Humans and Biodiversity: Network of Life

Biodiversity can be studied, protected, and conserved at three scales or levels: genes, species, and ecosystems. Genetic diversity refers to variation within the same species. Meanwhile, to perceive biodiversity is to observe the plurality of species; and species are groups of organisms that share common characteristics and are capable of reproducing themselves.

Likewise, ecosystems include the diverse species that are found in a defined place, as well as the interactions that occur between them (biotic) and with the environment that surrounds them (water, air, soil). These interactions can even occur between very distant ecosystems, such as between the Sahara desert and the Amazon, where sand and dust from the desert cross the Atlantic Ocean, which is very important for the functioning of the Amazon forests.

On a typical day, after waking up, without the intervention of plants and microorganisms in the forests and other ecosystems that filter the water that reaches the homes or the supply systems, it would be impossible to have quality water for drinking and bathing, even with the work of water treatment technologies. In addition, the clothing comes from natural fibers or animal skins, and cotton or linen are plants grown in the country. Mexico is the center of origin and domestication of one of the most used cotton species in the world: Gossypium hirsutum.

Biodiversity and the curious lad who set sail

On the morning of December 27, 1831, a ship left the port of Plymouth, located in the southwest of England, for South America. Charles was the young naturalist on board, a young man of only 22 years old with a small cargo of notebooks, presses, traps, and everything that his work onboard the HMS Beagle required. He had managed to get on board thanks to the recommendation of one of his Cambridge professors and the enthusiasm of the captain, Robert Fitz Roy, who shared with his guest his fascination for nature

The expedition, originally planned as a two-year mapping trip, would span almost five years across several continents, allowing young Charles to admire and study the creatures that excited him so much: brightly colored beetles, butterflies, iguanas, giant tortoises, colorful hummingbirds, and finches with varied beaks, mischievous monkeys and slow sloths, blue-footed boobies... As well as collecting "a good number of brightly colored flowers, capable of making a florist go crazy", as well as ferns and many other plants from the jungles and tropical forests, fossils and rocks, sending home one of the most amazing collections ever seen.

Twenty-eight years later, the observations and first ideas that emerged during that journey through the most extraordinary biodiversity, geography, and geology, added to a long life of meticulous and disciplined research, would lead him to write The Origin of Species, one of the most important books for modern science, which would change forever our way of seeing the world and the life that inhabits it. The name of the curious fellow in the Beagle was Darwin.

What is biodiversity?

Charles Darwin was inspired by some of the most biodiverse places on the planet, such as Brazil and Australia, but what does that word mean?

Biodiversity is the diversity or variety of living things, of life and its various manifestations, on all scales and across time and geographical space.

It is not a term used at the time of the voyage on the Beagle it was not until the mid-1980s, during a forum on biological conservation in the United States, that the word biodiversity was first used to name the diversity of life (Wilson, 1988).

In 1992, at the Earth Summit in Rio de Janeiro, Brazil, the Convention on Biological Diversity was signed to promote the conservation of the planet's biological heritage.

In this Convention, biodiversity is defined as the variability of living organisms from all sources including, in particular, terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part; it includes diversity within species, between species, and of ecosystems.

Humans are part of the planet's biodiversity that we share with other species, depend on it for survival, and have transformed it, as well as the environment, over thousands of years.

We are at a point where, as we will see further on, by our actions we have put this biodiversity at risk and are therefore endangering our civilization.

The three levels of biodiversity

Biodiversity can be studied, protected, and conserved at different scales or levels:

Genes

One of the first experiences that a newborn baby will have are the "hateful" comparisons of all his/her family: he/she has his/her grandfather's nose, his/her mother's eyes, his/her father's forehead and he/she grimaces just like uncle Eulalio. But, at the same time, the resulting combination of the genes of both parents will have given rise to an unrepeatable, unique being.

This is what the level of genetic diversity refers to, the variation within the same species; in the previous example it is our species, Homo sapiens, but the same can be observed in bacteria, horses, or pumpkins.

