Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings. BIOLOGY A GUIDE TO THE NATURAL WORLD FOURTH EDITION DAVID KROGH An Interactive Living World 1: Populations in Ecology

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Study of Ecology

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The Study of Ecology Ecology is the study of the interactions living things have with each other and with their environment.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. An Ecologist on the Job Figure 33.1

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Scales of Life There are five scales of life that concern ecology: –organism –populations –communities –ecosystems –the biosphere

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Scales of Life Figure 33.2 organism (sea lion) population (colony) community (giant kelp forest) ecosystem (Southern California coast) biosphere (Earth)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Populations: Size and Dynamics

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Populations Ecologists employ several means to estimate the size of populations of living things, among them counting animal droppings or surveying bird populations as they migrate.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Arithmetic and Exponential Growth Figure , ,000 exponential growth of water-flea population arithmetic growth of car production

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Arithmetic and Exponential Growth Figure 33.4

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Arithmetic and Exponential Growth The rapid growth that sometimes characterizes living populations is referred to as exponential growth or as the J-shaped growth curve.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Arithmetic and Exponential Growth Populations that initially grow, but whose growth later levels out, have experienced logistic growth, sometimes referred to as the S- shaped growth curve.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Models of Growth for Natural Populations Figure 33.5 K K Exponential growth Logistic growth More complex growth

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. How Long Between Generations? Figure 33.7 whale elephant human beaver mouse housefly Daphnia Paramecium E. coli

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Carrying Capacity (K) Carrying capacity, denoted as K, is the maximum population density of a given species that can be sustained within a defined geographical area over an extended period of time.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings r-Selected and K-Selected Species

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. K-Selected Species Some species are K-selected, or equilibrium, species. Tend to be physically large, Relatively stable environment, Give a lot of attention to few offspring.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. r-Selected Species Other species are r-selected or opportunist species. Physically small, Relatively unstable environment, Give little or no attention to the numerous offspring they produce.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. K-Selected and r-Selected Species Figure 33.8 K-selected equilibrium species r-selected opportunist species Population size: limited by carrying capacity (K) density dependent relatively stable Organisms: K r Population size: limited by reproductive rate (r) density independent relatively unstable larger, long lived produce fewer offspring provide greater care for offspring smaller, short lived produce many offspring provide no care for offspring

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Survivorship Curves Survivorship curves describe how long individuals of a species tend to live

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Survivorship Curves There are three idealized types of survivorship curves: –Late loss (type I) –Constant loss (type II) –Early loss (type III)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Survivorship Curves Figure 33.9 Most live until old age Die at all ages K-selected species r-selected species Most die at young age

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Thinking About Human Populations

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Population Pyramids An important step in calculating the future growth of human populations is to learn what proportion of the population is at or under reproductive age. A population pyramid displays this proportion.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Population Pyramids Figure Kenya: 2006Kenya: 2050United States: 2006 reproductive ages malesfemalesmalesfemalesmalesfemales

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Human Population Increase Many decades of explosive increase In decades to come, the world’s human population is projected to stabilize –From about 6.5 billion now to a maximum of about 9.2 billion just past This stabilization is due to a decrease in total fertility rate (number of children born, on average, to each woman in a population).

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Human Population Increase Figure Old Stone Age New Stone Age beginning of Agricultural Revolution beginning of agriculturally based urban societies Bronze Age Iron Age Middle Ages Modern Times beginning of Industrial Revolution bubonic plague fall of Roman Empire

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Big Changes in Fertility Figure – –2005

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The World’s Human Population Fertility in less-developed countries tends to be much higher than that in more-developed countries. The fertility in most European nations is now so low that the continent’s population stands to shrink significantly by mid-century.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The World’s Human Population The population of the United States, however, is projected to grow significantly during this same period. The primary factors bringing the U.S. increase about are immigration and a high total fertility rate relative to other developed nations.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The World’s Human Population Human population growth is a huge threat to the environment Natural resources consumed per person is of concern

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Per Capita and Total Carbon Emissions Figure U.S. per capita CO 2 emissions far exceed those in China, but China’s per capita emissions grew by 19% between 1997 and When coupled with China’s large population, this per capita growth meant that China’s total CO 2 emissions went from 59 percent of those in U.S. in 1997 to 72 percent of those in U.S. in 2003.