Secrets of the emergence of angiosperms

The emergence of many angiosperms (also known as flowering plants) on Earth, especially their rapid spread in the Cretaceous (approximately 100 million years ago) is thought to be due to the the ability to transform living conditions according to their needs.

In an article published in Ecology Letters, Wageningen Frank Berendse ecologist and Marten Scheffer announced that angiosperms have changed the environmental conditions in the Cretaceous period to suit their requirements. Thus, these researchers have come up with a completely new explanation for the problem that Darwin once considered one of the greatest secrets of evolution that he ever faced.

In the Cretaceous, the Earth's surface experienced one of the biggest changes in vegetation structure, a change that took place at an unprecedented pace at the time. Frank Berendse (professor of plant ecology and nature conservation), together with Marten Scheffer, (professor of aquatic ecosystems), two officials at Wageningen University, came together to learn this. how did it happen They seek answers in a very new direction.

Before the Cretaceous, our planet's vegetation mainly consisted of gymnosperms and ferns. Most of these plants were later replaced by a whole new group: the angiosperms, also known as flowering plants. During the Cretaceous period, about 125 million years ago, the first seeded plants appeared. Soon after, gymnosperms in the tropics were almost replaced by angiosperms. And by the end of the Cretaceous period (65 million years ago), the dominance of flowering plants was established in almost every corner of the world. Gymnosperms continue to exist only in the northern latitudes - as we see today.

Blue linen. The emergence of many species of angiosperms on Earth, especially their rapid spread in the Cretaceous (approximately 100 million years ago) is thought to be due to the ability to self-adapt to living conditions on demand. of them. (Photo: iStockphoto / Jostein Hauge)

The rapid rise of species-rich biodiversity - directly related to their invasion of the Earth - is one of the biggest questions Charles Darwin has ever encountered. A lot of fossils have been obtained from different species of angiosperms that appeared at the end of the Cretaceous period, while there were almost no fossils since this century. This is exactly the opposite of Darwin's opinion that the replacement of angiosperms only takes place slowly.

The big question is how is this tremendous change happening at such a rapid pace? Is it because - just before the Cretaceous period - the great Sauropod dinosaurs were excluded because the much smaller Ornithischian dinosaurs, and this newly emerging species has eaten off the seedlings of gymnosperms? Or is it because angiosperms have evolved simultaneously with many pollinators for their flowers?

According to Berendse and Scheffer, we need to think in a completely different direction. They claim that the angiosperm species have gained the ability to change the world to suit their needs. They grow faster and therefore need more nutrition. The world at that time was poor and almost completely covered by gymnosperms that had garbage that was difficult to decompose, so the soil was barren, and flowering plants had many difficulties to begin to grow. But in places where gymnosperms temporarily disappear, for example due to the effects of floods, fires or storms, angiosperms will have conditions to grow in number, from which they are able to self improve their living conditions with the decomposing rubbish they create.

According to Berendse and Scheffer 's theory, this leads to a positive result: from the beginning, angiosperms can grow more rapidly, and soon replace gymnosperms in many places throughout. world. Since then, the animals that eat the leaves and fruits of the angiosperm increase rapidly in number, facilitating the evolution of mammals, and finally the emergence of humans.

Refer:

Frank Berendse and Marten Scheffer. Interpretation for angiosperm radiation revisited for Darwin's 'abominable mystery'. Ecology Letters, Published Online: 2 Jul 2009 DOI: 10.1111 / j.1461-0248.2009.01342.x