the role of heredity and environment in students’ accounts of adaptation by selection and...

The Role of Heredity and Environment in Students’ Accounts of Adaptation by Selection and Phenotypic Plasticity

NARST Presentation Written by: JENNIFER DOHERTY, JONATHON SCHRAMM, AND ANDY ANDERSON

(Michigan State University)Culturally relevant ecology, learning progressions and environmental literacy

Long Term Ecological Research Math Science PartnershipApril 2011

Disclaimer: This research is supported by a grant from the National Science Foundation: Targeted Partnership: Culturally relevant ecology, learning progressions and environmental literacy (NSF-0832173). Any opinions, findings,

and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

JENNIFER DOHERTY, JONATHON SCHRAMM, AND ANDY ANDERSONMICHIGAN STATE UNIVERSITY

The Role of Heredity and Environment in Students’ Accounts of Adaptation

by Selection and Phenotypic Plasticity

Learning Progressions for Environmental Literacy

What is adaptation by selection?

Change in the distribution of individuals with specific hereditary information in a population as due to differential reproductive success.


What is phenotypic plasticity?

Phenotype: the morphology, behavior, and physiology and organism

Phenotypic plasticity: the ability of an organism to change its phenotype in response to changes in the environment.


Environment

genotype 1

genotype 2


MI 11th grader: I don't know what exactly is involved with that because like it's weird because like people, some people can keep their tan all winter long. And then others just can't. And then there are the people that can't even tan at all, they just burn and then go back to pale.

MI 11th grader: I don't know what exactly is involved with that because like it's weird because like people, some people can keep their tan all winter long. And then others just can't. And then there are the people that can't even tan at all, they just burn and then go back to pale.



Pfenning et al 2010


Why is this important for Environmental Literacy?

• Limits to adaptation by selection− selection must act on variation within population− organisms don’t have traits because we or they want to

• Limits to phenotypic plasticity− organisms have a limited ability to acclimate to changes or variation

their environment

• Understanding both adaptation by selection and phenotypic plasticity− Necessary for predicting effects of disturbances, including climate

change and other human impacts, on ecosystems

• Human managed ecosystems– Food and Fiber sustainability

• Natural ecosystems– Ecosystem services


Research literature regarding populations and evolutionary change

• Lamarckian (inheritance of acquired characteristics) • Teleological (trait acquisition is for a purpose) • Teleological reasoning is predominant among

students at all levels

A key characteristic of all of these misunderstandings is that they fail to consider the existence of standing variation in populations and its role in evolutionary change.

Anderson et al, 2002; Bishop & Anderson, 1990; Clough & Driver, 1986; Cummins et al1994; Scharmann & Harris, 1992;.

Bishop & Anderson, 1990, Brumby, 1984; Chan, 1998; Clough & Wood-Robinson, 1985; Evans, 2008; Lawson & Wesser, 1990; Nehm et al 2009, Rudolph & Stewart, 1998; Settlage, 1994; Tamir & Zohar, 1991

Proposed Learning Progression for Adaptation by Selection


Change in Population Questions

Insecticide

Farmers often spray their crops with chemicals to stop insects from eating their crops. Over time, more and more insects in the population are resistant to these sprays, so the farmers have to use different sprays to protect their crops.

Describe how this increase in resistance happens.



Level 4 for change in a population:

NY 12th grader: This occurs because the pesticide wipes out all of the non-resistant insects thus leaving the resistant insects to breed and reproduce and become a dominate trait in the population.

INTERVIEWER: Okay. How does an insect become resistant?

NY 12th grader: It's born with natural variation in genetic population. If there's a 100 bugs maybe 10 are resistant and then when the whole population is sprayed those 10 are left. So when the population eventually recovers those 10 will be the, will now be the entire 100 or they will be make up a large part of it and if the same pesticide is used over and over again eventually it won't have an effect because the entire population will be resistant to it.



Level 1 for change in a population:

CO 7th grader: The increase in resistance is most likely caused by the evolving animals in the environment of a farm. Lately we have talked about the changes animals and/or organisms use to change and adapt to their environment. These insects highly adapt to avoid the chemicals.

INTERVIEWER: Okay. How do they evolve?

CO 7th grader: They evolve by adapting to their surroundings or doing something to make them – make better use of their surroundings.

INTERVIEWER: Okay. And so – do you know anything about mechanism? So how does – how do they adapt?

CO 7th grader: Probably just by finding different ways to use their surroundings or finding different ways to do something.


Change in Population: InsecticideP

ropo

rtio

n of

Ans

wer

s

n = 187 n = 160L1-4 = 80% L1-4 = 85%


Change in Individual: Forest Edge

Forest Edge

A forest and the sunny field along the forest’s edge have the same species of plants. In the forest, the plants grow taller and have wider leaves, while in the field, they are shorter and have smaller leaves.

A. Why do you think you see this kind of difference between the plants?

B. What do you think might happen to the plants if you moved the plants grown in the field into the forest?

– 4% of middle school and 13% of high school responses were scored a level 4 for selection items

– 0% of middle school students and 1% of high school students recognized phenotypic plasticity.

Proposed Learning Progression for Nature of Phenotypic Traits


Plasticity InterviewINTERVIEWER: OK well what would you say a gene is?

MI 9th GRADER: Just a trait that they give from the parents

.…

MI 9th GRADER : I don't really think genes change.

…

INTERVIEWER: What kind of differences might there be in traits between a coyote that lived up here in this range and one that lived, say, down in Arizona?

MI 9th GRADER : Well the fur is definitely going to be lighter down here since the temperature is warmer and probably not as much food down here as in up here because more populated down here.

…

INTERVIEWER: So if we captured our coyote up here in this range and we trucked it down to the border there or to the Arizona dessert and let it go would you expect it to survive?

MI 9th GRADER : Yeah I think it could adapt.

…

INTERVIEWER: Do you think that, again, going back to the idea of genes they might have anything to do with the changes that would be happening in it's body? Would the genes be able to help the coyote to respond to that different environment do you think? [0:10:41]

MI 9th GRADER : I don't think they would. Because, like, a coyote down here is going to have different genes in the north.

INTERVIEWER: And the genes it has that were allowing it to live up here would not be very useful down there?

MI 9th GRADER : I don't think so. It's just - like hunting purposes it would be good but - that and breeding but as far as surviving I don't think so.


Conclusions

• Understanding adaptation by selection and phenotypic plasticity are both important for predicting effects of disturbances, including climate change and other human impacts, on both ecosystems

• We propose understanding the mechanism of adaptation by selection is not what is limiting students understanding of how individuals and populations change.

• Instead we propose that understanding the nature of phenotypic traits is their largest hurdle.

• Phenotypic plasticity is rarely addressed at the K-12 level in the context of evolution and we suggest it should be.


Types of traits affected by the environment

1. Increase or decrease in size or health of organism due to more or less resources

2. Change of gene expression due to change in environment

a) Developmental—irreversible change in organism architecture

b) Inducible—reversible change in organism


EnvironmentalChange

Differential Survival &

Reproduction

genotype 1

genotype 2

Differential Survival &

Reproduction

What is adaptation by selection?

the role of heredity and environment in students’ accounts of adaptation by selection and...

Documents

learning progressions

phenotypic plasticity

environmental literacy

selection selection

organism phenotypic

anderson et

bishop anderson

climate change