On a Sunday at the tianguis (open-air market) you see blue, white, yellow, and red corn, chiles in a thousand shapes, and fruits you can't find in other countries. All that variety is not just for your plate: it is part of what keeps the planet alive. What exactly is biodiversity, and why do we all lose out when it disappears?
The Three Levels of Biodiversity
Think about the Lacandon Jungle in Chiapas. There are jaguars that are not exactly alike, hundreds of different species of plants and animals, and nearby there are other very different ecosystems, like grasslands and rivers. At what levels is all that variety organized?
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Explain what biodiversity is and name its three levels, giving an example of each.
Explain what biodiversity is and name its three levels, giving an example of each.
Mexico is one of the few megadiverse countries in the world: a very large share of the planet's species lives within its territory. This is because it has very different climates, mountains, coasts, deserts, and jungles. Many of those species do not live anywhere else.
Examples of species endemic to Mexico:
The axolotl (Ambystoma mexicanum), which lives in the canals of Xochimilco.
The vaquita porpoise (Phocoena sinus), which lives only in the northern Gulf of California.
The volcano rabbit (teporingo), which lives in the high areas of central Mexico.
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What is an endemic species? Give an example of fauna or flora from the Iberian Peninsula or the islands.
What is an endemic species? Give an example of fauna or flora from the Iberian Peninsula or the islands.
Ecosystems give us many things without charging us. These benefits are called ecosystem services.
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Ecosystems provide us with ecosystem services free of charge, such as crop pollination, water purification, or fertile soil formation. Name two of these services and…
Ecosystems provide us with ecosystem services free of charge, such as crop pollination, water purification, or fertile soil formation. Name two of these services and explain what one of them involves.
A large proportion of the crops we consume depend on pollinating insects such as bees. Explain what would happen to food production if they disappeared, and what this…
A large proportion of the crops we consume depend on pollinating insects such as bees. Explain what would happen to food production if they disappeared, and what this teaches us about the value of biodiversity.
Besides the services, there are other reasons to protect it. They can be grouped like this:
Reason
Idea
Example
Biological
Each species has a function and species depend on one another.
Without pollinators, many plants do not bear fruit.
Cultural
The peoples of Mexico have built their identity and knowledge with living things.
The milpa (traditional cornfield), herbal medicine, the cempasúchil (marigold) flower on Day of the Dead.
Aesthetic
Nature gives us beauty and well-being.
Seeing the monarch butterflies in Michoacán.
Ethical
Living things have intrinsic value: they are worth something in themselves, not just for what they do for us.
Protecting the vaquita even though it brings in no money.
Potential value
Many medicines came from substances discovered in plants, fungi, and bacteria. For example, barbasco, a Mexican plant, was key to making hormones. But the vast majority of species have never been studied.
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Many medicines come from substances discovered in plants, fungi, or bacteria. Explain what is lost when a species that has not yet been studied becomes extinct (the…
Many medicines come from substances discovered in plants, fungi, or bacteria. Explain what is lost when a species that has not yet been studied becomes extinct (the potential value of biodiversity).
During a debate on the overexploitation of the aquifer that feeds the Doñana marshes, an agricultural spokesperson states: "Water is only useful when it irrigates crop…
During a debate on the overexploitation of the aquifer that feeds the Doñana marshes, an agricultural spokesperson states: "Water is only useful when it irrigates crop fields to produce food and jobs; letting it stay in the Doñana lagoons is wasting it because it does not produce any human benefit there."
a) Refute this argument by explaining to the spokesperson what ecosystem services are and provide two specific examples of direct or indirect benefits that the marshes provide to society.
b) Justify why Doñana must be protected based on its intrinsic value, regardless of any utility or economic benefit to humans.
After a severe drought, a field of a single variety of corn dries up almost completely, while a milpa with corn, beans, squash, and nearby wild plants still produces something. Why do they respond so differently to the same drought?
The graph summarizes an experiment: two prairies suffer the same drought and we measure how much of its initial production each one keeps. The prairie with more species loses much less. It is no coincidence: among the twelve species there were several drought-tolerant ones that made up for those that died.
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An ecosystem with many species tolerates a drought or a pest outbreak better than one with few species. Reason why, using the idea that if one species fails, others can…
An ecosystem with many species tolerates a drought or a pest outbreak better than one with few species. Reason why, using the idea that if one species fails, others can fulfill its function.
A logging company proposes replacing a mixed native forest with a clonal plantation of fast-growing eucalyptus, claiming that "by generating more plant biomass per year,…
A logging company proposes replacing a mixed native forest with a clonal plantation of fast-growing eucalyptus, claiming that "by generating more plant biomass per year, the plantation will capture more CO2 and improve the surrounding biodiversity."
a) Refute the company's claim by explaining how this change will affect trophic networks and the variety of ecological niches in the ecosystem.
b) Predict, with reasoned arguments, how each of the two forest stands will respond to the arrival of an insect pest or a period of extreme drought.
The graph shows the results of an experiment: two grasslands, meadow A with twelve plant species and meadow B with only three, experience the same drought, and the…
The graph shows the results of an experiment: two grasslands, meadow A with twelve plant species and meadow B with only three, experience the same drought, and the percentage of their initial production maintained by each is measured. Interpret the data in the graph and relate them to ecosystem stability.
Go back to the beginning: the variety at the tianguis, the milpa, or the jungle is not just decoration. It provides services, it has value for culture, science, and ethics, and it helps ecosystems withstand problems better.
Summary
Let's practice! 3 medium exercises in this section