66 million years ago, an asteroid hit the earth, resulting in the extinction of large non avian dinosaurs, and then 25 million years later, the large herbivores on earth disappeared.
After the asteroid hit the earth 66 million years ago, the earth was short of large herbivores for a long time, which slowed down the evolution speed of new species of plants, plants showed spiny defense characteristics, and the fruit volume increased. The latest study was conducted by the German integrated Biodiversity Research Center (IDIV) and the University of Leipzig, who used palm trees as a model system for validation. At the same time, researchers can also prove that these changes are very significant. Even if some large herbivores rise millions of years after the extinction of dinosaurs, they can only partially change the evolutionary characteristics of plants. At present, this latest research report is published in the Journal of the Royal Society B. It provides a deep analysis of the earth's ancient geology and helps to better understand the ecological environment after the extinction of current species.
66 million years ago, an asteroid hit the earth, resulting in the extinction of large non avian dinosaurs, and then 25 million years later, the large herbivores on earth disappeared. Due to the interaction between plants and herbivores, the question arises. Has the long-term disappearance and late rise of the so-called giant herbivores affected the evolutionary process of plants? And how?
The picture shows the wooden fruit of manicaria saccifera palm, which depends on large animals to spread
To answer this question, a research team composed of researchers from the German integrated Biodiversity Research Center (IDIV) and the University of Leipzig analyzed the fossils of ancient large herbivores and modern palm trees. Genetic analysis helped researchers track the evolution of plants before and after the disappearance of large herbivores. Therefore, they confirmed a common scientific hypothesis for the first time - the dinosaur era, Many palm species produce huge fruits, with spiny structures covering the trunk and leaves.
However, the team found that in the era of large herbivores, the "evolution speed" of new palm tree varieties with smaller fruits decreased, while the evolution speed of palm tree varieties with larger fruits tended to be stable. Therefore, even after the extinction of dinosaurs, palm trees also had huge fruits. Obviously, smaller animals may also eat larger fruits and spread seeds through their excreta.
"Therefore, we can refute the previous scientific hypothesis that large palm fruit completely depends on large herbivores for seed transmission and diffusion. We believe that the lack of large herbivores will further promote the emergence of more dense vegetation, in which plants with larger seeds and fruits have more evolutionary advantages," said Dr. renske onstein, the first author of the study and the University of Leipzig
However, plants also have defensive characteristics, with thorns on leaves and stems. During the alternating period of the rise of a new group of large herbivores after the extinction of dinosaurs, the varieties of palm trees with defensive characteristics decreased significantly. "In the absence of large herbivores, plant defense characteristics obviously no longer have evolutionary advantages. However, when a new batch of large herbivores appear on earth, most palm varieties appear defense characteristics again and continue to grow huge fruits," onstenn said
Through this latest research, researchers have gained a new understanding of species evolution and adaptability during and after the extinction of large herbivores, which is the most mysterious and unique period in the history of plant evolution. At the same time, it is helpful to understand how the extinction of large herbivores affects plant evolution in ancient times and help us better predict future ecological development. The researchers noted that during the period of alternation of large herbivores, some plant characteristics disappeared, which will affect important ecosystem functions and processes, such as seed transmission and animal herbivores. Therefore, the phenomenon of large animals tending to extinction due to human hunting and climate change may affect the current and future changes of plant communities and ecosystem characteristics.