This diversity is encoded in the genes present in an organism or a group of organisms. Genes contain the basic information and instructions for the development and functioning of an organism and are found in the cells, whether it is a single-celled organism or one with millions of cells. This information is passed on from generation to generation and can be modified through evolutionary processes that originate naturally by the interaction, during long periods, between living beings with other organisms and with their environment.

This variability within species is key to the survival of the species itself because when faced with changes in the environment, it allows some individuals to survive and transmit their information to the next generations.

Species

Visiting a zoo or a market are simple ways to understand this level of biodiversity; in turn, observing the plurality of species is the easiest way to perceive biodiversity.

Species are groups of organisms that share common characteristics and can reproduce with each other. For example, there are eight different species of Tlacuaches in Mexico, but despite being very similar, the Didelphis virginiana could not produce offspring with a female Didelphis marsupialis. Organisms (individuals) or groups of them (populations) should not be confused with the species.

To date, about 1,700,000 species of diverse taxonomic groups (from microscopic organisms to whales) have been described and although the total number of species on the planet is unknown, it is estimated that it may reach 13 million.

Organisms of the same species can be subdivided into populations, depending on the space they inhabit. For example, there are jaguar (Panthera onca) populations in Campeche, Chiapas, Jalisco, Quintana Roo, Sonora and Tamaulipas. This is the same species of cat, but in this case, the various populations usually do not have contact with each other.

Ecosystems

This level includes the various species found in a defined location, as well as the interactions that occur between them (biotic) and with the surrounding environment (water, air, soil). These interactions can occur even between very distant ecosystems, such as between the Sahara desert and the Amazon, where sand and dust from the desert, which crosses the Atlantic Ocean, are very important for the functioning of the Amazon forests.

Ecosystems can be analyzed from different perspectives and in reality, they have no limits since nature is a continuum on the planet (the Earth is itself a single system), so no set of components defines them, but when talking about them we always consider their biotic (living) and abiotic (non-living) components, as well as the interactions between them and an identifiable source of energy.

Three characteristics of ecosystems have been proposed that show the three levels (genes, species, and ecosystems) and allow their identification, analysis, and understanding:

Composition

These are the genes, species, populations, or ecosystems present in a given site. The Amazon rainforest in Brazil does not have the same plant or animal species as the Tuxtlas rainforest in Veracruz, Mexico.

Structure

It is how biodiversity is distributed in space, both horizontally and vertically. It includes biotic factors (the living organisms that interact with each other and with the environment) and abiotic factors, i.e., the physical and chemical components of the environment such as soil, light, and temperature. The combination of these factors produces similar ecosystems under similar conditions, for example, the pine forests of Canada or the German mountains, which are located at a similar altitude and latitude, with similar insolation and water availability.

Function

The biotic and abiotic elements (the structure) of an ecosystem are related through dynamic processes. By definition all ecosystems recycle matter and use energy; how these processes occur is what defines the functions of a particular ecosystem.

The energy processes of an ecosystem occur through trophic levels, i.e. the place an organism occupies in the food web about the original energy of the sun incorporated by primary producers (e.g. green plants).

An energy source is always required to maintain the functions and structure of ecosystems, that is why they are considered "open systems" since they require energy input to be maintained over time. Without the sun, life on Earth would have no energy to sustain itself.

Our relationship with biodiversity

When we think of biodiversity, the image of a distant and exuberant forest, full of mysteries and strange living beings, comes to mind. However, the diversity of biological forms is everywhere. Everyday life would not be possible without biodiversity. Every day, at all times, we have contact with it. Life in cities overshadows this relationship, which is, however, constant and necessary.

On a typical day, after waking up, it would be impossible to have quality water for drinking and bathing, even with the work of water treatment technologies, without the intervention of plants and microorganisms in forests and other ecosystems filtering the water that reaches homes or supply systems. Clothing made from natural fibers or animal skins is another example. Cotton or linen are plants grown in the country. Mexico is the center of origin and domestication of one of the most used cotton species in the world: Gossypium hirsutum.

Breakfast is another impossible time of day without biodiversity. A lunch containing, for example, a couple of eggs with beans and tortillas, orange juice, and a glass of milk can be analyzed.

