Important moments in the evolution of plants

As a general rule, and perhaps because this is the case most of the time, we tend to understand the evolution of species as a gradual process; A series of small changes that, over long periods of time, diversified life in its various forms and versions. However, at least when it comes to plants, this evolution may not have been cooked as slowly as we thought.

This is at least what was raised in a new study entitled Propagation innovations and pulse rise in plant complexity Recently published in the magazine Science. And so, to this day, It is assumed that there were two main moments that characterized the development of the plant kingdom. The first of these occurred about 350 million years ago, relatively early in the evolutionary history of plants, and corresponds to The emergence of the first seed plants.

However, according to data published by the Stanford University geosciences professor’s team, Andrew Leslie, the evolution of the complexity of plants stopped for about 250 million years, until just 100 million years ago another great evolutionary leap occurred that gave rise to most modern plants today: The emergence of flowers and the subsequent diversification of flowering plants.

Classify the degree of complexity of plants

To reach their conclusions, the researchers used a new, simple but novel technique Classification of the complexity of plants according to the order and number of their primary reproductive structures. Like we said, scientists have long assumed that plants became more complex with the arrival of seeds and flowers, yet the research findings provide new information about the timing and magnitude of these crucial changes.

“The most surprising thing is this kind of stagnation; this plateau in complexity after the initial development of the seed. But it is also surprising how a drastic change later, after so long, causes flowering plants to begin to diversify”Dice, Leslie. “The reproductive structures look different in all of these plants, but they all have roughly the same amount of structures throughout this fraction.”.

Count and compare: an unusual way for plants

Flowers are among the most diverse structures produced by any group of plants. They acquire colors, smells and shapes that attract all kinds of animals and serve as a beacon to the senses of different types of living creatures. Sometimes they are also complex structures: their petals, petals and pistils are intertwined in the most subtle and varied arrangements. Attract and deceive pollinators to spread their pollen from flower to flower.

This complexity makes it difficult for scientists to compare flowering plants with other types of plants such as ferns or some conifers, which have simpler reproductive systems. For a long time, precisely these differences led botanists in their investigations to focus on characteristics within each family of plants, and to study the evolution of plants with and without flowers in a general and discrete manner.

In this sense, the most revolutionary thing about Leslie and his team’s research is that they overcame these differences Design a system that categorizes plants based on one observation: the number of different parts that make up their reproductive structures.

Thus, scientists have classified about 1,300 species of terrestrial plants that arose on Earth from 420 million years ago to the present. “This tells a fairly simple story about the reproductive evolution of plants in terms of form and function: the more functions the plants are and the more specific they are, the more parts they have.”Researcher details. “This is a useful way to think about the large-scale changes that span the entire history of plants.”, Add.

From bushes to flowers

When terrestrial plants first diversified in the early Devonian period, about 420 million to 360 million years ago, the Earth was much warmer, without trees or land vertebrates. Spiders like scorpions and moths roamed the ground among the small, irregular vegetation, and the tallest terrestrial creature was a 20-foot (20 ft) mushroom that resembled a tree trunk.

After the Devonian period, significant changes occurred in the animal kingdom: terrestrial animals, for example, evolved to have large body sizes and more diverse diets, insects diversified and dinosaurs appeared. However, plants did not show much change in their reproductive complexity until they had developed flowers.

Insect pollination and seed dispersal by animals may have appeared more than 300 million years ago, but It won’t be until the last 100 million years Intimate interactions with pollinators fueled the complexity of flowering plants“. “There was a long period of time when plants would have interacted with insects the way flowering plants now react, however, if this happened, it wouldn’t happen with the same degree of complexity.”Leslie adds.

Upper Cretaceous period

In the Upper Cretaceous period, between about 100 and 66 million years ago, Earth looked more like the planet we know today: “Something like Yosemite National Park without the flowering trees and shrubs.”According to the world. “The second installment of complexity was more dramatic than the first, emphasizing the unique nature of flowering plants.”. This period gave rise to the passion flower, which can have 20 different types of parts, more than twice that of non-flowering plants.

According to the researchers, this new classification reflects the career diversity of those who are alive today and how they came to be who they are today: “They basically split their work to do to be more efficient at what they have to do” Leslie concludes. Which is basically what any organism does: try to pass on its genetic information to the next generation.

Source: Hector Rodriguez/National Geographic,

Reference article: https://www.nationalgeographic.com.es/naturaleza/dos-momentos-clave-evolucion-plantas_17356,