Transcript 05_EcoEvol
Announcements September 1, 2006 No class on Monday! Have a great weekend. Turn in your ecological footprint for extra credit http://www.earthday.net/footprint/index.asp Basics of Ecology and Evolution (part 1) Lecture Objectives: 1. Be introduced to the diversity of life on Earth 2. Understand the scientific definition of Ecology and Evolution 3. Learn basic concepts of Ecology and Evolution What is biological diversity? “the variety and variability among living organisms and the ecological complexes in which they occur” U.S. Office of Technology Assessment (1987) Scales or types of biological diversity: Genetic diversity - Amount of genetic variation within or among populations of a given species. Species diversity - The number of species in a given community. Community level diversity - Variation in species assemblages based on variation in habitat within an ecosystem type. Ecosystem level diversity - Variation in ecosystems across a landscape or region. What is a species? Species are groups of interbreeding organisms. Biological Species Concept (E. Mayr) Taxonomy: the study of types of organisms and their relationships. Linnaeus (1707-1778) originator of modern scientific classification of plants and animals Classification ranked according to - similarity - common ancestry Scientific Classification Animalia Kingdom Chordata Phylum Aves Class Falconiformes Order Accipitridae Family Genus Haliaeetus Species leucocephalus King Phillip Can Order Fried Green Snails The Kingdoms of Life Organisms are classified into groups based on how they make a living Plants Protists Animals Bacteria Fungi Archaebacteria The Kingdoms of Life Organisms are classified into groups based on how they make a living Prokaryotes: do not have membrane bound nucleus nor other organelles, are unicellular. Bacteria Archaebacteria The Kingdoms of Life Organisms are classified into groups based on how they make a living Plants Animals Fungi Protists Eukaryotes: have membrane bound nucleus and other organelles, can be multicellular or unicellular. How many species are there? 1.4 -1.7 million described 10-100 million estimated Diversity Insects Plants Arthropoda Mollusks Fungi Algae Fish Flatworms Roundworms Earthworms Birds Jellyfish, Corals Reptiles Starfish Sponges Bacteria Amphibians Mammals Animal Diversity Over 1 million different species of animals have been described 34 Animal Phyla < 5 % of described animals have a backbone Vetebrates Invertebrates Phylum Porifera: The Sponges Phylum Cnidaria: jellyfish sea anemones coral Hydra Phylum Ctenophora: The Comb Jellies Phylum Platyhelminthes: The flatworms Phylum Nemertea: The Ribbon Worms Phylum Nemata: the roundworms Phylum Annelida: The Segmented Worms Christmas tree worm Earthworm Leech Phylum Onychophora: Velvet worms Phylum Tardigrada: Water Bears Phylum Arthropoda: Crustaceans Lobster Crab Water fleas Insects Phylum Arthropoda: Ants beetle Butterfly cockroach Phylum Arthropoda: Centipedes and Millipedes Phylum Arthropoda: Spiders Phylum Mollusca: Clam Snail Octopus Phylum Echinodermata: Starfish Sea Urchin Phylum Chordata: Tunicates Vertebrates Plant Diversity Food webs: All species in a community are interconnected to varying degrees. An estimate of interactions among species between only 2 trophic levels (10,000 plants and 100 herbivores) in Hawaii Sheppard et al. 2004 Mol. Ecol. From Cohen et al. 2003 PNAS Keystone species: a species that plays an essential role in community stability. Umbrella species: a species that can be used as a surrogate for the heath/status of the entire community. (tend to need a lot of area) Indicator Species: a species that provides information about the quality of an area. (could be rare or a habitat specialist) Do all species matter? Is there redundancy in communities? Paul Ehrlich made an analogy between species in communities and rivets on the wing of an airplane. Removing a few rivets from an airplane is undoubtedly safe. How many are you willing to remove? On average, there are only 2 degrees of separation between any two species in a food web. Many species are in danger of extinction If current trends continue, 1/5 of all current plant and animal species could be gone or on the road to extinction by 2030. WHY?? Why are species declining? Percentage of threatened or endangered species in the U.S. imperiled by: Habitat degradation and loss - 85% Invasive species - 49% Pollution - 24% Overexploitation - 17% Disease - 3% Dave Wilcove et al. 1998 BioScience Rarity: A species that is either very uncommon throughout its range, or its range is very small. Endemism: An endemic species occurs no where else. Most common on islands. Photo: Darren Irwin Why value diversity? Motivation can be based on many principles. Ethical Moral Aesthetic Monetary Spiritual Environmental Anthropocentric Basic Ecological Concepts Ecology – the study of the interrelationship between organisms and their environment Environment – everything that affects an organism it its lifetime •Organisms interact with their environment •Survival of each individual depends on getting enough to eat and not being killed •Survival of the species depends on births being higher than deaths Environment can be divided into biotic and abiotic factors Biotic - Living portions of the environment Predation, parasitism, competition, etc. Abiotic - Nonliving factors Rain, soil type, temperature, etc. All organism have a range of requirements that determines where they can live The biotic and abiotic factors of any particular place determine where they do live All organisms need resources to grow and reproduce food water places to live mates Often, there are not enough resources for all individuals in the population Many individuals die before reproducing Some individuals are better at surviving and reproducing than others What is Evolution? The process of change in the traits of populations over time. Process by which species' characteristics change over generations. Traits must have genetic basis. Evolution does not occur within an individual. Evolution does not occur within a generation. What is Evolution? Adaptive evolution occurs primarily through natural selection Natural Selection is the process that determines which individuals within a species will reproduce and pass their genes to the next generation. Points to Know 1. Be familiar with the system for classifying living things. 2. What is biological diversity. 3. Understand the difference between the biotic and abiotic environment; know examples of each. 4. What types of resources do organisms need to survive and reproduce?