ecologie et macroévolution ihpst philbio 20/03/2008 julien delord ceres-erti

45
Ecologie et Ecologie et macroévolution macroévolution IHPST IHPST Philbio Philbio 20/03/2008 20/03/2008 Julien Julien Delord Delord CERES-ERTI

Upload: edward-roberts

Post on 29-Dec-2015

216 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Ecologie et Ecologie et macroévolutionmacroévolution

IHPSTIHPST PhilbioPhilbio 20/03/200820/03/2008

Julien DelordJulien Delord CERES-ERTI

Page 2: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

• Introduction: Do ecological communities exist (and Introduction: Do ecological communities exist (and evolve)?evolve)?

• 1. Presentation of the Unified Neutral Theory of 1. Presentation of the Unified Neutral Theory of Biodiversity (UNTBB)Biodiversity (UNTBB)

• 2. The (epistemological) non-neutrality of neutral models2. The (epistemological) non-neutrality of neutral models- Neutrality and falsity (in biology)- Neutrality and falsity (in biology)- Neutrality as a strategy towards generality and unification- Neutrality as a strategy towards generality and unification

• 3. Neutrality and the unification of evolutionary theory3. Neutrality and the unification of evolutionary theory - Neutral theories in genetics and in ecology- Neutral theories in genetics and in ecology- « L-neutrality » and « L+1 neutrality »- « L-neutrality » and « L+1 neutrality »- « Grand Unification » or « domain unification »?- « Grand Unification » or « domain unification »?

- Communities as evolutionnary entities- Communities as evolutionnary entities

• ConclusionConclusion- - Theory change in ecologyTheory change in ecology

Neutral Theories in Ecology and Neutral Theories in Ecology and EvolutionEvolution

Page 3: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

« Are phenomenological communities causal systems? » (Sterelny 2006) = Are communities structured, functionally organized with effects on the fate of populations they are composed of? (downward causation)

3 criteria: - Boundedness- Internal regulation- Emergent property effects

For Sterelny, they fail to meet these criteria…

For most ecologists, communities are structured by niche competition and niche assembly rules!!!

Page 4: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Frederic CLEMENTS (1874-1945)

« Comme un organisme, la formation naît, croît, mûrit et meurt. En outre chaque formation climacique [ayant atteint le climax] est capable de se perpétuer, en reproduisant avec une fidélité absolue les étapes de son développement », 1916.

Déterminisme des successions végétales

Henry GLEASON (1882-1975)

« Le phénomène de la végétation dépend complètement des phénomènes des espèces individuelles »

Assemblage des végétations au hasard

Dynamiques des communautés végétales

Organicisme vs. Individualisme

Page 5: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Introduction : Do ecological communities Introduction : Do ecological communities exist and evolve ?exist and evolve ?

Community 1

A: 25% B: 25% C: 25% D: 25%

Community 2

A: 80% B: 5% C: 5% D: 10%

D

C

B

A

Ecological CommunityEcological Community

Group of populations from different species interacting with each other and sharing the same spatio-temporal framework.

Species Richness

Relative Species Abundance

Page 6: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

McGill Brian J. et al., “Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework”, Ecology Letters, 10, 2007, p. 995-1015.

27 different models of Species Abundance Distribution

Page 7: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Jared Diamond (1975) a été le premier à explorer l’idée selon laquelle il existe des règles qui gouvernent l’assemblage des

communautés:

La diversité des communautés dépend de leur structuration

Ressources restantes

Page 8: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

- How to explain species How to explain species biodiversity in ecological biodiversity in ecological communities ?communities ?

- How to explain the curves of How to explain the curves of relatives species abundance ?relatives species abundance ?

--Is the niche Is the niche conceptconcept

necessary ?necessary ?

--From case-study From case-study rules to general rules to general deductive laws !deductive laws !

1. The Unified Neutral Theory of Biodiversity1. The Unified Neutral Theory of Biodiversity and Biogeography (UNTBB)and Biogeography (UNTBB)

Page 9: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Courbes SAD (Surface Abundance Distribution)

Page 10: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Principles of UNTBB

Definition: Ecological community : Group of trophically similar and sympatric species

Conservation law: Neutrality : The assumption of a complete identity of ecological interactions affecting community organisms, i. e. a per capita ecological equivalence (in terms of reproduction and death rates + speciation) among all individuals of every species.

