A NEW MACROEVOLUTIONARY MODEL OF MARINE INVERTEBRATE DIVERSIFICATION DRIVEN BY PLATE TECTONICS AND KINEMATICS

THE MARINE INVERTEBRATE FOSSIL RECORD PROVIDES THE MOST COMPREHENSIVE HISTORY OF HOW THE DIVERSITY OF ANIMAL LIFE HAS EVOLVED THROUGH TIME. ONE OF THE MAIN FEATURES OF THIS RECORD IS A MODEST RISE IN DIVERSITY OVER NEARLY A HALF-BILLION YEARS. THE LONG-STANDING VIEW IS THAT ECOLOGICAL INTERACTIONS SUCH AS RESOURCE COMPETITION AND PREDATION SET UPPER LIMITS TO GLOBAL DIVERSITY, WHICH, IN THE ABSENCE OF EXTERNAL PERTURBATIONS, IS MAINTAINED INDEFINITELY AT EQUILIBRIUM. WE CHALLENGE THIS PARADIGM AND HYPOTHESIZE THAT THE APPARENT STABILITY OF MARINE INVERTEBRATE DIVERSITY THROUGH THE PHANEROZOIC (APPROX. 541 MILLION YEARS AGO TO PRESENT) IS LINKED TO THE RECYCLING OF THE OCEAN CRUST, WHICH IS CONTINUOUSLY BEING CREATED AND DESTROYED AT MID-OCEAN RIDGES AND SUBDUCTION ZONES, RESPECTIVELY. USING EARTH S GEODYNAMIC EVOLUTION MODELS AND SOPHISTICATED STATISTICAL METHODS FOR CAUSAL INFERENCE, WE PROPOSE TO ESTABLISH CAUSE-EFFECT RELATIONSHIPS BETWEEN THE GEOLOGICAL HISTORY OF THE SEAFLOOR AND THE DIVERSITY DYNAMICS OF DEEP-SEA BENTHIC INVERTEBRATES. OUR OBJECTIVES ARE I) TO DETERMINE WHETHER OR NOT THE RECYCLING OF THE OCEANIC CRUST HAS CONTRIBUTED TO CONSTRAINING THE DIVERSIFICATION OF MARINE INVERTEBRATES AND II) TO QUANTIFY THE EXTENT TO WHICH CHANGES IN THE RATES OF SEAFLOOR SPREADING AND SUBDUCTION LED TO SECULAR VARIATIONS IN GLOBAL DIVERSITY LEVELS. FOR INSTANCE, THE SLOWDOWN OF SEAFLOOR SPREADING IS EXPECTED TO HAVE INCREASED THE TIME ELAPSED BETWEEN THE FORMATION AND DESTRUCTION OF OCEAN BASINS, THEREBY ALLOWING MORE TIME FOR THE GROWTH OF DIVERSITY. CONVERSELY, HIGH TURNOVER RATES OF THE OCEANIC CRUST WOULD HAVE SHORTENED THE HISTORY OF THE SEAFLOOR AND, AS A CONSEQUENCE, THE TIME AVAILABLE FOR THE DEVELOPMENT OF DIVERSITY. THIS INNOVATIVE PROPOSAL CAN RADICALLY CHANGE OUR VIEW OF THE MECHANISMS UNDERLYING THE DIVERSITY DYNAMICS OF DEEP-SEA BENTHIC INVERTEBRATES THROUGH TIME.