Transcript Lamarck`s Theory of Evolution Tendency Toward Perfection

• Evolution is defined as gradual change
over time
• Time being one critical element of the
definition.
Jean Baptiste Lamarck
• Author of first
systematic theory of
evolution
• Theory on the
evolution of acquired
characteristics
• Believed that
modifications of form
due to environmental
circumstances
Lamarck’s Theory
• Use it or lose it
• Internal drive toward
complexity caused
inheritance of
acquired
characteristics
• The giraffe’s neck is
the classic example
Lamarck’s theory
• At some point in the past, giraffe’s found
themselves in an environment where they
had difficulty reaching food on the tops of
tree. They had to stretch their necks and in
doing so, physically lengthened them.
• This longer neck was passed on to the
next generation, who stretched even
further, resulting over time in giraffes
having long necks.
Lamarck’s Theory of
Evolution
• Inheritance Of Acquired Traits
– Traits Acquired During Ones Lifetime
Would Be Passed To Offspring
Clipped ears of dogs could be passed to offspring!
Lamarck’s Theory of
Evolution
• Tendency Toward Perfection
• Organisms Are Continually Changing
and Acquiring Features That Help Them
Live More Successfully In Their
Environment
• Example: Bird Ancestors Desired To
Fly So They Tried Until Wings
Developed
Lamarck’s Mistakes
• Lamarck Did NOT Know how traits
were inherited (Traits are passed
through genes)
• Genes Are NOT Changed By
Activities In Life
• Change Through Mutation Occurs
Before An Organism Is Born
Charles Darwin the
Naturalist
Charles Darwin
• The Author of the On the Origin of Species
• The most notable evolution theorist of our
time
• Known for his famous voyage on “The
Beagle”
Charles Darwin
• Born in England
• Wealthy, sophisticated English family
• 1827 dropped out of medical school &
entered Cambridge to prep for the clergy
• Became a meticulous observer of natural
phenomena & collector of specimens
• at 22 was taken aboard HMS Beagle as
a naturalist on a scientific expedition
around the world
• Arrived at the Galapagos Islands on
September 15th, 1835
• 5 week stay – was on land 19 days
collecting & observing
In 1831, the young naturalist Charles Darwin set
off on a five-year sail around the world that
would profoundly change not just his life, but the
course of science as well. Commissioned to
collect samples of flora and fauna from the HMS
Beagle’s ports of call, Darwin left England firmly
believing, like everyone else, that God had
created every living thing on Earth exactly as it
appeared. His specimens told him otherwise,
however, and when the Beagle docked in
England, core tenets of the theory of evolution
had been shaped. Yet it would be 20 years
before he would make his ideas public; Darwin
feared that disclosing his radical views would be
the equivalent of committing career suicide and
was moved to publish only when another
scientist independently arrived at the same
conclusions as he. That event sparked a debate
that continues to this day.
Charles Darwin
• In 1831 he sailed to
the Galapagos
Islands in the HMS
Beagle
• He left England on
this voyage at 22 yrs.
Old
• He published his
theory of evolution 30
years later
The HMS Beagle
THE BEAGLE WAS 90 FEET LONG, WITH 74 PEOPLE
ABOARD
Darwin Left England in 1831
Darwin returned 5 years later in 1836
13 major islands, 6 minor islands, & 40 smaller rock formations & reefs
– 3000 square miles of land covering 17,000 miles of ocean located
600 miles west of Ecuador
Galapagos Islands
• Volcanic in origin – oldest are 325 million
years old
• Hot spot formation theory
• Still active volcanoes
• Never connected to the mainlands
Galapagos Islands
• Until their discovery in 1535, life here
evolved in isolation producing strange &
marvelous species
• 8 Habitats to accommodate a large variety
of species:
Open sea
Rocky shores
Mangrove coasts
Transitional zone
Rocky islets
Sandy beaches
Arid zone
Highlands
Bartolome Island – arid zone
North Seymour Island – transition zone
Rocky Islets
Black Sand Beach
Flamingos on the mangrove coasts
Rocky shores
Red Sand Beach
Highlands
View atop a inactive volcano
Darwin and the Galapagos
• He focused
evolutionary
principles on
populations
• Why were there so
many different plants
and animals found in
the Galapagos?
Animals of Galapagos
Galapagos Penguins
Land Iguana
Pink Flamingo
Frigate Bird
Galapagos Tortoise
Tortoise nesting video
There are currently only 11 subspecies
Left in the world today.
