The "Tortoise and Rabbit Race" of Species Evolution

an ecologically diverse marine coral reef community rich in fish and corals. Photo Source: John H.R. Burns , perhaps, is the key to the diverse reproduction of living things.
Researchers from the Department of Biology at the University of Hawaii at Hilo published their new study on the Earth's animal biodiversity patterns in the journal Science on February 28th, suggesting that animal diversity in the modern oceans could be explained by lower extinction rates among animal populations rather than higher rates of origin, as previously predicted.
today, marine animals are more diverse than at any time in the history of life on Earth, and we've been trying to describe how they've become like this." Matthew Knope, the study's author and an assistant professor of biology, told China Science Daily.
, a professor of evolutionary biology at the University of California, Berkeley, who was not involved in the study, said understanding how biodiversity is made up of space and time has been a focus of biological research. One of the main difficulties is that the current biodiversity model is determined by origin and extinction, and while it is difficult to clarify the role of extinction, one can infer the rate of origin by studying existing biodiversity.
addition, more than 99 percent of the life on Earth has been extinct, and only a small number can be preserved as fossils. How to reconstruct the changing law of the earth's historical biodiversity through the incomplete fossil record is a major scientific problem.more than half a century ago, John Hutchinson, an English botanist, asked, "Why are there so many animals?" And replied that adaptive ecological differences allow species to coexist and lead to diversification of classifications.
fact, in many modern ecosystems, ecological differentiation and taxonomic diversity are closely related. Ecological differentiation can allow for the exploration of more ecological positions, reduce competition and promote species formation. However, if causality is reversed, a similar correlation can arise between ecological differentiation and taxonomic diversity, and more species formation events provide opportunities for ecological differentiation.
addition, Knope said, taxonomic diversity is due to differences in origin and extinction rates, while the contribution of extinction to ecological differentiation and the coupling of taxonomic diversity has received less attention. Therefore, the nature of the relationship between ecological differentiation and taxonomic diversity remains an unresolted central issue in biology, especially in the extinction events of the entire paleontological time scale and the history of the Earth's animals.
the modern oceans seem to give scientists a chance to test assumptions. So the researchers decided to use marine animal evolution to study how the coupling between ecological and taxonomic diversity has evolved over the past 500 million years, resulting in a modern relationship between ecological differentiation and taxonomic diversity on a global scale.
" fossil record provides a unique perspective on the problem, with differentiated and diverse relationships that can be traced over time, and the effects of origin and extinction clearly separated. Knope said.the trajectory of marine life is not smooth. They have experienced life eruptions, mass extinctions, disappeared over hundreds of millions of years of history, and prospered again.
the Cambhan period, some 541 million years ago to 485 million years ago, the Earth's biodiversity and complexity exploded, known as the Cambic eruption. The Camburo outbreak was one of the most important events in the history of life evolution, and most of the animal species appeared during this period.
, there have been five global mass cluster extinctions in known Earth's history. The first was the mass extinction of organisms at the end of the Otau era more than 400 million years ago. The mass extinction devastated marine ecosystems, leading to the extinction of 85 per cent of marine species at the time.
this period, a large ice sheet was formed, with a total size of 150 million cubic kilometers, more than six times the total of the Earth's Antarctic and Arctic ice sheets today. At that time, global sea levels plummeted by 100 to 150 metres, and the vast majority of marine life suffered.
mass extinction 372 million years ago, the second known mass extinction in Earth's history. The event has devastated life on Earth again, with about 82 percent of marine species disappearing. It was 36 million years after the end of the mass extinction that marine species re-emerged on a large scale.
Nanjing University's Yan Xuan team and Shen Shuzhong, a member of the Chinese Academy of Sciences, selected 3,112 strata profiles and 260,000 fossil data from 11,268 marine fossil species to reconstruct the paleo-generational marine biodiversity curve from about 540 million to 240 million years ago. The paper was published in Science on January 17.
researchers have recreated the detailed processes of the three largest extinction events in geological history and two major biological radiation events. Of these, 252 million years ago, the largest extinction event ever identified by humans led to the rapid extinction of about 80 per cent of marine life within tens of thousands of years. The occurrence of this event is closely related to the rapid warming of the global climate at that time. Two important biological radiation events occurred between 490 million and 470 million years ago and 340 million to 300 million years ago, respectively, and were in sync with the gradual cooling of the global climate at that time.To find out who shaped the oceans where life is now thriving, Knope, in collaboration with institutions such as the University of Connecticut and Stanford University, surveyed fossils of about 20,000 marine animals from the past 500 million years, as well as about 30,000 living marine animals.
s findings clearly show that in modern oceans, the most ecologically diverse animal groups also have the largest number of species. Knope said.
found that members of ecologically flexible groups were able to resist extinction, especially during mass extinctions, which mainly affected ecologically similar groups.
In other words, the dizzying variety of species seen in the oceans today, such as fish, arthropods and modes, do not have higher rates of origin than less common species, but because they have lower extinction rates over a long period of time.
Gillespie said the study provided the most detailed and detailed analysis of the fossil record to date, clearly demonstrating the importance of "slow and stable" genealogical development, which is a key factor in determining which genealogies have the highest diversity.
in a clever analysis of large amounts of data from the fossil record, Knope et al. directly addressed a key question in biology: why certain types of animals occupy a very wide range of ecological niches, according to Michal Kowalewski, a professor of invertebrate palaeontology at the University of Florida. "Furthermore, this study highlights the unique value of palaeontological data in assessing the core issues of biology and exploring the historical roots of modern biospheres." Kowalewski told China Science Daily.
Shen Shuzhong believes that understanding the driving mechanisms of major biological events is of great significance for understanding the earth's biodiversity today and the sixth mass extinction facing mankind and its relationship to global climate change.
Knope said: "Perhaps the fable of the tortoise-and-rabbit race is a good explanation for marine animal diversity: some species have been diverse in the early days, but have since been overtaken by others, which are more ecologically diverse, more evolutionaryly stable, and have strong resistance to mass extinctions while having a stable diversity ratio." Information
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