APES Test 1 Part 2 Flashcards
Biodiversity boosts economies through tourism and recreation
Ecotourism generates economic opportunities for local residents by increasing spending at local businesses, hiring local guides, and supporting parks that employ locals.
It can alleviate poverty by bringing jobs and income to economically challenged areas.
Kenya and Tanzania are prime examples where ecotourism significantly contributes to the economy, with Tanzania receiving a quarter of its foreign income from ecotourism.
Countries like Costa Rica, Australia, Belize, and the United States also benefit significantly from ecotourism.
Popular ecotourism sites can suffer from overdevelopment and excessive visitor numbers, which can harm natural assets and wildlife.
Despite potential drawbacks, ecotourism provides a strong financial incentive to preserve natural areas and minimize environmental impacts.
People value connections with nature
Some benefits of biodiversity extend beyond economic and practical aspects, touching on deeper values.
The concept of biophilia, popularized by biologist Edward O. Wilson, suggests that humans have an innate love for nature and an emotional connection to other living beings.
Evidence supporting biophilia includes: - Affinity for parks and wildlife - Love for pets - High real estate value for properties with natural views - Interest in outdoor activities such as hiking, bird-watching, fishing, hunting, and backpacking
Williams’ research indicates that access to wildlife and green spaces can reduce stress, increase happiness, enhance mental acuity, and improve physical health.
Do we have ethical obligations toward other species?
Many people believe that living organisms have an inherent right to exist.
Humans, unlike other animals, have conscious reasoning abilities and can make deliberate decisions.
Our ethical sense has developed from our intelligence and ability to choose.
Society’s ethical considerations have expanded over time, leading to biocentric or ecocentric worldviews.
These worldviews support the idea that other organisms have intrinsic value and an inherent right to exist.
The conservation of biodiversity can be justified on ethical grounds alone.
Human disturbance creates winners and losers
Human activities alter ecosystems and landscapes, creating “winners” and “losers” among plants and animals.
Altering natural systems often makes areas more similar to each other by spreading human influence and shaping environments to meet human needs.
Landscapes are made more open by clearing vegetation for farms, pastures, towns, and cities.
Pollution is frequently created as a result of human activities.
The impacts of human activities are similar across different regions and cultures, leading to predictable outcomes for certain types of organisms.
Species that benefit from human-induced changes and those that are harmed tend to have predictable attributes.
Winning species are generalists able to fill many niches, tolerate disturbance, and use open habitats or edges
Ex. house mouse
Losing species tend to be those that specialize on certain resources, have trouble coping with change, and rely on mature and well-vegetated habitats
Ex. tiger
Geographically widespread species are more likely to succeed in a changing world with human impact compared to species limited to small areas.
Mainland species generally fare better than island species in adapting to changes.
Many populations are declining
Biodiversity loss today is primarily due to gradual declines in population sizes of many species, rather than outright extinction.
This phenomenon, known as “defaunation” or “the great thinning,” is often unnoticed but can severely impact ecological systems.
Shrinking populations face two main issues: loss of genetic diversity and reduction in geographic range, both of which increase vulnerability to further declines.
Many species now have smaller populations and occupy less area than they historically did.
Significant population declines have been documented among large mammals in the Serengeti and East Africa, leading to losses in species diversity, genetic diversity, and ecosystem diversity.
The Living Planet Index (LPI) was developed by the World Wildlife Fund and the United Nations Environment Programme to measure changes in vertebrate population sizes globally.
The LPI compares current population sizes to those in the baseline year of 1970.
The most recent data compilation includes trends from 16,704 populations of 4005 vertebrate species.
Between 1970 and 2014, the LPI fell by 60%, indicating a significant decline in the average population sizes of fishes, birds, mammals, reptiles, and amphibians.
Biodiversity decline is primarily driven by losses in freshwater species, especially in tropical regions where deforestation has been severe since 1970.
Temperate regions have experienced lower biodiversity losses due to forest regrowth, better pollution control, and ecological restoration efforts.
