darwin’s theory on the origin of species
Post on 16-Feb-2016
35 Views
Preview:
DESCRIPTION
TRANSCRIPT
DARWIN’S THEORYON THE ORIGIN OF
SPECIES
Natural Variation Even within a species individuals
vary from each other
Discussion QuestionThese are the same species of moth. The
two are naturally occurring variations.
Describe situations where the coloration would be an advantage for the moth.
How We Use Variation Artificial selection – nature provides
the variation and humans select the variations they find useful
Evolution by Natural Selection Natural Selection – the traits being
selected (which therefore increase over time) contribute to an organism’s fitness in its environment
Natural Selection The struggle
for existence Survival of the
fittest Descent with
modification
Struggle for Existence
Members of each species compete regularly to obtain food, living space, and other necessities of life
Run fast, behavioral tactics, camouflage
Survival of the Fittest Individuals better
designed for the environment where they live will survive and reproduce most successfully
Fitness is the result of successful adaptations
Survival of the Fittest Fitness – the ability to survive and
reproduce in a specific environment Adaptation – an inherited characteristic
that increases an organism’s chance of survival
Discussion Question Give three examples of animals
with designs that help their survival.
Tale of the Peacock Online Video Clip http://
www.pbs.org/wgbh/evolution/educators/course/session4/explain_a.html
Or: “Why Sex?” (PBS Evolution Series) minutes 17:00 – 28:00
KEY CONCEPTOver time, natural selection results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment.
Com
mon
Des
cent
Evidence for Evolution
1) Fossil record2) Animals with
similar selection pressures evolve similar features
3) Homologous structures
4) Similarities in early development
Genetic Toolkit Online Video Clip http://
www.pbs.org/wgbh/evolution/educators/course/session4/engage_a.html
(5 min)
similar habitats & similar structures
homologous structures
similarities in embryology
top related