Bio 102 - Ecology
density-independent factors that limit population growth
affect all populations in similar ways, regardless of the population size • unusual weather • natural disasters • seasonal cycles • certain human activities—such as damming rivers and clear-cutting forests
how do movement corridors harm
allow the transfer of diseases and parasites
What are ecological disturbances and how do they affect species diversity?
an event that changes a community, removes organisms from it, and alters resource availability
ecosystem diversity
community and ecosystem diversity across a landscape of an entire reigion
which of the following causes populations to shift most quickly from an exponential to a logistic population growth
competition for resources
greenhouse gas
gases that affect the earth's atmosphere by reflecting infrared radiation back toward Earth: water vapor, CO2, etc
endangered species
in danger of becoming extinct throughout all or a significant portion of its range
global change
includes alterations in climate, atmospheric chemistry, and broad ecological systems
Community Ecology
A community is a group of populations of different species in an area. Community ecology examines how interactions between species, such as predation and competitions, affect community structure and organizations.
how do movement corridors help
promote dispersal and reduce inbreeding
random pattern
the individuals in a population are spaced in an unpredictable way
What is climate and what factors contribute to it?
the long-term prevailing weather conditions in an area
What is carrying capacity and why is it important?
the maximum population size particular environment can support -(K)
minimum viable population size (MVP)
the minimum population size at which a species can survive -depends on factors that affect a population's chances for survival over a particular time
realized niche
the niche actually occupied by that species
Fundamental niche
the niche potentially occupied by that species
abiotic factors
the nonliving chemical and physical attributes four major abiotic components of climate: -temperature -precipitation -sunlight -wind
species richness
the number of different species in the community
biotic factors
the other organisms that make up the living component of the environment
the feeding relationships between species in a community is called
trophic structure
how can biodiversity hotspots be maintained
with nature reserves
What determines global climate patterns?
largely by solar energy and the planet's movement in space
primary succession
occurs where no soil exists when succession begins
Mutualism
(+/+ interaction), is an interspecific interaction that benefits both species
Facilitation
(+/+ or 0/+) is an interaction in which one species has positive effects on another species without direct and intimate contact
Commensalism
(+/0 interaction), one species benefits and the other is neither harmed nor helped
Herbivory
(+/− interaction) refers to an interaction in which an herbivore eats parts of a plant or alga
Predation
(+/− interaction) refers to an interaction in which one species, the predator, kills and eats the other, the prey -feeding adaptations -behavioral adaptations -defensive adaptations
Parasitism
(+/− interaction), one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process
Interspecific competition
(−/− interaction) occurs when species compete for a resource that limits their growth or survival -competitive exclusion -ecological niche *fundamental vs realized niche *character displacement
How does a food web differ from a food chain? How is it a more realistic picture of trophic structure?
-A food web is a branching food chain with complex trophic interactions -Species may play a role at more than one trophic level
Defensive adaptations
-Cryptic coloration, or camouflage, makes prey difficult to spot -bright warning coloration, called aposematic coloration -Batesian mimicry, a palatable or harmless species mimics an unpalatable or harmful model -Müllerian mimicry, two or more unpalatable species resemble each other
Tropical Forest Biome
-Distribution: Equatorial and sub-equatorial regions -Temperature: Averages 25-29 oC. -Rainfall: Tropical rain forest: 200-400 cm annually; tropical dry forests 150-200 cm (monsoons) with a six to seven month dry period. -Organisms: Greatest species diversity; 5-30 million insect spps, animals adapted to the vertical layers -Human Impact: Rapid human population growth is now destroying many tropical forests
How do bodies of water regulate temperatures in the surrounding area?
-During the day, air rises over warm land and draws a cool breeze from the water across the land. -As the land cools at night, air rises over the warmer water and draws cooler air from land back over the water, which is replaced by warmer air from offshore -The California Current carries cold water southward along western North America, help produce California's costal fog. The Gulf Stream carries warm water from the equator to the North Atlantic and warms Europe.
How does the sun's radiation on a spherical earth cause latitudinal variations in climate?
