Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 51 Introduction to Ecology: Population Ecology

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Population density Number of individuals of a species per unit at a given time Population dispersion (spacing) Clumped dispersion Uniform dispersion Random dispersion

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Dispersion of individuals with a population

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Dispersion in a sand pine population in Florida

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Four factors that produce changes in population size Natality Mortality Immigration Emigration

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Intrinsic rate of increase (r max ) Maximum rate at which species or population can increase under ideal conditions Carrying capacity (K) is the largest population that can be maintained –Exponential population growth (J- shaped curve) –Logistic population curve (S-shaped curve)

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Exponential population growth

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Carrying capacity and logistic population growth

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Density-dependent factors Regulate population growth by affecting a large proportion of the population as population rises Examples include predation, disease, and competition

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Density-dependent factors and negative feedback

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Density-independent factors Limit population growth but are not influenced by changes in population density Examples include hurricanes and blizzards

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Semelparous reproduction Expend their energy in a single, immense reproductive effort Iteroparous reproduction Exhibit repeated reproductive cycles throughout their lifetimes

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Semelparity

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Species exhibiting an r strategy Emphasizes a high growth rate Organisms typically have small body size, high reproductive rates, short life spans, and they inhabit variable environments

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Species exhibiting a K strategy Maintains a population near the carrying capacity of the environment Species often have large body size, low reproductive rates, long life spans, and they inhabit stable environments

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Survivorship curves Type I –Mortality is greatest in old age Type II –Mortality is spread evenly across all ages Type III –Mortality is greatest among the young

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Survivorship curves

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Survivorship curve for a herring gull population

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Source habitats Preferred habitats Local reproductive success is greater than local mortality Local individuals disperse from source habitats

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Sink habitats Lower-quality habitats Individuals may suffer death or poor reproductive success

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Source and sink populations in a hypothetical metapopulation

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Human population growth World population reached 6.3 billion in 2003 Per capita growth rate has declined from peak in 1965 of about 2% per year to 1.3% Scientists predict zero population growth by the end of the 21st century

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Human population growth

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Population characteristics Highly developed countries –Low birth rate, low infant mortality, low fertility rate, long life expectancies, and high GNI PPP Developing countries –High birth rate, high infant mortality, high fertility rate, short life expectancies, and low GNI PPP

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Comparison of 2003 population data in developed and developing countries

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Birth and death rates in Mexico, 1900–2000

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Age structure influences dynamics Possible for country to have replacement-level fertility and still experience population growth Young age structure causes a positive population growth momentum as large prereproductive age group matures

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Age structure diagrams

Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 51 Introduction to Ecology: Population Ecology Developing countries tend to have people overpopulation that degrades the environment Developed countries have consumption overpopulation that degrades the environment