Co-evolution of animals and plants in tropical rain forests the way plants spread seeds

All species on earth have experienced the process of emergence, reproduction and evolution in the past 3.5 billion years, and some of them interact with each other in the process of evolution. it is this interaction that we see today that there are not only independent species in nature, but also many behaviors and phenomena, such as the interaction between plants, the food chain relationship between animals, the mutual utilization between plants and animals, and so on. Animals and plants move forward hand in hand on the long road of co-evolution, together with the interpretation of many amazing stories.

People often lament the beauty of flowers and the sweetness of fruits in nature. Are they God's masterpieces? Is it an accidental product of nature? We now know that they are the result of the co-evolution of animals and plants over long years. In temperate regions, the flowers of many plants tend to be yellow, white, purple or blue because insects in these places have a poor discrimination of bright red. In the tropics, the flowers of plants are often red, because butterflies and hummingbirds in these places are good at distinguishing bright colors. For insect-pollinated plants, pollination is achieved by insects or hummingbirds. When animals are looking for flowers for nectar, their bodies are glued with pollen, and when visiting other flowers, the previous pollen is scattered on the stigma of the latter, pollinating the plant. In this process, insects get food, flowers are pollinated, and animals and plants benefit each other and complement each other. This interdependence sometimes coevolves surprising phenomena. One side of animals and plants seems to exist entirely to adapt to the other. For example, the mouthparts of some butterflies are just suitable for the lips of orchids. The length and shape of some flower tubes coincide with the beak of honey-gathering hummingbirds. This is the so-called "coevolution".

We might as well look at two examples of co-evolution of pollinators and plants.

Hummingbirds are pollinators of many kinds of plants in the rainforests of South America. Hummingbirds' beaks can be roughly divided into two types: long and curved and short and straight. The first type of bird is suitable for collecting nectar from slightly curved long tube-shaped flowers, which are widely distributed and produce high nectar; the second type of bird is suitable for collecting nectar from short, straight, short tube-shaped flowers, which generally secrete less nectar and often attract many pollinating insects. Although long-beaked hummingbirds can also eat honey from short-tube flowers, they generally prefer long-tube flowers, and as long as they stay near them, they are often driven away by other short-beaked birds. Long-beaked hummingbirds fly fast and can fly long distances to feed on nectar that cannot be used by short-billed hummingbirds. Interestingly, almost all plants pollinated by hummingbirds can secrete the same amount of nectar, perhaps because hummingbirds disdain to patronize flowers that produce less honey.

In the New World rainforests, many orchids rely entirely on certain types of bees to pollinate. In fact, orchids do not secrete nectar, but can release aroma from petal secretory cells. Male bees like to "bathe" the aroma in the secretory zone and bring it back to their nests for storage or even chemical reactions, prompting their antennal glands to secrete hormones that attract females. Each time the drones enter the orchid, the drones land on the labellum and touch the sticky disk at the base of the pollen block; when they leave the flower, they can carry away a mass of gelatinous pollen. When the drones flew to another flower to collect honey, the pollen block happened to touch the slime stigma of the orchid, so it pollinated the orchid. Interestingly, these orchids have extremely meticulous requirements for pollinators, and bee species that are too large or too small are not suitable for the shape of orchids and cannot touch their reproductive organs. What is more intriguing is that different kinds of orchids can secrete different types of aroma, while different species of bees choose different aromatic types, so orchids living in the same area can attract their corresponding bees to pollinate themselves. Popularly speaking, the beauty and fragrance of flowers are not to dress up nature, but to advertise themselves.

In addition to flowers, the coordination and mutual benefit of animals and plants is also common in fruits. Tropical rain forests abound in wild fruits of all colors, and yellow fruits are especially favored by many arboreal primates. Recent studies have shown that the visual systems of many fruit-eating primates in South America are particularly sensitive to yellow. So far, the physiological mechanism of this phenomenon is not very clear, but the meaning of this feature in animal survival adaptation has been understood: it makes it easier for animals to find yellow fruits embellished in green leaves. We know that most of the immature fruits are green and are not easy to be found in the leaves, because the seeds are not yet mature and the intervention of animals can only bring losses to plants. Once the seed is ripe, the pericarp usually turns yellow, and the eye-catching color attracts animals to come a long way to eat the fruit, which often swallows the seed while swallowing the pulp and then excreting it. As a result, the seeds move to a new place with the animals, and the plant population can be expanded to a new space. Therefore, we say that these physiological characteristics of animals and plants are not accidental products, but the result of co-evolution with each other.