The corn used to make tortillas is a grass plant native to central Mexico, domesticated over thousands of years thanks to the patience and empirical knowledge of Mesoamerican farmers. For this reason, it has enormous cultural importance and forms part of the identity of Mexicans. Currently, the National Commission for the Knowledge and Use of Biodiversity reports that there are 59 native breeds of corn in Mexico.

The bean is also a plant native to Mexico, currently, 50 different varieties are identified in the country, each with particular characteristics (color, size, flavor) and adapted to the various local conditions in which they develop. In addition to being a highly nutritious plant, beans perform a very important ecological function, since bacteria capable of fixing nitrogen in the soil live in their roots, an essential element for plant growth.

Drinking orange juice not only requires orange trees but also bees and other insects that pollinate the flowers of this and many other trees and plants, thus allowing the fruits to be produced.

Finally, if breakfast includes eggs and milk, both products have their origin in two of the most used domestic animals in the world: chickens and cows. Humans have domesticated at least 28 species of animals such as cows, goats, sheep, pigs, horses, camels, chickens, quails, geese, ducks, and a long list of other animals to obtain food and other products, as well as to help themselves with farm work.

According to data from the United Nations Food and Agriculture Organization, there are around 1,500 million cows and more than 20 billion chickens in the world. Maintaining this number of animals (which are only a part of the domestic animals that we humans raise) requires enormous extensions of territory, which has meant the destruction of many ecosystems on the planet, producing negative effects that affect all the inhabitants of the Earth.

In just one example, what it takes for a person in a city to start their day, it is shown how living beings (including humans, of course) constantly depend on other organisms to exist and satisfy their needs, through the complex web of biodiversity. Everything we do is related to biodiversity.

Life depends on the life

There is another dimension, beyond people's everyday needs, in which the existence of living beings, in their vast diversity, is the key to the very existence of life.

The cycles that make life as we know it today occur in ecosystems. The planet Earth functions as a gigantic system in which an endless number of processes of exchange of energy and materials occur simultaneously, with regulatory mechanisms, many of which are not yet fully understood (or even known). A good part of these processes depends directly or indirectly on living beings and their interactions, especially the cycles of water, oxygen, carbon, nitrogen, etc., which are cycles of planetary impact.

According to Naeem Sh. et. al. (1999):

There are critical processes at the ecosystem level that influence plant productivity, soil fertility, water quality, atmospheric chemistry, and many other local and global environmental conditions that ultimately affect human well-being.

These processes, called ecosystems, are controlled by both the diversity and composition of plant, animal, and microbe species in a community. Human modifications to the living community in an ecosystem - as well as to the collective biodiversity on Earth - can then alter ecological functions and the life-support services that are indispensable to the well-being of human societies.

Substantial changes, especially losses of biodiversity, have already occurred at local and global levels. The main cause has been the widespread human transformation of once highly diverse natural ecosystems into relatively species-poor, managed ecosystems. Recent studies suggest that such reductions in biodiversity can alter both the magnitude and stability of ecosystem processes, especially when biodiversity is reduced to the low levels typical of managed systems.

One way to understand, study, measure, and value the functions of biodiversity in the processes that sustain life on the planet (and within it, human life) is through ecosystem services, that is, the tangible (obvious) and intangible (imperceptible) benefits that are obtained from ecosystems. The ecosystem services approach has helped to clarify the importance of biodiversity and the processes associated with it and makes the link between ecosystems and human well-being evident.

According to the Millennium Ecosystem Assessment-a force of 1,360 scientists from 95 countries who in 2005 assessed the current state of biodiversity across the planet-there are four types of ecosystem services: provisioning, regulating, supporting, and cultural.

Provisioning services are the tangible benefits we obtain from ecosystems, such as food, water, vegetable fibers, fuels (wood and coal), medicinal compounds, pigments, and chemical compounds such as resins that are used in the manufacture of various products and materials for building or papermaking, among other uses.

Many plant species are used directly as medicines, or the active agents in them are identified and replicated through biotechnology. Seventy-five percent of the medicines that have been developed have their origin in various plant species.