-Latitudinal variation in sunlight intensity is caused by the curved shape of Earth -Sunlight strikes the tropics, most directly -At higher latitudes, where sunlight strikes Earth at an oblique angle, light is more diffuse
What are the benefits of species diversity?
-More productive and more stable in their productivity -Able to produce biomass (the total mass of all individuals in a population) more consistently than single species plots -Better able to withstand and recover from environmental stresses -More resistant to invasive species, organisms that become established outside their native range
ecosystem fragmentation
-The boundaries, or edges, between ecosystems are defining features of landscapes -
exponential growth curve
-The rate of population increase under ideal conditions is called exponential growth. -Curve is J-shaped -Populations grow more quickly as they get larger -This type of growth is characteristic of animals in a new environment but it cannot be sustained -It can be calculated using the exponential growth model equation: [(dN)/(dt)] = r(max)N t is time or the generation of population, N is the population size, and r is the growth rate [(births-deaths)/N]. This is a constant or the factor that our population increases by.
What are life history traits?
-The traits that affect an organism's schedule of reproduction and death they include: -age of first reproduction -frequency of reproduction -number of offspring -amount of parental care
Coral reefs
-are formed from the calcium carbonate skeletons of corals (cnidarians) -Shallow reef-building corals live in the photic zone in warm (about 20-30C), clear water; deep-sea corals live at depths of 200-1,500 m -Corals require high oxygen concentrations and a solid substrate for attachment -A coral reef progresses from a fringing reef to a barrier reef to a coral atoll
Benthos
-consists of the seafloor -Organisms in the very deep benthic (abyssal) zone are adapted to continuous cold and high water pressure -Substrate is mainly soft sediments; some areas are rocky
Open ocean (pelagic)
-constantly mixed by wind-driven oceanic currents -Oxygen levels are high -Turnover in temperate oceans renews nutrients in the photic zones -This biome covers approximately 70% of Earth's surface
what fields of study are included in conservation biology
-ecology -evolutionary biology -molecular biology -genetics -physiology
declining population approach to studying biodiversity
-focuses on threatened and endangered populations that show a downward trend, regardless of population size -emphasizes the environmental factors that caused a population to decline
what are the 3 main components of biodiversity? state why each is important.
-genetic diversity -species diversity -ecosystem diversity
habitat loss
-greatest threat of biodiversity -loss of biodiversity
what are the main threats to biodiversity?
-habitat loss -introduced species -overharvesting -global change
why do moderate levels of disturbance result in an increase in community diversity
-habitats are opened up for less competitive species
Streams and rivers
-have varying environmental conditions from headwater to mouth. Headwater streams are generally cold, clear, turbulent, swift, and oxygen-rich; they are often narrow and rocky -Downstream waters form rivers and are generally warmer and more turbid; they are often wide and meandering and have silty bottoms -Salt and nutrients increase from headwaters to mouth; oxygen content decreases from headwaters to mouth
A population is correctly defines as
-inhabiting the same general area -belonging to the same species
what 3 human-caused environmental changes are named?
-nutrient enrichment -accumulation of toxins -climate change
Intertidal zones
-periodically submerged and exposed by the tides -Intertidal organisms are challenged by variations in temperature and salinity and by the mechanical forces of wave action -Oxygen and nutrient levels are high -Substrate varies from rocky to sandy
logistic growth curves.
-predicts that population growth will slow and eventually stop as population density increases -a description of idealized population growth that is slowed by limiting factors -To model logistic growth, the formula for exponential growth, is multiplied by an expression that describes the effect of limiting factors on an increasing population size. population growth= r(max)N[(K-N)/K] -Curve is s-shaped -Start out with logistical growth and then growth slows and levels off when you reach K -This is a more realistic model because growth is limited
acid precipitation
-rain, snow, sleet, or fog with a pH <5.2 -contains sulfuric acid and nitric acid from the burning of wood and fossil fuels
What are interspecific interactions (general definition)? How are they summarized?
-relationships between different species in a community -Examples are competition, predation, herbivory, symbiosis (parasitism, mutualism, and commensalism), and facilitation -Interspecific interactions can affect the survival and reproduction of each species, and the effects can be summarized as positive (), negative (−), or no effect (0)
what are 2 benefits of biodiversity to humans
-species related to agricultural crops can have important genetic qualities -medicine -ecosystem services: purification of air and water, detoxification and decomposition of wastes, crop pollination, pest control, soil preservation
Define trophic structure and give an example of a food chain.
