Bio 122 Lecture Test 4

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Ecology

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scientific study of the interactions between organisms and the environment

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scales of ecology from smallest to biggest

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organismal, population, community, ecosystem, landscape, and global ecology

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biosphere

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that global ecosystem, the sum of all the planet's ecosystems

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global ecology

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examies the influence of energy and materials on organisms across the biosphere

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landscape/seascape

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mosaic of connected ecosystems

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landscape ecology

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focuses on the exchanges of energy, materials and organisms across multiple ecosystems

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ecosystem

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the community of organisms in an area and the physical factors with which they interact

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ecosystem ecology

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emphasizes energy flow and chemical cycling among the various biotic and abiotic components

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community

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a group of populations of different species in an area

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community ecology

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deals with the whole array of interacting species in a community

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population

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a group of individuals of the same species living in an area

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population ecology

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focuses on factos affecting population size over time

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organismal ecology

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studies how an organism's structure, physiology, and (for animals) behavior meet environmental challenges

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climate

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long-term prevailing weather conditions in an area

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4 major abiotic components of climate

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temperature, precipitation, sunlight and wind

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macroclimate

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consists of patters on the global, regional and landscape level

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microclimate

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determined by fine-scale difference in the environment that affect light and wind patterns

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seasonality

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increases steadily towards the poles

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abiotic factors

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nonliving attributes (temperature, light, water and nutrients

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biotic factors

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living organisms that are part of an individual's environment

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biomes

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major life zones characterized by vegetation type (terrestrial biomes) or physical environment (aquatic biomes)

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climograph

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plots the temperature and precipitation in a region

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ecotone

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area in intergradiation where terrestrial biomes usually grade into each other, without sharp boundaries

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disturbance

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an event (a storm, fire or human activity) that changes a community.

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tropical rain forests

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rainfall is relatively constant

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tropical dry forests

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precipitation is highly seasonal

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tropical forests

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distribution is in equatorial and subequatorial regions. have vertical layering, with intense competition. high diversities

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desert

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occur in bands near 30 degress north and south of the equator and in interior of continents. precip. is low and highly variable. plants and animals have many adaptations for lack of water

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savanna

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equatorial and subequatorial regions. precipitation is seasonal. temp avgs (24-29 C) but is more seasonally variable than in the tropics. many of the grasses and plants are fire adapted.

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temperate grassland

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precip is highly seasonal. winters are cold (often below -10C) and dry; summers are hot (~30 C) and wet.

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northern coniferous forect

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taiga. spans northern N. Am. and Eurasia and is the largest terrestrial biome on earth. precip varies; winters are cold and summer may be hot. conifers dominate this biome

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temperate broadleaf forest

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found at midlatitudes in N. hempisphere. significant amounts of precip fall during all seasons as rain or snow. winters avg 0 C; summers are hot and humid (near 35 C)

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tundra

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covers expansive areas of the arctic; apline tundra exists on high mtntops at all latitudes. precip is low in arctic and higher in alpine. winters are cold and summers rel. cool. has permafrost

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permafrost

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a permanently frozen layer of soil; prevents water infiltration

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aquatic biomes

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account for the largest part of the biosphere in terms of area

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photic zone

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has sufficient light for photosynthesis

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aphotic zone

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receives little light

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pelagic zone

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the photic and aphotic zones

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abyssal zone

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deep in the aphotic zone (about 2,000-6,000 m deep)

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benthic zone

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the organic and inorganic sediment at the bottom of all aquatic zones

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benthos

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the communities of organisms in the benthic zone

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detritus

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dead oraganic matter that falls from the productive surface water and is an important food source

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thermocline

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a temp boundary that separates warm upper layer from cold deeper water

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turnover

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mixing of waters. mixes oxygenates water from the surface with nutrient-rich water from the bottom

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oligotrophic lakes

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nutrient-poor and generally oxygen-rich

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eutrophic lakes

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nutrient-rich and often depleted of oxygen if ice covered in winter

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zooplankton

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drifting heterotrophs that graze on phytoplankton

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wetland

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a habitat that is inundated by water at least some of the time and that supports plants adapted to water-saturated soil

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estuary

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a transition area between river and sea. salinity varaies with the rise and fall of the tides. nutrient-rich and highly productive

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intertidal zone

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periodically submerged and exposed by the tides. oxygen and nutrient levels are high. substrate varies from rocky to sandy.

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oceanic pelagic zone

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constatly mixed by wind-driven oceanic currents. oxygen levels are high. covers aprox 70 % of earth's surface

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density

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the number of individuals per unit area or volume

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dispersion

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the pattern of spacing among individuals within the boundaries of the population

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immigration

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the influx of new individuals from other areas

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emigration

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the movement of individuals out of a population

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clumped dispersion

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individuals aggregate in patches

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uniform dispersion

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where individuals are evenly distributed.