Regulating services are the benefits obtained from the interactions between living beings in ecosystems and the processes that are generated from them. These services include pollination, local and global climate regulation, removal of air pollutants, water purification, pest control, and soil retention.

Cultural services are intangible benefits that we obtain through the beauty of natural systems, which promote art and knowledge and recreation, creativity, and cultural diversity, including identity, traditions, and a sense of belonging.

Support services enable the existence of other types of ecosystem services. In this case, the benefits are indirect and occur over long periods, among them are the formation of soil that allows the existence of fertile land and thus the growth of forests, jungles, etc.; primary production, which is the production of organic matter through the processes of photosynthesis or chemosynthesis; the water cycle and biogeochemical cycles (of phosphorus, nitrogen, carbon).

The value of biodiversity

For a couple of decades, several research groups around the world have been working to establish the economic value of various ecosystem services. One of the first efforts was made by Robert Costanza and collaborators (1997), in which they evaluated 17 services (including pollination, food production, nutrient recycling, water supply, bio-biological control, and culture) of 16 biomes or large ecosystems of the planet (including reefs, temperate forests, ocean, grasslands, lakes, deserts, tundra, farming areas, urban areas) and concluded that these generated 33 trillion dollars a year.

This amount was almost double the total economic wealth generated in the world during the same period ($18 trillion per year).

Another ecosystem service whose economic value has been calculated is pest control. A study published in the Proceedings of the National Academy of Sciences of the United States of America found that pest control provided by bats generates more than $1 billion per year globally (Maine and Boyles, 2015). This means that if there were no bats, countries would have to pay an exorbitant amount of money to prevent various pests, especially insects, from destroying crops and thus jeopardizing the food supply of the human population.

Although it is clear that biodiversity is valuable for many more reasons than just the provision of ecosystem services or its economic value, this way of looking at it has made it easier to understand that biodiversity loss generates economic costs (as well as environmental and social costs) that must be avoided.

Thanks to this understanding of the environmental damage caused by the current model of development and consumption, the importance of preserving and adequately managing biodiversity have begun to be taken into account in public policy planning (which are actions and programs that governments establish to maintain and improve the quality of life of the inhabitants of a country or region).

Mexico, a megadiverse country

Mexico is one of the megadiverse countries on the planet. This means that an extraordinary number of species and ecosystems (and, therefore, genetic diversity) are found in its territory. The 17 megadiverse countries of the planet are home to 70 percent of the world's known species; Mexico, in particular, is home to about 10 percent of the known species.

This diversity has its origin in the particular location and orography of the national territory. According to Imaz (2010) in the country

"... two biogeographical regions overlap, the Nearctic (characteristic of North America) and the Neotropical (characteristic of Central and South America). In the area where both regions meet, there is flora and fauna from the north and south of America, as well as species endemic to this transition zone. Another cause that adds to this biological richness is that in our country there are almost all types of natural environments known on Earth, a characteristic that is only shared with India and Peru. Most of the national territory is covered by deserts (37 percent), followed by coniferous and oak forests (19.34 percent) and dry tropical forests (14.14 percent)".

For all these reasons, Mexico is in the first place at a global level of species for some of the best-known groups on the planet. For example, it is second in reptile species (802), eighth in birds (1,096), third in mammals (535), fifth in amphibians (361), and in plants with flowers (23, 424), of which 669 are cactus (47.7 percent of the total known species) and 1,260 are orchids (5 percent of the known species).

It also has large extensions of coral reefs, which are considered the most productive marine ecosystems with the greatest diversity and complexity on the planet.

In Mexico, three coral reef areas are recognized:

a) the Pacific coast including Baja California -whose reef was defined as the "Serengeti of the sea" (for its diversity and beauty) by French oceanographer Jacques Cousteau-, some of the coastal states and the Marías and Revillagigedo Islands,

(b) the coasts of Veracruz and Campeche in the Gulf of Mexico; and

c) the east coast of the Yucatan Peninsula (from Isla Contoy to Xcalak, including the atoll of Banco Chinchorro, where the Mesoamerican reef, the second largest barrier reef on the planet, is located).