Dependant Variables:Relative species abundance and species numberParameters:Reproduction rates, death rates, speciation rates, community size (= number of individuals), limits to dispersal.

Page 11: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Principles of UNTBB (Cont’d)

Hypothesis:« Communities are open, nonequilibrium assemblages of species largely thrown together by chance, history and random dispersal » (Hubbell, 2001, p.8)

Process: Ecological drift: demographic stochasticity in a neutral community (~ genetic drift)

Result: Curves of relative species abundance at equilibrium between speciation and extinction (stationary dynamics)

Page 12: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Markovian process

Page 13: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Theoretical developments

Random walk of the abundance of ith species under ecological drift

(The initial relative species abundance is 0.5 - ergodic )case)

Page 14: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

A brief reminder of population genetics:

how to calculate the proportion of homozygotes at equilibrium between mutation and drift.

Page 15: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Theoretical developments

How to calculate the probability of drawing two individuals from the same species at equilibrium

between speciation and ecological drift.

Let be the speciation rate per generation and JM the number of individuals in metacommunity M.

Page 16: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Theoretical developments

F2 = 1 / 1+ 2 JM Feq = 1 / 1 + 2Nμ

= 2 JM

is named by Hubbell the fundamental biodiversity number because this dimensionless number controls not only the

equilibrium species richness but also the equilibrium relative species abundance in the metacommunity.

Page 17: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Some results and predictions of UNT on biodiversity dynamics

By generalization, Hubbell extends this rationale to the case of 3 individuals randomly chosen in JM , etc., then J

individuals belonging to S species.

Page 18: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Etienne R., Alonso D., McKane A. J., « The zero-sum assumption in neutral biodiversity theory », Journal of Theoretical Biology, 248, 2007, p. 522-536.

Page 19: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI
Page 20: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Dornelas M. et al., “Coral reef diversity refutes the neutral theory of biodiversity”, Nature, 440, 2006, p. 80-82.

Page 21: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Epistemological questions:Epistemological questions:

Ecology and its recurrent « Physics envy »

In search for laws, regularities and generality

The concept of generality: from universality (spatio-temporal unboundedness) to invariance (Van Fraassen, Laws and Symmetry, 1991)

Invariance as a conservation law (when a certain value is conserved through time despite the changes of the system)

Neutral models as a quest for invariance in ecology

Generality should enhance unification

Page 22: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Conservation law in physics (sub-atomic level) vs. conservation law in ecology (macroscopic world)

In particle physics, conservation laws (i. e. conservation of energy) give rules to make sense of the data and to define the ontology of particles.

In ecology, the ontology is already defined but the rules are not known. They are interpreted in light of the discrepancy between expected patterns and empirical data.

Problems:

1. Theoretical: the underdetermination of theories 2. Empirical: the confirmation of the neutral model

2. The (epistemological) non-neutrality 2. The (epistemological) non-neutrality of neutral modelsof neutral models

- Neutrality and falsity (in biology)- Neutrality and falsity (in biology)

Page 23: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

3. Neutrality and the unification of 3. Neutrality and the unification of evolutionary theoryevolutionary theory

Neutral theories in genetics and in ecologyNeutral theories in genetics and in ecology

Comparative approach of neutralityComparative approach of neutrality

in genetics and in ecologyin genetics and in ecology

Page 24: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Hu X.-S., He F. & Hubbel S. P. (2006), “Neutral theory in macroecology and population genetics”, Oikos, 113, 3, p. 548-56.

Page 25: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Type d’Allèle

Individu

Natural selection Neutral Theory of Biodiversity

Species

Class of individuals

Community

Individual

Espèce

Allèle

Type d’Allèle

Individu

Espèce

Allèle

Class of Alleles

Individual

Species

Allele

Evolver

Interactor

Replicator-Interactor

Niche ???

Neutral theory of evolution

Evolver

Replicator-Interactor

Page 26: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

UNT and phylogenyUNT and phylogenyLast consequence of Hubbell ’s theory for

phylogeny (but not the least), UNT models show that the organization of biodiversity at different

scales is intrinsically fractal.

Page 27: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

UNT and phylogenyUNT and phylogeny

On the fractal dimension of biodiversity :

Hubbell : “ If biodiversity is a perfectly homogeneous fractal, this implies that a satisfactory answer to the question - how many species are there ? – cannot really be answered except operationally.It requires a definition of the scale of aggregation that we call species! »  (p.263)

This implies a pluralist or arbitrary fixation of the level of “ ranking ”for the species.

