WelcomeAbout
StaffContactEvent CalendarThe EvoS FundBooksWebsitesTutorialStart Your Own
Seminars
Fall 2007
Barbara EhrenreichJonathan HaidtHoward RachlinCarlo MaleyJeffrey CarpenterPeter TurchinJack SchultzScott Turner
Spring 2008
Anthony BiglanWilliam CreskoPatricia HawleyAndrew DeWoodyJoseph LeDouxJames NoonanBarbara FinlayGordon GallupRichard PouyatElizabeth Adkins-ReganJames MacKillop
Fall 2008
David Sloan WilsonBarbara OakleyBNP SymposiumRichard MichodMichael BellRandy OlsonWilliam RomeyChris ReiberSteven BrownBrian Boyd
Spring 2009
Dennis EmbryDavid HackerSteven PlatekSue MargulisSue Savage-RumbaughSteven NeubergHarvey WhitehouseThomas SeeleyGeorge LevineHelen Fisher
Video: "The Drive to Love and Who We Choose"
Fall 2009
Liza MoscoviceDiane M. Doran-SheehyKaren HollisPeter O. GrayChris KuzawaSteven SiegelRolf Quam
Rolf Quam 10/30/2009 EvoS Seminar Presentation
Bill JankowiakBaba BrinkmanPeter B. GrayMassimo Pigliucci
Massimo Pigliucci 12/4/2009 EvoS Seminar Presentation
Spring 2010
John GowdyDaniel LendeWilliam Harcourt-SmithTodd K. ShackelfordIain CouzinBruce HoodMelissa Emery ThompsonNancy EasterlinSteve NowickiJohn Marshall TownsendJoan Silk
Fall 2010
Josh BongardFred SmithDarryl de RuiterJay BelskyKari SegravesJulie SeamanLisa Karrer and David SimonsRick HarrisonRebecca SearTom LangenDaniel Kruger
Spring 2011
Steven C. HayesAndreas Duus PapeJessica LightMaryanne FisherGreg UrbanAndreas Koenig & Carola BorriesDaniel NettleDeane BowersCharles T. Snowdon
Fall 2011
David Sloan WilsonDavid C. LahtiRichard R. ShakerSergio AlmécijaHugo MercierLeslie C. AielloMark E. RitchieAdam LaatsLinda IvanyRalph M. GarrutoAdam Siepel
Spring 2012
John RieffelDr. Linda S. RayorDan EisenbergKevin L. PolkAndrew C. GallupKevin M. KniffinDavid DobbsNicole CameronJonathan HaidtDr. Joseph L. Graves, Jr.
Fall 2012
Barry X. KuhleCraig Eric MorrisCarin PerillouxDavid Sloan WilsonEric AlaniJesse BeringEli BridgeJaak Panksepp
Spring 2013
John TeehanRobert HolahanJenny Kao-KniffinShara BaileyHod LipsonDominic JohnsonMatthew HareCraig Eric MorrisBrooks MinerMichael RoseDavid Sloan Wilson
Fall 2013
Steven BrownNina FeffermanJohn Gowdy and Lisi KrallWarren Douglas AllmonTrenton HollidayJonathan GottschallArnab RoyDavid SchafferMichele GelfandJames SobelPatrick RoosEvoS Food Panel
Spring 2014
Daniel O’BrienBruce RobertsonRobert S. FeranecHeather FiumeraLuther H. MartinBjorn GrindeSarah RadtkeAleksey KolmogorovKathleen Sterling & Sébastien LacombeDebate! Evolutionary Psychology vs. Feminist CritiqueEducation Brown Bag
Fall 2014
Gad SaadT. Joel WadeNelson G. Hairston, Jr.Francis J. YammarinoDerek TurnerMatthew M. GervaisBernd BlosseyRolf QuamKelsey DancauseSharon Street
Spring 2015
Debra LiebermanMichael BerkmanDavid Sloan WilsonJason Munshi-SouthMa’ikwe Schaub LudwigJustin GarsonRéginald AugerDavid DaviesPatrica WrightCraig Eric MorrisMeredith E Coles
Fall 2015
Aaron J. Sams
Suggest a Speaker
Students
Undergraduate Students
Undergraduate Student AssociationSUNY Broome Transfer Course ListUndergraduate RequirementsUndergraduate Courses
Graduate Students
Graduate Student OrganizationGraduate RequirementsGraduate Courses
Others
EvoS from a DistanceNon-Matriculated Students
Faculty
Becoming InvolvedEvoS as an Institute for Advanced StudiesLeslie HeywoodCo-hosting
Projects
Early Childhood Education WorkshopInsect SamplingEvoS Lifestyle Project"What's New in EvoS" Podcast
Alumni Corner
Andrew C. GallupLiza R. MoscoviceJustin R. GarciaJennifer Campbell-SmithMichael L MillerCraig Eric MorrisDaniel Weinstein
 

