[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/7249\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n 1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n 2) Linking back to our original story\u003Cbr \/\u003E\n 3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n \n\u003Cdiv\u003E\n \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003EThe evolution of biodiversity: ever-increasing or did it hit a ceiling? \u003C\/h2\u003E\u003Cp\u003EIncreasing knowledge on historical\u0026nbsp;patterns of biodiversity could also help us understand animals\u2019 ability to adapt and what climate change means for evolution.\u003C\/p\u003E\u003Cp\u003EThe traditional view is that species have increased in diversity continuously over the past 200 million years,\u0026nbsp;particularly in the last 100 million, leading to more diversity now than ever before. But some recent studies suggest biodiversity has tended to stay largely the same, with only occasional surges.\u003C\/p\u003E\u003Cp\u003E\u2018Our findings strongly contradict past studies that suggested unbounded diversity increases at local and regional scales over the last 100 million years,\u2019 said a \u003Ca href=\u0022https:\/\/royalsocietypublishing.org\/doi\/10.1098\/rspb.2020.0372\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Efresh study\u003C\/a\u003E on terrestrial species. It found no evidence of a rise in diversity in the past 66 million years, following a brief two- to three-fold increase over a couple of million years after the mass extinction of the dinosaurs at the end of the Cretaceous Period and as mammals began to thrive.\u003C\/p\u003E\u003Cp\u003EThe story was similar for a study on \u003Ca href=\u0022https:\/\/science.sciencemag.org\/content\/368\/6489\/420\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Emarine species\u003C\/a\u003E, with the researchers finding little change in ocean biodiversity over the past 200 million years.\u003C\/p\u003E\u003Cp\u003E\u2018We find that ecosystems are relatively stable in terms of how much diversity they have over tens to hundreds of millions of years,\u2019 said Professor Richard Butler, a palaeobiologist at the University of Birmingham, UK, who worked on both studies as part of the \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/637483\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003ETERRA\u003C\/a\u003E\u0026nbsp;project. \u2018Rather than seeing exponential increases, it\u2019s more like a short-term quite dramatic increase and then a relatively flat line.\u2019\u003C\/p\u003E\u003Cp\u003EThe findings imply that diversity is capped at a certain limit and that species numbers are ultimately limited by factors such as the availability of \u003Ca href=\u0022https:\/\/www.sciencedaily.com\/releases\/2019\/02\/190218123129.htm\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Eresources like water and space\u003C\/a\u003E, says Prof. Butler. Various researchers have been moving towards this view for some time, he says, but new approaches like those adopted in the TERRA project have helped bolster the evidence.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EInflation\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EProf. Butler explains that the changing picture is being revealed by methods that help reduce the long-standing challenge experts have faced of biases in the fossil record. The issue is that the higher abundance of preserved fossils in the more recent past leads to artificial inflation of diversity.\u003C\/p\u003E\u003Cp\u003EOne of their approaches has been to take a regional view rather than a global one. \u2018There\u2019s been a tradition in the field that what we\u2019re interested in is trying to understand global biodiversity\u2026 but as you go deeper in time, you might have whole continents that aren\u2019t sampled (as no fossils have been found) for some time intervals,\u2019 said Prof. Butler.\u003C\/p\u003E\u003Cp\u003EThe researchers built on data collected over the past 20 years in the \u003Ca href=\u0022https:\/\/paleobiodb.org\/#\/\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EPaleobiology Database\u003C\/a\u003E, which gathers global taxonomic data for organisms throughout geological history. They then created algorithms to sample similar-sized areas where fossils had been found through time.\u003C\/p\u003E\u003Cp\u003EUsing these methods,\u0026nbsp;their studies highlighted significant variations in diversity at different locations across time \u2013 such as it tending to be much higher at the equator than at the poles \u2013 emphasising the need for a regional view to get the full picture.\u003C\/p\u003E\u003Cp\u003EThe researchers have also started working to integrate their results with the data of climate modellers. They want to see how climate shifts have affected the distribution of biodiversity over deep time, which they are doing by looking at the types of conditions that prevailed globally and in different parts of the world when certain animals were around.\u003C\/p\u003E\u003Cp\u003EProf. Butler notes, however, that estimating the level of biodiversity from the fossil record is still challenging given the many gaps in the database. For example, teeth are much harder to use for distinguishing dinosaur than mammal species.\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003E\u2018Whether life diversified (continuously) by way of numerous jumps and steps\u2026 or in fact reached a kind of full capacity and then didn\u2019t shift much is still hotly debated.