Creationism in Crisis
How Trees Evolved Over the Last 21,000 years
How Trees Evolved Over the Last 21,000 years
The composition of tree species, as here in southern Germany, is linked to climate changes over the past 21,000 years.
The diversity of present tree species is shaped by climate change in the last 21,000 years
Mixed Woodland, Wales
Incidentally, 21,000 years is more than twice as long ago as creationists believe Earth was magicked into existence by a magic man using magic words. Also, there was no sign of a global flood a few thousand years ago.
Beta diversity is a measure of how diversity differs between locations.
Beta diversity is a term used in ecology to describe the variation in species composition among different habitats or ecosystems. It refers to the differences in species richness (the number of species) and species composition (the identity of the species present) among different communities or sites.The team found a close link between the global pattern of tree biodiversity and global temperature changes since the peak of the last ice age.
Beta diversity can be measured in different ways, including using indices such as the Jaccard index, the Simpson index, or the Bray-Curtis index. These indices provide a measure of the degree of dissimilarity between communities based on their species composition.
Beta diversity is important in ecology because it provides insights into the distribution of species and the factors that influence their distribution. For example, if beta diversity is high between two habitats, it suggests that the environmental conditions in those habitats are different and may support different sets of species. Conversely, if beta diversity is low, it suggests that the environmental conditions are similar and may support similar sets of species.
Beta diversity can also be used to assess the effects of human activities on biodiversity. For example, if beta diversity is lower in an area that has been impacted by human activities, it suggests that those activities have homogenized the habitat and reduced the diversity of species that can survive there.
In summary, beta diversity is a key concept in ecology that helps us understand the variation in species composition among different habitats or ecosystems, and can provide insights into the factors that influence species distribution and the impacts of human activities on biodiversity.
References:ChatGPT. (20 Apr 2023). Tell me about beta diversity in the science of ecology. [Response to a user question].
- Baselga, A. (2010). Partitioning the turnover and nestedness components of beta diversity. Global Ecology and Biogeography, 19(1), 134-143.
- Ferrier, S., & Guisan, A. (2006). Spatial modelling of biodiversity at the community level. Journal of Applied Ecology, 43(3), 393-404.
- Jost, L. (2007). Partitioning diversity into independent alpha and beta components. Ecology, 88(10), 2427-2439.
- Legendre, P., & De Cáceres, M. (2013). Beta diversity as the variance of community data: dissimilarity coefficients and partitioning. Ecology Letters, 16(8), 951-963.
- Vellend, M. (2016). The conceptual foundations of ecological diversity revisited. Ecology Letters, 19(8), 912-923.
Retrieved from https://chat.openai.com/
The Aarhus University News release explains the study:
A research team led by Aarhus University, in collaboration with researchers from more than 50 research institutes around the world, has assessed how past climate changes have affected how the composition of tree species in one area differs from the composition of neighbouring areas on six continents.
[…]
They found that the global pattern of beta diversity in terms of tree species, species characteristics and evolutionary history was closely linked to temperature changes since the peak of the last ice age, which was about 21,000 years ago. Moreover, they show that the effects of historical climate variations on the beta diversity were stronger than the effects of current climatic conditions.
Most of the tree species
It should be added that the researchers have only studied the angiosperm tree species – i.e., species that produce seeds enclosed within a carpel. Angiosperms make up about 80 per cent of all plant species, and some of the most common angiosperm tree species are oak, beech, birch, maple, linden, maple, willow, palm, and eucalyptus.
The researchers combined data from five openly shared databases of tree species and their distributions, with information on the phylogenetic relations between species, and their ecomorphological attributes.
Two different effects on forests
They then divided the effects of ancient climate change on different habitats into two components, each with its own technical term:The authors found that the influence of the two components shifted from the equator to the poles.
- Turnover – i.e. changes due to species replacement. If one species goes extinct in a habitat, another species comes in and fills its ecological role. It turns out that the greater the temperature changes an area has experienced since the Ice Age, the less replacement has occurred in that area.
- Nestedness. In beta diversity, this term describes a pattern in which the composition of species in a diverse habitat is a subset of the species composition in a different and less diverse one – such that the more diverse habitat contains all the species found in the less diverse one, plus additional species. This is an important concept in understanding the organization of biodiversity because it can help identify areas that are more important for conservation. Habitats with nested species compositions may have lower overall biodiversity, but may contain species not found in other habitats, making them essential for preserving overall biodiversity. And the greater the temperature changes an area has experienced, the more nestedness has occurred. Climate fluctuations have thus wiped out local species that have not been replaced.
In tropical areas, turnover – i.e. species replacement – was the most important factor in determining changes in species composition between localities, due to rapid species change.
In temperate regions, nestedness was the primary mechanism for determining changes in species composition, probably because the paleoclimatic changes have lead to gradients in the loss of species.
A tool for ecology scienceBecause the Earth's climate has changed enormously through geological time, exploring the effects of past climate change on current biodiversity provides an opportunity to understand the risks emerging from ongoing and future human-induced climate change.
Dr. Wubing Xu, first author
Center for Biodiversity Dynamics in a Changing World (BIOCHANGE)
Department of Biology
Aarhus University, Aarhus, Denmark.
The purpose of the study, which has just been published in Science Advances, is to supply the ecology science with a tool to solve the major challenge of understanding how ongoing and near-future climate change reshapes the distribution of biodiversity and ecosystem functioning.
The researchers point out that the study also provides a new understanding of the challenges to ecosystem protection and management of efforts to mitigate the impacts of such changes.
Crucial roles
Trees and tree diversity play crucial roles for terrestrial ecosystems, global biodiversity, and humans. This study confirms and extends our previous findings of the high sensitivity of tree diversity to paleoclimatic changes on a global scale. It also suggests that ongoing climate change has the potential to dramatically influence global biodiversity and ecosystem properties not just via direct effects, but also via its effects on trees as ecosystem engineers.
Professor Jens-Christian Svenning, co-author
Center for Biodiversity Dynamics in a Changing World (BIOCHANGE)
Department of Biology
Aarhus University, Aarhus, Denmark.I hope these findings can aid the development of conservation and management plans that consider the long-term and diverse impacts of climate change on all biodiversity dimensions. Only then is there a realistic chance that we will reach goal A of Kunming-Montreal's Sustainable Development Goals for 2050.
Assistant Professor Alejandro Ordonez, senior author
Center for Biodiversity Dynamics in a Changing World (BIOCHANGE)
Department of Biology
Aarhus University, Aarhus, Denmark.
More detail is given in the team's open access paper in Nature Advances:
AbstractAgain, contrary to what creationist frauds assure their cult, the scientists have no difficulty fitting the observable evidence into an evolutionary framework, complete with the environmental changes that cause the observed biodiversity.
As Earth’s climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta-diversity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta-diversity across all three biodiversity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta-diversity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional diversity of angiosperm trees worldwide.
Wu-Bing Xu et al.
Global beta-diversity of angiosperm trees is shaped by Quaternary climate change
Sci. Adv.9, eadd8553(2023).DOI:10.1126/sciadv.add8553
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)
And of course, it goes without saying that they found no evidence of the sort of massive discontinuity that there would have been, had there really been the genocidal global flood, creationists like to imagine, just a few thousand years ago.
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