Another relevant aspect of Mexican biodiversity has to do with the high degree of endemism, that is, when a species is only found in one place or region of the world, it is said to be an endemic species of that place or region. In Mexico, 30.7 percent of mammal species are endemic (particularly bats and mice), as are 57 percent of reptiles, 48.2 percent of amphibians, 11.4 percent of birds, 29.9 percent of sponges, and 54.9 percent of conifers.

Many of these species are found in small areas, for example, the Lacandonia schismatics plant only exists in a couple of square kilometers of the Lacandon Jungle in Chiapas.

Species that occupy very small distribution areas are known as micro endemics. Mexico also has an important number of these species, such as cacti, mice, and some amphibians, such as the Ajolote (Ambystoma mexicanum).

These biological and geographic characteristics that make Mexico a megadiverse country are reflected, according to Imaz (2010), in the development of great cultural richness and wide knowledge and management of the biological resources themselves throughout the country.

In Mexico, there are more than 60 native groups, many of them located in areas with high biodiversity. Thus, it is in the indigenous and rural territories where a significant portion of the national biodiversity and the ecosystem services associated with this wealth are protected. Biodiversity and culture transform and shape each other. Human groups and their culture (their tastes, knowledge, activities, rituals, etc.) are a novel force in the evolution of species, thanks to the domestication of plants and animals that have contributed to and transformed natural wealth. At the same time, regional biodiversity shapes the food, religious, social, and economic practices and habits of human groups. In the codices and other historical documents, it can be seen that the number of species used by the inhabitants of Mexico in the 16th century was as great as the current one. Corn, diverse beans and pumpkins, cotton, avocado, vanilla, and other important species originated in Mexico, where they were domesticated.

Biodiversity at risk

Despite its importance, biodiversity is at risk. Humans have greatly altered the global environment, modifying the biogeochemical cycles of the Earth system, transforming soils and landscapes, and increasing the mobility of some organisms to new locations.

One of the main causes of biodiversity loss is habitat degradation. A degraded habitat has lost species and the associated ecological processes, diminishing (or even eliminating) its capacity to sustain itself over time, to resist climatic phenomena such as droughts, fires, or floods, and to generate ecosystem services.

Habitat degradation may be due to deforestation where vegetation cover is partially or removed to make way for agricultural, livestock, urbanization, or industrialization activities. The removal of vegetation cover can also generate the fragmentation of habitats, leaving islands more or less isolated amid transformed environments. This generates adverse conditions for many groups of living beings that end up disappearing in these patches.

Another type of deforestation occurs when certain species are systematically eliminated from their habitats, such as tree species whose wood is considered precious, as is the case with mahogany and cedar. By eliminating these elements of the ecosystem, it loses part of its structure and functions.

According to Chapin S. et. al. (2000), these are as many human activities that are dramatically transforming the structure of the Earth system, affecting the planet's biodiversity by transforming the conditions that sustain it:

Fossil fuel combustion and deforestation, which have increased the concentration of atmospheric carbon dioxide (CO2) by 30 percent in the last three centuries (more than half of this increase occurred in the last 40 years). The concentration of methane has doubled and the concentrations of other gases that contribute to global warming have increased.

It is expected that over this century if the course of the fossil-fuel economy is not drastically changed, these gases will cause the fastest climate change the Earth has experienced since the end of the last ice age 18,000 years ago - or perhaps much earlier.

The increase in the planet's average temperature will cause (or is already causing) changes in rainfall patterns in many regions, the melting of polar ice, mountain glaciers, and the increased intensity of extreme weather events such as hurricanes.

The temperature of a region is key to various biological processes, such as mating, oviposition, seed germination, or fruit production. A change in the average temperature of a region can cause, for example, the eggs of a larva to hatch after the eggs of the birds that feed on those larvae, putting the chicks at risk due to a lack of food. On the other hand, the available habitat for a given species may be reduced, as in the case of birds from temperate climates such as quetzals; in other cases, environmental changes threaten the permanence of entire ecosystems such as coral reefs and many coastal ecosystems.

