Conservation Biology - PDF

Conservation Biology Reading: Bio 2e, Chp 47 Optional, Freeman, Chp. 54 The Karner blue butterfly, a local endangered species. From the Michigan Nature Association website.  Learning Goals Students should be able to distingui...

Conservation Biology Reading: Bio 2e, Chp 47 Optional, Freeman, Chp. 54 The Karner blue butterfly, a local endangered species. From the Michigan Nature Association website.  Learning Goals Students should be able to distinguish between ecology, conservation biology, and environmentalism. Students should be able to contrast several of the reasons for conservation. Students should understand a few of the key factors influencing conservation, including the inevitable economic compromises and potential human impact of conservation.  The Biodiversity Crisis Scientists have named and described nearly 2 million species Biologists estimate 8.7 million species exist on Earth, possibly many more. Humans have altered the face of the earth-converting natural habitats to human use, changing the carbon cycle, the nitrogen cycle, and shifting a great deal of earth’s productivity to our own uses. Humans are rapidly pushing many species toward extinction and have altered the balance of the atmosphere in such a way as to change the climate in the future. – Essentially, we are causing a sixth major mass extinction. The beginning of a human dominated earth is sometimes referred to as the start of a new geological time period, the “Anthropocene”, and the extinction we are causing is sometimes called the biodiversity crisis.  Conservation biology, is an applied science, which seeks to preserve species, natural habitats, and ecosystem services, integrates several fields – Ecology – Physiology – Molecular biology – Genetics – Economics – Evolutionary biology – It is NOT environmentalism, a political viewpoint, though conservation biology might inform political or economic policies informed by environmentalist ideals.  Four Levels of Biodiversity Biodiversity has several main components – Genetic diversity – Species diversity – Ecosystem diversity – High level Taxonomic Diversity  Genetic Diversity Genetic diversity comprises genetic variation within a population and between populations Natural and human-cultivated species are loosing genetic diversity, currently Natural populations of animals restricted to nature preserves loose genetic variation. – Zoo animals are particularly susceptible to this, and perhaps worse, evolve for conditions in zoos that do not suit them to the wild.  Among our human- cultivated species, shifts in the way we practice agriculture and use animals has imperiled genetic diversity. – Low genetic diversity among our agricultural crops puts our food supply at risk of disease, and limits our ability to develop new strains in the future. – Centuries of breeding Newfoundland domestic animals are at risk of loss because breeds are Pony obsolete.  Species Diversity Species diversity is the variety of species in an ecosystem or throughout the biosphere According to the U.S. Endangered Species Act – An endangered species is “in danger of becoming extinct throughout all or a significant portion of its range” – A threatened species is likely to become endangered in the foreseeable future  Conservation biologists are concerned about species loss because of alarming statistics regarding extinction and biodiversity Globally, 12% of birds, 21% of mammals, and 32% of amphibians are threatened with extinction Extinction may be local or global  Philippine eagle Yangtze River Dolphin (Probably Extinct) Endangered Rusty patched bumblebee Species Prairie fringed orchid Javan rhinoceros  The local extinction of one species can have a negative impact on other species in an ecosystem – For example, flying foxes (bats) are important pollinators and seed dispersers in the Pacific Islands  Ecosystem Diversity Human activity is reducing ecosystem diversity, the variety of ecosystems in the biosphere More than 50% of wetlands in the contiguous United States have been drained and converted to other ecosystems  Higher Level Taxonomic Diversity Some major branches on the tree of life are represented by just a handful, or just one, species. This is higher level taxonomic diversity-loss of these species would mean the disappearance of a whole family, order, or class of organisms. For example, the Tuatara, two species of reptile endemic to islands off the coast of new Zealand, are the last remaining members of the class Rhyncocephala, a taxonomic group that flourished before the age of dinosaurs.  Learning Goal Students should be able to contrast several of the reasons for conservation.  Justifications for Biodiversity Conservation Self Interest Theistic/Philosophical/Aesthetic/Ethical  Self-Interest Intact ecosystems provide some, or all, of the following; Food Recreation Materials Scientific Value Water supply Climate regulation Other Ecosystem services  Scientific Value of Biodiversity Species related to agricultural crops can have important genetic qualities – For example, plant breeders bred virus-resistant commercial rice by crossing it with a wild population In the United States, 25% of prescriptions contain substances originally derived from plants – Examples; the rosy periwinkle contains alkaloids that inhibit cancer growth. This is a flower originally native to Madagascar rainforests. The pacific yew tree contains a terpenoid that has revolutionized the treatment of breast cancer. It is native to rainforests of the Pacific Northwest, and was considered a nuisance by loggers. Rosy Periwinkle, left, Pacific Yew Tree, right.  