Biodiversity is the diversity and diversity of life on the earth. The degree of diversity can be viewed from three levels: genetic diversity, species diversity and ecosystem diversity. Biodiversity is not evenly distributed around the world; Because the climate near the equator is warm and the primary production is higher, the biodiversity in the tropical region is generally abundant; Although the tropical rainforest ecosystem covers less than 10% of the earth's surface, it has about 90% of the world's species. Marine biodiversity is higher in the western Pacific coast (the highest sea surface temperature) and the mid-latitude areas of the oceans. The distribution of species diversity presents a latitude gradient. Biodiversity tends to be concentrated in biodiversity hotspots and will become more prosperous over time. However, due to the main consequences of deforestation, it is expected that biodiversity may slow down in the future. Biodiversity is closely related to many processes (evolution, ecology and culture) that sustain life.
Rainforest is an example of biodiversity on this planet, and usually has a large amount of species diversity.
Severe environmental changes often lead to mass extinction. It is estimated that more than 99.9% (more than 5 billion species in total) of all species that have survived on the earth have been extinct. At present, there are about 10 million to 14 million species in the world, of which about 1.2 million have been registered, and more than 86% have not been described. The total number of related DNA base pairs is estimated to be 5.0x1037, weighing 50 billion tons. In contrast, the total biomass of the biosphere is estimated to be up to 4 trillion tons of carbon. In July 2016, scientists identified 355 gene combinations from the last common ancestor (LUA) of all living things on the earth.
The age of the earth is about 4.54 billion years. The current consensus is that the earliest evidence of life on the earth can be traced back to at least 3.5 billion years ago, that is, the Archaean era after the hot magma of the Mesozoic began to solidify. Microbial mat fossils were found in sandstone 3.48 billion years ago in Western Australia. Graphite found in metamorphic sedimentary rocks 3.7 billion years ago in western Greenland is also the physical evidence of early biomaterials. In 2015, "traces of biological material" were found in rocks 4.1 billion years ago in Western Australia. One of the researchers was quoted as saying: "If life on the earth appears relatively quickly, it may also be normal to put it in the universe."
Since the beginning of life, there have been five mass extinctions and several small-scale extinctions, leading to a sharp decline in biodiversity on a large scale; Then, after the massive loss of biological diversity in a cyclical manner, it is often accompanied by a sharp rise in biological diversity. However, after the emergence of human beings, biological diversity continued to decrease, and genetic diversity was also damaged. It was called the sixth extinction - Holocene extinction; Human impact is the main cause, especially habitat damage. Biodiversity has many positive effects on human health, and the negative effects presented by a few studies can be considered as a fault.
Agricultural biodiversity or agricultural biodiversity is a subset of biodiversity, mainly related to agriculture. According to the definition of the Food and Agriculture Organization of the United Nations (FAO), agricultural biodiversity is the diversity and variability of animals, plants and microorganisms directly or indirectly used in food and agriculture, including crops, livestock, forestry and fisheries. Agricultural biodiversity consists of genetic diversity and species diversity of various food, feed, fiber, fuel and medicine, non-farming species diversity (such as soil microorganisms, predators, pollinators) that maintain agricultural production, diversity in agricultural ecosystems, and even the overall environmental biodiversity that supports agricultural ecosystems (agriculture, animal husbandry, forest and aquatic). Agricultural biodiversity is the result of natural selection and careful selection and improvement by people for thousands of years. People's food and livelihood security depend on the continuous management of various important biological resources related to food agriculture, which is also very important for climate adaptation and climate mitigation.
