DIVERSITY ON CORAL REEFS

DIVERSITY - PERSPECTIVES 1) taxonomic 2) ecological 3) genetic 4) functional

DIVERSITY – WHAT IS IT? 1) Number of taxa (=richness) 2) Measure of evenness in abundance N species equally common > N species of unequal abundance DIVERSITY ≠ RICHNESS

DIVERSITY – Spatial Scales 1) Within habitat (  ) 2) Between habitats (  ) 3) Regional ( 

DIVERSITY – Phylogenetic Scales -diversity can depend on the taxonomic level species phylum > <

DIVERSITY – Phylogenetic Scales Number of animal phyla34 Number that are solely marine 17 Number with both marine a and non-marine members 16 Number that are solely non-marine (terrestrial) 1 33 of 34 phyla represented in marine biome

Phylum Diversity in Hawaii

FISH DIVERSITY On coral reefs – about 4000 species (1/3 of all known marine fish) Indo-Pacific – about 3000 reef fish British Columbia – 325 marine fish Indonesia/Philipines/PNG – about 2500 reef fish

Why are coral reef environments so diverse? 1) Environmental favourability 2) Productivity 3) Habitat heterogeneity 4) Niche diversity 5) Niche breadth 6) Interspecific interactions 7) Evolutionary processes - Historical stability - Speciation rates - Extinction rates

Diversity in reef ecosystems (How does diversity affect ecosystem function?) 1) Photosymbioses SymbiontsHosts Symbiodinium Cyanobacteria Chlorophytes Diatoms Rhodophytes Chrysophytes Algae Ciliates Foraminifera Sponges Cnidaria Flatworms Molluscs Echinoderms Ascidians

Diversity in reef ecosystems (How does diversity affect ecosystem function?) 2) Redundancy in guilds -differences in diversity have little effect Clipperton Island (eastern Pacific)

Diversity in reef ecosystems (How does diversity affect ecosystem function?) 2) Redundancy in guilds -differences in diversity have little effect Clipperton Island (eastern Pacific) Clipperton Tropical Eastern Pacific Richness in shallow water, nearshore fish

Redundancy in guilds No differences in reef structure

D IVERSITY Latitudinal diversity patterns

BIOGEOGRAPHIC ZONES Indo- West Pacific (IWP) Western Atlantic Eastern Pacific East Atlantic

BIOGEOGRAPHIC ZONES

Paleontological/Tectonic Factors Early Cretaceous Tethys Sea

Seafloor spreading widens Atlantic

Movement of Africa separates Indian Ocean and EA

Isthmus of Panama emerges and separates WA and EP

Separation of bioregions – What are the effects on fauna? 1. Western Atlantic -Cenozoic extinctions -extinctions associated with the closing of the Isthmus of Panama

Separation of bioregions – What are the effects on fauna? 2. Eastern Pacific -fauna of Florida and California - similar -extinctions associated with the closing of the Isthmus of Panama

Separation of bioregions – What are the effects on fauna? 3. Eastern Atlantic -extinctions associated with the closing of the Tethys seaway

-can happen via: Speciation 1) Vicariance event Species A + B + C Species C Species B Species A

-can happen via: Speciation 2) Founder event (Bottleneck) Small genetic diversity bottleneck Large genetic diversity

-can happen via: Speciation 2) Founder event (Bottleneck)

Role of the Indo-West Pacific Bioregion Centre of diversification?

Role of the Indo-West Pacific Bioregion Hydrodynamic sink?