North America has seen a significant decline in bird populations, with a 29% reduction since 1970, equating to 3 billion fewer birds.
Recent studies highlight the decline of insects, which are crucial for supporting food webs, with some insect declines being more severe than those of vertebrates.
The potential loss of insects could lead to catastrophic ecosystem collapses, often referred to as “Insect Armageddon” or “Insect Apocalypse.”
Extinction is irreversible
Extinction occurs when the last member of a species dies, resulting in the species ceasing to exist.
Local extinction, or extirpation, is the disappearance of a population from a specific area, but not globally.
Extirpation can lead to extinction over time.
The black rhinoceros has been extirpated from most of its historic range in Africa, with at least three of its subspecies already extinct.
Human impact is the primary cause of extirpation and extinction today, although these processes also occur naturally at a much slower rate.
If species did not naturally go extinct, Earth would still have dinosaurs, trilobites, ammonites, and many other ancient creatures.
Paleontologists estimate that approximately 99% of all species that ever lived are now extinct.
Most extinctions before human beings appeared happened individually for independent reasons, at a rate known as the background extinction rate.
Fossil records suggest that for mammals and marine animals, on average, 1 species out of every 1–10 million has gone extinct each year.
Earth has experienced five mass extinction events
Extinction rates have significantly exceeded the background extinction rate at several points in Earth’s history.
Over the past 440 million years, Earth has experienced five mass extinction events, each eliminating more than one-fifth of life’s families and at least half of its species.
The most severe mass extinction occurred at the end of the Permian period, about 250 million years ago, resulting in the extinction of nearly 90% of all species.
The best-known mass extinction event happened 66 million years ago at the end of the Cretaceous period, likely caused by an asteroid impact and possibly widespread volcanism, leading to the extinction of the dinosaurs and many other groups.
The Quaternary period may experience the extinction of over half of all species if current trends persist.
Today’s mass extinction is similar in scale to previous ones but differs in two key ways: - It is caused by human activities. - Humans will also suffer the consequences of this extinction.
We are setting the sixth mass extinction in motion
Human activities have caused numerous species extinctions over the past few centuries.
The dodo bird, native to Mauritius, went extinct in the 17th century due to sailors, with only a few body parts remaining in museums.
North American birds driven to extinction in the past two centuries include the Carolina parakeet, great auk, Labrador duck, and passenger pigeon.
The Bachman’s warbler and Eskimo curlew are almost certainly extinct, and the ivory-billed woodpecker is likely extinct.
Species such as the whooping crane, Kirtland’s warbler, and California condor are currently on the brink of extinction.
Human arrival on islands and continents has historically led to waves of extinction.
In Hawai’i, half of the bird species went extinct after Polynesians arrived.
Human arrival on other oceanic islands, including New Zealand and Madagascar, also led to the extinction of birds, mammals, and reptiles.
In Australia, dozens of large vertebrate species died off after human arrival approximately 50,000 years ago.
North America lost 33 genera of large mammals, such as camels, lions, horses, mammoths, mastodons, saber-toothed cats, and giant ground sloths, following human arrival over 13,000 years ago.
Species loss is accelerating due to population growth and resource consumption, putting strain on habitats and wildlife.
The current global extinction rate is tens to hundreds of times greater than the background extinction rate and is increasing.
The International Union for Conservation of Nature (IUCN) maintains the Red List to monitor threatened and endangered species.
As of 2019, 28% of the 98,512 species evaluated by scientists were at risk of extinction.
Among the best-studied groups, 25% of mammal species, 14% of bird species, and 40% of amphibian species are threatened with extinction.
In the United States, 237 animal species and 38 plant species have gone extinct in the past 500 years.
Several major causes of biodiversity loss stand out
Five primary causes of population decline and species extinction: habitat loss, pollution, overharvesting, invasive species, and climate change.
These factors are intensified by human population growth and increasing per capita consumption of resources.
