What Does the Fossil Record Show About Recovery? Brook Milligan - - PowerPoint PPT Presentation

▶

Apr 02, 2024 265 likes •438 views

What Does the Fossil Record Show About Recovery? Brook Milligan Department of Biology New Mexico State University Las Cruces, New Mexico 88003 brook@nmsu.edu Fall 2009 Brook Milligan What Does the Fossil Record Show About Recovery? What

SLIDE 1

What Does the Fossil Record Show About Recovery?

Brook Milligan

Department of Biology New Mexico State University Las Cruces, New Mexico 88003 brook@nmsu.edu

Fall 2009

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 2

What are the questions?

How does biodiversity recover from extinctions?

Is it rapid enough to keep pace with extinctins? Is there a significant lag between extinctions and recovery? Does extinction create empty niches that can be rapidly filled by new species? Does recovery increase the rate of recovery?

Is recovery different for background and mass extinctions? Does the answer depend on how recovery is measured?

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 3

How can they be answered?

Must know:

temporal sequence of extinctions temporal sequence of origination

Need:

quantified relationship between extinction and recovery

Difficulties

both extinction and recovery have a significant stochastic component

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 4

Two approaches

Cross-correlation Spectral analysis

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 5

Cross-correlation: Methods

Calculate cross-correlation between extinction and origination Identify significant cross-correlations Determine phase shift

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 6

Fossil Record: Diversity, Extinction, Origination

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 7

Fossil Record: Cross-correlation

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 8

Fossil Record: Expectations from Distortions

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 9

Cross-correlation: Results

10 MY lag from extinction to origination Lag does not depend greatly on:

means of quantifying extinction/origination presence/absence of mass extinctions completeness of fossil record

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 10

Spectral analysis: Methods

Transform time series into spectral domain Identify frequencies beyond confidence intervals

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 11

Fossil Record: Diversity, Extinction, Origination

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 12

Spectral Analysis

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 13

Spectral Analysis

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 14

Fossil Record: Rates of Extinction and Origination

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 15

Spectral analysis: Results

Extinction: all frequencies within confidence interval Origination: only short wavelength frequencies significantly reduced Rapid response for origination lacking

Brook Milligan What Does the Fossil Record Show About Recovery?

SLIDE 16

Implications

Significant lag between extinction and recovery Lag present for all types of extinction events Recovery cannot occur rapidly Current human impacts will leave a signature on biodiversity for millions of years

Brook Milligan What Does the Fossil Record Show About Recovery?