Alien species = ecological air disaster?
In nature, there are certain phenomena that are difficult to explain by science: some animals, although similar in appearance and genetically identical, have very different habits, such as cats and rabbits; some animals lead to convergence of shapes due to similar feeding methods, but they are not the same species at all, and they are not even half related.
hummingbird
For example, hummingbird hawk moths and hummingbirds.
Hummingbird hawk moth
On August 20, 2016, Guangdong photographer Xiao Ou and his party were passing through a jungle in Dinghu Mountain when they found many bees, moths and butterflies collecting honey, including some hummingbird-like elves. The elves quickly caught everyone's attention, took pictures, and asked the relevant experts — after all, according to domestic textbooks, there is no hummingbird species in China.
Since then, various parts of the country have reported the discovery of "hummingbirds", is there a mistake in the textbook?
Hummingbirds are the smallest birds in the world and have only been found in the Americas, especially in the rainforests of South America. In China, the "hummingbird" that people see is actually an insect that resembles it - the small bean long-beaked moth.
The English name of this moth is Hummingbird Hawk-moth, literally translated as hummingbird hawk moth, mainly distributed in Asia, southern Europe, North Africa and North America. Due to environmental reasons such as air pollution, they have become increasingly rare in our country.
Hummingbird hawk moths are known as the "four unlikes" in the insect world. It is like a butterfly, and it moves during the day like a butterfly, the mouthparts are long beak tubes, and have expanded antennae with large tips, and there are colorful, beautiful and dazzling wings; it is like the bees of the hymenoptera, flying in the flowers in summer and autumn to collect nectar and make a clear and recognizable buzzing sound; it is also like a hummingbird, lying out at night, rarely resting, and when feeding, like hummingbirds, sometimes galloping among the flowers, sometimes circling in front of the flowers.
The relationship between hummingbird hawk moths and hummingbirds is not similar to that of rabbits and cats, platypuses and ducks, and unlike humans and gorillas (98% of which are genetically identical), there is also a certain connection between populations, and hummingbirds and hummingbirds are basically two unrelated organisms.
Hummingbirds, collectively known to swifts in the hummingbird family, are the smallest known birds in the world, weighing only 2 grams. They are able to hover in the air by flapping their wings quickly (up to 80 times per second). The hummingbird gets its name from the buzz of flapping its wings, and it's also the only bird that can fly backwards.
And the hummingbird eagle moth is obviously not a bird, so what kind of species is it closer to? Scientists have studied deeper and found that they are actually close relatives of butterflies.
For China, the hummingbird hawk moth is a typical exotic species. The arrival of alien creatures often occurs quietly, and these so-called "invaders" can merge with new ecosystems without a trace – people always turn a deaf ear to the spread of exotic flowers and plants and the Cuban tree frogs that appear in their backyards.
Cuban tree frog
Nowadays, economic and cultural exchanges between various countries and regions are becoming more and more frequent, and the choice of routes for species migration is becoming more and more abundant. So how did the hummingbird Ying'e, who was native to the Americas and did not have the ability to fly long-distance across the ocean, come to China? Experts speculate that the hummingbird hawk moth should have come to China with a large number of U.S. imports of agricultural products, just as the American white moth came with a wooden box that packed imported equipment.
American White Moth
Regarding exotic species, we are most familiar with the hairy crab exported from China to Europe.
102 years ago, a farmer spotted a creature with fluffy claws and dancing claws on the banks of a river in northern Germany, and he immediately decided to show it to a local museum – the first appearance of the "Chinese river crab" before European residents.
How did hairy crabs cross oceans to Europe? It turned out that when the five ports of commerce were carried out at the end of the Qing Dynasty, many European merchant ships came to China. In order to increase the stability of merchant ships, they would fill the water storage tanks with ballast water, which was directly extracted from the Huangpu River. After these merchant ships arrived at their own ports, they would discharge ballast water, so many hairy crab seedlings would land in Europe with ballast water.
Because the hydrological conditions of the various european water systems are similar to those of the Yangtze River, hairy crabs that come to Europe breed and form populations in the local area. Since arriving in Europe, these octopus "immigrants" have been keeping the locals busy. Hairy crabs are exotic species in Europe and pose a direct threat to fish such as eels in local waters, thereby altering the balance of local ecosystems.
When it comes to exotic species that cause global headaches, we have to mention the hyacinth (commonly known in China as water hyacinth).
In 1884, the hyacinth native to Venezuela in South America was sent to the New Orleans Exposition in the United States, people from all over the world saw its gorgeous flowers, they brought it back to their respective countries as an ornamental plant, who knew that the strong reproductive ability of the hyacinth has since become the number one harmful plant that makes countries nervous. In Africa, hyacinths are all over the Nile; in Thailand, hyacinths are all over the Chao Phraya River; and in the southern United States, the Gulf of Mexico is also crowded with dense hyacinths, which not only causes boats to be impassable, but also causes fish and shrimp to disappear, and the river water stinks; in China's Yunnan Dianchi Lake, it was once called "ecological cancer" by experts because of the crazy spread of water hyacinth.
In the face of various environmental tragedies, people can't help but wonder: Are alien species the result of biological invasion?
Scientists have found that species invasion is not a win-lose game, and it is not the process of replacing native species with invaders in a 1:1 (or 1:2 or even higher) ratio.
Alien species can only be called biological invasions if they have adverse effects on indigenous agriculture, ecological environment and human and animal health. Of course, the "alien" of an alien species is defined by the original ecosystem into which it enters.
Moreover, invaded ecosystems often have sufficient available resources, but lack natural control mechanisms and are quite frequently entered by humans. Thus, whether it is a marine or terrestrial ecosystem, alien species actually increase the level of local biodiversity to some extent. In other words, species invasions are unlikely to lead to the collapse of local ecosystems. Species active around the world can increase the diversity of endemic species, but not the total number of species on earth.
Although some alien species have disrupted the local ecological balance, caused huge economic losses to indigenous peoples, and some have even caused the tragic extinction of some species, this situation is extremely rare. In fact, most alien species do not have a significant impact on the migration site, and they have become integrated with the local environment.
As far as China is concerned, since Zhang Qian returned to Chang'an from a mission to the Western Regions, Chinese history has opened a new chapter in the introduction of exotic species. Grapes, carrots, peas, pomegranates, walnuts and other species began to be introduced to the Central Plains along the Silk Road. The species of corn, peanuts, mangoes, betel nuts, figs, oil palms and other species are not native to China, they are all important species that have been introduced to China for hundreds of years.
It can be seen that alien species are not all invasive species, and the introduction of alien species should not be equated with ecological disasters. If we do not treat all alien species with hostility, but make good use of them, will the outcome improve?