Page 28: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Are neutrality in genetics and ecology comparable?

Historical differences :

The neutral theory of molecular evolution appeared as a solution to a problematic in evolutionary genetics and as a consequence of new developments in molecular biology (high protein polymorphism).

“The theory of molecular evolution by mutation and random drift led to Kimura’s prediction that those amino acids or nucleotide changes that have the least consequence would evolve faster” (J. Crow, Neutral models in biology, 1987, p. 13).

UNTBB as an elaborated null model???

What is selection for UNT ? (Rules of niche assembly ?)

Page 29: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Neutrality in a hierarchical systems

• Neutrality relative to level L+1 (replicator <> interactor)

• Neutrality relative to level L (replicator-interactor)

Example of « contextual » neutrality: genetic drift and transposons

NeutralityNeutrality

Page 30: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Level Level L+1L+1

(species)(species)

Level LLevel L

(individuals)(individuals)

YesYes NoNo

YesYes UNTBBUNTBBApparent Apparent neutralityneutrality

NoNo « free » « free » replicatorsreplicators

Species Species selectionselection

« L neutrality » and « L+1 « L neutrality » and « L+1 neutrality »neutrality »

Page 31: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Kimura’s neutral theory was defined as a « L+1 neutrality » with respect to natural selection

Hubbell’s neutral theory of biodiversity was defined as a « L neutrality » with respect to differential replication

Page 32: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

- « Grand Unification » or « domain unification »?- « Grand Unification » or « domain unification »?

Is a neutral synthesis of evolutionary theory possible ?

Ecological drift vs deterministic “rules” of niche assembly

Genetic drift vs natural selection

Incompatibility

- Ecological drift requires non-neutral mutations- Ecological drift would induce different speeds of genetic drift

Incompatibility

Page 33: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI
Page 34: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Gould’s hierarchical Gould’s hierarchical macroevolutionary macroevolutionary

theorytheory

Page 35: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Vrba and Gould « The hierarchical expansion of sorting and selection: sorting and selection cannot be equated », Paleobiology, 12, 1986, p. 217-28.

Page 36: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Stephen J. Gould’s approach

Species selection: Species selection:

- Emergent species-level trait- Emergent species-level fitness

- Aggregate traits- Neutral traits

- 2 Confusions : 2 Confusions : - The nature of extinction (why dissymetry between speciation and extinction???) (p. 669)- Species drifting and clade drifting (p. 718)

« True » species

selection

Page 37: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Gould’s analogy between micro- and

macroevolution

Page 38: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Gould’s analogy Gould’s analogy between micro- between micro-

and and macroevolution macroevolution

Page 39: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Hiérarchies historiques et Hiérarchies historiques et fonctionnellesfonctionnelles

Page 40: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

UNTBB is both a macroecological and a macroevolutionary theory :

Evolution at the community level is ecology !!!

(The equivalent of genetics at the community level is ecology)

« Domain unification » in Evolution« Domain unification » in Evolution

MacroevolutioMacroevolutionn

MegaevolutionMegaevolution - - Fauna and floraFauna and flora- Geological times- Geological times

Punctuated equilibrium theory,Punctuated equilibrium theory,fractal dynamics, etc.fractal dynamics, etc.

MesoevolutionMesoevolution -Communities et meta- Communities et meta- communitiescommunities

- Ecological times- Ecological times

UNTBBUNTBB

Interspecific competitionInterspecific competition between between neutral individuals neutral individuals OrOr Niche assemblyNiche assembly

MicroevolutioMicroevolutionn

Darwinian Darwinian evolutionevolution

- Populations- Populations- Adaptations- Adaptations

Natural selectionNatural selection(mutation, sélection, migration)(mutation, sélection, migration)

Intraspecific competitionIntraspecific competition

Molecular evolutionMolecular evolution - Populations- Populations- Neutral variations- Neutral variations

Neutral theory of molecular Neutral theory of molecular evolutionevolution(mutation, genetic drift)(mutation, genetic drift)

Interallelic competitionInterallelic competition

Page 41: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Alleles

Organism

Species

Genus or family

Conclusion: 2 macro-ecoevolutionary strategiesConclusion: 2 macro-ecoevolutionary strategies

Page 42: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Conclusion

3 major challenges for the UNTBB:1. Ecology:

• “Neutral theory is limited because it is incapable of predicting which species are rare or abundant” (Tilman, 2004)…

Frustration for disappearance of causes, forces, etc:

Opportunity for ecologists to move from typological to population thinking!!

