BIOL 1103 1st Edition Lecture 2 ECOLOGY Population Growth and Regulation 1 Population consists of all the members of a particular species that live within an ecosystem 2 Ecosystem a defined geographical area 3 Populations make up a community a group of interacting populations 4 Biosphere large ecosystem that comprises all of Earth s livable surface 5 Ecology the study of the interrelationships of organisms with each other and with the nonliving environment Change in Population Size 1 Birth 2 Death 3 Net Migration IF births exceed deaths exponential growth occurs this is when a very large number is added to the population during each succeeding generation Usually explained by Carrying capacity and by using a J Graph Biotic Potential max rate at which a population can grow and its 5 influences 1 The age at which the organism first reproduces 2 The frequency of reproduction 3 The average number of offspring produced each time 4 The length of the organism s reproductive life span 5 The death rate of individuals Population Size interaction between biotic potential and environmental resistance Exponential growth usually happens under unusual conditions Exponential growth occurs temporarily when environmental resistance is reduced 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 Invasive species are organisms with a high biotic potential that are introduced into ecosystems where they did not evolve and where they encounter little environmental resistance EX family buys a snake as a pet and then releases the snake into the wild The snake is now called an INVASIVE SPECIES Density independent factors limit populations regardless of their density Ex Dinosaurs going extinct Density dependent factors become more effective as population density increases Ex animals hunting for food during high breeding times Competition interaction between individuals who attempt to use the same limited resource which limits population size in a density dependent manner Humans Natural selection has favored those who are able to bear and take care of their offspring Community Interactions The FOUR 4 major community interactions are 1 Competition 2 Predation 3 Parasitism 4 Mutualism Ecological Niche all physical environmental conditions necessary for survival and reproduction of a given species No two species ever occupy exactly the same ecological niche within the same natural community Ecological Niche influence on Competition Competition when two organisms attempt to use the same limited resources Predators eat OTHER living things Predators are usually than their Prey Coevolution Ex has given lions very sharp teeth and claws or tearing prey Camouflage Mimicry members of one species having evolved to resemble another species