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LIFE…AS WE KNOW IT!! 1 • Biosphere : layer of Earth that supports life roughly 13 miles thick ( 7 miles into atmosphere and 7 miles down into the oceans !!!) • Biomes : large regions of the globe defined by similar climate (T and precipitation) and vegetation – specific place on the map • Ecosystems: All of the living organisms and the nonliving environment in a particular place ( lg. ecosystems – small ecosystems) 2 http://www.blueplanetbiomes.org/world_biomes.htm 3 POPULATIONS: group of organisms, in same species (able to interbreed), in same area, at same time…“the 3 S’s” 5.1 4 Population Dynamics • Populations change constantly in size and composition…what types of things in the environment limit the growth of a population? ***ANSWER! 5 Population Dynamics • Populations change constantly in size and composition…what types of things in the environment limit the growth of a population? ***ANSWER: – Limited food and water – Predator increase (including hunting) – Climate and Weather conditions (drought, flood, tornado) – Diseases (immigration; close contact) – Space – Pollution • They experience changes in their gene pool over time: – births, deaths, immigration (into), emigration (out of) 6 2 FACTORS THAT LIMIT POPULATION GROWTH • 1. Density-dependent factors = dependent on the # of organisms in a given area. *limited resources, predation, disease *intraspecific (between members of the same species) and interspecific (between members of different species) competition • 2. Density-independent factors = environmental conditions that limit growth (regardless of # of organisms). *weather and climate are the most impt. * “natural” disasters (flood, fire, tornado, hurricane, etc.) 7 Cover up!!!!!! 8 Factors That Affect Population Growth/Declin: BIOTIC FACTORS: ABIOTIC FACTORS • predation • disease & • water • shelter • space • weather • climate • sunlight • nutrients (soil) parasitism • food availability • mating • human impacts 9 Growth Curves models that explain/depict how populations change over time. • 2 Types: 1. Exponential: “J” shaped curve -rate of growth stays the same…continuous -population size increases steadily -ex. bacteria 2. Logistic: “S” shaped curve -“J” shaped that is limited by a density-dependent factor -death rate = birth rate -shows carrying capacity = the population size (max. #) that an environment can support. 10 examples • Exponential growth • Logistic growth 11 12 Checking for understanding (3 parts) • COMPLETE THE FOLLOWING (either on your iPad---then email to me; OR on a half sheet of paper): • Answer reading check question after reading “Human Population” pg. 107 • Graphing: #7 on pg. 107 • Pg. 103 Fig. 1: What distinguishes one zebra population from another zebra population? 13