Chapter 40: Population Ecology & the Distribution of Organisms Flashcards
What influences the distribution of terrestrial biomes?
Earth’s Climate
What are aquatic biomes?
diverse and dynamic systems that cover most of Earth
What limits the distribution of species?
interactions between organisms and the environment
What do biotic and abiotic factors affect?
population density, dispersion, and demographics
What are population dynamics influenced strongly by?
life history traits and population density
What is ecology?
the scientific study of the interactions between organisms and their environment
What is population?
a group of organisms of the same species living in the same geographic area
What is a community?
a group of populations of different species
What is an ecosystem?
a community of organisms in an area and the physical factors with which those organisms interact
What is a landscape?
a mosaic of connected ecosystems
What is a biosphere?
the global ecosystem (the sum of the planet’s ecosystem)
What does the global ecology examine?
the distribution of organisms on Earth
What does landscape ecology focus on?
factors controlling exchange of energy, materials, and organisms across ecosystems
What does ecosystem ecology look at?
energy flow and chemical cycling in an eosystem
What does community ecology look at?
interactions between species.
What is population ecology?
how an organisms structure, physiology and behavior meet the challenges posed by the enviroment
What is the most significant influence on the distribution of organisms on land?
climate
What is climate?
long-term, prevailing weather conditions in a given area
What are the four major components that make up climate?
temperature, precipitation, sunlight and wind
What are global climate patterns determined by?
the input of solar energy and Earth’s movement
What exerts seasonal, regional, and local effects on climate?
the changing angle of the sun over the year, bodies of water, and mountains
What are biomes?
major life zones (ecosystem) characterized by vegetation type (in terrestrial biomes) or by physical environment (in aquatic biomes)
What causes latitudinal patterns of biome distribution?
the latitudinal patterns of climate over the Earth’s surface
What is a climograph?
a plot of the annual mean temperature and precipitation in a particular region
What are the 6 biomes?
desert, grassland (temperate), temperate broadleaf forest, tropical forest, northern coniferous forest, arctic and alpine tundra
What is plotted on the x-axis of a climograph
Annual mean precipitation (cm)
What is plotted on the y-axis of a climograph?
Annual mean temperature (C)
Some arctic tundra ecosystems receive as little rainfall as deserts but have much denser vegetation. What climatic factor might explain the difference?
sunlight and wind
Why are some biomes rich in species abundance?
species abundance is related to primary productivity (productivity is higher in ecosystems with abundant light energy and warmer temperatures)
What can the distribution of biomes be modified by?
a disturbance
What is a disturbance?
an event such as a storm, fire, or human activity that changes community
What are most terrestrial biomes named for?
predominant vegetation
What are most terrestrial biomes characterized by?
microorganisms, fungi, and animals adapted to that particular environment
What are aquatic biomes characterized by?
the physical and chemical environment (marine biomes vs. freshwater biomes)
What are aquatic biomes divided into?
vertical and horizontal zones
What is the photic zone?
a zone in aquatic biomes where there is sufficient light for photosynthesis
What is the aphotic zone?
a zone in aquatic biomes where little light penetrates
What is the benthic zone?
the bottom of all aquatic biomes
What are benthos?
the community of organisms that live in the benthic zones
What is the littoral zone?
where waters close to shore that are shallow enough for rooted plants
What is a thermocline?
a narrow layer of abrupt temperature change which separates the warm upper layers from cold deeper water
What do marine algae and photosynthetic bacteria do?
supply much of the world’s oxygen and consume large amounts of atmospheric carbon dioxide
What is an oligotrophic lake
A lake that is nutrient poor and oxygen rich (sterile)
What is an eutrophic lake?
a lake that is nutrient rich and often depleted of oxygen when heterotrophs use up oxygen at the end of summer
What is a wetland?
a habitat that is inundated by water at least some of the time supports plants that are adapted to water saturated soil
What is an estuary?
a transitional area between river and sea. Water in this area is often described as brackish because it is a mixture of fresh and salt water
What is an intertidal zone?
an area that is periodically submerged and exposed by the tides
What are species distribution are consequence of?
both ecological factors and evolutionary history
What is disperal?
the movement of individuals away from their area of origin or from centers of high population density
What are biotic factors?
living factors in an environment
What are abiotic factors?
non-living factors in an environment
What does population ecology explore?
how biotic and abiotic factors influence the density, distribution and size of a population
What Is population density?
the number of individuals per unit area or volume
What factors increase population density?
births and immigration
What factors increase population density?
deaths and emigration
What does ZPG stand for?
Zero Population Growth
When does ZPG occur?
when births equal deaths
What are patterns of dispersion?
the pattern of spacing among individuals within the boundaries of the population
What are three basic patterns of dispersion?
clumped, uniform, and random
A male stickleback fish attacks other males that invade its nesting territory. Predict the likely pattern of dispersion for male sticklebacks?
Uniform
What is demography?
the study off the vital statistics of populations and how they change over time
What are life table?
age-specific survival and reproductive rates of individuals in a population. These are produced by following the fate of a cohort.
What does type 1 survivorship show?
low death rate at birth and middle life and then death rate increases sharply in older age groups. low infant mortality. associated with high parental care
What does type II survivorship show?
relatively constant birth and death rate.
What does type III survivorship show?
high death rates early in life, but then death rates decline for older age groups. Usually associated with many offspring and low parental care.
What is population growth rate
the change in the number of individuals in a given area over time
What is the formula for population growth rate?
r = (births-deaths/N)
What is exponential population growth
described as an idealized population growth in an environment with unlimited resources.
What shape curve is exponential population growth?
J-shaped
What is intrinsic rate of increase
the per capita rate at which an exponentially growing population increases in size at each instant in time (ideal conditions, unlimited resources)
What is carrying capacity?
the maximum population size that a particular environment can sustain (K)
What is logistical population growth?
it charts the growth of a population with unlimited resources when the population is low (exponential growth), but then the rate of population growth approaches zero as the population size nears the carrying capacity
What is true about the birth and death rate during exponential growth?
birth rate is much greater than death rate
What is true about the birth and death rate as the population approaches the carrying capacity?
birth rate begins to decrease and/or death rate increases
What Is true about the birth and death rate at the carrying capacity?
rates are roughly equal
What makes up an organism’s life history
due to limited resources, there must be a tradeoff between survival and reproductive traits (frequency, number of offspring, and parental care), which make up an organisms’ life history/
What is k-selection?
selection of life history traits that are sensitive to population density and carrying capacity
What is r-selection?
selection of life history traits the maximize reproductive success in uncrowded environments
What happens at large population sizes?
negative feedback is provided by density-dependent regulation which halts population growth through mechanisms that reduce birth rates or increase death rates
What are the 6 density-dependent mechanisms?
competition for resources, predation, disease, toxic wastes, territoriality, intrinsic factors
What are density-independent mechanisms?
factors that are unrelated to population density. These factors will affect the same % of a population regardless of population density.
