The rotifer and the yeast: An experiment to study how multicellularity could evolve in nature William C. Ratcliff and Jennifer Pentz Georgia Institute.

Slides:



Advertisements
Similar presentations
Discover Biology FIFTH EDITION
Advertisements

Lesson 6.1 Objectives  How scientists use fossils to learn about the history of life  How organisms evolved more complex forms over time  About mass.
Evolution and Ecology.
The Evolution of Multicellularity. agenda Evolution overview Microevolution and macroevolution Evolution of multicellularity--a laboratory investigation.
Evolution!. Evolution Natural Selection Early Life on Earth Evidence for Evolution Misc. $100 $200 $400 $500 $300 $100 $200 $400 $500 $300 $100 $200 $400.
Whose theory of evolution is this?
Objective: Understand the Main Events in the History of Life through a Timeline Key Words: Evolution, prokaryotic, eukaryotic cell, extinction, simple,
CHAPTER 1-INTRODUCTION 1.1 – Levels of Organization B. EcosystemAll organisms + nonliving components C. CommunityAll organisms in an area D. Population.
The rotifer and the yeast: An experiment to study how multicellularity could evolve in nature William C. Ratcliff and Jennifer Pentz Georgia Institute.
Evolution Test Review Session!!
Unit 6: Evolution The process of change over time Charles Darwin developed the theory of how living things evolve.
Unit 5: Evolution Notes.
How Does Natural Selection Really Work?
DARWIN. DESCENT WITH MODIFICATION All species of organisms living on Earth today are descended from ancestral species All species of organisms living.
Big IdeasDarwinOver TimeTermsExamples 100.
Change Over Time … Evolution Objectives: 1.Define evolution. 2.How do we know the living world has changed over time? 3.What can you learn from fossils?
Natural Selection Problem
How Does Evolution Work? Part 1: Defining Evolution through Natural Selection.
15-1 Notes: Adaptations and Natural Selection
Beginnings: The Big Bang  Earth formed more than 4 billion years ago Nanobes Life in Thermal Pools.
Extensive evidence indicates that life on Earth began more than 3 billion years ago. Fossils found in ancient rocks have given us many clues to the.
Evidence of Evolution. Evolution  The process by which life has changed over time.  Macroevolution  Microevolution.
Bellwork: January 9 Copy the questions and write your answers! Mrs. PigglyWiggly is a carrier of the sex-linked hemophilia allele, and Mr. PigglyWiggly.
Do Now Self-reflect: think about your progress, how do you think keeping a homework/exit slip tracker help you improve in class? 3-4 sentences P. 37.
Evolution & Speciation
- When a species diverges over time into two different species, resulting in a species becoming less like the original one - Live in different ways than.
17.1 Genes and Variation.
You DO NOT need to write this Bellwork ! Two species of mice live in a field in the middle of East Texas. One mouse species is white with black spotting.
15-3 Darwin Presents His Case. Slide 2 of 25 Publication of On the Origin of Species  15.3 NOTES #1  Outline the events leading to Darwin’s theory.
EVIDENCE FOR THE THEORY Evolution. Evidence for Evolution 1) Developmental Biology  Embryology ( study of embryo’s) After fertilization in the first.
Change Over Time. Dramatic changes have occurred on Earth over time  Climates have changed, forests have become deserts, and seas have dried up. These.
Unit 5 Jeopardy Happy HeredityRacy Reproduction Evolve or Extinction Awesome Adaptation Naughty Natural Selection
Ch 04 Origins of Life/ Natural Selection Ch 04 Section 1 Section 2.
 Evolution is the change in the inherited traits of a population of organisms through successive generations  Two factors at work:  Processes that.
 Section 6 Atmospheric Oxygen
Why do scientists use a classification system? To organize many diverse organisms (biological diversity) What is a theory? A well-supported,testable explanation.
Evolution & Changes Over Time UNIT 3. Changes over time, also known as evolution is a process by which modern organisms have descended from ancient organisms.
Chapter 15: Darwin’s Theory of Evolution
MESSANA 8 TH GRADE 5.01 Interpret ways in which rocks, fossils, and ice cores record Earth's geologic history and the evolution of life including: Geologic.
12. Natural Selection – Day 3  Essential Question: How does genetic diversity allow or prevent a species ability to adapt to its environment?  Learning.
Darwin’s Theory of Evolution by Natural Selection Ms. Eramchuk.
Chapters 16 Darwin’s Theory of Evolution. Chapter 16 Darwin’s Theory of Evolution Evolution- The process by which organisms have changed over time.
BELL WORK: Answer the following question: Two species of mice live in a field in the middle of East Texas. One mouse species is white with black spots,
Darwin vs. Lamarck. Lamarck Darwin Jean-Baptiste LaMarck French, Early 1800’s Theory of Inheritance of Acquired Characteristics Two main points…
Trashketball!. 1. A group of similar organisms that can mate with each other and produce fertile offspring…  A. populations  B. species  C. fossils.
5 Evolution and Community Ecology CHAPTER. Black and White, and Spread All Over Zebra mussels and quagga mussels were accidentally introduced into Lake.
Evolution by natural selection How do species change over time?
NEW CHAPTER The History of Life on Earth CHAPTER the BIG idea Living things, like Earth itself, change over time. Earth has been home to living things.
17.3 Darwin and Natural Selection: What Darwin knew  Darwin understood the fossil record and explained it by combining the two popular ideas of gradualism.
History of Evolution Chapter 9. Which came first?
CH 15 Darwin’s Theory of Evolution 15-1 The Puzzle of Life’s Diversity 15-2 Ideas that Shaped Darwin’s Thinking 15-3 Darwin presents his Case 15-1 The.
Wednesday May 4 th Big Idea: Inheritance, Variation, and Adaptation Daily target: I can examine traits and describe how they are homologous or analogous.
The Theory of Evolution by Natural Selection
BES 10/10 and 10/11 Please take out your lab book and purple inventory sheet Get ready to hear your new seat!
Earth History in 1 Hour Imagine if Earth’s History was squished to fit into one hour, from 8 am-9am.
The History of Life on Earth
Evolution of Living Things
DO NOW Pick up notes and Review #8..
EVOLUTION Chapter 16.
Warm up Humans evolved from apelike ancestors. What are some differences in traits between us and other primates? Dogs evolved from wolves. How are dogs.
DO NOW In box on note sheet Why is variation important?
The Theory of Evolution
BIO 111: Foundations of Biology
Human Evolution.
The Theory of Evolution by Natural Selection
Evolution Part Two.
Chapter 22 How Genetic Variation is Maintained within Populations
Chapter 14.1 Goodness of Fit Test.
First, let’s talk about the word THEORY…
Fitness and the Rate of Evolution
Presentation transcript:

The rotifer and the yeast: An experiment to study how multicellularity could evolve in nature William C. Ratcliff and Jennifer Pentz Georgia Institute of Technology

Multicellularity has evolved at least 25 times in the history of life! Grosberg R. K., and R. R. Strathmann Annu. Rev. Ecol. Evol. Syst. 38:

Examples of independently-evolved multicellular lineages

Let’s take a moment to imagine the world without multicellular organisms

This is a photo of Mars © NASA

The transition from uni- to multicellularity was one of a few events in the history of life that allowed for the evolution of large and complex organisms we see today This is a photo of Mars © NASA

The transition from uni- to multicellularity was one of a few events in the history of life that allowed for the evolution of large and complex organisms we see today This transition occurred in the deep past (more than 200 million years ago) and most early multicellular forms have been lost to extinction This is a photo of Mars © NASA

The transition from uni- to multicellularity was one of a few events in the history of life that allowed for the evolution of large and complex organisms we see today This transition occurred in the deep past (more than 200 million years ago) and most early multicellular forms have been lost to extinction So how on earth do we study it? This is a photo of Mars © NASA

We could invent a time machine and observe this process as it’s happening …or we could study it in the lab

Time travel in a test tube The left is a picture of the unicellular ancestor and the video is the evolved multicellular ‘snowflake’ yeast.

How did they do this? 24 hour, shaking incubation centrifuge 100g for 10 seconds discard upper 93% of media transfer to fresh media Use gravity to select for clustering genotypes because clusters of cells settle more quickly than single cells.

Independent evolution of the ‘snowflake’ yeast in all 10 replicate populations

Two steps are required for the transition to multicellularity

Step 1 – the evolution of clusters The first step in this transition is the evolution of cluster formation from single-celled ancestors This could be beneficial for many reason in nature: Predator evasion Metabolic cooperation UV resistance Y55 - Unicellular Saccharomyces cerevisiae (bakers yeast)

Step 2 – multicellular yeast adapt Three things must be true for multicellular yeast to adapt

Clusters must vary from one another Snowflake Not snowflake (clumpy yeast)

Cluster variation must be heritable Snowflake yeast make more snowflake yeast Clumpy yeast make more clumpy yeast

Cluster variation much affect fitness The three components of Step 2 are known as evolution via natural selection.

These experiments clearly show that multicellularity can quickly evolve in a test tube Unicellular ancestor 0 days of evolution Snowflake yeast 60 days of evolution 300 generations! Pictures of populations from every week during the evolution of snowflake yeast Ancestor2 weeks1 week3 weeks4 weeks5 weeks8 weeks6 weeks

But wait! You might be thinking…centrifuges are not found in nature but… that does not mean that conditions favoring cluster formation don’t exist in nature!

What do you think will happen if we feed yeast to a hungry predator (a rotifer)? Snowflake yeast are about as big as the rotifer’s head!

How you will test this hypothesis? Multicellular yeast may avoid predation because they are too big to eat

How you will test this hypothesis? Give hungry rotifers unicellular and multicellular yeast Multicellular yeast may avoid predation because they are too big to eat

How you will test this hypothesis? Give hungry rotifers unicellular and multicellular yeast Examine the ability of the rotifers to eat each yeast strain by counting them in rotifer stomachs Multicellular yeast may avoid predation because they are too big to eat

How you will test this hypothesis? Give hungry rotifers unicellular and multicellular yeast Examine the ability of the rotifers to eat each yeast strain by counting them in rotifer stomachs Analyze these results statistically using a chi- squared test Multicellular yeast may avoid predation because they are too big to eat