-the feeding relationships between organisms in a community -It is a key factor in community dynamics
Lakes
-vary in size from small ponds to very large lakes -Temperate lakes may have a seasonal thermocline; tropical lowland lakes have a year-round thermocline -Oligotrophic lakes are nutrient poor and generally oxygen-rich. Eutrophic lakes are nutrient rich and often depleted of oxygen in the deepest zone in the summer and if covered with ice in the winter. -Runoff from fertilized land and dumping of waste lead to nutrient enrichment, which can produce algal blooms, oxygen completion, and fish kills and make the lake oligotrophic.
a population of ground squirrels has an annual per capital birth rate of 0.06 an dan annual per capita death rat of 0.02. Calculate an estimate of the number of individuals added to (or lost from) a population of 1,000 individuals in one year.
1,000 - (1,000 x 0.02) + (1,000 x 0.06) = 40 individuals added
Population Ecology
A population is a group of individuals of the same species living in an area. Population ecology analyzes factors that affect population size and how and why it changes through time.
Ecosystem Ecology
An ecosystem is the community of organisms in an area and the physical factors with which those organisms interact. Ecosystem ecology emphasizes energy flow and chemical cycling between organisms and the environment.
biomagnification
Concentrates toxins at higher trophic levels, where biomass is lower
Define population density and give an example.
Density is the result of an interplay between processes that add individuals to a population and those that remove individuals -birth -death
Savanna Biome
Distribution: Equatorial and sub-equatorial regions Temperature: Averages 24-29 oC but is more seasonally variable than in the tropics. Rainfall: 20-30 cm annually but is more seasonally variable Organisms: Scattered trees adapted to drier conditions, fires are common. Mammals such as wildebeests, zebras, lions, and hyenas Human Impact: Fires set by humans may help maintain this biome. Cattle ranching and over-hunting reducing large mammal populations.
Tundra Biome
Distribution: covers expansive areas of the Arctic; alpine tundra exists on high mountaintops at all latitudes Temperature: Winters average -30C; summers average <10C) Rainfall: 20 to 60 cm annually in artic tundra but may exceed 100 cm annually in alpine tundra. Organisms: Permafrost, restricts growth of plant roots; mosses, dwarf shrubs, trees, and lichens; musk oxen, caribou, reindeer, bears, wolves, and foxes; many migratory bird species nest in the summer Human Impact: Settlement is sparse, but tundra has become the focus of oil and mineral extraction
Temperate Broadleaf Forest Biome
Distribution: found at midlatitudes in the Northern Hemisphere, with smaller areas in Chile, South Africa, Australia, and New Zealand Temperature: Winters average 0C; summers are hot and humid (near 35C) Rainfall: 70 to 200 cm annually Organisms: Deciduous trees in the Northern Hemisphere and evergreen eucalyptus in Australia; in the Northern Hemisphere, many mammals hibernate in the winter; birds migrate to warmer areas Human Impact: forests have been heavily settled on all continents but are recovering in places.
Temperate Grassland Biome
Distribution: occur at midlatitudes, often in the interior of continents Temperature: Summer is hot ( near 30C);winter is cold (often below -10C) Rainfall: 30 to 100 cm annually with dry winters and wet summers. Organisms: grasses and forbs, are adapted to droughts and fire; large grazers such as bison and wild horses and small burrowers such as prairie dogs Human Impact: Because of deep fertile soils, most grasslands in North America and Europe were converted to agriculture.