Lonesome George
• George is a Pinta
Island Tortoise
• He is the very LAST
one known in
existence
• There is a reward of
$10,000 offered by
the zoo association if
a female is found
Charles Darwin Research Center
• International, nonprofit organization for scientific research,
environmental education & conservation
• Founded in 1959
• Captive breeding program for endangered giant tortoises & land
iguanas
The Boobys
Blue Footed booby
Red footed booby
Masked booby
Blue Footed Booby
• http://www.youtube.co
m/watch?v=oYmzdvM
oUUA
• Mating Dance
Waved Albatross
Animals of the Galapagos
Sea Lions
Marine iguana
Sally Lightfoot Crabs
Darwin’s Ideas
Darwin at 31
• Evolution is due to
genetic variation and
natural selection on
heritable characters
• Recognized natural
selection as the
mechanism in 1838
Sketch of genetic line
Darwin’s 5 Major Theories
• 1. The organisms steadily evolve over time (evolution
theory)
• 2. Different kinds of organisms descended from a
common ancestor (common descent theory)
• 3. Species multiply over time (speciation theory)
• 4. Evolution takes place through the gradual change of
populations (gradualism theory)
• 5. The mechanism of evolution is the competition among
vast numbers of unique individuals for limited resources
under selective pressures, which leads to differences in
survival and reproduction (natural selection theory)
Weaknesses in Darwin’s natural
selection theory
• 1. Blending inheritance was favoured rather than
discrete Mendelian genes (which was unknown at the
time)
• 2. No knowledge of Mendelian genetics was available
• 3. Phyletic gradualism was favoured as the type of
speciation
• 4. Fecundity (fertility) was not emphasized in the
description of fitness
• 5. Sexual selection: Sexually selected characters were
seen as ornaments but they may be advertising genuine
male qualities (Hamilton & Zuk, 1982)
Evidence used in Darwin’s Natural Selection Theory
• 1. Biogeography: Distinct features of cosmopolitan
species and the presence of endemic species (Darwin's
finches: of the 14 finch species of the Galapagos islands,
13 are endemic)
• 2. Morphology and embryology: Homologous structures
among related species; similarities in the embryos of
related species
– Homologous Structure-features that are similar in structure but
appear in different organisms and have different functions; offers
support for common ancestor
– Analogous Structure-perform a similar function but are not
similar in orgin
• 3. Palaeontology: Gradual change in the fossil record,
evident extinctions
• 4. Taxonomy and systematics: Morphological similarities
among related taxa
Vestigial Structures
Compare Lamarck & Darwin
Lamarck
Darwin
Concept of
Species
Population all same
(identical characteristics)
capable of transformation
during lifetime
Population w/similar
characteristics, variation
common depending on
environment. No
transformation in lifetime,
only through genetic means
Mechanism of
new species
Modified during life & then
inherited by offspring.
Change directed to meet
survival
Natural Selection. Variation
exists regardless of
organisms' needs. Those
most fit survive & reproduce
Example
Giraffe’s neck, fiddler crab
Galapagos finch, eyesight
of the hawk
Potential Proof Adaptations
Adaptations, fossil records,
homologous structures,
biogeographical diversity
patterns
Natural Selection
• Darwin is credited with the theory of
evolution by natural selection.
• Natural selection is that the strongest
survive and propagate and therefore
increase the strength of the species
• “Survival of the Fittest”
– Fitness-an organism’s ability to survive &
reproduce
Darwin Finches
• Once on the islands,
various species
established
themselves and
determined territories
• Evolution then set in
and many unique
species, such as
Darwin’s finches
resulted
Darwin Finches and Natural
Selection
• The finches probably
descended from one
type of ancestor and
due to isolation and
through chance,
different climates,
natural forces, and
food type, evolved
into the 13 different
types of finches
Darwin Finches on the Galapagos
• 1. Small billed ground finch Geospiza fuliginosa
2. Medium billed ground finch Geospiza fortis
3. Large billed ground finch Geospiza magnirostris
4. Sharpbill ground finch Geospiza difficillis
5. Cactus finch Geospiza scandens
6. Large cactus finch Geospiza conirostris
7. Vegetarian finch Platyspiza crassirostris
8. Small tree finch Camarhynchus parvulus
9. Medium tree finch Camarhynchus pauper
10. Large tree finch Camarhynchus psittacula
11. Carpenter finch Cactospiza pallida
12. Mangrove finch Cactospiza heliobates
13. Warbler finch Certhidea olivacea
Cactus finch nest
• The Darwin Finches are the most common birds
on the Galapagos Islands and can be seen in
the arid and wet zones. Of the 14 species of
Darwin Finch in the world, thirteen are found on
these islands and the fourteenth species on the
Coco Islands. Some populations are commonly
found but others such as the mangrove finch
which has a population of approximately 100, is
only found in one particular area on Isabella
Island.
Feeding of the Finches
• some eat fruit and seeds
• other insects
• some can even suck the blood from
marine birds on the islands when they
can't find their usual food.
• Certain varieties of finch clean the ticks
from the shells of the giant tortoises.
Peppered Moths
http://www.biologycorner.com/worksheets/pepperedmoth.html
Natural Variation
• Some cows give more milk
• Some plants bear larger fruit
• Some humans are taller than others
Much of this variation is inherited & passed on to
the next generation
Humans may take advantage of this variation by
breeding certain organisms together with the
desired trait (artificial selection)
Natural selection • Something like artificial selection occurs in
nature – called natural selection
• However, the traits being selected contribute to
an organism’s fitness without human control
• There is always a struggle for existence & the
“fitness” of an organism depends on its survival
& its reproductive success (survival of the fittest)
Example:
faster = better predator
camouflage
behavior
better protection from extremes
Evidence for evolution by natural selection in
contemporary populations:
• 1. The resistance of the house fly (Musca
domestica) to DDT first reported in 1947,
• 2. The change in the frequencies of
differently colored peppered moths with
industrial revolution in England
• 3. The resistance of bacteria to antibiotic
drugs
Adaptation
• These changes increase the chance of
survival & thus the traits that allow for
survival are passed on the next generation
Speciation
• Formation of a new species
• As new species evolve, populations become
reproductively isolated from each other (they
cannot interbreed) called reproductive isolation
• Behavioral isolation occurs when 2 populations
are capable of interbreeding but have
differences in courtship rituals & are then not
attracted to each other
• Geographic isolation – 2 populations are
separated by geographic barriers such as rivers,
or mountains
• Temporal Isolation occurs when 2 organisms
reproduce at different times