LEARNING GOAL #1LEARNING GOAL #2LEARNING GOAL #3 Students will understand that: phenotypic variation has genetic and environmental components; inheritance is the result of shared DNA. Students will understand that: differences in fitness among individuals result from differences in the ability to survive and reproduce. Students will understand that: heritable variation arises independently of environmental conditions. Title of Unit Natural selection Context As part of an introductory course for biology majors, mid-semester, after Mendelian genetics; Experience with Excel, graphing, regression analysis AbstractIntroduces the concept of natural selection

TRAIT: Pea Flower Color Do you think that variation in this trait is: A.Under genetic control B.Under environmental control C.Under a combination of genetic and environmental control D.Insufficient information to determine Day 1: activity 1

TRAIT: puppy appearance Do you think that variation in this trait is: A.Under genetic control B.Under environmental control C.Under a combination of genetic and environmental control D.Insufficient information to determine

Do you think that variation in this trait is: A.Under genetic control B.Under environmental control C.Under a combination of genetic and environmental control D.Insufficient information to determine TRAIT: Near Sightedness

TRAIT: Plant height in two populations of Joshua trees Do you think that variation in this trait is: A.Under genetic control B.Under environmental control C.Under a combination of genetic and environmental control D.Insufficient information to determine

TRAIT: Puppy Appearance TRAIT: Tree height in two populations of Joshua trees TRAIT: Pea Flower Color TRAIT: Near Sightedness Assignment: What kind of information would you need to answer the question: is it genetic variation, environmental variation, or both? List the type(s) of data and/or experiments that will provide evidence about genetic versus environmental contributions to trait variation.

So what would a plot look like if we plotted a trait that had a strong genetic basis? Offspring arm length Parental Arm Length Short Long Day 1: activity 2

Offspring Flower Width (mm) Parent Flower Width (mm) 1.Do the relationships above allow you to make an hypothesis about the contribution of genetics to trait variation? 2.Which of these traits has a larger genetic contribution to trait variation? Offspring Height (in) Parent Height (in) Day 1: activity 3

Homework Plot the data provided (by hand or using Excel) Interpret what this plot indicates about the degree to which variation in this trait is due to genetic differences between individuals. Be prepared to discuss your interpretation at the start of the next class period. Day 1: homework

SAMPLE OF STUDENT GRAPH PARENT BEAK SIZE (mm) OFFSPRING BEAK SIZE (mm) Day 2: activity 1

Offspring Flower Width (mm) Parent Flower Width (mm) What would this graph look like if seeds were transplanted to different environments? A.Even # tables: you plant seeds in a greenhouse with carefully controlled homogeneous environments. B.Odd # tables: you plant seeds in a field with variable moisture and nutrient conditions. Day 2: activity 2

Reading and assignment Read textbook chapter on Natural Selection Read excerpt of Into Thin Air by Jon Krakauer on climbing Mt. Everest Think about the photo above Class collaboration document – Ways that high altitude cause a stress on organisms – How the two men in the photo are different Day 3-0

Selective forces at high altitude Day 3-1

Class collaborative document with discussion High altitude stresses: – Low oxygen – Cold temperatures – Less food – Higher UV – Shorter growing seasons How the two men are different – One requires oxygen to be at high altitude Effects of low oxygen – Breathing problems – Sleeping problems – High altitude sickness Day 3-1

Short term effects of low oxygen (less oxygen in the blood) Day 3-2

How low altitude animals handle low oxygen Breathe more Carry more oxygen in the blood – Pump more blood – Make more blood Day 3-2

Adapted from Storz 2007 Day 3-2 Hemoglobin saturation (%) Oxygen partial pressure in body tissue (mm Hg)

Day 3-3

A low altitude native visits a high-altitude native. Which one burns more energy sleeping? A. High-altitude native B. Low-altitude native C. They are both the same Adapted from Beall 2009 Day 3-3

Background information: – Variation: Native Tibetans have two physiological phenotypes Low oxygen saturation High oxygen saturation – Variation is genetically determined: oxygen saturation phenotype has a genetic basis (Mendelian trait) What other information do we need to demonstrate that this trait is under natural selection? Day 3-3

Adapted from Beall et al 2004 Day 3-3 Physiological phenotype Data measured at high elevation

Which of the following represents the best prediction for the relative frequencies of the two oxygen saturation types in the Tibetan population? Day 3-3

Day 3-4

Deer Mice Adapted from Storz 2007 Day 3-4

Minute essay In one sentence, summarize the major points of today’s lesson. Day 3-4