Do NowBacillus thuringienses (Bt) bacteria produce a natural insecticide (kills insects). Widespread use of Bt has lead to Bt resistance among insects. Why is this occurring?

a) Individual insects that have mutations providing resistance to Bt can survive in the presence of Bt. The survivors pass this Bt resistance on to their offspring.b) Bt-resistant insects increase in the population by chance. There are so many insects that some of them are resistant to each type of insecticide.c) In the presence of Bt, individual insects evolve to become Bt resistant.d) Natural selection causes insects to generate genes providing resistance to Bt.

** choose and justify your answer**

• Get back with your groups. • You have 15 minutes to check in on your

presentations. CHECK EACH OTHER.• You present tomorrow! Presentations are due

to me electronically by 7:30am tomorrow.

• Topic: Natural selection• Essential question: How do organisms change

over time?

How do organisms change over time?

• several different mechanisms can produce change in organisms over time

• one of these mechanisms is natural selection

• natural selection is the process whereby organisms that are more adapted to their environment are more likely to survive and reproduce

how does natural selection work?

• individuals show variation in traits• these variations are passed from parents to

offspring (they are heritable)• some individuals are more successful at

surviving and reproducing than others• individuals with favorable variations are more

likely to survive and reproduce

how does natural selection work?

University of California Museum of Paleontology's Understanding Evolution (http://evolution.berkeley.edu)

individuals in this population of beetlesvary in their color

color is a heritable trait

some beetles are more likely to survive and reproduce than others

crows prefer to eat green beetles

brown beetlesspecifically are more likely to survive and reproduce

they pass on their brown color to their offspring

over many generations, the population will consist of brown individuals

important terminology: brown beetles are more “fit”

• fitness is the ability of an individual to survive and reproduce in its environment

• “survival of the fittest”

important terminology: brown color is “adaptive”

• an adaptation is a trait or characteristic that increases the survival or reproduction of an individual relative to individuals without the trait

Galapagos finches: an example of natural selection in action

• Rosemary and Peter Grant and colleagues performed studies of finches on Daphne Major over many decades

• they have been able to witness natural selection in action

Galapagos finches

• medium ground finch (Geospiza fortis) eats seeds by cracking them with its beak

• the Grants measured bird size, beak size and what they were eating every year

there is variation in beak size in the population

• beak size is correlated with size of seeds the finch collects and eats: bigger beaks, bigger seeds

beak size is heritable

• big beaked parents have babies with big beaks• small beaked parents have babies with small

beaks

individual finches vary in their success at surviving and reproducing

• severe drought in 1977 caused plants to produce very few seeds, many finches starved to death and did not reproduce

survival and reproduction was correlated with having a large beak

• the most abundant seeds during the drought were large, hard seeds

large seeds of Tribulus cistoides

survival and reproduction was correlated with having a large beak

• finches with large beaks were more likely to survive and reproduce

misconceptions about natural selection

• an individual does not change in response to natural selection

• the characteristics and make up of populations change in response to natural selection

• natural selection is not forward looking• there is no ideal end point to natural selection• natural selection is not “perfect”• organisms cannot be adapted to future

environmental conditions

misconceptions about natural selection

• selection does not act for the good of the species– if a trait increased the fitness of the group while

reducing the individual’s fitness, it would strongly be selected against• e.g. alarm calls by monkeys that warn the group but

draw attention to the caller, causing it to get eaten

misconceptions about natural selection

Bacillus thuringienses (Bt) bacteria produce a natural insecticide. Widespread use of Bt has lead to Bt resistance among insects. Why is this occurring?

a) Individual insects that have mutations providing resistance to Bt can survive in the presence of Bt. The survivors pass this Bt resistance on to their offspring.b) Bt-resistant insects increase in the population by chance. There are so many insects that some of them are resistant to each type of insecticide.c) In the presence of Bt, individual insects evolve to become Bt resistant.d) Natural selection causes insects to generate genes providing resistance to Bt.

