Landscape dynamics determine the evolution of biodiversity on Earth - The University of Sydney
A dynamic and changing Earth.
Creationists insist that Earth is 'fine-tuned' for life; but as anyone who understands biology will know, life is 'fine-tuned' for Earth and the tuning process is called evolution by natural selection.
The observable fact that, over time, species have either evolved or gone extinct gives the lie to the 'fine-tuned for life' assertion because, if that were true, there would be no selection pressure for change and the fossil record would show no change.
In fact, the fossil record wouldn't exist as we know it because there would have been no evolution beyond the first free-living, single-celled prokaryote organisms because their environment would have been perfect for them.
Yet, as we know from daily observation, Earth is a changing and dynamic planet with periodic climate change, earthquakes and volcanoes caused by the slow process of plate tectonics, changing oxygen and carbon dioxide levels caused by the rise and fall of major ecosystems, and changing ocean currents caused by a number of different factors, not the least of which are climate change and plate tectonics. Then there are the cosmological changes caused by the Milankovitch cycles.
One of the consequences of this dynamic change is the way the Earth's surface is continually being recycled over geological time by erosion, transportation in water and sedimentation in ocean deposits as nutrients, then subduction and mountain-building and eventual resurfacing through volcanic activity. This gives changing levels of nutrients in the oceans that affect biodiversity both in the seas and on land.
This is the conclusion of a study by a team of geologists jointly led by Dr Tristan Salles of The University of Sydney, Sydney, New South Wales, Australia, and Dr Laurent Husson of Université Grenoble-Alpes, Grenoble, France. They have shown an association between changes in nutrient levels due to sedimentation and mass extinctions. Their findings are published open access in Nature and are explained in a University of Sydney news release:
For more technical detail and illustrations of this dynamic effect on biodiversity, we can turn to the team's open access paper in Nature
Movement of rivers, mountains, oceans and sediment nutrients at the geological timescale are the central drivers of Earth’s biodiversity, new research published today in Nature has revealed.
The research also shows that biodiversity evolves at similar rates to the pace of plate tectonics, the slow geological processes that drive the shape of continents, mountains and oceans.
“That is a rate incomparably slower than the current rates of extinction caused by human activity,” said lead author Dr Tristan Salles from the School of Geosciences.
The research looks back over 500 million years of Earth’s history to the period just after the Cambrian explosion of life, which established the main species types of modern life.
The discovery in 1994 of the ancient Wollemi pine species in a secluded valley in the Blue Mountains west of Sydney gives us a glimpse into the holistic role that time, geology, hydrology, climate and genetics play in biodiversity and species survival.Earth’s surface is the living skin of our planet. Over geological time, this surface evolves with rivers fragmenting the landscape into an environmentally diverse range of habitats. However, these rivers not only carve canyons and form valleys, but play the role of Earth’s circulatory system as the main conduits for nutrient and sediment transfer from sources (mountains) to sinks (oceans).
While modern science has a growing understanding of global biodiversity, we tend to view this through the prism of narrow expertise. This is like looking inside a house from just one window and thinking we understand its architecture. Our model connects physical, chemical and biological systems over half a billion years in five-million-year chunks at a resolution of five kilometres. This gives an unprecedented understanding of what has driven the shape and timing of species diversity.
Dr Tristram Salles, co-senior author
School of Geosciences
The University of Sydney, Sydney, New South Wales, Australia.
The idea that landscapes play a role in the trajectory of life on Earth can be traced back to German naturalist and polymath Alexander von Humboldt. His work inspired Charles Darwin and Alfred Wallace, who were the first to note that animal species boundaries correspond to landscape discontinuities and gradients.
Water and sediment flux.Researchers mapped how rivers drove sediment into the oceans over a 540 million year period.