Challenge of the reconciliation with the niche perspective, like the niche construction: from idealized invariant to ceteris paribus laws.

• Dynamics of species substitution

Page 43: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Conclusion

2. Evolution:

• How to test the neutral nature of species substitution at the community level ?

• Community invasion rate as a test for species substitution???

• The unification of macro-and microevolution !!!

• More collaboration between paleoevolution and community ecology with regard to species evolution (for a better contribution to the emergent property/emergent fitness debate)?????

Page 44: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI

Bibliography

- Dornelas M., Connolly S. R., Hughes T. P., “Coral reef diversity refutes the neutral theory of biodiversity”, Nature, 440, 2006, p. 80-82.- Etienne R., Alonso D., McKane A. J., « The zero-sum assumption in neutral biodiversity theory », Journal of Theoretical Biology, 248, 2007, p. 522-536.- Holt Robert D., “Emergent neutrality”, Trends in Ecology and Evolution, 21, 10, 2006, p. 531-533.- Hu X.-S., He F. & Hubbel S. P., 2006, “Neutral theory in macroecology and population genetics”, Oikos, 113, 3, p. 548-56.- Hubbell Stephen P., 2001, The Unified Neutral Theory of Biodiversity and Biogeography, Princeton and Oxford, Princeton University Press.- Leigh Jr. E. G., « Neutral theory : a historical perspective », Journal of Evolutionary Biology, 20, 2007, p. 2075-2091.- McGill Brian J. et al., “Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework”, Ecology Letters, 10, 2007, p. 995-1015.- Sterelny, K., Local Ecological Communities, Philosophy of Science, 73, 2006, p. 215-231. - Tilman, D., “Niche tradeoffs, neutrality, and community structure: a stochastic theory of resource competition, invasion, and community assembly”, Proc. Natl. Acad. Sci., 101, 2004, p. 10854–10861.- Volkov Igor, Banavar Jayanth R., Hubbell Stephen P., Maritan Amos, “A neutral theory and relative species abundance in ecology”, Nature, 424, 2003, p. 1035-1037.- Volkov Igor, Banavar Jayanth R., Hubbell Stephen P., Maritan Amos, “Patterns of relative species abundance in rainforests and coral reefs”, Nature, 450, 1 november 2007, p. 45-49.

- Dornelas M., Connolly S. R., Hughes T. P., “Coral reef diversity refutes the neutral theory of biodiversity”, Nature, 440, 2006, p. 80-82.- Etienne R., Alonso D., McKane A. J., « The zero-sum assumption in neutral biodiversity theory », Journal of Theoretical Biology, 248, 2007, p. 522-536.- Holt Robert D., “Emergent neutrality”, Trends in Ecology and Evolution, 21, 10, 2006, p. 531-533.- Hu X.-S., He F. & Hubbel S. P., 2006, “Neutral theory in macroecology and population genetics”, Oikos, 113, 3, p. 548-56.- Hubbell Stephen P., 2001, The Unified Neutral Theory of Biodiversity and Biogeography, Princeton and Oxford, Princeton University Press.- Leigh Jr. E. G., « Neutral theory : a historical perspective », Journal of Evolutionary Biology, 20, 2007, p. 2075-2091.- McGill Brian J. et al., “Species abundance distributions: moving beyond single prediction theories to integration within an ecological framework”, Ecology Letters, 10, 2007, p. 995-1015.- Sterelny, K., Local Ecological Communities, Philosophy of Science, 73, 2006, p. 215-231. - Tilman, D., “Niche tradeoffs, neutrality, and community structure: a stochastic theory of resource competition, invasion, and community assembly”, Proc. Natl. Acad. Sci., 101, 2004, p. 10854–10861.- Volkov Igor, Banavar Jayanth R., Hubbell Stephen P., Maritan Amos, “A neutral theory and relative species abundance in ecology”, Nature, 424, 2003, p. 1035-1037.- Volkov Igor, Banavar Jayanth R., Hubbell Stephen P., Maritan Amos, “Patterns of relative species abundance in rainforests and coral reefs”, Nature, 450, 1 november 2007, p. 45-49.

Page 45: Ecologie et macroévolution IHPST Philbio 20/03/2008 Julien Delord CERES-ERTI