Resistance to disease (crops) Higher yield varieties (crops) Food (new plants) Medicines and technologies – Example; Taq polymerase, from Thermus aquaticus, a hot springs organism. Without this organism, genetic engineering would be impossible.  The loss of species also means loss of genes and genetic diversity The enormous genetic diversity of organisms has potential for great human benefit  Ecosystem Services Ecosystem services encompass all the processes through which natural ecosystems and their species help sustain human life Some examples of ecosystem services – Purification of air and water – Detoxification and decomposition of wastes – Cycling of nutrients Carbon Sequestration – Moderation of weather extremes – Pest control – Pollinators  Biodiversity: Importance to Humans Example: – Pollination: Total value of pollinators worldwide exceeds 150 billion per year. – Most of this is provided, for free, by unmanaged pollinators. Human-centered aesthetic reasons are very important historically in the United States. In the 19th century, it was widely believed that humans require regular experiences with natural settings in order to stay emotionally and psychologically healthy. John Muir (right), an important American  Ethical Considerations Ethical, aesthetic, and spiritual motivations underpin many conservation efforts. Right-a conservation in Thailand is rooted in Bhudist principles. Conservation of natural monuments A legacy of the aesthetic view of conservation is that many areas set aside for conservation in the US are designated areas of natural beauty, Such as the Rainbow Bridge National Monument in AZ  Threats to Biodiversity Most species loss can be traced to five major threats – Habitat destruction – Change in Ecosystem Processes Locally – Introduced species – Overharvesting – Global change  Habitat Destruction and Habitat Fragmentation Most of the grasslands and forests of the Northern Hemisphere were destroyed by the end of the nineteenth century. The grasslands of the southern hemisphere are now vanishing, and tropical forests are disappearing at a rate of about 2% per year. This type of destruction has become the norm for most biological communities, as the human population expands our economic needs require resources from more and more land. The remaining habitat is often broken into many small fragments, which are separated by large areas of land under cultivation or other human uses, effectively reducing a single "continent" into many "islands".  Fragmented Habitats Support Smaller Populations Essentially, every habitat fragment becomes a biological "island" (analogous to continental shelf islands, rather than the oceanic kind). – As in the Mac Arthur Wilson model, the smaller the island, the smaller the population of any given species it can support. – Small populations are at much greater risk of extinction due to random events, such as weather, disasters, and natural fluctuations in their population. Here is a fragment seen from the air  Additionally, smaller populations support less genetic variation, which could lead to the fixation of harmful alleles and the ultimate extinction of the population (for very small fragments), or simply inhibit their ability to evolve in response to changing conditions  Fragmented Habitats Frequently Lack Critical Ecosystem Processes Fire, certain types of grazing, and other forces fundamentally important to the ecology of organisms, are altered when a habitat is broken into fragments. Additionally, edge effects fundamentally alter habitat. For certain species, this can be critical to their ability to survive. – For instance, places where human habitation borders nature preserves frequently have weedy plants, fire is controlled, domestic cats and dogs escape and prey on native wildlife, and human noise and activity disturb the behavior of certain animals.  The edge habitats have different effects on different species. – Some large mammals, such as coyotes and raccoons, reach much higher densities in edge habitats because they are able to take advantage of human resources (garbage), and return to the safety of the preserve. Taking this a step farther,raccoons in the US, and red foxes in England, have even penetrated urban areas to become part of the city, reaching high densities. – Other mammal species cannot tolerate edge environments, wolves and mountain lions do not like humans and cannot live on the edge (in cases where they try, very bad things might happen. This is a natural area in Massachusetts.  Example: The brown headed cowbird is a native to the United States. – It is a brood parasite, evicting the eggs of other species to replace them with its own. – Cowbirds prefer edge habitats. Now that forests are fragmented, there are few safe areas from cowbirds, and forest interior species such as bluebirds are suffering a major loss of fitness in some areas. Habitat Change and Disruption of Ecosystem Processes – Surviving areas of natural habitat often change because humans have fundamentally altered natural ecosystem processes.  