The megadiverse countries are those with high levels of biodiversity. The first time the term was used was in 1997 in an investigation by researcher Russell Mittermeier.
Mittermeier estimated the number of species of different taxonomic groups to establish the list of countries with the greatest diversity in the world. Subsequently, in 2002, the first meeting of megadiverse countries was held in Cancun (Mexico).
From this initiative, it has been sought to generate consultation and cooperation mechanisms to promote the preservation and sustainable use of biodiversity. The 17 countries with the greatest diversity in the world have 70% of the world’s biological diversity in just 10% of the planet’s territory.
Most of the megadiverse countries are located in the tropical zone, they have large territorial extensions with varied physiography and diversity of landscapes. In America, the megadiverse countries are Brazil, Colombia, Mexico, Venezuela, Ecuador, the United States, Peru and Guatemala.
Characteristics of megadiverse countries
Biological diversity is greater in those areas of the planet with conditions that are close to biological optimum. The different taxonomic groups tend to diversify when there is abundant water available, sufficient solar radiation, availability of nutrients and favorable climatic conditions.
Most of the megadiverse countries are located in the tropical belt, which promotes a greater diversity of species. This greater diversity is associated with optimal environmental conditions for the development of the species.
Likewise, the influence of the biota (group of living beings) of the northern and southern hemispheres contributes to the presence of a greater number of species. Thus, one cause of the high biodiversity of Mexico is the influence of the flora and fauna of the northern and southern part of America
Landscape and physiographic variability
The megadiverse countries present a very varied physiography, combining areas of plains and mountains that cover a great altitude range. These regions combine a complex geological history and a tropical climate that has allowed the development of diverse landscapes.
Therefore, a great diversity of ecosystems has been formed in large rivers, deltas, wide mountain ranges and other geographical features. For example, Venezuela has a relatively small territory and has a great biodiversity associated with its high geographic variability.
In this country you can find coastal plains, mountain ranges (including tepuis or sandstone tabular mountains), deserts and plains. Furthermore, the altitudinal gradient of these landscapes extends from sea level to 5000 meters above sea level.
Biological isolation processes
When populations of different species are isolated from each other by geographical accidents, the diversification of these groups is promoted. Thus, we have the classic example of the great diversity of finches (birds) in the Galapago Islands (Ecuador).
Another factor that has contributed to the formation of a greater number of species in some areas is the climatic variations in geological time. For example, in the tropical Andes the successive glacial and interglacial processes favored the isolation and diversification of different groups.
Level of endemism
The term endemism refers to species or taxonomic groups whose distribution is limited to a specific geographic area. As an example we can point to the Cactaceae (cactus) family that is endemic to America.
Generally, endemic groups are more common in isolated geographical areas such as islands or high mountains. This is because isolation has allowed the group to diversify under those particular environmental conditions.
Endemisms are an important element to assess the biological diversity of a region, since they are species that only inhabit that area of the world. Thus, for example in Madagascar all endemic amphibians are endemic to the country.
The area occupied by a given country can be a factor that contributes to having a greater diversity of species. This is due to the fact that a greater extension allows the development of a greater diversity of landscapes and ecosystems.
For example, the United States of America is considered a megadiverse country mainly thanks to its territorial extension. Likewise, China has a large area that is one of the factors that determines its high biodiversity.
The human being and its cultural expressions are considered one of the elements that define the biodiversity of a region. Likewise, cultural diversity is expressed in the different uses, forms of domestication and cultivation of plants and animals that contribute to increasing agro-diversity.
In this sense, countries like Mexico, Peru and China have a high cultural diversity that is an important element of their mega diversity.
Is Mexico a megadiverse country?
Mexico is located in the south of North America and connects with South America through Central America. Therefore, it is influenced by the Holartic (biological kingdom of the Northlands) and Neotropical (biological kingdom of tropical America) biota.
The country is considered the fifth most megadiverse in the world for its diversity of vascular plants (23,424 species). Thus, in Mexico there are 47% of the world’s Cactaceae species (669), of which 518 are endemic.
In addition, a large number of mammals (564 species) and reptiles (864 species) are present. It also has 2,695 species of fish that represents 10% of all known species in this group in the world.
The reptiles of Mexico represent around 12% of the known species in the world, ranking second after Australia.
One of the relevant elements of the Mexican megadiversity is its rich cultural diversity. In Mexico there are about 66 indigenous languages and a wide and ancient agricultural culture, being considered an important center for the domestication of plants.
The level of species exclusive to Mexico is quite high and it is estimated that around 54% of the plants are endemic. Likewise, 30% of mammalian species, 57% of reptiles and 48% of amphibians are only found in Mexican territory.
