Biodiversity: Overview and Types

Biodiversity encompasses biological variety across various levels, traditionally measured by species count and individual numbers within species.
Modern biodiversity measures consider genetic, population, and ecosystem levels to prioritize preservation efforts.
Biodiversity loss, like the extinction of the passenger pigeon, dodo, or woolly mammoth, seems inconsequential in the short term, but accelerated extinction rates threaten human welfare.
Tropical rainforests, high-diversity ecosystems, are being deforested for timber and agriculture, posing risks to human well-being.

Species diversity quantifies species number in an area; e.g., North and Central America have 2,078 bird species.
Diverse species distribution is more valuable than equal distribution; uneven abundance reduces overall diversity.
Roughly 1.5 million species have been identified, but the planet likely holds at least 10 million or more undiscovered species, especially microscopic organisms.

Genetic diversity, the raw material for adaptation, is crucial for a species' future.
Genetic variation translates to chemical diversity, creating diverse chemicals with potential medicinal uses.
Examples of drugs derived from natural sources include eptifibatide from rattlesnake venom.

Ecosystem diversity considers the variety of ecosystems on Earth.
Ecosystem loss involves more than just species extinction; interactions, coadaptation, and productivity are also lost.
The prairie ecosystem, once spanning central North America, is largely gone, impacting soil productivity.

Biodiversity is unevenly distributed globally highlighting endemic species found only in specific locations, like the Barton Springs salamander.
Tropical regions hold the highest biodiversity, with higher numbers of endemic species. Tropical regions also have more biodiversity hotspots.
Hypotheses for latitudinal biodiversity gradients include age of tropical ecosystems, greater solar energy input in the tropics, and longer speciation time. Understanding the link between energy and increased species richness is still under investigation in the tropics.

Loss of biodiversity indirectly threatens other species, impacting ecosystems and resources.
Biodiversity supports human well-being through agriculture, resource extraction, and direct benefits.

Many medicines originate from naturally produced chemicals, particularly plant secondary compounds.
Traditional societies possess knowledge about plant-based medicines, but science is also actively exploring these compounds.
Examples include aspirin, codeine, digoxin, atropine, and vincristine. Plant-derived medicines are becoming more refined but there is still value to developing new medicines from natural sources.

Crop diversity has been crucial to agriculture since its inception.
Wild forms of crops hold untapped genetic diversity essential for breeding improved varieties.
Ecosystem services, like pollination by honeybees and other pollinators, and pest control by various organisms, are essential to agriculture.

Wild fish supply protein for billions globally, but production has declined since 1990, often due to overfishing.
Overfishing disrupts marine ecosystems causing economic and social hardship. Smaller fish are increasingly exploited as populations of larger fish decline.

The combination of growing human populations and unsustainable resource use is the major threat to biodiversity.
Three key drivers: habitat loss, overharvesting, and introduction of exotic species. Climate change is also a significant growing issue impacting biodiversity.

Habitat loss is a major driver of extinction, as species lose their environments.
Deforestation for timber and agriculture impacts biodiversity, particularly in tropical regions such as Sumatra and Borneo.

Overexploitation of resources can lead to species collapse as has occurred to western Atlantic cod.
Common resources, often seen in fisheries, are subject to overexploitation. Economic pressures and unregulated access exacerbate overfishing.

Invasive species, introduced by humans, often outcompete native species for resources or introduce diseases.
Examples include zebra mussels in the Great Lakes and the European green crab in San Francisco Bay; invasive fungus have had substantial ecological damage globally.

Anthropogenic warming, driven by greenhouse gas emissions, is a significant threat to biodiversity.
Climate change alters habitats, disrupts species timings, and shifts species ranges. Polar bears face major threats as sea ice decreases.
Ocean levels will rise due to meltwater, impacting coastal ecosystems.

Preserves, protected areas, are key for conservation, but their effectiveness is hampered by size, enforcement, and climate change impacts.
Establishing buffer zones, using large preserves over small, and making use of wildlife corridors are important factors in design considerations.
Biodiversity hotspots are geographically focused areas important for conservation.

Biodiversity change is driven by speciation and extinction rates.
Mass extinctions, a series of dramatic extinction events are evident in the fossil record and are under research to better understand the causes.
A sixth mass extinction due to human activities is underway and is significantly altering species distributions. The past 500 years have seen many species go extinct.

Estimating extinction rates is difficult due to unnoticed extinction events of organismal groupings other than larger vertebrates.
Estimates of the current extinction rate, using historical data, are substantially greater than the background extinction rate.
Projected future extinction rates are significant.

Conservation strategies include adopting legislation, establishing preserves, restoring habitats, and promoting changes in human behaviour patterns and beliefs.
Treaties, like CITES and the Endangered Species Act, aim to control human actions and preserve species and habitat.
Zoos are actively involved in conversation and education, though the effectiveness of captive breeding programs remains questioned, while education efforts appear to be beneficial to behaviour change.
Habitat restoration projects, such as the reintroduction of wolves in Yellowstone, can significantly benefit biodiversity.