Species diversity and energy in a monotrophic level community

1
Species diversity and energy in a mono-trophic
level community

• PhD student Rémi Vergnon
• Supervisors
• Dr Nick Dulvy (CEFAS, UK)
• Pr Rob Freckleton (University of Sheffield, UK)
• Dr Yunne Shin and Dr Philippe Cury (IRD Sète,
  France)

2
Introduction
Species diversity
Human-induced disturbances
Ecosystem services
Community level two species diversity models
dealing with energy partitioning
3
Energy and species diversity

• Both species diversity models
• Group of organisms competing for a common source
  of energy
• Niche-based models1 trait differences
• Neutral models2 prevalence of stochastic
  processes
• Levels of neutrality
• Species equivalence
• Influence of migration

How to extend to entire trophic webs this
energetic approach?
4
The size spectrum theory

• Marine systems
• Organisms of similar size competition for common
  energy source
• Groups of large individuals feed on groups of
  small individuals
• Energy jumps down the food web through predation

Starting simple species diversity within a
mono-trophic level community
5
Starting simple phytoplanktonic species
diversity

• Mono-trophic level community neutrality or
  niche?
• Data L4 station (British Channel)
  phytoplanktonic community
• Initial hypothesis
• Within the community
• Core species driven by niche-based processes
• Infrequent species influenced by migration

6
Infrequent species
7
Core species
Hypothesis niche-based, one single group of
competing organisms
8
Core species

• Literature3 phytoplanktonic species within domes
  should be functionally close
• Domes consequences of competition, predation

9
Measuring species similarity
Abundance

• Mutual information4
• High values related dynamics
• similar species
• Low values no relation

Time
10
Measuring species similarity
11
Conclusions

• Feed a model
• Strong influence of migration
• Size-based functional units
• True niche-based models
• Current work analysis of multi-trophic levels
  communities

References 1 Magurran 2004. Measuring
Biological Diversity 2 Hubbell 2001. The Unified
Neutral Theory of Biodiversity and
Biogeography 3 Kerr and Dickie 2001. The Biomass
Spectrum 4 Cazelles, B., 2004. Symbolic dynamics
for identifying similarity between rhythms of
ecological time series