Richard Michod

Department of Ecology and Evolutionary Biology
University of Arizona

Cooperation and conflict during the evolution of individuality in the volvocine green algae

Friday, October 3, 2008
Lecture Hall 8, 4:00 PM

Abstract

Our understanding of life is being transformed by the realization that evolution occurs not only among individuals within populations, but also during evolutionary transitions in individuality (ETIs), when groups of individuals become so integrated that they evolve into new higher-level individuals. Indeed, the hierarchical organization of the living world is a consequence of a series of evolutionary transitions: from genes to gene networks to the first cell, from prokaryotic to eukaryotic cells, from cells to multicellular organisms, from asexual to sexual populations, and from solitary to social organisms. It is a major challenge to understand why (environmental selective pressures) and how (underlying genetics, population structure, physiology, and development) the basic features of an evolutionary individual, such as fitness heritability, indivisibility, and evolvability, shift their reference from the old level to the new level. In the talk, I consider the transition from unicellular to multicellular organisms, using the volvocine green algae as a model experimental system. These algae comprise both uni- and multicellular forms and various levels of individuality and complexity. How and why do groups become individuals? These are the central questions motivating our work. I consider the hypothesis that germ-soma specialization is fundamental to the conversion of cell groups into true multicellular individuals. I discuss work addressing this hypothesis using both ultimate (evolutionary) and proximate (mechanistic) approaches, employing theoretical, experimental and comparative methods.

Our theory predicts that evolutionary transitions in individuality involve a series of cooperation, conflict and conflict mediation cycles. In addition, the trade-off between fitness components (viability and reproduction) is a major factor leading to cooperation in groups and driving the transition from unicellular to multicellular life. In particular, we predict that the convex curvature of the trade-off selects for specialization and that the curvature shifts from concave to convex as cell-group size increases. We have tested our models in two ways by taking a how and why approach. We have studied the origin of the genetic basis for reproductive altruism in the multicellular Volvox carteri by showing how an altruistic gene may have originated through co-option of a life-history trade-off gene present in a unicellular ancestor. Second, we ask why reproductive altruism and individuality arise only in the larger members of the volvocine group (recognizing that high levels of kinship are present in all volvocine algae groups). Our answer is that the selective pressures leading to reproductive altruism stem from the increasing cost of reproduction with increasing group size which creates a convex curvature of the trade-off function. By using standard population concepts and theories such as fitness, fitness tradeoffs, altruism, kin selection, life history evolution, and social evolution, we can explain a major evolutionary transition in individuality: the evolution of complex multicellular individuals from unicellular and colonial ancestors.

Biography

Richard Michod is professor and department head of the Department of Ecology and Evolutionary Biology, University of Arizona. His professional interests include evolutionary transitions in individuality, theoretical population biology. evolutionary genetics of microorganisms, and philosophy of biology. In addition to his own research, he participates in a NSF IGERT program at the University of Arizona titled “Evolutionary, computational, and molecular approaches to genome structure and function.”

Readings

  1. Evolution Of Complexity in the Volvocine Algae: Transitions in Individuality Through Darwin’s Eye
  2. Evolution of individuality during the transition from unicellular to multicellular life
  3. The group covariance effect and fitness trade-offs during evolutionary transitions in individuality

Tags: ,

Fall 2008 Seminar Series Icon