Industrial nitrogen fixation for agricultural fertilizers and other human activities has more than doubled the rate of natural nitrogen fixation carried out by ecosystems. These chemicals wash away with rainfall and reach soils and water bodies in remote locations, triggering processes of land salinization, lake eutrophication, and extensive marine regions.

When a body of water becomes eutrophic, the entry of large amounts of nitrogen and phosphorus (two compounds that are fundamental for life but in excess behave as contaminants) promotes the massive growth of algae and other plants on the surface of the water, which trap all the nutrients and impede the passage of light. This causes the rest of the living beings present in these aquatic ecosystems to die, collapsing the system. Eventually, these algae and plants die from a lack of nutrients.

Humans have transformed between 40 and 50 percent of the earth's ice-free surface, turning grasslands, forests, and wetlands into agricultural and urban systems.

Civilization dominates (directly or indirectly) about one-third of the net primary productivity, that is, the production of biomass by plants when photosynthesized and which represents the basis of food webs.

Virtually all fisheries on the planet are overexploited.

Human communities use 54 percent of the available freshwater; this use is expected to increase to 70 percent by 2050.

The mobility of people has led to the transport of organisms across geographical barriers that have long kept the Earth's biotic regions separate. The introduction of exotic species, that is, species that are native to other parts of the planet and that are accidentally or intentionally taken to places where they do not naturally occur, represents one of the greatest threats to biodiversity. The impacts of these species can be catastrophic on ecosystems. A list of the 100 most dangerous invasive species on the planet has even been drawn up. Unfortunately, 43 of these species have been recorded in Mexico.

Together, these changes have altered the Earth's biological diversity and are causing its loss at a rate that has only occurred in the major catastrophes of the planet's history.

Based on the study of the fossil record, the life span of species in various groups has been estimated; for example, mammal species are considered to be extinct after 1 million years of origin (Lawton and May 2005).

While extinction is a natural process, the current rate or speed of extinction is much faster than the natural extinction rate. It is estimated that species are becoming extinct 100 to 1,000 times faster and that in the next few decades it will be 1,000 to 10,000 times faster.

Therefore, several researchers around the world consider that we are in the middle of the sixth great extinction, comparable to the extinction event that 65 million years ago eliminated the dinosaurs (Ceballos, et. al. 2015).

According to the 2009 Global Biodiversity Outlook, 12 percent of birds, 21 percent of mammals, 28 percent of reptiles, 30 percent of amphibians, 35 percent of invertebrates, 37 percent of freshwater fish, 70 percent of plants are at risk of extinction.

What is lost by losing biodiversity?

The loss of biodiversity implies the loss of ecosystem services, the impoverishment of the systems that generate food, quality water, and clean air, but it also means the loss of a fundamental part of the cultural wealth and identity of the people. In addition, degraded ecosystems are more vulnerable to sudden environmental changes, and their probability of collapsing and disappearing is increased. This means that they are less resilient - the ability of a system (ecosystem, culture) to cope with change and sustain itself over time without losing its identity as a system.

Knowing how many species are at some level of risk of disappearing requires information about the species and habitats of a given country or region over several decades. This is not always possible, so in many cases, one has to use available information and make risk estimates based on it.

In Mexico, species in some risk categories are listed in the Official Mexican Norm NOM-059-SEMARNAT-2010, which is a legal tool to protect national biodiversity.

Based on this standard, there are 475 species in danger of extinction, of which 38.5 percent correspond to plants, mainly cactus. In addition, there are 896 threatened species (including 142 reptile species and 340 plant species) and 1,283 subject to special protection, which means that they could become threatened or endangered and strategies for their protection must be initiated. Of these last ones, 154 species of amphibians, 152 birds, and 104 mammals stand out.

Defending biodiversity

The loss of biodiversity can lead to a point of no return that puts the planet's productive, economic, social, and cultural systems at risk. As mentioned, it is considered a key element for life and societies, as they are known today, to persist. If the rate of species extinction continues to increase, it will take the earth system to a point that may compromise the existence of human civilization in the following centuries. Action is needed to reduce the current loss of biodiversity and prevent the degradation of biological and cultural heritage.