Desert Biome
Distribution: occur in bands near 30o north and south of the equator and in the interior of continents Temperature: may be hot (50C) or cold (-30C) with seasonal and daily temperature variation Rainfall: low and highly variable, generally less than 30 cm per year Organisms: plants are adapted for heat and desiccation tolerance; scorpions, ants, beetles, snakes, lizards, migratory and resident birds, and seed-eating rodents; many are nocturnal Human Impact: Urbanization and conversion to irrigated agriculture have reduced the natural biodiversity of some deserts
Chaparral Biome
Distribution: occurs in midlatitude coastal regions on several continents Temperature: Summer is hot (30C); fall, winter, and spring are cool (10-12C) Rainfall: 30-50 cm annually with rainy winters and dry summers. Organisms: dominated by shrubs and small trees; many plants are adapted to fire and drought; browsing mammals, insects, amphibians, small mammals, and birds Human Impact: heavily settled and reduced due to agriculture and urbanization. Human contribute to fires that sweep across.
Northern Coniferous Forest Biome (Taiga)
Distribution: spans northern North America and Eurasia and is the largest terrestrial biome on Earth Temperature: Winters are cold; summers may be hot (e.g., Siberia ranges from −50C to 20C) Rainfall: 30 to 70 cm annually Organisms: Conifers such as pine, spruce, fir, and hemlock dominate; migratory and resident birds and large mammals such as moose, brown bears, and Siberian tigers Human Impact: Northern coniferous forests are being logged at a fast rate and old-growth stands are being lost.
List the levels of ecology from organisms thru biosphere.
Global Lanscape Ecosystem Community Population Organismal
Organismal Ecology
Organismal ecology, which includes the subdisciplines of physiological, evolutionary, and behavioral ecology, is concerned with how an organism's structure, physiology, and behavior meet the challenges posed by its environment.
How do r-selected and k-selected populations differ in life histories?
Populations with so-called r-selected life history traits produce more offspring and grow rapidly in unpredictable environments. Populations with K-selected traits raise fewer offspring and maintain relatively stable populations.
How are the sun and Earth's axis responsible for seasons?
Seasonal variations of light and temperature increase steadily toward the poles. Seasonality at high latitudes is caused by the tilt of Earth's axis of rotation and its annual passage around the sun. June solstice: Northern hemisphere receive direct sunlight but the southern hemisphere and the season is summer. The southern hemisphere receives slanting sunlight and its winter.
What is an ecotone?
The area where different terrestrial biomes merge without sharp boundaries
A food web
a branching food chain with complex trophic interactions
Lanscape Ecology
a landscape (or seascape) is a mosaic of connected ecosystems. Research in landscape ecology focuses on the factors controlling exchanges of energy, materials, and organisms across multiple ecosystems.
Symbiosis
a relationship where two or more species live in direct and intimate contact with one another -parasitism -mutualism -commensalism
biodiversity hotspots
a relatively small area with a great concentration of endemic species and many endangered and threatened species -good choices for nature reserves, but identifying them is not always easy -can change with climate change
extinction vortex
a small population is prone to inbreeding and genetic drift, which draw it down an -key factor: loss of genetic variation
thermocline
a temperature boundary in oceans and most lakes that separates the warm upper layer from the cold deeper water
Character displacement
a tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species
Estuary
a transition area between river and sea; salinity varies with the rise and fall of the tides (low levels of dissolved oxygen)
which of the following is an example of cryptic coloration?
a walking stick, which is an insect that resembles a twig
effective population size
based on the population's breeding potential -estimated by Ne = (4NfNm/Nf+Nm) where Nf and Nm are the numbers of females and the number of males that successfully breeed
why are conservation efforts often opposed by some
because of human demands and the ecological role of the target species is an important consideration in conservation
secondary succession
begins in an area where soil remains after a disturbance
What features can limit the distribution of a population? Give examples.
biotic features (other species) limit the distribution of organisms: -predation (+, -), -herbivores (+, -), -mutualism (+, +), -parasitism (+, -), and -competition (-,-)
How are organisms added to a population? How are they removed from the population?
birth and death
Feeding adaptations
claws, teeth, stingers, and poison
if a meteor impact or volcanic eruption injected a lot of dust into the atmosphere and reduced the sunlight reaching the Earth's surface by 70% for one year, which of the following marine communities most likely would be least affected?
deep-sea vent
deserts typically occur in a band around 30 degrees north and 30 degrees south latitude because
descending air masses originating from the tropics tend to be dry
sustainable development
development that meets the needs of people today without limiting the ability of future generations to meet their needs
which of the following choices causes all of the others in creating global terrestrial climates?