Example Pacific Salmon are very important ecologically and economically off the West Coast of North America. Salmon species have experienced dramatic declines over the past few decades due to a variety of factors, many of which result from human habitat modification. Hydroelectric dams have resulted in increased juvenile mortality and made many habitats inaccessible to migrating salmon. Additionally, human logging and agriculture has silted and modified many of their upstream habitats, causing a drop in recruitment.  Introduction of Exotics Human activities are creating the worldwide faunal interchange. This is an uncontrolled experiment in community ecology, with the potential result of a massive loss of gamma diversity worldwide caused by the loss of endemic species. Most exotic species that arrive on new continents do not spread or establish themselves, but the ones that do often succeed spectacularly, causing change to native ecosystems that results in many extinctions.  Example-The Snake that Ate Guam. Boiga irregularis, the brown tree snake, is an arboreal snake native to New Guinea, Australia, and the Solomon Islands. It is a small, nocturnal, rear-fanged snake. Boiga irregularis was introduced to Guam in the late 1940s, probably by hitching a ride in the wheel well of a plane. Since that time, it has literally eaten most of the endemic birds of Guam to extinction. Since there are no other native snakes in Guam (other than a blind, burrowing species), the bird fauna there evolved no natural defenses.  Thus, is an incredibly effective predator of birds and their nests. – In Australia, competition and predation keep it in check, but the simpler ecosystem of Guam has allowed it to increase in numbers to up to 20 individuals per square acre of jungle (among the highest ever recorded for a snake). – It also causes other problems in Guam, including numerous power outages resulting from large numbers of snakes resting on power lines. Overexpolitation Stellar's Sea Cow-this huge sirenian mammal lived in the reached a length of 26 feet and could way seven thousand pounds or more. It existed on a diet of kelp, and could not dive or swim quickly. It was delicious, and was hunted to extinction by sailors within 30 years of its discovery  What Makes A Species Vulnerable to extinction? Endemism Rarity Small Population Size Ecological Specialization Beauty/Usefulness to Humans/Competitor with Humans  Endemism- Species that are restricted to a particular, small area, are more vulnerable to extinction  Rarity-Rarity is not the same thing as endeminsm, endemics can be very common in the restricted area where they do occur. "Naturally rare" species have low population densities, but may be widely distributed and have respectable population sizes. We do not completely understand the ecological factors that make some species "naturally rare", but when a common species gradually becomes rare, it is often a prelude to extinction. "Naturally rare" species can be a challenge to conservation, because they are difficult to monitor and it is very difficult to ensure that sufficient habitat is set aside for them.  Small Population Size-Small population sizes render a species very vulnerable to extinction, through reduced genetic variation via genetic drift, the potential for inbreeding depression, and demographic stochasticity caused by random ecological disasters.  Ecological Specialization-Ecological specialists are more prone to extinction because there are only a few ways they can 'fit themselves into" an ecosystem. They must have certain interspecific relationships in order to feed, obtain mates, have places to live, or maintain competitive superiority. The loss of other species in the community, or habitat change due to human activity, can change these factors, and render a formerly successful species vulnerable to extinction.  Useful to Humans or A Competitor of Humans: Species that cross the paths of humans often suffer for it. – Humans have a way of killing all the pretty things, harvesting all the useful things, and hunting to extinction everything that could be perceived as a competitor. For instance, fishermen in San Francisco Bay area often despise the California Sea Otter, despite its important place in the ecosystem of the California Coast, because of its perceived status as a competitor. They are protected now, however, they were nearly hunted to extinction for their pelts. Crocodiles kill pets. They are often hunted and killed for their hides. Rattlesnakes, despite their critical role in ecosystems, are rounded up and killed in the Southwestern United States. Many reptiles, mammals, birds, and fish, are hunted for the pet trade.  Clicker Question Which of the following species is extinct? A Honey Bees B Purple Loostrife C The Stellar’s Sea Cow D Boiga irregularis E None of the above  Learning Goal Students should understand a few of the key factors influencing conservation, including the inevitable economic compromises and potential human impact of conservation.  