The transformation of the vision and appreciation of living beings with which humans share the planet is at the center of environmental ethics, a current of thought whose objective is to modify economic, political, and social systems to move toward a state in which people achieve well-being within the limits of the planetary system, that is, without leading to the collapse of the systems of which human communities are a part and on which their existence depends. In other words, it is about achieving sustainability in the organization of societies.

The arguments of environmental ethics for the conservation of biodiversity start from recognizing the intrinsic value and the right to existence of the living beings with which humanity shares the planet since they are part of the complex networks and processes that make up life as we know it. It calls for respect, responsible and thoughtful use of biodiversity and its resources.

The interdependence between different species and elements of ecosystems is another argument of environmental ethics to justify the conservation of biodiversity as a whole since the loss of one species can trigger processes that lead to the extinction of many others.

Natural Protected Areas, a model of conservation and sustainability

However, it is now considered imperative to find a balance between the conservation of species and ecosystems and the needs of the human populations that depend on them. Hence, the most successful conservation models today look at local communities, their knowledge, culture, economic needs, and how these can be harmonized with the preservation of local biodiversity.

Among these models, Mexico's Natural Protected Areas (NPAs) are the most important conservation mechanism available to different levels of government to protect the country's biodiversity and ecosystems. They represent areas of the territory or of national waters that have some kind of protection regime, which restricts and regulates diverse human activities, such as urbanization, the installation of infrastructure, logging, or the exploitation of natural resources. In the NPAs, programs of management, conservation, and sustainable use of biodiversity must be established.

According to the Convention on Biodiversity, by 2020 the national coverage protected by each country should correspond to 17 percent of its land territory plus 10 percent of its marine territory, if applicable.

In Mexico, NPAs cover a little more than 25 million hectares, that is, about 14 percent of the national territory, both marine and terrestrial, so a larger portion of the territory must be incorporated into one of the categories or modalities of conservation.

Protected natural areas preserve various environmental services, such as purifying air and water, mitigating droughts, floods, and hurricanes, conserving and nourishing soils, maintaining the water and nutrient cycle, conserving pollinators and seed dispersers, functioning as a carbon sink, maintaining biodiversity, and offering unparalleled landscapes and natural settings.

In the Biosphere Reserves, for example, core zones with greater use restrictions are established, as well as buffer zones, in which human communities live and can carry out certain economic activities and use natural resources, as long as they are sustainable and per management plans, such as ecotourism.

Thus, the NPAs provide work directly or indirectly to thousands of Mexican families, especially peasants, who, in turn, contribute their knowledge and culture for the adequate conservation of these places.

Conclusion

The development model based on the growing production and consumption of energy, materials, resources, and goods has generated serious impacts on the planet's biodiversity, which are unprecedented in the history of the Earth and whose effects will be greater in the decades to come.

This means that humanity has a serious responsibility to take action to stop the degradation and loss of biodiversity by transforming the relationships and paradigms on which they are based, generating strategies to prevent further environmental damage, and correcting the current course of the dominant civilization model.

Almost certainly, the hope for the future lies in greater diversity: biological, cultural, of ideas, of actors, of productive strategies, of conservation actions, and visions of the world. In the construction of a sustainable future for all, solidarity, teamwork, respect in relationships with other people and other living beings will be fundamental values.

Biodiversity is clothing, food, shelter, resource, provides services, is the indispensable basis of culture and art, it is the key to the cure of many diseases and probably the solution to many human dilemmas. But, in addition, biodiversity is surprising, it wonders those who admire it and it is an inexhaustible source of inspiration.

More than 150 years after Charles Darwin wrote The origin of the species, it is worth remembering the final paragraph of its text, one of the most beautiful produced by science and that reflects the human fascination with the biodiversity of this planet, the only inhabited one known at the moment:

There is greatness in this vision of life, which with its different forces, has originated in one or a few forms; and that, while this planet has been spinning according to the law of gravity, from such a simple origin, an infinite number of the most beautiful and wonderful forms have evolved, and continue to do so.

Source: SEMARNAT Environmental Information Notebooks