\u2019 \u0026amp;nbsp;\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EProfessor Michael Benton, University of Bristol, UK\u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ETrends\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe complexity of teasing out historical biodiversity trends is emphasised by the \u003Ca href=\u0022https:\/\/journals.plos.org\/plosbiology\/article?id=10.1371\/journal.pbio.1000493#pbio.1000493-McPeek1\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Edifferent picture\u003C\/a\u003E found in the past studies of Dr H\u00e9l\u00e8ne Morlon, an evolutionary ecologist at the French National Centre for Scientific Research.\u003C\/p\u003E\u003Cp\u003EHer results suggested no set limit on biodiversity, unlike the work of TERRA, but slowdowns in the rate at which new species emerge as ecological niches or habitats become more crowded over geological time. \u2018We found models where diversity is not bounded \u2013 with a fixed number of species that doesn\u2019t change \u2013 and it\u2019s not exponentially increasing, but there\u2019s this type of slowdown in the way that diversity accumulates,\u2019 she said.\u003C\/p\u003E\u003Cp\u003EDr Morlon has found \u003Ca href=\u0022https:\/\/onlinelibrary.wiley.com\/doi\/abs\/10.1111\/ele.13382\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Efurther evidence\u003C\/a\u003E for such slowdowns as part of a project she leads called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/616419\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EPANDA\u003C\/a\u003E, which has sought to develop better models and tools for harnessing data in evolutionary, or phylogenetic, trees to study diversification at a finer scale. Among its results, the researchers have identified \u003Ca href=\u0022https:\/\/journals.plos.org\/plosbiology\/article?id=10.1371\/journal.pbio.1002532\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Efive main diversification patterns\u003C\/a\u003E among vertebrates, providing a framework for understanding the evolution of biodiversity in deep history.\u003C\/p\u003E\u003Cp\u003EThey also had a surprise result. They found evidence that cooler periods over the past 66 million years \u003Ca href=\u0022https:\/\/www.ncbi.nlm.nih.gov\/pubmed\/28373536\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Ecoincided with faster rates of body size evolution\u003C\/a\u003E in birds and mammals, even though they found that overall diversification tends to \u003Ca href=\u0022https:\/\/onlinelibrary.wiley.com\/doi\/abs\/10.1111\/ele.13382\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Eslow in cooler climates\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003EThe researchers suggest that this result could be because body sizes have a specific relationship to temperature\u0026nbsp;or, more widely, that\u0026nbsp;certain traits might be\u0026nbsp;decoupled from\u0026nbsp;diversification. All this suggests that further research\u0026nbsp;is needed on the links between the evolution of body traits and diversification.\u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u2018The link between different levels of evolution is super complicated and not well-known,\u2019 said Dr Morlon. \u2018We need pretty complicated models that are not that easy to develop.\u2019\u003C\/p\u003E\u003Cp\u003EBut while there is still much to unravel, developments in this area may apply to modern-day issues too.\u003C\/p\u003E\u003Cdiv\u003EWhile researchers emphasise that past evolutionary trends are not directly translatable to today because of the vastly different timescales, they say studies could provide some clues about the ability of species to adapt and the combinations of characteristics such as feeding patterns or size that put species at risk. This research could also provide implications for how human-driven climate change might affect future evolution.\u003C\/div\u003E\u003Cp\u003E\u0027We can estimate at these timescales what happens when you change temperature by that many degrees \u2013 what\u2019s the effect on evolutionary rates?\u2019 said Dr Morlon. \u2018It also at least gives perspective to understand how biodiversity might answer to current changes.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EDiversification \u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EMeanwhile, the debate about diversification continues.\u003C\/p\u003E\u003Cp\u003EProfessor Michael Benton, who studies vertebrate palaeontology at the University of Bristol, UK, has been a strong proponent of continually rising biodiversity and still leans towards that view.\u003C\/p\u003E\u003Cp\u003EWhile agreeing that the fossil record is incomplete, he says the broad outline of the order of fossils is not misleading and broadly documents the \u2018rise and fall of major groups through time.\u2019\u003C\/p\u003E\u003Cp\u003EProf. Benton cites the example of the proliferation of birds to today\u2019s 10,000 species. To suggest that biodiversity has remained constant since birds came into being is like suggesting that bird species replaced a similar number of pre-existing species of flying animals, he says.\u003C\/p\u003E\u003Cp\u003ESimilarly, he said: \u2018There was a time when animals didn\u2019t form reefs or burrow under the seabed; then those innovations emerged and this presumably allowed a net increase in biodiversity\u2019.\u003C\/p\u003E\u003Cp\u003EHe agrees, however, that the answers remain far from clear cut and much more work is needed to get to the bottom of it \u2013 but that the many advances in computational tools give a big helping hand.\u003C\/p\u003E\u003Cp\u003E\u2018It still seems to be unresolved to what extent the fossil record gives a reasonable picture of life,\u2019 said Prof. Benton. \u2018Whether life diversified (continuously) by way of numerous jumps and steps\u2026 or in fact reached a kind of full capacity and then didn\u2019t shift much is still hotly debated.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU. 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