Plant and animal species in biodiversity hotspots are currently suffering devastating losses. Biodiversity hotspots now cover only 1. Factors, such as pollution, exploitation of land, invasive species, deforestation , and climate change are the leading causes of habitat loss and destruction [ 11 ]. The fact that these factors are widespread creates challenges for the species that manage to survive; and with an ever-changing climate and unpredictable circumstances, species that cannot resist the changing environment or move to a more suitable habitat will likely become extinct [ 4 ].
When we think about the future of biodiversity on Earth, we need to consider the role we play in climate change. The consequences of climate change are extremely widespread, threatening even places untouched by humans [ 12 ]. In order to protect our planet, we can start by making small changes in our daily lives. Taking action by recycling, picking up trash, being conservative with our water consumption, and limiting pollution by walking, biking, or taking public transportation are ways that we can help the environment.
We can also come up with our own ideas, as we educate ourselves on biodiversity by reading about different places and living things. As we have learned, a region with a large number of species is considered to be biodiverse.
There are 36 biodiversity hotspots on our planet, and these areas are dazzling, unique, and full of life. Plants, animals, and other living organisms that populate these places are rare and many of them are only found in these specific geographic areas. These biodiversity hotspots are currently at risk of being destroyed [ 13 ]. See Figure 1 for the location of the location of the Tropics on the globe. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Biodiversity: life — a status report. Nature — Extinction by numbers. Nature —5. Biodiversity: turning up the heat on hotspots. Biodiversity hotspots: a shortcut for a more complicated concept. Testing the adaptive radiation hypothesis for the Lemurs of Madagascar. Open Sci. Roughly a third of these are believed to be at some risk of extinction.
Diversity is concentrated in certain areas and is highest in the tropics, in a band around the equator, declining progressively toward the polar regions. Specific places with high overall diversity or high levels of endemism — arrays of species found nowhere else — are often called hotspots and include parts of the southwestern United States and Mexico , Brazil , California , and South Africa , as well as Hawaii, Madagascar, New Zealand , and other islands across the world.
Of course, every intact ecosystem — hotspot or not — is important to preserve, not only because they all provide services, such as clean water and climate moderation, but also because each contains a unique ecological composition and priceless evolutionary information.
The Earth's biodiversity is the result of 4 billion years of evolution — change in the inherited traits of a population of organisms from one generation to the next. Up until about million years ago, life consisted of single-celled organisms. The history of biodiversity during the Phanerozoic era the past million years begins with the rapid growth of the Cambrian explosion — the period in which most phyla of multicellular organisms appeared. Over the next million years, global diversity showed little overall trend and was marked by periodic, massive losses of diversity classified as mass extinction events.
The largest of these occurred about million years ago and is often called the P-Tr or Permian-Triassic extinction event; various mechanisms, ranging from increased volcanic eruptions to a drastic decrease in the air's oxygen, are thought to have contributed to the P-Tr, which killed about 96 percent of all marine species and an estimated 70 percent of land species.
The most recent mass extinction, the K-T event, happened 65 million years ago and ended the reign of the dinosaurs. The causes of previous mass extinctions aren't fully understood, but extinctions tend to occur when long-term stresses like climate change are compounded by sudden shocks. Four of the previous five mass extinction events were probably caused by greenhouse gas emissions and associated global warming ; only the K-T event appears to have been a non-warming impact.
Most biologists agree that our era comprises a new, sixth mass extinction, the Holocene extinction event, caused by ongoing human impacts on the biosphere — primarily numerous forms of habitat destruction and fragmentation. Global warming will soon trump other threats as the leading cause of extinction.
Scientists such as E. Except for the last 1, years, global biodiversity has been relatively constant over most of human history, but the history of life is characterized by considerable change. The estimated magnitude of background rates of extinction is roughly 0. Current rates of extinction are discussed in Key Question 3. A mismatch exists between the dynamics of changes in natural systems and human responses to those changes.
This mismatch arises from the lags in ecological responses, the complex feedbacks between socioeconomic and ecological systems, and the difficulty of predicting thresholds. Multiple impacts especially the addition of climate change to the mix of forcing functions can cause thresholds, or rapid and dramatic changes in ecosystem function even though the increase in environmental stress has been small and constant over time. Understanding such thresholds requires having long-term records, but such records are usually lacking or monitoring has been too infrequent, of the wrong periodicity, or too localized to provide the necessary data to analyze and predict threshold behavior C28 , S3.
Shifts to different regimes may cause rapid substantial changes in biodiversity , ecosystem services , and human well-being. Regime shifts have been commonly documented in pelagic systems due to thresholds related to temperature regimes and overexploitation C Some regime shifts are essentially irreversible, such as coral reef ecosystems that undergo sudden shifts from coral-dominated to algal-dominated reefs C The trigger for such phase shifts usually includes increased nutrient inputs leading to eutrophic conditions and removal of herbivorous fishes that maintain the balance between corals and algae.
Once the thresholds both an upper and a lower threshold for the two ecological processes of nutrient loading and herbivory are passed, the phase shift occurs quickly within months , and the resulting ecosystem—though stable—is less productive and less diverse. Consequently, human well-being is affected not only by reductions in food supply and decreased income from reef-related industries diving and snorkeling, aquarium fish collecting, and so on , but also by increased costs due to diminished ability of reefs to protect shorelines.
