Get out your clickers Get out your laptops i pads i phones or other internet connected device Go to wwwcodecarnivalcom Click on the first link Dont click any further Natural Selection ID: 225172
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Slide1
Pre-Tidbit Instructions
Get out your clickers
Get out your laptops,
i
-pads,
i
-phones, or other internet connected device
Go to
www.codecarnival.com
Click on the first link
Don’t click any further!!Slide2
Natural Selection
John Burke, Matt Elrod-Erickson, Sandra Johnson, Troy Nash, Chris Peterson, Mike
Rischbieter
, Dorset Trapnell17 May 2013Slide3
Context of Unit
Introductory Biology course for majors
Class of 21-50 students, already divided into working groups of 4
Foundational knowledge from earlier unitsMendelian geneticsMechanisms of hereditySlide4
Unit Learning Goals
Students will understand…
the
definition of natural selection the source(s) of phenotypic variationhow natural selection drives evolution in a populationSlide5
Unit Learning Outcomes
Students will be able to…
define evolutionary fitness (relative v/s absolute)
predict the relative importance of fertility & viability differences to overall fitnessidentify types of selective forces and how they affect fitnessexplain relationship between random mutation and non-random selective processespredict responses to changing selective pressurecompare and contrast outcomes of differing modes of selection (directional, disruptive, stabilizing)Slide6
Tidbit Learning Outcomes
Students will be able to…
define
evolutionary fitness (relative v/s absolute)
predict the relative importance of fertility & viability differences to overall fitness
identify
types of selective forces and how they affect fitness
explain
relationship between random mutation and non-random selective processes
predict
responses to changing selective pressure
compare
and contrast outcomes of differing modes of selection (directional
,
disruptive
, stabilizing
)Slide7
Tidbit Preparation
As part of the larger unit on natural selection, students will have been assigned a news brief reading assignment on Galapagos FinchesSlide8
Clicker Question
According to the article, the change in beak size in Galapagos finches was driven by _____.
competition
predationgene flowmutualismSlide9
Clicker Question
Where did the variation come from?
Some finches mutated because they needed smaller beaks.
Some finches had access to more seeds, so they grew larger beaks.Undirected chance mutation in beak size gene(s). Some finches hybridized with another species of bird with different sized beaksSlide10
Imagine a population of plants
With mutation and no selective pressure
Parent
Offspring in
the 8 other
squares.Slide11
Biomorph Simulation
Use control/command and +/- to adjust
size
of boxUse “reset” button to reset initial populationTake 2 minutes and get used to programClicking on one of the offspring will make it the parent of the next generationIt will move to blue center box8 new offspring will be randomly generatedNow take 1 minute to simulate the effects of random mutations
through at least 15 generationsRandomly select offspring with
out regard to their morphologySlide12
Clicker Question
In the previous demo, you saw all manner of shapes and sizes in the plant population over lots of generations when no selective pressure was applied. What does this imply about the effects of mutations on phenotypes?
A. Provide a continuous source of variation
B. Mutations alone do not lead to directional changeBoth A and BNeither A nor BSlide13
Imagine a population of plants
With a selective pressure – access to sunlight
Group activity
Come up with a hypothesis for a morphological change that would be advantageous in the above scenario (2 minutes)Run the simulation, consistently selecting for the morphological trait of your choice (2 minutes)Note: Once finished, don’t hit the reset button!!Slide14
3 possible outcomes of selecting for increased branching Slide15
In the same population of plants
The environment changes…
Group Activity
Propose what might happen in the environment that might alter/reverse the previous trend (2 minutes)Continue the simulation, consistently selecting for the new morphological trait of your choice (2 minutes)Slide16Slide17
Peppered Moth Group Activity
These are two phenotypes of the same species of moth, which is heavily preyed upon by birds. The white morph was much more common prior to the industrial revolution. With the rise of industry, pollution and soot started to darken tree trunks. On a
notecard
, answer the following:1) Why are there different colors of moths? (1 minute)2) Given the changes caused by the industrial revolution, predict what happened to the relative frequencies of these two color morphs. Explain your answer. (2 minutes)
3) What would happen if all the predatory birds died? Explain your answer.
(
3 minutes)Slide18
Acknowledgements
Norris Armstrong – Facilitator Extraordinaire!
Kathrin Stanger-Hall – Director Southeast RSI
Groups 2 and 3 for their helpful reviewsDon Raber, Provost – Presbyterian CollegeMichelle Momany, Plant Biology Department Head – University of GeorgiaLynn Boyd, Biology Chair – Middle Tennessee State University