The Environment Week 4 Notes
The Environment Week 4 Notes ENVT 0845-005
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This 7 page Class Notes was uploaded by Katrina Salamon on Friday February 5, 2016. The Class Notes belongs to ENVT 0845-005 at Temple University taught by Dr. Udoeyo in Winter 2016. Since its upload, it has received 26 views. For similar materials see The Environment in Professional Education Services at Temple University.
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Date Created: 02/05/16
February 1, 2016 Organism and Population Ecology and Evolution Population: a group of individuals from the same species who occupy a specific geographic location Population growth: European rabbit in Australia o Nonnative with few predators o Population exploded Genetic Change o DNA controls growth an development o Environment can alter DNA Frogs in Great Lakes Pesticides The Cell: Fundamental unit of life o Cell structure categorizes: o Prokaryotes Small, single celled, DNA in a single chromosome Bacteria and archaea are prokaryotic cells o In a prokaryotic cell, the DNA is coiled into a region called the nucleoid (nucleuslike) and no membrane surrounds the DNA. o Eukaryotes Single or multicelled Membraneenclosed organelles DNA in multiple chromosomes Plants, animals, fungi and protists are eukaryotic cells. A eukaryotic cell contains a membraneenclosed nucleus and various other organelles (“little organs”), which perform specific functions in the cell. The nucleus and ribosomes are involved in the genetic control of the cell. The nucleus contains most of the cell’s DNA o The endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes are involved in the manufacture, distribution, and breakdown of molecules. o Mitochondria in all cells and chloroplasts in plant cells are involved in energy processing Chemical functions The cell is the site of life’s most important chemical functions Photosynthesis o Used by plants and some protists and bacteria o Uses sunlight, CO , 2nd H O,2 o Plants and algae absorb CO , 2rom the atmosphere and H O f2om soil or fresh water o Produces carbohydrates (sugars) and O 2 o Carbohydrates power cellular processes Chemical functions o Chemosynthesis—environment with no light Creates sugars from inorganic chemicals, hydrogen sulfide, CO2, and O2 o Used by bacteria in ecosystems with no light Ocean depths o Cellular respiration: the most prevalent and efficient catabolic pathway for the production of ATP o Carbohydrates broken to power functions Releases CO2 and H2O Nearly all organisms use Requires oxygen (aerobic) o Cellular respiration takes place in the cytoplasm of prokaryotes o In the eukaryotes, cellular respiration takes place in the mitochondria o Organisms use the energy from cellular respiration to power all of their life processes (physical, reproductive, behavioral functions) o Steps in cellular respiration generates different chemicals for building the macromolecules (proteins nucleic acid, starch and lipids) Anaerobic respiration (an: without) o Works without O 2 o Carbohydrates are partially broken down to produce CO , m2thanol or ethanol o Yields less energy about 1020% Reproduction adds new individuals to the populations Asexual reproduction o Simple cell division o Genetically identical offspring Sexual reproduction o Requires two individuals Gametes produced to form a zygote o Genetically diverse offspring In a healthy body, cell division allows for o Growth o The replacement of damaged cells, and o Development from an embryo into an adult Cell division is o Reproduction at the cellular level o Produces two “daughter” cells that are genetically identical to each other and the original “parent” cell, o Cell division is used for reproduction of singlecelled organisms, growth of multicellular organisms from a fertilized egg into an adult, repair and replacement of cells, and production of sperm and eggs. Reproduction adds new individuals to the population Population growth o Growth rate=(births + immigration)(death + emigration) o Birth ratebirths o Death rate (morality rate) o Immigration rate Number entering population o Emigration rate Number leaving the population February 3, 2016 Patterns of growth Exponential growth o Growth accelerates with each generation Arithmetic growth o Growth is constant Population growth rate o Percentage of change Doubling time=70 (“70 is a constant number”) divided by the population growth rate Exponential growth: a case study in o 1890, 60 European starlings released in NYC o 10 years later, tens of thousands o 1920s millions of starlings across New England o 1970 starlings across entire United States o Exponential growth Survivorship o Probability of an organism dying during a particular interval Species survivorships vary widely o Starling vs. bald eagle o Type I—most die old—large animals o Type II—young and old die equally—birds o Type III—most die young—fish Fertility Rate o Rate of reproduction Changes with age Agespecific fertility rates o Offspring produced at age ranges o In humans there is an age beyond which reproduction ceases Total fertility rates o Potential number of offspring o For a population to grow, total fertility rate