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Species Diversity Alpha, Beta, and Gamma Diversity • alpha ~ number in a small area or ecosystem • beta ~ rate of change across habitats; how quickly do you gain species as you move out of one habitat and into another • gamma ~ changes across landscape level gradients • Alpha is a count, beta and gamma are rates of change What is a species? • Biological species: a group of populations whose individuals have the potential to interbreed and produce fertile offspring. • Problems with the biological species concept • hybrids, especially in plants, but also in animals and asexually reproducing organisms • highlights importance of maintaining genetic diversity below the species level • Evolutionary Significant Unit (ESU) • a population significantly different ecologically or genetically than other groups of the same species • how much is “significant”? • Distinct Population Segment • similar to ESU, but can also be based on political boundaries • convenient for management, not very scientific How Many Species Exist? • 1.7 million described using the Linnean system • Somewhere between 10 and 100 million • 13 million used as a working estimate • Estimates based on known species • Cryptic species are a source of underestimation, as are those that are difficult to identify (bacteria) • A lot to lose and a lot to learn! Intrinsic Value • Value independent of its usefulness to people or the ecosystem • If you accept this, conservation priorities are easy, protect by risk. Lists • IUCN Red List • Convention on International Trade in Endangered Species (CITES) • National and State Lists • Red List categories • Extinct: over 1000 species have gone extinct since 1600 • Extinct in the Wild: dozens EW or successfully reintroduced after being EW • Critically Endangered: extremely high risk of extinction in the wild • Endangered: very high risk of extinction in wild • Vulnerable: high risk, most threatened species fall in here • Near Threatened: Close to qualifying as threatened • Least Concern: Widespread and abundant • Data Deficient and Not Evaluated: Majority of species are NE Red List Criteria • Reduction in population size of 30-90% • Geographic range small, isolated, or only known from a single site or decreasing; occurrence/occupancy under extreme fluctuation • Small and declining population size • Quantitative analysis showing probability of extinction in the wild is 50% in 10 years or three generations. Understanding Rarity • Geographic range: local endemics, rare because they only live in one small place • Habitat specialists: Occur in specific and rare habitats, rare because their habitat is rare • Local population size: occur at low densities • Some relatively abundant species very threatened, some rare species have stable populations • Should the rare ones be listed? Understanding Abundance • Abundance does not guarantee security • American chestnut • Passenger pigeon Instrumental Value • Food • includes microorganisms like bacteria and yeast • wild relatives of domestic species • yaks and buffalo endangered, wild auroch extinct in 1627 • wild species as sources of new domesticates • Wild plants and animals • Medicine, both traditional and modern • Silphion was a wild plant used as a contraceptive. Went extinct by 77 AD because of over-exploitation. • Textiles, construction materials, trinkets, luxury goods • wood, furs, ivory • Fuel, Oils, and Waxes • Recreation, Pets, Ornamental Plants, and Ecotourism • Ecosystem Services • pollination (valued at $200 billion), nutrient cycling, water quality control Spiritual Value • Biophilia • existence values Scientific and Educational • Template for engineering and design • airplane wings • radar and sonar • Studies of genetics and evolution Ecological Values • • • • Species interactions Ecosystem structure Ecosystem function Some species values more than others • dominant species ~ abundant • controller species ~ control flow of energy and nutrients • keystone species ~ role disproportionately larger than abundance • Ecological extinction occurs when a species is too rare to fulfill its ecological role • Ecosystem roles can change over longer time periods Strategic Values • Flagship species • Charismatic • Umbrella species • Charismatic and have broad patterns of ecosystem use • Conservation of this species, will conserve a lot of others • Indicator species • Easy to monitor • Provide information about ecosystem health or status of other species Realized and Potential Values • Gap between currently realized values and potential future values Uniqueness Values • Some genera have hundreds of species, some have only one • More relatives? More replaceable • or at least a suitable approximation • but you can wipe out a whole group that way • fishing down the food web • Species that overlap functionally less valuable than ones that do not. • Taxonomic levels arbitrary Which values do we choose for conservation prioritization • • • • • • Intrinsic ~ protect by risk Instrumental ~ protect by usefulness Spiritual Scientific & Educational ~ conservation of model organisms? Ecological Strategic ~ flagship, umbrella, indicator • problems with indicators as a target? • Potential Future Value?