Credit: Ashley Dineen
Researchers are looking into the ancient oceans to unravel the complexity of mass extinctions, past and future. The new study of Earth's greatest extinction by scientists at the California Academy of Sciences and the University of Wisconsin-Milwaukee sheds light on how ecosystems change thanks to such transformational events. Research, published today in Biological listsSuggests that those who survived had many of the same ecological roles as their predecessors, with one catch – there was a sharp increase in the number of individuals with modern traits, such as greater mobility, higher metabolism and more varied eating habits. These durable distinctions were better suited for regeneration, making ecological interactions more intense in the process: fish were more agile, various predators and marine invertebrates, such as molluscs, became more defensive. Observations on this system and its inhabitants can help in conducting modern protection in the identification of the most resistant and best-equipped species of the Earth in the face of environmental stress.
"We are interested in understanding why some species and communities have survived and recovered better than others," says Dr. Ashley Dineen, a former postdoctoral researcher at the Academy and current scientist at the Museum of Invertebrate Paleontology at the UC Museum of Paleontology in Berkeley. "For a long time biology has focused on the number of species that survive extinction, but we must also ask what did these species do and how they reacted to stress – these insights are important when we push our planet into an increasingly uncertain future. "
The mass extinction, often referred to as the "Great Dying", took place 252 million years ago and often serves as the plenipotentiary of the modern era. Like today, the climate regime has passed from a colder period to a warmer one. This climatic fluctuation, driven by massive eruptions of volcanoes that ejected harmful gases, increased the temperature and acidity of the oceans, decreased the oxygen concentration, broke powerful ocean currents and changed the ocean system to its head.
Researchers studied fossils that inhabit invertebrate ocean such as clams, snails, corals and sponges from Utah, Nevada and Texas. This region once was a shallow outskirts of the ancient and vast Panthalassa ocean. Using numerical methods, the team grouped species that survived the naval war into functional groups with similar characteristics, such as omnivorous mobile omnivorous mammals such as sea urchins, to better understand the ecological transformation after the Great Dying.
"We learned from our analysis that in addition to documenting the number of species that arise during ecological renewal, we need to know what they actually did – what scientists call their functional diversity," says Dr. Peter Roopnarine, academic curator of Geology. "This helps us to understand if the system has shifted towards favoring species with different reactions to stress."
One surprising discovery: the results of the study showed a significant ecological continuity among species – where the species that were destroyed during the dying had the same characteristics as those that followed. However, during the convalescence period there has been a significant change in the number towards larger and more active people who are strikingly similar to the inhabitants of our modern oceans. This change in functional pressure can be the hallmark of the ecosystem on the road to recovery.
"Our next step is to determine what species you want on the recovery fronts," says Dineen. "For example, if you have a reef with twenty different species of corals, but all react the same to stressors, then all will be similarly struck with anxiety. But on a separate reef, if you have twenty species of coral and each reacts differently to stress, the chance of losing the entire reef is lower, and having various mechanisms to deal with a critical situation is crucial for a future characterized by growing environmental stressors. "
The research team hopes that their discoveries of surviving species will help scientists identify our modern – and urgently needed – security priorities.
"We often focus on estimating the number of species in the ecosystem, but we should also learn how – and how well – these species will survive and concentrate efforts to protect," says Dineen. "If we take into account the mass extinction that we are dealing with today, it is clear that we need to take into account the entire systems before it is too late to improve the course."
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