What are the megadiverse countries?
Next we will present the countries that occupy the first 12 places in mega-diversity in the world, ordered by continents:
On this continent are seven of the megadiverse countries on the planet. In addition to Mexico, which, as we already indicated, occupies the fifth place among the countries with the greatest biodiversity, we have:
It ranks first among the world’s megadiverse countries due to the number of vascular plant species (56,215 species) and amphibians (779 species) that inhabit its territory. Furthermore, in Brazil there are a large number of mammals (648 species) that are surpassed only by Indonesia and 1,712 species of birds.
On the other hand, in the country there are more than 16,000 endemic plant species and almost 800 species of amphibians, reptiles, birds and mammals are exclusive to the region.
Likewise, its great territorial extension (8,515,770 km²) and geographical location contribute to its enormous biodiversity. Likewise, in Brazil there is most of the Amazon River, which has the largest basin in the world.
This country has a territorial extension (1,142,748 km²) that is seven times less than that of Brazil, but it is the second in biological diversity in the world. Its richness of vascular plants is 48,000 species and there are about 634 species of amphibians.
On the other hand, it is the country with the largest number of bird species in the world with 1,815 species.
Regarding the number of endemisms, it has 16,000 species of plants exclusive to the country, ranking fourth in the world. In addition, it has around 600 endemic species of amphibians, reptiles, birds and mammals occupying the fifth position worldwide in these taxonomic groups.
Venezuela has a smaller territorial extension than countries like Brazil and Colombia, but it has a high biodiversity, ranking sixth in the world. This country has more than 21,000 species of vascular plants, of which around 5,000 are endemic species.
Furthermore, its diversity of birds (1,392 species) is quite high, being higher than that of China and Mexico.
This country is crossed by the equatorial line and ranks seventh in the world among the megadiverse regions of the world. In Ecuador there are approximately 21,000 species of vascular plants and 271 species of mammals.
Likewise, it has a high number of species of birds (1,559), amphibians (462) and reptiles (374).
In the eighth place is Peru with 17,144 species of vascular plants, 441 species of mammals, 298 species of reptiles and 420 species of amphibians. However, this South American country ranks second worldwide in number of bird species (1,781), after Colombia.
Likewise, with just over 4,000 endemic plant species it surpasses Ecuador and the United States in this area.
Being the third country in the world by geographical extension, it is home to a large number of species, which places it as the ninth megadiverse country. It has more than 17,000 species of vascular plants, 400 species of mammals, 750 of birds, 500 of reptiles and 306 of amphibians.
In this continent are the countries that occupy the third and fourth place in the world in mega-diversity.
China appears in third place for the number of plant species (32,200 species) fundamentally. In addition, it also has an important diversity of bird species (1,221 species).
In terms of endemic species, this country ranks eighth in plant endemisms, with about 9 to 10,000 species. The endemism of amphibians, reptiles, birds and mammals is around 450 species, ranking seventh worldwide.
The country ranks fourth in mega-diversity in the world with 29,375 species of vascular plants. Likewise, it ranks first in the world in number of mammal species and fourth in birds.
In endemic species of plants, amphibians, reptiles, birds and mammals, it is placed in second place worldwide with about 16,000 species of plants and about 800 species of animal groups.
This island-continent is located in most global lists of megadiverse countries in tenth place. The country has 15,638 species of vascular plants, 376 species of mammals, 851 of birds, 880 of reptiles and 224 of amphibians.
It is important to note that it has the largest number of reptile species in the world, including endemic species. It is estimated that approximately 89% of Australian reptiles are endemic.
Additionally, due to its condition of geographic isolation, it has a high degree of endemism in other groups with around 14,000 endemic plant species and more than 600 species of amphibians, birds and mammals.
Democratic Republic of Congo
This African country has extensive forests still little explored, including the Congo River basin (3,373,000 km²) which is the second largest in the world. The Democratic Republic of the Congo ranks eleventh among the megadiverse countries on the planet.
Currently 10,000 species of plants are known (3,000 endemic), 400 of mammals, 1,000 of birds, 280 of reptiles and 216 of amphibians.
In twelfth place on the list of megadiverse countries is the island of Madagascar. This territory has 9,505 species of vascular plants, 161 species of mammals, 262 of birds, 300 of reptiles and 234 of amphibians.
One of the most relevant aspects of the country’s biological wealth is its high level of endemism, which is close to 80%. Important endemisms occur in this region in groups such as lemurs (primates), three families of birds and endemic species of baobabs (Malvaceae).
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