** choose and justify your answer**

Do Now

Re-read your Natural selection notes from yesterday. 1. Highlight key terms and ideas2. Write a summary at the bottom

*I will be coming around to stamp this today*

Your grade on presentation

• 20 points possible • 15 points from presentation – above standard is extra credit– I will be filling out the rubric as you do your

presentation• 5 points from your peer evaluation rubric – number of points based on the distribution of work. – Equal distribution, everyone gets 5 points. – People who didn’t do their share get less than 5

points. – People who did no work get 0 points.

2nd Presentations

• Columbia: http://prezi.com/r9m7c0cggyhy/edit/?auth_key=lqbtd2a&follow=5usok_zfweva

• Emoryhttps://docs.google.com/a/apps.everettsd.org/presentation/d/1ZcyL1NYf2OUJ7MuiU--unJcgsQoAXMuoUKf-aq0Xaf8/edit?pli=1#slide=id.p

• Harvard https://www.youtube.com/watch?v=iQdgbeKfyCM

• MIThttps://prezi.com/7ubx-21wv3tz/intro/?utm_campaign=share&utm_medium=copy

• Northwestern (ppt – Antibiotic resistance solution)

• Stanford (ppt – overprescription)

• UCLA: http://prezi.com/rpuzw_pxdkb_/edit/?auth_key=vyawflb&follow=jfkqe0n8fwju

3rd Presentations• UCLA

https://docs.google.com/a/apps.everettsd.org/presentation/d/1KT36dGG9tMueeMsR9V_Cd4vkzD_hHz4-Wtfi5fzi_rY/edit#slide=id.p

• Stanfordhttps://docs.google.com/a/apps.everettsd.org/presentation/d/1_5PfiBcH-3Z-fIePy4yJfsBSxvULP9TJTIffGvYpnFc/edit#slide=id.p

• Northwestern: https://prezi.com/2vwqbl0jn1u3/antibiotic-use-in-agriculture/

• MIThttp://prezi.com/x7kzhcyl4lye/?utm_campaign=share&utm_medium

• Harvardhttps://docs.google.com/a/apps.everettsd.org/presentation/d/1ADBB4o_ZxWujxcAtIWI5LJW0IuvwEKcqBVsLMalyAQI/edit

• Emoryhttps://docs.google.com/presentation/d/1SQRqmT2w9iNNwAnNYoybFY3RaywR3-nkXymoq5FWEg0/edit?usp=sharing_eid&invite=COLR2aMN&pli=1#slide=id.p

• Columbiahttps://docs.google.com/a/apps.everettsd.org/presentation/d/1Juf1PyEpELKuonNe9YADLwnMdBp-yEsdqw2LLiYnRRw/edit

6th Presentations• Columbia

https://docs.google.com/a/apps.everettsd.org/presentation/d/1mLpKW1KsmTE10xSlx-3rhqT6b_dHLLqudbjwGt7rtUM/edit?pli=1#slide=id.p

• UCLA http://prezi.com/bfysiuj3pewn/edit/?auth_key=rxlc7yl&follow=rocmxp6dteh7

• Harvard• Stanford

https://prezi.com/2onp94g58m2u/antibiotic-presentation/?utm_campaign=share&utm_medium=copy

• MIThttps://docs.google.com/presentation/d/1X4rduHzvjVkVs3w5yttRpIx5KzbRiEHCx6thGxn2D5A/edit?usp=sharing_eid&invite=CKCkvMIE&pli=1#slide=id.p

• Emory: http://prezi.com/nka9ibbkm-xe/edit/?auth_key=ec74ono&follow=8gn_fffgsltl

• Northwestern

https://docs.google.com/a/apps.everettsd.org/presentation/d/13n0mfuf5PJGiqOeRJQzUNegJKcug0BSoV57rqx_6g0c/edit?pli=1#slide=id.g62ed40749_00

Quiz tomorrow!

• Bacteria• Antibiotics• Adaptations• Variation• Fitness• Biotic potential (concepts, not math)• Natural selection(after the quiz we will finish up the presentations)

Do Now

1. What is the variation in this population?2. Why are some mice white and some grey?3. What is the selective pressure (what is

causing the change in the population) in this example?