Algal reefs are more prone to being broken up in storm events, leading to shoreline erosion and seawater breaches of land C Introduced invasive species can act as a trigger for dramatic changes in ecosystem structure, function, and delivery of services.
Biodiversity plays an important role in ecosystem functions that provide supporting, provisioning, regulating, and cultural services. These services are essential for human well-being. However, at present there are few studies that link changes in biodiversity with changes in ecosystem functioning to changes in human well-being.
Protecting the Catskill watersheds that provide drinking water for New York City is one case where safeguarding ecosystem services paid a dividend of several billion dollars.
Further work that demonstrates the links between biodiversity, regulating and supporting services , and human well-being is needed to show this vital but often unappreciated value of biodiversity C4, C7, C Species composition matters as much or more than species richness when it comes to ecosystem services.
Ecosystem functioning, and hence ecosystem services, at any given moment in time is strongly influenced by the ecological characteristics of the most abundant species, not by the number of species. The relative importance of a species to ecosystem functioning is determined by its traits and its relative abundance.
Thus conserving or restoring the composition of biological communities , rather than simply maximizing species numbers, is critical to maintaining ecosystem services C Local or functional extinction, or the reduction of populations to the point that they no longer contribute to ecosystem functioning, can have dramatic impacts on ecosystem services.
Local extinctions the loss of a species from a local area and functional extinctions the reduction of a species such that it no longer plays a significant role in ecosystem function have received little attention compared with global extinctions loss of all individuals of a species from its entire range. Loss of ecosystem functions, and the services derived from them, however, occurs long before global extinction. Often, when the functioning of a local ecosystem has been pushed beyond a certain limit by direct or indirect biodiversity alterations, the ecosystem-service losses may persist for a very long time C Changes in biotic interactions among species—predation, parasitism, competition, and facilitation—can lead to disproportionately large, irreversible, and often negative alterations of ecosystem processes.
In addition to direct interactions, such as predation, parasitism, or facilitation, the maintenance of ecosystem processes depends on indirect interactions as well, such as a predator preying on a dominant competitor such that the dominant is suppressed, which permits subordinate species to coexist.
Interactions with important consequences for ecosystem services include pollination; links between plants and soil communities , including mycorrhizal fungi and nitrogen-fixing microorganisms; links between plants and herbivores and seed dispersers; interactions involving organisms that modify habitat conditions beavers that build ponds, for instance, or tussock grasses that increase fire frequency ; and indirect interactions involving more than two species such as top predators, parasites, or pathogens that control herbivores and thus avoid overgrazing of plants or algal communities C Many changes in ecosystem services are brought about by the removal or introduction of organisms in ecosystems that disrupt biotic interactions or ecosystem processes.
Because the network of interactions among species and the network of linkages among ecosystem processes are complex, the impacts of either the removal of existing species or the introduction of new species are difficult to anticipate C See Table 1. Table 1. As in terrestrial and aquatic communities , the loss of individual species involved in key interactions in marine ecosystems can also influence ecosystem processes and the provisioning of ecological services.
For example, coral reefs and the ecosystem services they provide are directly dependent on the maintenance of some key interactions between animals and algae. As one of the most species-rich communities on Earth, coral reefs are responsible for maintaining a vast storehouse of genetic and biological diversity.
Substantial ecosystem services are provided by coral reefs—such as habitat construction, nurseries, and spawning grounds for fish; nutrient cycling and carbon and nitrogen fixing in nutrient - poor environments; and wave buffering and sediment stabilization. The total economic value of reefs and associated services is estimated as hundreds of millions of dollars. Yet all coral reefs are dependent on a single key biotic interaction: symbiosis with algae.
Biodiversity affects key ecosystem processes in terrestrial ecosystems such as biomass production , nutrient and water cycling, and soil formation and retention—all of which govern and ensure supporting services high certainty. The relationship between biodiversity and supporting ecosystem services depends on composition, relative abundance, functional diversity , and, to a lesser extent, taxonomic diversity. If multiple dimensions of biodiversity are driven to very low levels, especially trophic or functional diversity within an ecosystem, both the level and stability for instance, biological insurance of supportive services may decrease CF2 , C Region-to-region differences in ecosystem processes are driven mostly by climate, resource availability, disturbance, and other extrinsic factors and not by differences in species richness high certainty.
In natural ecosystems , the effects of abiotic and land use drivers on ecosystem services are usually more important than changes in species richness. Plant productivity , nutrient retention, and resistance to invasions and diseases sometimes grow with increasing species numbers in experimental ecosystems that have been reduced to low levels of biodiversity. In natural ecosystems, however, these direct effects of increasing species richness are usually overridden by the effects of climate, resource availability, or disturbance regime C Even if losses of biodiversity have small short-term impacts on ecosystem function, such losses may reduce the capacity of ecosystems for adjustment to changing environments that is, ecosystem stability or resilience, resistance, and biological insurance high certainty.
The loss of multiple components of biodiversity, especially functional and ecosystem diversity at the landscape level, will lead to lowered ecosystem stability high certainty.
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