

reptiles from which they were thought to have evolved • ARCHAEOPTERYX has characteristics of both birds and

reptiles It had feathers and wings like a bird but a reptile skeleton Had teeth & lizard like tail

EVIDENCE SUPPORTING EVOLUTION: MISSING LINKS

Archaeopteryx

More Fossils

Fossil TrilobiteFossil Gastropod

More FossilsFossilized Fish

More FossilsJoggins Fossil Cliffs in Nova Scotia

Hylonomus sp.

More Fossils

Mt. Field & The Burgess Shale Canadian Rocky Mountains

More Fossils from The Burgess Shale

WORKS THAT INFLUENCE DARWIN’S THINKING

Carl Linneaus Compared organisms &

noted shared characteristic Laid foundations for

binomial nomenclature Father of taxonomy &

ecology studies

WORKS THAT INFLUENCE DARWIN’S THINKING

James Hutton Father of modern geology Theories on geology &

geologic time• Theory of Uniformitarianism =

“the principle that the same processes that shape the universe occurred in the past as they do now, and that the same laws of physics apply in all parts of the knowable universe.”

If Hutton is correct the the earth must be older than previously thought

WORKS THAT INFLUENCE DARWIN’S THINKING

Sir Charles Lyell

Principles of Geology is a book by the Scottish geologist Charles Lyell. Published in three volumes in 1830–33, it established Lyell's credentials as an important geological theorist and popularised the doctrine of uniformitarianism (first suggested by James Hutton). The central argument in Principles was that "the present is the key to the past:" That geological remains from the distant past can, and should, be explained by reference to geological processes now in operation and thus directly observable

Lyell visited Joggins Nova Scotia

WORKS THAT INFLUENCE DARWIN’S THINKING

Georges Buffon

Influenced both Lamarck & Darwin Darwin himself, in his foreword to

the 6th edition of the Origin of Species, credited Aristotle with foreshadowing the concept of natural selection but also stated that "the first author who in modern times has treated it in a scientific spirit was Buffon".