Understanding these pressures is crucial for addressing and reversing biodiversity loss.
Several major causes of biodiversity loss stand out: Habitat Loss
Habitat loss is the single greatest threat to biodiversity
Because organisms have adapted to their habitats over thousands or millions of years of evolution, any sudden, major change in their habitat will likely render it less suitable for them
Habitat is lost when it is destroyed outright or when it becomes fragmented or degraded
Many human activities alter, degrade, or destroy habitat
urban and suburban development and sprawl; supplant natural ecosystems
Farming resplaces diverse communities with simplified ones of only a few plant species
Grazing modifies grasslands, and can lead to desertification
Clearing forests removes the food and shelter that forest-dwelling organisms need to survive
Damming rivers creates reservoirs upstream while affecting water conditions and floodplain communities downstream
Habitat loss often occurs through gradual degradation and fragmentation, where continuous habitats are broken into smaller patches by activities like farming, logging, and development.
As habitat fragmentation proceeds across a landscape, animals and plants requiring the habitat disappear from one fragment after another
Habitat fragmentation can prevent animals from moving freely, leading to local extinctions in isolated patches.
Conservationists use habitat corridors to connect fragmented habitats, allowing animals to travel between them and maintain populations.
Habitat loss is the primary cause of population decline for terrestrial vertebrates.
Migratory songbirds in North America have declined due to forest loss and fragmentation in both their breeding and wintering grounds.
North America’s Great Plains have been almost entirely converted to agriculture, with less than 1% of original prairie habitat remaining, leading to an 82-99% decline in grassland bird populations.
More than half of Earth’s temperate forests, grasslands, and shrublands had been converted by 1950, primarily for agriculture.
Currently, habitat loss is most rapid in tropical rainforests, tropical dry forests, and savannas.
Wetlands within most biomes are particularly threatened, with over half of the wetlands in the contiguous U.S. and Canada drained for agriculture
Several major causes of biodiversity loss stand out: Pollution
Pollution harms organisms through various means, including air, noise, light, and water pollution.
Air pollution degrades forest ecosystems and affects the atmosphere and climate.
Noise and light pollution disrupt animal behavior.
Water pollution impairs fish and amphibians.
Agricultural runoff with fertilizers, pesticides, and sediments harms many species.
Toxic chemicals like heavy metals, PCBs, and endocrine disruptors poison people and wildlife.
Plastic waste in oceans can strangle, drown, or choke marine creatures.
Oil spills have dramatic and well-known effects on wildlife.
Pollution is less significant as a cause of population decline for plants and vertebrate animals compared to habitat loss.
For insects and arthropods, chemical pesticide pollution is a major cause of population declines, though habitat loss is also significant.
Several major causes of biodiversity loss stand out: Overharvesting
Human population growth and consumption are leading to the rapid removal of many species, outpacing their ability to reproduce.
Deforestation is causing the disappearance of tree species like teak and mahogany.
In Africa, species such as gorillas and other primates are at risk of extinction due to hunting for bushmeat.
Overharvesting in oceans has severely depleted fish stocks and driven the Atlantic gray whale to extinction, with other whale species now threatened or endangered.
Thousands of sharks are killed annually for their fins, significantly reducing the population of large marine animals to just 10% of their historical numbers, impacting marine food webs.
K-selected species, which are large, long-lived, and have few offspring, are particularly vulnerable to hunting. Examples include elephants, which have been heavily poached for their ivory.
A global ban on the commercial trade of ivory in 1989 initially helped elephant populations recover, but poaching surged again after 2005 due to high black-market prices.
From 2011 to 2018, over 240,000 African elephants were killed, threatening the species’ future.
In response to the poaching crisis, the United States and China implemented national bans on the ivory trade.
Illegal global trade in wildlife products exceeds $20 billion annually, causing significant declines in animal populations.
Rhinoceros populations have plummeted due to poaching for their horns, which are falsely believed to have medicinal properties and are sold as luxury items in Asia.