In groundbreaking research a team of scientists - from the University of Sydney, ISTerre at the French state research organisation CNRS and the University of Grenoble Alpes in France - has proposed a unified theory that connects the evolution of life in the marine and terrestrial realms to sediment pulses controlled by past landscapes.Fast forwarding nearly 200 years, our understanding of how the diversity of marine and terrestrial life was assembled over the past 540 million years is still emerging. Biodiversity patterns are well identified from the fossil record and genetic studies. Yet, many aspects of this evolution remain enigmatic, such as the 100 million years delay between the expansion of plants on continents and the rapid diversification of marine life.
Beatriz Hadler Boggiani, co-author
PhD student
University of Sydney, Sydney, New South Wales, Australia.
Instead of considering isolated pieces of the environmental puzzle independently, the team developed a model that combines them and simulates at high resolution the compounding effect of these forces.Because the evolution of the Earth’s surface is set by the interplay between the geosphere and the atmosphere, it records their cumulative interactions and should, therefore, provide the context for biodiversity to evolve.
Dr Laurent Husson, co-senior author
CNRS, ISTerre
Université Grenoble-Alpes, Grenoble, France.
“It is through calibration of this physical memory etched in the Earth’s skin with genetics, fossils, climate, hydrology and tectonics by which we have investigated our hypothesis,” Dr Salles said.
Using open-source scientific code published by the team in Science in March, the detailed simulation was calibrated using modern information about landscape elevations, erosion rates, major river waters and the geological transport of sediment (known as sediment flux).
Sediment fluxes to the oceans (pink) vs diversity of marine animals (black) over the past 540 million years. The correlation is striking. (Extinction events are marked)Source: Nature
This allowed the team to evaluate their predictions over 500 million years using a combination of geochemical proxies and testing different tectonic and climatic reconstructions. The geoscientists then compared the predicted sediment pulses to the evolution of life in both the marine and terrestrial realms obtained from a compilation of paleontological data.
When comparing predicted sediment flux into the oceans with marine biodiversity, the analysis shows a strong, positive correlation.In a nutshell, we reconstructed Earth landforms over the Phanerozoic era, which started 540 million years ago, and looked at the correlations between the evolving river networks, sediment transfers and known distribution of marine and plant families.
Manon Lorcery, co-author PhD student
Université Grenoble-Alpes, Grenoble, France.
On land, the authors designed a model integrating sediment cover and landscape variability to describe the capacity of the landscape to host diverse species. Here again, they found a striking correlation between their proxy and plant diversification for the past 450 million years.
In his 1864 novel A Journey to the Centre of the Earth, Jules Verne attributes this to his fictitious hero, Professor Otto Lidenbrock:
“Animal life existed upon the Earth only in the secondary period, when a sediment of soil had been deposited by the rivers and taken the place of the incandescent rocks of the primitive period.”Dr Salles said: “This observation by Professor Lidenbrock to his nephew Axel fits strikingly well with our hypothesis. So, it should be no surprise that Jules Verne was greatly inspired by Humboldt’s work.”
AbstractThings for creationists to ignore here are:
The long-term diversification of the biosphere responds to changes in the physical environment. Yet, over the continents, the nearly monotonic expansion of life started later in the early part of the Phanerozoic eon1 than the expansion in the marine realm, where instead the number of genera waxed and waned over time2. A comprehensive evaluation of the changes in the geodynamic and climatic forcing fails to provide a unified theory for the long-term pattern of evolution of life on Earth. Here we couple climate and plate tectonics models to numerically reconstruct the evolution of the Earth’s landscape over the entire Phanerozoic eon, which we then compare to palaeo-diversity datasets from marine animal and land plant genera. Our results indicate that biodiversity is strongly reliant on landscape dynamics, which at all times determine the carrying capacity of both the continental domain and the oceanic domain. In the oceans, diversity closely adjusted to the riverine sedimentary flux that provides nutrients for primary production. On land, plant expansion was hampered by poor edaphic conditions until widespread endorheic basins resurfaced continents with a sedimentary cover that facilitated the development of soil-dependent rooted flora, and the increasing variety of the landscape additionally promoted their development.