Weighing Conflicting Demands Conserving species often requires resolving conflicts between habitat needs of endangered species and human demands For example, in the U.S. Pacific Northwest, habitat preservation for many species is at odds with timber and mining industries. – In fact, resource extraction industries provide a good source of jobs in the short term, but do not always provide consistent jobs for local economies… attractive natural areas are sometimes more consistent in attracting potential sources of investment or income. Managing habitat for one species might have positive or negative effects on other species  Commercial Whaling The international whaling commission is an international body that has existed since 1946, to provide for the proper conservation of whale stocks. In the face of overwhelming evidence that most species of whales were declining in number and many were in immediate danger of extinction, including the Commission on International Trade in Endangered Species, the IWC voted for an international moratorium on whaling. Several countries, particularly Japan, Russia, Norway, and Iceland, who have cultural traditions of whaling, initially voted against the moratorium and have never been comfortable with a continued moratorium.  The IWC is a voluntary organization not backed up by treaty. Countries that favor continued whaling, such as Japan, kept in check by the other countries, by political maneuvering. – (although Japan does a fair amount Above, Fin whale abundance over time of whaling despite the ban).  Even in protecting large, charismatic megafauna of obvious importance to the world’s oceans, cooperation has been difficult, because of the economic impact on people in some countries. It is sometimes portrayed as a “rich countries” bullying whalers in poorer countries issue - despite the impressive standards of living in in Japan and Norway. Yet, if more than a handful of countries went back to whaling, Protecting other sea creatures of no population of whales would economic importance, such as Atlantic survive for long – right, fin cod or bluefin tuna presents obvious whale challenges.  Ironically, whale watching has grown into a much larger industry than whaling. It earns about 2.1 billion dollars per year, and employs about 13,000 workers. A whale is worth a great deal more alive than dead. Even in Japan, the whale watching is worth 33 million dollars a year, and whaling amounts to about 31 million a year. Even the most optimistic estimates of profitability of a return to whaling place the industry’s value at 1.7 billion a year, and this accounts for the misguided notion that killing whales will increase fish stocks for fishermen. Conservation costs jobs. Failure to conserve usually costs many more jobs.  Establishing Protected Areas Conservation biologists apply understanding of ecological dynamics in establishing protected areas to slow the loss of biodiversity. Below-the Cape Horn Biosphere Reserve seeks to preserve biotic and cultural diversity  An important question is whether to create fewer large reserves or more numerous small reserves One argument for large reserves is that large, far-ranging animals with low-density populations require extensive habitats Smaller reserves can get at a greater diversity of habitats-and are often simply more possible. Right-Cook County Forest Preserves  Marine reserves in the Fiji islands are closed to fishing, which actually improves fishing success in nearby areas – The preserve provides an ecosystem service-a habitat for immature fish and a spawning ground. On land, reserves might also provide reservoirs for pollinators, and other ecosystem services as well – In Costa Rica, Canada, Austraila, and The United States, it has been established that natural habitats provide a reservoir of pollinators that benefit adjacent farmland.  Conflicting Demands- Stingless bees such as this Meliponula bee are invaluable to rainforest ecosystems, and important unmanaged pollinators of human crops. Introduction of honeybees in South and Central America poses a potential threat to them.  Monarch Butterfly Biosphere Reserve Reserva de Biosphera de la Mariposa Monarcha The world heritage site encompassing most of the overwintering sites for the Eastern population of Monarch butterflies. Michoacan, and Privately held areas were Mexico, states of designated as a federal Mexico reserve between 1980 and 2000  A flickr image of a Mazahua person Most of the North by Thomas Aleto American monarchs overwinter here between October and March, in high densities. The area is a mountainous region only 62 miles north of Mexico city, inhabited by several groups of The Mazahua people indigenous people. have inhabited this region for centuries  By preserving this habitat-many other rare species are protected, but illegal logging is a concern for the monarch, and restricting land use ensures survival of other species.  Though the monarch migration is an important seasonal phenonmenon- associated with the return of departed loved ones during Day of the Dead, the indigenous people in the region don’t have it easy economically. Balancing the needs of conservation and restrictions on land use is an ongoing concern.