Tigers in Asia face threats from both poaching and habitat loss, with body parts fetching high prices on the black market for use as aphrodisiacs.
Half of the world’s tiger subspecies are extinct, and the remaining tigers occupy only 1% of their historical range.
In Africa, protecting wildlife is perilous due to well-armed poachers backed by organized crime syndicates, leading to frequent and deadly confrontations with park rangers.
The demand for luxury wildlife products by wealthy consumers in Asia, Europe, and America has severe repercussions for African communities.
Scientists are employing various technologies to combat poaching, including radio collars, satellite tracking, drones, and forensic DNA testing to identify the origins of poached ivory and focus enforcement efforts.
Several major causes of biodiversity loss stand out: invasive species
Invasive species are a significant cause of biodiversity loss.
Non-native species introduced to new environments often perish, but some survive and thrive.
Surviving invasive species may proliferate due to the absence of their natural predators, parasites, and competitors.
This proliferation can lead to the displacement of native species.
In some cases, invasive species can push native species toward extinction.
Introductions of species can be accidental or intentional, with significant ecological impacts.
Accidental introductions include animals escaping from the pet trade, seeds clinging to travelers, and aquatic organisms transported in ship ballast water.
Intentional introductions, such as the Nile perch in Lake Victoria, can provide benefits like food but also cause ecological harm by driving native species to extinction.
Island species are particularly vulnerable to introduced species due to their lack of evolved defenses against new parasites, predators, and competitors.
Invasive species can include microscopic pathogens, such as those causing malaria and avian pox in Hawai’i, which have devastating effects on native species.
The role of introduced species is debated; while they often cause economic and ecological damage, some, like the European honeybee, provide economic benefits.
Human impact has altered all ecosystems, creating novel communities of native and non-native species that sometimes increase local biodiversity and maintain ecosystem functions.
Several major causes of biodiversity loss stand out: Climate change
Emissions of greenhouse gases from fossil fuel combustion are warming the atmosphere, altering climate patterns, and increasing the frequency of extreme weather events like droughts and storms.
In the Arctic, significant warming is causing sea ice to melt, impacting both polar bears and human populations.
Warming temperatures are causing organisms to shift their geographic ranges toward the poles and higher altitudes, but some species may not be able to adapt or move quickly enough.
Mountaintop species face a high risk of extinction as they cannot move higher to escape warming temperatures.
Trees may struggle to disperse toward the poles at a sufficient rate to survive.
As species shift their ranges, they encounter new communities of prey, predators, and parasites, leading to potential mismatches and increased risks.
Climate disruption is predicted to increase the risk of extinction for many thousands of plant and animal species worldwide.
A mix of causes threatens many species
Multiple factors are causing the decline of many species, including the monarch butterfly.
Industrial agriculture and chemical herbicides in the United States and Canada have eliminated most milkweed plants, which are essential for monarchs.
Monocultures and insecticides intended for crop pests also harm monarchs and other beneficial insects.
Each fall, monarchs from eastern and central North America migrate to a single valley in Mexico to spend the winter.
Illegal logging in these Mexican forests threatens the monarchs’ winter habitat, while others work to protect the trees, butterflies, and the ecotourism revenue they generate.
The decline of amphibian populations worldwide is attributed to a combination of complex factors.
Entire populations of frogs, toads, and salamanders have disappeared, with at least 170 species presumed extinct.
Key causes include habitat destruction, chemical pollution, invasive species, climate change, and chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis.
Scientists believe that these factors interact and amplify each other’s effects, creating a “perfect storm” leading to the collapse of amphibian populations.
Researchers are designing responses to amphibian declines.
The IUCN conservation action plan includes protecting and restoring habitats, cracking down on illegal harvesting, enhancing disease monitoring, and establishing captive breeding programs.
Efforts to save vanishing species are global, with many people involved.
The search for solutions to the biodiversity crisis is dynamic and inspiring.
Scientists are developing innovative approaches to sustain Earth’s diversity of life.
