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. Smithand 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?

Deep sea species richness

Deep sea rock record

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 long-term correlation

Deep sea short-term correlation I

Deep sea short-term correlation II

Modeling

Modeling results

Modeling results

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Deep sea conclusions

Questions:• 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

Other diversity curves