Fig. 1: Physiographic evolution and associated patterns of erosion-deposition across the Phanerozoic.
a, goSPL12,13 simulations showing high-resolution palaeo-landscape, heterogeneous landforms and drainage networks, under the influence of surface processes, at 155 Ma and 11 Ma. b, Erosion and sedimentation rates; positive values correspond to deposition in endorheic basins and depressions, and negative ones to erosion across mountain ranges and along major river upstream channels, at 155 Ma and 11 Ma. c, Total endorheic sediment coverage since 540 Ma (in red) with cumulative mean erosion rates on continents (blue), and instantaneous global net sediment flux to the ocean for specific time intervals (purple).
Fig. 4: Continental sediment deposition and physiographic complexity, and diversity of vascular plants, during the Phanerozoic.
a, Predicted cumulative area covered by sediments (red curve) and diversity of tracheophyte species throughout the Phanerozoic1 (green curves). The Pearson coefficient of 0.91 indicates a strong positive correlation between the two main curves. b, Top: temporal distribution of the physiographic diversity index (PDIV; Methods) with lower (Q1; 25%), median (Q2) and upper (Q3; 75%) quartiles. Probability density function (PDF) is used to estimate the likelihood of having a specific PDIV for each time interval. Bottom: temporal evolution of the physiographic variety index (PVAR given by the interquartile range of PDIV (Q3-Q1). c, Multivariate regression analysis (ordinary least squares (OLS) regression curve) carried out on normalized cumulative area covered by sediments (SCOV) and physiographic variety (PVAR) gives a strong statistically significant relationship (P value < 2.2 × 10−16). The resulting regression equation is defined by 0.019 + 0.27PVAR + 0.61SCOV. Analysis of variance shows a high dependence of plant diversity dynamics on these abiotic parameters (R2 ≈ 0.9).
Botanical icons by Rebecca Horwitt, available at full size and open access from https://sites.psu.edu/rhorwitt/.Fig. 2: Reconstructed sediment flux and continental sedimentary basin evolution.
a, Simulated global erosion flux, net sediment flux delivered to the ocean and endorheic sedimentation flux; and major orogenic episodes for the Phanerozoic (CAMP, Central Atlantic Magmatic Province). b, Global changes in total continental area, and in modelled endorheic basin area. Cm, Cambrian; O, Ordovician; S, Silurian; D, Devonian; Carb, Carboniferous; P, Permian; Tr, Triassic; J, Jurassic; K, Cretaceous; Pg, Palaeogene; Ng, Neogene.
Extended Data Fig. 1: Global scale Phanerozoic landscape evolution model.
Left panels represent simulated physiographies for 4 time-slices accounting for surface processes impact and highlighting continental topography and associated river networks (dark blue). Right panels show associated erosion/deposition rates (blue/red respectively) for the considered time-slices.Extended Data Fig. 2: Comparisons between predicted elevations and corresponding paleo-elevation map.
a. Top 3 panels show the input elevation conditions for 155 Ma at 0.1o resolution (SW201814) and bottom ones represent model outputs (0.05o resolution), highlighting the geomorphological imprints of surface processes on the landscape. b. Temporal change between imposed tectonic rates from corrected topography and erosion rates at 155 Ma (blue curve). This curve is used to estimate when dynamic equilibrium conditions have been reached. c. Corresponding continental hypsometric curves for the given paleo-elevation at 155 Ma (purple) and simulated one (black). Red curve in the inset shows the differences between the two hypsometric curves.
Salles, T., Husson, L., Lorcery, M. et al.
Landscape dynamics and the Phanerozoic diversification of the biosphere. Nature (2023). https://doi.org/10.1038/s41586-023-06777-z
Copyright: © 2023 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
- The fact that, as the Theory of Evolution predicts, there is a close correlation between environmental change and biodiversity.
- How well the geological and fossil record mesh and support that theory.
- How a dynamically changing Earth is the cause of so much of the biodiversity we see today, in contrast to what a stable, fine-tuned Earth would produce.
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