Population and Community Ecology
45.1 Population Demography
Demography is the study of population dynamics, using statistical and mathematical tools.
Population Size and Density
Scientists study population size and density using a variety of field sampling methods, including quadrats and mark-recapture.
Scientists gain insight into a species' biology and ecology from studying spatial distribution of individuals.
Demography, or the study of population dynamics, is studied using tools such as life tables and survivorship curves.
45.2 Life Histories and Natural Selection
Life History Patterns and Energy Budgets
Energy budgets and life history strategies determine the type of reproductive capacity displayed by a population.
45.3 Environmental Limits to Population Growth
When resources are unlimited, a population can experience exponential growth, where its size increases at a greater and greater rate.
Logistic growth of a population size occurs when resources are limited, thereby setting a maximum number an environment can support.
45.4 Population Dynamics and Regulation
Population regulation is a density-dependent process, meaning that population growth rates are regulated by the density of a population.
Theories of Life History
Modern theories of life history incorporate life and survivorship factors with ecological concepts associated with r- and K-selection theories.
45.5 Human Population Growth
Human Population Growth
The exponential growth of the human population could lead to potential impacts such as food shortages and further global warming.
Overcoming Density-Dependent Regulation
Humans have modified their environment to prevent disease and provide shelter and food, overcoming density-dependent population limits.
Economic Development and Long-Term Consequences of Growth
A population's growth is strongly influenced by the proportions of individuals of particular ages, which in turn is influenced by economic development.
45.6 Community Ecology
Predation, Herbivory, and the Competitive Exclusion Princ...
Predation and herbivory are two methods animals use to obtain energy; many species have developed defenses against them.
Commensalism, mutualism, and parasitism are three symbiotic ways organisms interact with each other with differing degrees of benefit.
Characteristics of Communities
Communities are shaped by foundation species and keystone species, while invasive species disrupt the natural balance of an area.
When disturbances occur, succession allows for communities to become re-established over periods of time.
45.7 Behavioral Biology: Proximate and Ultimate
Innate Behaviors: Movement and Migration
Innate behaviors, such as kinesis, taxis, and migration, are instinctual responses to external stimuli.
Innate Behaviors: Living in Groups
Animals communicate using signals, which can be chemical (pheromones), aural (sound), visual (courtship displays), or tactile (touch).
Innate Behaviors: Altruism
Altruistic behaviors may be explained by the natural instinct to improve the chances of passing on one’s genes.
Innate Behaviors: Finding Sexual Partners
In mating, there are two types of selection (intersexual, intrasexual) and three mating systems (monogamous, polygynous, polyandrous).
Simple Learned Behaviors
Simple learned behaviors include habituation and imprinting, both of which are important to the maturation process of young animals.
In classical conditioning, a behavior is paired with an unrelated stimulus; in operant conditioning, behaviors are modified by consequences.
Cognitive Learning and Sociobiology
Cognitive learning relies on cognitive processes such as reasoning and abstract thinking; it is much more efficient than conditioning.