Is there a rock-bias to diversity patterns in the deep sea?
Is there a rock-bias to diversity patterns in the deep sea? Graeme T. Lloyd, Andrew B. Smith and Jeremy R. Young
Fossil record is our only record of the diversification of life
Diversity correlates with rock record on land… Peters and Foote 2001 Smith and McGowan 2007
…but what about the deep sea?• Widely regarded as the best record we have: – Larger spatial extent than land – Abundant and widespread taxa – Near continuous sedimentation – Well studied (e.g. DSDP/ODP/IODP)
The database• Study group is Coccolithophores• Novel compilation from North Atlantic• Compiled from 40 years ODP/DSDP data• 46,538+ occs from 14405+ samples• High temporal resolution (nanno zones)Questions:• What is the deep sea diversity pattern?• What is the deep sea rock pattern?• Are the two correlated to any degree?
Correlation tests• First both time series were log-transformed• Long term test: – Simple correlation• Short term tests: – First differences (absolute) – Moving average differences (relative to long term trend)• Degree (rho) and significance (p) of correlations determined using Spearman rank
Deep sea conclusionsQuestions:• What is the deep sea diversity pattern? – Linear rise with short-term fluctuations• What is the deep sea rock pattern? – Exponential rise with short-term fluctuations• Are the two correlated to any degree? – Yes, strongly and significantly, over both long-term and short-term – N sites is a good predictor of species richness