must exceed 2 Generation time o Time between mothers and offspring o Shortest generation times will have highest population growth rates 22 Albertosaurus fossils were unearthed in the Red Deer Bone Bed, Alberta, Canada Gregory Erickson examined growth lines in bones Determined age of the 22 specimens Number of lines in bone shows the age of the animal Determined survivorship curve for Albertosaurus This curve is similar to type 1 survivorship Populations cannot grow forever o Limits to growth: Carrying capacity The number of organisms the environment can support Results in logistic growth curve (S shape) Competition reduces reproduction rate Not all populations exhibit an S curve o Some exceed carrying capacity Populations fluctuate around carrying capacity Population then crashes in response to changes in supply The death rate soon exceeds the birth rate Other limits on population growth o Temperature o Space o Chemicals/nutrients Range of tolerance Span between minimum and maximum values for survival Range of tolerance for various factors determine habitat and niche Habitat: Environment organism depends on temperature, humidity, living elements Niche: Role organism fills. Charles Darwin: Connection between inheritance, variations in behavior and a species ability to persist in an environment Species evolve: when a population moves into new environment and discovers new niches Adaptations: o Inherited structure, functions, behaviors o Give survival, reproductive advantage Natural selection: o Most fit leave more offspring, their adaptation becomes more common o Less fit have fewer offspring, their adaptation becomes less common Source of natural variation o Mutation Chance changes in DNA Environmental influence UV radiation, chemicals, Pollution, etc. Three types of natural selection o Directional selection One extreme end of range of variation favored o Stabilizing selection Middle range of variation favored o Disruptive selection Removes medium sized phenotypes Other sources of genetic change o Random events alter frequency of variations o Small population susceptible o Genetic drift Founder effect o Genetics change from immigration of small group February 5, 2016 The evolution of species Species: organisms that can breed and produce fertile offspring (New Species) Mechanisms to prevent interbreeding: o Reproductive isolation Breeding barriers Geographic (mountains, rivers, etc.) Temporal (breeding seasons) New species o Reproductive isolations Behavioral (courtship rituals Structural (genital compatibility) o Distinct species may sometimes interbreed (lions and tigers. Their offspring are sterile) Taxonomy o Classification of organisms (description, identification, and naming) o Hierarchical system Shows evolutionary relationship Each level includes level below Each species given two part name Genus, species (Example: Lepus townsendii, Homo sapiens). Every genus starts with a capital letter. Species is lowercase. Again, “Homo sapiens”. The hierarchy of life: Organisms classified based on evolutionary ancestry o Phylogenetic trees depict ancestry Show physical characteristics that classify Physical characteristics must reflect evolutionary ancestry Chapter 5: Human population Growth 7 billion human beings on earth (as of autumn 2011) Rapid population growth o Some say it’s the source of all problems o Increase impact o Rate of consumption Rates regionally and economically based Humans originated in Africa 100,000 years ago, and spread across the continents Demographer: people who study the size, density and distribution of populations. Three periods of growth o Preagricultural period: caused by global migration 100,000 years Development of human culture Advancement of tool making Tens of thousands of years to double Population 510 million at end Periods of growth: commenced with the industrial revolution around 1800 Technologies powered by fossil fuels o Increased food production Sanitation, medicine o Death rates decline o Rate of population growth accelerated Our current period: population 7 billion Demographic transition model o As a society advances, human population growth foes through stages o Stage 1: Before economic development Low availability of food High prevalence of disease Death rate high Birth rate high Worlds poorest countries one hundred years ago Demographic transition model o As a society advances, human population growth goes through three stages o Stage 3: Fertility transition People may delay starting families Families may limit number of children Death rate stays low Birth rate decreases Population growth slows United states is now in the fertility transition o Stage 4 Stability transition Low birth and death rate Birth and death rates equal Zero population growth, or negative growth Japan, Italy and Spain are now in stage 4 Human population growth rate: percentage change in the number of people living in an area over a certain time period. Direct consequence of births, deaths and migration. Birth rates Influenced by various factors o Wealth More wealth, lower birth rates o Age Agespecific birth rates Children born in a year per/1000 women within age classes
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