The change in the smell of fruit follows the same principle. The flesh is bitter and tasteless when it is not ripe, but once it is ripe, it will emit an attractive aroma, and a strong smell can attract nocturnal animals such as cotton kangaroos and honey bears, which are also voluntary disseminators of seeds. In South America, many species of bats feed on fruit. They use their sense of smell to find delicacies. These flying mammals have extremely high metabolic rates and are often able to spew out tiny undigested seeds shortly after eating flowers and fruits, causing a "seed rain" in the sky.

A variety of interesting animal adaptation behaviors can be observed in the rainforest. In fact, plants also have many adaptation behaviors. Although these strategies are less significant than animals, they are equally ingenious and interesting. Here we take a look at how plants "manipulate" their seed disseminators.

The seeds of many fruits in the rainforest are fusiform and covered with smooth pulp, which is closely linked to the seeds, so that the seeds "drill" into the belly of the animals as they suck the flesh. For animals, these seeds are "pollutants" because they do not provide animals with any nutrition or energy, but for plants, seeds are swallowed by animals and brought to a new place is a way for them to pass on the family line and expand their population. and the pulp is just bait to attract animals.

Also to attract animals to spread seeds, some plants have even evolved deception. There is a tall legume in the rainforest whose pods crack when they are ripe, and the red and black seeds are exposed, especially striking in the sun. Birds in the distance often think they are delicious fruit, fly over and take them away. By the time the birds realize that they have been cheated and throw away the seeds, the latter may have been moved dozens of meters away. In a more clever trick, a French scientist found something called "fake sugar" in some fruits from the African jungle. The chemical composition of fake sugar is originally protein, but it tastes sweet. Scientists believe that this is also a way for plants to attract animals to spread seeds, because many primates like to eat sweet fruits.

There are all kinds of dried fruits in the rainforest, and their fruits and seeds are often odorless and tasteless, but these unostentatious seeds still encounter "well-intentioned" communicators-rodents and ants. We know that in temperate regions, squirrels and chipmunks have a habit of storing food in autumn in preparation for overwintering. In the tropics, this kind of animals also have the same behavior, because there is no distinction between autumn and winter, but there is also a harsh season in which food is scarce. As a result, these clever people buried the seeds in the ground in order to prepare for famine when the fruit was abundant. Unexpectedly, plants have already evolved corresponding strategies, and some seeds will quickly take root and sprout once they encounter the right environment. At the Nureg ecological station in the Amazon rainforest, a cameraman photographed a very dramatic scene in which a stinging rat painstakingly buried a huge seed under the root of a tree, but after a while, by the time it came to look for "rations", the seed had grown into a two-foot-tall seedling.

What is little known is that a group of arboreal ants also eat seeds. The nests of these ants are built with mud stuck to the depressions of the tree trunks, and they toil to transport the seeds they have found everywhere to the nests, but some seeds germinate quietly and quickly as soon as they enter the nest. As a result, over time, one plant after another grew around the nest, and the bare nest was transformed into a vibrant "ant garden".

In the tropical rainforests of the earth, about 70% of plants rely on animals to spread their seeds. An American tropical ecologist has systematically studied the relationship between the size and color of fruits in South American rainforests and their seed disseminators. He found that fruits in rainforests can be divided into two categories: small red fruits and large yellow fruits. The seed disseminators of the former are birds, while those of the latter are mammals. Another French expert deeply studied the relationship between domain utilization behavior and plant succession of howler monkeys and found that the structure of young vegetation in the areas where howler monkeys often sleep was significantly different from that in other places. the seedlings of plant species fed by howler monkeys are obviously dense in these places. It turns out that howler monkeys eat a lot and do not move very often, so many of the swallowed seeds are excreted to the same area, and the seeds then develop into seedlings. After a few decades, the structure of this small forest will be slightly different from that of the neighboring forest, which explains why the vegetation of the primitive tropical rain forest is not very evenly distributed, more or less patchy.

This is how nature weaves itself into an intricate web with the evolution of life, and all links are directly or indirectly related to each other. It seems to have made careful arrangements for each species! Nature is really a simple beauty, wonderful poems, intoxicating dreams, magical mysteries!

Time: 2019-04-16 Click: