Transcript Lamarck-Darwin

Who am I?
What did I do?
Jean-Baptiste Lamarck
 One of the first to recognize that living things change over
time and propose a mechanism
 Proposed:
 Individuals can acquire or loose certain traits during their
lifetime based on its amount of use or disuse. These
acquired changes are then passed on to their offspring.
 3 Principles of Lamarck’s Hypothesis
 Tendency Toward Perfection
 Use and Disuse
 Inheritance of Acquired Traits
Charles Darwin
 One of the first to collect such vast data regarding
species change
 Spent decades cataloguing data and refining theory
 1859: Published On the Origin of Species by Means of Natural
Selection
 Proposed:
 Variation of traits exists within populations
 Nature selects for specific traits which enable organisms to
survive in their environment
 These individuals are more likely to produce greater number
of offspring which will inherit these traits
 Over time, species changes
Darwin’s Finches
A Quick Comparison
Lamarck
Darwin
1. Environment changes,
creating need for change
1. Variation of heritable features
exists within a population
2. Individuals develop new
features so that they can
survive.
2. Environment screens out (selects)
features contributing to survival,
and eliminates others.
3. Newly acquired traits get
passed onto offspring.
4. New species
3. Those with traits which help
survival tend to have more
offspring, who inherit these
traits.
4. New species
The Fast, The Weird, The UGLY!
How Did These Things
Happen?
1.
Cheetahs can run faster than 60 miles per hour when in pursuit of
prey. How would an evolutionary biologist explain how this ability
evolved, assuming their ancestors could only run 20 miles per hour?
2.
Many cave organisms are blind. In fact, for many, their eyes have
become vestigial (useless) structures. How would an evolutionary
biologist explain how this inability to see evolved from sighted
ancestors?
3.
Naked mole rats have several morphological (relating to the body) as
well as behavioral adaptations which allow them to live in a eusocial
system within a harsh and unforgiving environment. Make a list of
as many of these characteristics as you can. How would an
evolutionary biologist explain how these unique characteristics
evolved from ancestors which did not possess these traits?
What Have We Learned
About Evolution?
1.
Evolution proceeds by the process of variation, a genetically random
process, and selection, an environmentally driven non-random
process.
2.
Organisms do not get what they "need" through "inner wants" or
through "use and disuse' "Individual intentions do not play a role.
3.
Acquired characteristics are not passed on to offspring
4.
Mutations are not directed for the benefit of the individual.
5.
Evolution is not random. It is driven by the non-random, yet nondirected, process of selection.