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territoriality

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defense of a bounded space against other individuals

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random dispersion

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the position of each individual is independent of other individuals

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demography

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the study of the vital statistics of a population and how they change over time, particularly death and birth rates

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survivorship curve

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a graphic way of representing the data in a life and plots the cohort

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cohort

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a group of individuals of the same age

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survivorship curves that are classified into 3 general types

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1: low death rates during early and mid life and in increase in death rates among older age grps
2: a constant death rate over the organism's life span
3. high death rates for the young and a lower death rate for survivors

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carrying capacity

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max population sizee the environment can support

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life history

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comprises the traits that affect its schedule of reproduction and survival

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3 main variable of life history

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1. age where reproduction begins
2. how often the organism reproduces
3. how many offspring are produced during each repro. cycle

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semelparity (Big-bang reproduction)

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species that usually reproduce once and die (often found in unpredictable environments)

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iteroparity (repeated reproduction)

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species that produce offspring repeatedly (often found in stable environments)

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K-selection

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density-dependent selection, selections for life history traits that are sensitive to population density

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R-selection

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density-independent selection, selects for life history traits that maximize reproduction

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density-independent populations

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birth rate and death rate do not change with population density

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density-dependent populations

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birth rates fall and death rates rise with population density.

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mechanisms of density-dependent population regulation

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competition for resources, toxic wastes, predation, territoriality, disease, intrinsic factors

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population dynamics

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focuses on the complex interactions between biotic and abiotic factors that cause variation in population size

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biological community

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an assemblage of populations of various species living close enough for potential interaction

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interspecific interactions

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relationships between species.
competition, predation, herbivory, symbiosis and facilitation

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Interspecific competition

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occurs when species compete for a resource in short supply

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competitive exclusion

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local elimination of a competing species

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competitive exclusion principle

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states that two species competing for the same limiting resources cannot coexist in the same place

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ecological niche

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total of a species' use of biotic and abiotic resources

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Resource partitioning

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differentiation of ecological niches, enabling similar species to coexist in a community

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fundamental niche

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the niche potentially occupied by that species

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realized niche

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the niche actually occupied by that species

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Batesian mimicry

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a palatable or harmless species mimics an unpalatable or harmful model

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Müllerian mimicry

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two or more unpalatable species resemble each other

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herbivory

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refers to an interaction where an herbivore eats parts of a plant of alga

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Symbiosis

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a relationship where two or more species live in direct and intimate contact with one another

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types of symbiosis

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parasitism, mutalism and commensalism

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endoparasites

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Parasites that live within the body of their host

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ectoparasites

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Parasites that live on the external surface

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obligate mutualism

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one species can't survive without the other

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facultative mutualism

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both species can survive alone

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commensalism

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one species benefits and the other is neither harmed nor helped. hard to document b/c any close association likely affects both species

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Facilitation

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describes an interaction where one species can have positive effects on another species without direct and intimate contact

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Species diversity

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the variety of organisms that make up the community and has two components: species richness and relative abundance

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Species richness

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the total number of different species in the community

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Relative abundance

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the proportion each species represents of the total individuals in the community

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invasive species

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organisms that become established outside their native range

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trophic structure

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the feeding relationships between organisms in a community

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Food chains

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link trophic levels from producers to top carnivores

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food web

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a branching food chain with complex trophic interactions

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omnivory

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where species may play a role at more than one trophic level

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Dominant species

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those that are most abundant or have the highest biomass

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Keystone species

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exert strong control on a community by their ecological roles, or niches

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Ecosystem engineers

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cause physical changes in the environment that affect community structure

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intermediate disturbance hypothesis

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suggests that moderate levels of disturbance can foster greater diversity than either high or low levels of disturbance

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2 key factors that affect a community's species diversity

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latitude and area. Species richness is especially great in the tropics and generally declines along an equatorial-polar gradient

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species-area curve

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quantifies the idea that, all other factors being equal, a larger geographic area has more species

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conservation biology

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seeks to preserve life and intergrates several fields: ecology, physiology, molecular bio, genetics, evolutonary bio

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3 main components of biodiversity

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genetic, species and ecosystem

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genetic diversity

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comprises genetic variation within a population and btwn populations

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endangered species

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in danger of becoming extinct throughout all or a significant portion of its range

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threatened species

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likely to become endangered in the foreseeable future

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Ecosystem services

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encompass all the processes through which natural ecosystems and their species help sustain human life

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examples of ecosystem services

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purification of air and water
detox and decomp of wastes
cycling of nutrients
moderation of weather extremes

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species loss can be traced to four major threats

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–Habitat destruction
–Introduced species
–Overharvesting
–Global change

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Overharvesting

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human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to rebound

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Habitat fragmentation

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The boundaries, or edges, between ecosystems are defining features of landscapes

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movement corridor

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is a narrow strip of quality habitat connecting otherwise isolated patches that promote dispersal and help sustain populations

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biodiversity hot spot

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a relatively small area with a great concentration of endemic species and many endangered and threatened species

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zoned reserve model

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recognizes that conservation often involves working in landscapes that are largely human dominated

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Human-caused changes in the environment include

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–Nutrient enrichment
–Accumulations of toxins
–Climate change
–Ozone depletion

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Critical load

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the amount of added nutrient that can be absorbed by plants without damaging ecosystem integrity

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greenhouse effect

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CO2, water vapor, and other greenhouse gases reflect infrared radiation back toward Earth;

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Sustainable development

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development that meets the needs of people today without limiting the ability of future generations to meet their needs

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biophilia

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Our behavior reflects remnants of our ancestral attachment to nature and the diversity of life