Biodiversity & Palaeobiology
Banner image shows modern latitudinal biodiversity of terrestrial verebrates.
Modern Latitudinal Diversity and Environment
We are working to understand what determines modern biodiversity on a global scale, see O'Malley et al., 2023, for details.
Spectral Analyses
We have developed and applied wavelet spectra algorithms to quantify species richness (essentially number of species per patch of ground on Earth, labeled "spx" in picture) as a function of location and scale.
These approaches provide means to quantify the strength of correlations between biodiveristy and the environment at specific locations and, importantly, scales.
The calculated strength of relationships, formally coherence and cross wavelet power, between species richness and environmental variables (elevation, precipitation, mean annual temperature & temperature range) at big (>3500 km) scales for a transect through the Americas is shown in the wide figure above. Higher values = higher coherence.
History of life on Earth
We have been working to understand the history of life on Earth. To map commonalities between palaeobiological time series (e.g. Phanerozoic marine genera) and environmental time series (e.g. stable isotopes as proxies for climate change) we have been developing cross wavelet spectral techniques and applying them to large inventories of biological and palaeobiological data. This work is in its early stage but shows that we can reliably identify parts of these time series that have similar and large signals throughout time and as a function of frequency. They have helped us to address questions about the apparent existence of periodicities in palaeobiological time series and to map hysteresis (as phase differences) between biological and environmental time series.
Figure: Comparison of the time-frequency content of diversity, number of marine sedimentary packages and sea level time series. (a) Blue = sea level time series; black = diversity. Gray labeled bands = mass extinction events. (b) Cross wavelet power spectrum of sea level and diversity. (c) Blue = sea level; black = sedimentary packages. (d) Coloured contours = cross wavelet power spectrum for sea level and packages. Black contours = cross wavelet power spectrum from sea level and diversity (panel b): solid line = 0.1, dashed line = 1, dotted line = 10 (see Roberts & Mannion, 2019, for details).