Florian Hartig

Department of Biometry and Environmental System Analysis

Florian Hartig

Department of Biometry and Environmental System Analysis

Dynamic versus evolutionary stability - divergent insights from coexistence theory and evolutionary ecology

Florian Hartig1,2, Tamara Münkemüller1,3, Karin Johst1, Ulf Dieckmann4

1) UFZ Leipzig 2) University of Freiburg 3) Laboratoire d’Ecologie Alpine, Grenoble 4) IIASA Laxenburg

http://florianhartig.wordpress.com/ INTECOL 2013, London,

Figures by Ernst Haeckel, scans by Kurt Stüber, MPI Köln

Florian Hartig

Department of Biometry and Environmental System AnalysisPage 2

Introduction: Niches, coexistence mechanisms and the paradox of the plankton

► Why are there so many species?

– Resource partitioning avoids competitive exclusion Hutchinson ‘57

– Not sufficient to explain the „paradox of the plankton” Hutchinson ‘61

► Large number of more complex equalizing / stabilizing mechanisms

► Storage effect, colonization-competition trade-offs, Janzen-Connell, … e.g. Chesson, ’00, Holt ‘09

► Relative importance for community assembly and macroecological patterns still one of the most contested ecological questions e.g. Adler et al., 2013, Hubbel ’97, ‘01

Florian Hartig

Department of Biometry and Environmental System Analysis

Relative nonlinearity of competition (RNC)

► Dynamic mechanism that allows two species to coexist on the same resource(s) Armstrong & McGehee ’80, Chesson ‘84

► Differing nonlinear response to resource, no species superior at all levels of resource availability

► Endogenous fluctuations of the resource regulate coexistence

► Difficult to detect RNC, importance in the field still unclear Adler et al., 2013, Huisman & Weissing ’99, but see also Descamps-Julien & Gonzalez ‘05, Metcalf et al. ’08

Page 3

‚slow‘ growing

sp. majority

‚fast‘ growing

sp. majority

Stable

resource,

fast growth

advantageousslow

advantageous

Florian Hartig

Department of Biometry and Environmental System Analysis

Trade-off in density-dependence could give rise to relative nonlinearity

► Same intrinsic growth and carrying capacity, but different density compensation (parameter b)► Maynard Smith and

Slatkin, generalized Ricker, Hassel

► Methods: Individual-based models (IBMS) and population models

Small b

Large b

Florian Hartig

Department of Biometry and Environmental System Analysis

Log time to competitive exclusion

Average time to competitive exclusion shows stabilization through RNC

► Known that these models

allow for RNC Münkemüller et al

’09

► Combination of

undercompensating and

overcompensating

species orders of

magnitude more stable in

IBM

b of species 1

b of

spe

cies

2

neutral

stabilized

Florian Hartig

Department of Biometry and Environmental System Analysis

Invasibility analysis casts doubt on evolutionary stability

► Shape of the PIPs

suggests RNC is not

evolutionarily stable e.g.

Dieckmann ’97

► The same result for a

number of other models

Log invasion growth rate

Resident b1

Inva

der

b2

Florian Hartig

Department of Biometry and Environmental System Analysis

IBM simulations confirm that evolution leads to collapse of coexistence

► Similar: Huisman &

Weissing ’99, Shoresh et

al. ’08

► Also similar: Metcalf et

al. ’08

Florian Hartig

Department of Biometry and Environmental System Analysis

Are there trade-offs that allow evolution of relative nonlinearity?

► Possible find a family of curves that respect the fundamental trade-off (better growth at high resources = lower growth at low resources) but allows RNC to evolve?

► Answer: Yes, but this need very specific “tuning”

Florian Hartig

Department of Biometry and Environmental System Analysis

Discussion

► One of the first studies that looks at the probability of RNC evolving in a generic situation but see Metcalf et al. ’08

► Main finding: within our assumptions (trade-off growth below / above K), sympatric evolution of RNC seems possible, but rather unlikely

► Unless there is some mechanism creates these specific trade-offs► RNC might still temporarily stabilize strategies that are obtained in allopatry

► Still relatively little known about the evolutionary properties of current coexistence theory

► For example, similar, but somewhat more favorable recent findings for the temporal storage effect Abrams et al. ‘12, Snyder & Adler ’11

Florian Hartig

Department of Biometry and Environmental System Analysis

Thank you!

Hartig, F.; Münkemüller, T.; Johst, K. & Dieckmann, U. (under review) On the sympatric evolution of coexistence by relative nonlinearity of competition

Preprint available at http://arxiv.org/abs/1308.3114

Support from ERC advanced grant 233066 (FH), EraNet BiodivERsA project ANR-11-EBID-002 (TM), European Commission, the European Science

Foundation, the Austrian Science Fund, the Austrian Ministry for Science and Research, and the Vienna Science and Technology Fund (UD).

Page 10