Transcript Unit Thirteen Change Over Time

Adaptation: process by which an
organism/population becomes better suited for their
environment.
• Camouflage, Morphology, Behavior, Biochemical
• List behavioral adaptations.
• Explain the idea of “survival of the fittest” using the term
adaptation/adapt.
Change Over Time
Aka: Evolution
Theories of Evolution
• Evolution refers to change over time.
• Several scientists have contributed to the current
theory of evolution. The theory is constantly
changing-that is why it is a theory!
• Lamarck
– Similar species descended from the same ancestor.
– First to state that organisms change over time.
– Lamarck believed acquired traits were passed on to
offspring and that is how species change over time.
– Passing of acquired traits was easy to disprove.
Who was Charles Darwin?
• Trained in the church but studied science.
• Took a job on the HMS Beagle as a
naturalist traveling to South America and
the Galapagos Islands for 5 years.
• Noticed finches in different areas had beaks
that were suited for the food in that area.
Adaptive radiation: because of differences in
the environment, many different forms of a
speices emerge.
• Darwin’s Evidence of Evolution
– Similar Structures
Homologous Structures: same structure but used for the
different function. Ex. Forearm of humans and the wing bones
of a bat.
Ex. wings of a bird and wings of a bat.
– Vestigial Organs
• Once very important but now reduced in size and function
– Embryology
– Fossils
• All of these pieces of evidence point to a common
ancestor.
• Darwin and Wallace
– Both proposed that species were changed by natural
selection.
– The organisms that were best adapted to their
environment would survive to reproduce. =fitness
– If a trait is favorable, what will happen to that trait
in the population?
– If a trait is selected against what will happen to that
trait?
– What will happen to the genes (alleles) associated
with these traits?
Title: Bear Lab / 3.4/ 40 pts.
• Question/Purpose:
• Background: Paragraph form.
• Read Story
• Define evolution.
• Answer Background Questions
•
•
•
•
•
Hypothesis: Write a possible answer to the question
Draw Data Tables
Read procedure!!!
Collect Data and Create a graph for the second table.
Conclusion
• Review how Evolution by Natural Selection
Works:
– Organisms would grow unlimited if it were not for the
environment.
– The environment (nature) determines which traits are
favorable or not so…The mechanism of evolution is
natural selection.
– The most “fit” organisms will survive to reproduce and
the species will change.
Bear Lab / 3.4 / 60 pts.
• Day 1 Review
• Day 2:
• Hypothesis: What will happen to a recessive allele
if the environment selects against it?
• Data:
–
–
–
–
Genotype data tables
Above the AA and Aa columns write ‘SAD’.
Above the aa column write ‘HAPPY’.
Collect Data and Graph Table 2
• Conclusion
Types of Natural Selection
•
•
•
•
Stablizing: the average trait is best
Disruptive: both extreme traits are best
Directional: one extreme trait is best
Diagrams.
• Which type of selection is shown when insects become resistant
to pesticides?
MRSA
Types of Natural Selection
•
•
•
•
•
Stablizing: the average trait is best
Disruptive: both extreme traits are best
Directional: one extreme trait is best
Diagrams
Part B on your Worksheet – 8 minutes.
How do organisms evolve so much they make a new
species?
• Definition of a species: similar organisms that can
reproduce to create fertile offspring
Making a new species
•Requires isolation and evolution in different
directions
•Isolation can be because of a physical or
behavioral barrier.
–Physical - geographic isolation.
–Behavioral- non-mating because of
unrecognizable courtship rituals.
• This results in divergent evolution and
eventually a new species.
How fast does change occur?
• Very slowly
– Punctuated or gradual
• Convergent evolution: Unrelated species
evolve similar traits because their
environments are the same OR it is a really
good trait!
• Co-evolution: organisms evolve together
– Ex. Flowers and pollinators
• Evolution works on genes to change
populations of species over time, not on
individuals.
• What role do genes play????
– If a phenotype is unfavorable in an environment, the
genotype for that trait will decrease in the
population. (BEAR LAB!!!)
• What types of organisms do we use to study
populations?
• Discovery Video Clip
• Question: Do large, colorful tail feathers in male peacocks
help the individual to survive or the species? Which is more
important?
• Sexual Selection
– Selection of an individual based on certain traits
that are favorable to the opposite sex but not
necessarily favorable in the environment.
• Artificial Selection-humans decide the favorable
traits. Ex. Dog Breeding, Agriculture