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Corrección del autor: Puntos calientes globales de cambio de las marismas y emisiones de carbono
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Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
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Salt stress—which can be triggered by high salt concentrations in a plant’s environment—can significantly affect plant growth and crop production by influencing photosynthesis and the absorption of water and nutrients.
Plant cell cytoplasm has a high solute concentration, which causes water to flow from the soil into the plant due to osmosis. However, excess salt in the surrounding soil increases the soil solute concentration, reducing the plant’s ability to take up...
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Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle.
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Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.
In land plants, the uppermost cell layer of a plant leaf, called the epidermis, is coated with a waxy substance called the cuticle. This hydrophobic layer is composed of the polymer cutin and...
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Speciation usually occurs over a long evolutionary time scale, during which the species may be isolated or continue to interact. If two emerging species start to interbreed, reproductive barriers may be weak, and gene flow can occur again. At this point, the selection of hybrids across the two populations may either stabilize the newly mixed group into a single population or reinforce the distinction between them as new species. Speciation may occur gradually or rapidly, and in some...
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The Earth’s hydrosphere includes all of the areas where the storage and movement of water occurs. Since water is the basis of all living processes, the cycling of water is extremely important to ecosystem dynamics.
The water cycle begins as the sun warms surface water on the land and in oceans, causing it to evaporate and enter the atmosphere as vapor. The water vapor condenses into clouds and eventually falls as precipitation in the form of rain, snow or hail.
After falling back to the...