differential heating of Earth's surface
Resource partitioning
differentiation of ecological niches, enabling similar species to coexist in a community
which of the following terms is used by ecologists to describe the community interaction in which one organisms makes the environment more suitable for another organism?
facilitation
genetic diversity
diversity within a single species
What features can limit the dispersal of a population? Give examples.
ecological and evolutionary interactions through time
which of the following levels of ecological organization is arranged in the correct sequence from most to least inclusive?
ecosystem, community, population, individual
Global Ecology
examines how the regional exchange of energy and materials influences the functioning and distribution of organisms across the biosphere
keystone species
exert strong control on a community by their ecological roles, or niches -not necessarily abundant
Behavioral adaptations
hiding, fleeing, forming herds or schools, and active self-defense
overharvesting
human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound
uniform pattern
individuals are most likely interacting and equally spaced in the environment
which statement best describes the evolutionary significance of mutualism
interaction increases the survival and reproductive rates of mutualistic species
What levels of organization are considered in species interactions?
interspecific interactions and intraspecific interactions
Wetlands
inundated by water at least sometimes and support plants adapted to water-saturated soil (low levels of dissolved oxygen)
which of the following is likely explanation for why invasive species take over communities into which they have been introduced?
invasive species are not held in check by the predators and agents of disease that have always been in place for native species
threatened species
is likely to become endangered in the near future
Define species diversity
is the variety of organisms that make up the community -It has two components: species richness and relative abundance
the growing season would generally be shortest in which of the following biomes?
northern coniferous forest
Food chains
link trophic levels from producers to top carnivores
Competitive exclusion
local elimination of a competing species because of strong competition
relate minimum viable population and effective population size
minimum viable population determines the effective population size
what are usually the first photosynthetic organisms to colonize during primary succession?
moss, fungi, and lichens
movement corridor
narrow strip of habitat connecting otherwise isolated patches
dwarf mistletoes are flowering plants that grow on certain forest trees. they obtain nutrients and water from the vascular tissues of the trees. the trees derive no known benefits from the dwarf mistletoes and can be harmed if nutrients and water are scarce in the environment. which of the following best describes the interactions between dwarf mistletoes and trees?
parasitism
climograph
plots the temperature and precipitation in a region
which of the following are important biotic factors that can affect the structure and organization of biological communities?
predation, competition
What is growth rate and how is it calculated?
r is the growth rate [(births-deaths)/N]. This is a constant or the factor that our population increases by.
biomanipulation can best be described as
removing many of the organisms at the next higher trophic level so that the struggling trophic level below can recover
clumped pattern
resources are often unequally distributed and individuals are grouped in patches
density-dependent factors that limit population growth
result in - declining births and - increases in deaths depends on population size is called a density-dependent limiting factor • competition • predation • parasitism • disease
which of the following best describes resource partitioning?
slight variations in a species' niche that allow similar species to coexist
how can the edges of the fragments be useful
some species take advantage of edge communities to access resources from both adjacent areas
introduced species
species that humans move from native locations to new geographic regions
small population approach to studying biodiversity
studies processes that can make small populations become extinct
which of the following events might you predict to occur if the tilt of Earth's axis relative to its plane of orbit was increased to 33 1/2 degrees?
summers and winters in the united states would likely become warmer and colder, respectively
What is the focus of population dynamics?
the complex interactions between biotic and abiotic factors that cause variation in population size
species diversity
the diversity of many species
biosphere
the global ecosystem—the sum of all the planet's ecosystems and landscapes
in models of logistic population growth,
the population growth rat slows dramatically as N(number of organisms) approaches K
relative abundance
the proportion each species represents of all individuals in the community
ecology
the scientific study of the interactions between organisms and the environment
Define ecological succession
the sequence of community and ecosystem changes after a disturbance
Ecological niche
the specific set of biotic and abiotic resources used by an organism
demography
the study of the vital statistics of a population and how they change over time
dominant species
those that are most abundant or have the highest biomass -most competitive in exploiting resources -most successful at avoiding predators and disease
How do scientists sample for population size?
various techniques such as: -count an indicator like nests, burros, tracks etc -mark and recapture of animals
