BIOL 1050 Lecture 31 Outline of Last LectureI. EcosystemsII. Energy FlowIII. Nutrient CyclingOutline of Current LectureI. Biodiversity II. Biodiversity lossCurrent LectureI. Biodiversity a. Biodiversity is the variety of life on earth i. Can be applied in many ways1. Genes and allelesa. The number of alleles in a species2. Speciesa. The number of species in an ecosystem3. Ecosystemsa. The number of ecosystems in a regionb. The value of biodiversityi. Utilitarian value1. Biodiversity can provide materials or processes that make our lives betterii. Aesthetic value1. Biodiversity can be beautiful to look at and pleasant to experienceiii. Symbiotic value1. Biodiversity can provide imagery that conveys meaningful abstract ideasiv. Naturalistic value1. Biodiversity can provide the satisfaction that comes from direct contact with nature c. What is biodiversity?i. Biodiversity is more than just a counting of species. It encompasses the genetic variability among organisms within a species, the variety of different species, and the variety of ecosystems on earth. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. Conservation biology is the interdisciplinary field that addresses how to preserve the natural resources of earth. Drawing on data, knowledge and insights from biology, economics, psychology, sociology, and political science, one of the goals of conservation biology is the preservation and protection of biodiversity. iii. The blue whale is the largest mammal in the world and the largest animal ever known to have lived on earth. Once lost, a species can never be re-createdd. Where is most biodiversity?i. Biodiversity varies with latitudeii. As you move away from the equator toward the pole in either direction biodiversity is reduced e. Factors that influence biodiversityi. Solar energy availability1. Greater access to solar energy, the fuel for life, provides increased specie richness2. Evolutionary history of an areaa. Communities’ diversity over time. The more time that passeswithout a climatic event, such as an ice age, the greater the diversity in an area. 3. Rate of disturbancea. A habitat with an intermediate amount of disturbance tends to have the greatest species richnessf. Biodiversity hotspotsi. There are 25 biodiversity hotspots around the world that, while covering less than 1% of the world’s area, have 20% or more of the worlds speciesii. Biodiversity hotspots occur where there is overall high biodiversity of mammalsII. Biodiversity lossa. Extinction reduces biodiversityb. Two categories of extinctionsi. Mass extinctions1. A large number of species become extinct over a short period of time due to extraordinary and sudden environmental change2. We are currently in a mass extinction right now 3. During mass extinctions, a species’ biology does not influence the risk of extinction (just bad luck, catastrophic event)ii. Background extinction1. These extinctions occur at lower rates during times other than mass extinctions2. With background extinction, species biology matters (genes, ect.)1. Factors that influence the risk of background extinctiona. Geographic range:i. Extensive vs. restricted1. Species restricted in their range are more vulnerable than those with extensive rangesb. Local population sizei. Large vs. small1. Specie with small population sizes are at increased risk of extinction c. Habitat tolerancei. Broad vs. narrow1. Species with narrow habitat tolerance are at agreater risk of extinction than species with broader habitat tolerances c. Current extinction rates are 1000x greater than background ratesi. The rates of extinction of birds and mammals has been steadily increasing with a dramatic increase during the last 150 yearsd. Likely to have a world occupied by fewer species that thrive on disturbance e. Causes of biodiversity crisisi. Habitat destruction1. Single greatest threat to biodiversity2. Deforestation in the tropics is a leading cause of biodiversity loss3. Habitat fragmentationa. Leads to smaller populations that are isolated so less gene flow between populations b. Relationship between size of an area and the number of species it can support=species-area curve ii. Introduced species1. Human introduction of organisms to areas where they previously did not live2. Many now common3. Some intentional, some accidental4. Can cause rapid extinctions 5. Disastrous disruptions: exotic speciesa. Problemi. Exotic species can threaten native populationsb. Causei. Often introduces both accidentally and intentionally, by humans. Once introduced, exotic species can multiply, unchecked by predation, overwhelming competitors and irreversibly altering ecosystems.c. Strategies for solutioni. Better regulation and restriction of intentional introductions; better vigilance against accidental introductionsiii. Overexploitation1. When rate of human use of a species outpaces its ability to reproduce2. Overfishing is a major problem for some speciesiv. Effects of pollution 1. The release of poisons, excess nutrients, and other wastes into the environment2. Causes eutrophication, acid rain, global warming, ozone