ENS 201 Chapter 11, Spring 2008

Biodiversity Chapter 11 Outline: • What is biodiversity? Types of biodiversity? • What is a species? How many species currently exist? • What are the benefits of biodiversity? • What are the various human-caused threats to biodiversity? • How can we protect biodiversity?  Enacting Hunting & Fishing Laws  Identifying all endangered species  Habitat Protection  International Wildlife Treaties (CITES)  Captive Breeding Biodiversity and Species • Biodiversity: All forms of life that are currently found on Earth • Biodiversity Types:  Genetic Diversity: variety of the genes among members of the same species or kind  Species Diversity: variety of species found in different habitats on Earth  Ecological Diversity: variety of ecosystems such as forests, deserts, grasslands, streams, lakes, oceans, wetlands, etc. found on Earth What is a species? • Species - Organisms of the same kind that are able to breed in nature and produce fertile offspring • Species identification  Based on morphological characteristics (size, shape, color, skeletal structure), and chemical and genetic traits - DNA sequencing technology is increasingly used to distinguish species How many species currently exist? • Currently:  1.4 million species identified  3-50 million species estimated  Invertebrates: - 70% of all known species - Probably most of yet to be discovered species • Tropical rainforests and coral reefs are biodiversity hotspots  NA and Europe only contain 10-15% of all known species BENEFITS OF BIODIVERSITY • Food: ~ 80,000 edible wild plant species could be utilized by humans  Directly, as they are OR  As a source of genetic material to improve domestic crops • Drugs and Medicines  More than half of all prescriptions contain some natural product  Pharmaceutical companies actively prospect tropical countries for medicinal products The rosy periwinkle form Madagascar provides anticancer drugs that now make childhood leukemia and Hodgkin’s disease highly remissible. It may be recognized as a popular flowering ornamental plants Ecological Benefits of Biodiversity • Soil formation • Waste disposal (biodegradation) • Air and water purification • Solar energy absorption (food webs) • Nutrient cycling (biogeochemical and hydrological cycles) Aesthetic & Cultural Benefits of Biodiversity • Contact with nature can be psychologically, emotionally, and physically restorative • A particular species or landscape may be inextricably linked to a sense of identity and meaning Birdwatching & wildlife observation contribute more than $29 million each year to the US economy • Nature appreciation is economically important  Ecotourism can be an important form of sustainable economic development, provided that we do not abuse the places & cultures we visit Threats to Biodiversity • Species extinction: elimination of a species  Normal process: in undisturbed ecosystems, the background rate of extinction appears to be one species per decade  Currently: human impacts is causing thousands of extinctions annually  If current trends continue => up to 50% of species may become extinct in the next 50 - A biodiversity loss of geological proportions (this time not caused by asteroids or volcanoes) Human-Caused Threats to Biodiversity • Habitat Destruction  Habitat loss is the biggest reason for current increase in extinction - Destruction of forests, wetlands, coral reefs, & other biologically- rich ecosystems around the world threatens to eliminate thousands to millions of species  Habitat fragmentation: divides populations into isolated groups vulnerable to catastrophic events Decrease in wooded area of Cadiz Township in Wisconsin during European settlement • Invasive (Exotic, alien, non-native) Species Introductions  Organisms introduced (accidentally or intentionally) into habitats where they are not native  In their new territory, they thrive free of predators, diseases, or resource limitations  Can be thought of as biological pollution - E.g., Kudzu Vine  Has blanketed large areas of the southeastern US  Can grow 18-30 m/year smothering everything in its path Human-caused threats to biodiversity Human-Caused Threats to Biodiversity • Pollution  Toxic chemicals (pesticides, lead, dioxin…)  species extinction - Direct toxicity at high levels - Indirect effects (bioaccumulation & biomagnification)  Global warming (fossil fuel combustion)  ecosystems disruption & species extinction Human-Caused Threats to Biodiversity • Overharvesting  Over-harvesting of game species - American Passenger Pigeon  200 years ago: most abundant bird on earth  Completely extinct within 100 years - Whales  Fish stocks have been seriously depleted by over- harvesting - At least ¾ of commercial oceanic species are over- harvested Human-Caused Threats to Biodiversity • Commercial Products and Live Specimens  Despite international bans on trade in products from endangered species, wildlife smuggling (furs, horns, & live specimen) can be very profitable - Tiger or leopard fur coats can bring $100,000 in Japan or Europe - Birds collectors will pay 10,000 for a rare hyacinth macaw from Brazil  The mortality rate in live animal trade is very high Parts from endangered species for sale on the street in China • Use of animal products in traditional medicine and prestige diets is a major threat to many species • Predator and Pest Control  Many animal populations have been greatly reduced or exterminated because they are regarded as dangerous to humans, livestock, or crops - Every year the US government animal control agent trap, poison, or shoot thousands of coyotes, prairie dogs, & other species considered threats to people, domestic livestock, or crops Human-caused threats to biodiversity How can we protect biodiversity? • Enacting hunting and fishing laws • Identifying all endangered species, & saving as much biodiversity as possible, regardless of its usefulness to humans  Endangered species are those considered in imminent danger of extinction  Threatened species are those likely to become endangered, at least locally, in the near future  Vulnerable species are those that are - Naturally rare, or - Have been locally depleted to a level that puts them at risk Endangered species often serve as a barometer for the health of an entire ecosystem and as protector for a myriad of less well-known creatures • Habitat protection  preservation of ecosystems supporting maximum biological diversity rather than species-by-species approach  Species are preserved in the wild  Latest management strategy is How can we protect biodiversity? • International Wildlife Treaties  E.g.: Convention on International Trade In Endangered Species (CITES) - 1975 - Regulated trade in living specimens & products derived from listed species • Captive breeding  Breeding programs in zoos and botanical gardens are one method of saving threatened species  Problems: - Zoos have limited space for captive breeding, & will never be able to protect the complete spectrum of biological diversity - Ultimate problem: Natural habitat may disappear while we are conserving the species itself How can we protect biodiversity?