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Bio 181 NCSU exam 2
Bio 181 NCSU Dr. Engell-Ecology: populations and communities; ecosystems
| Term | Definition |
|---|---|
| population | same species, same time, same place |
| community | all populations in an area |
| ecosystem | community and abiotic factors |
| biosphere | entire realm in which organisms exist |
| species | group of interbreeding organisms that produce fertile offspring and that do not ordinarily breed with members of other groups; genetic barriers exist between different species |
| density | number of individuals per unit area |
| dispersion | pattern of spacing with geographic boundaries of populations ex: uniform, random, clumped |
| growth | depends on biotic potential-fastest reproductive rate possible for a population under ideal conditions, differs from one species to another (results in exponential growth) |
| applications of exponential growth model | microbiology (growth of bacteria), initial colonization of new habitat, insect rearing (prediction of yield), plant or insect population growth of introduced species fisheries (prediction of fish dynamics) |
| population growth (r) | the change in the number of individuals in the population per unit time; if r is positive population is growing; if r is negative population is declining, if r is 0, then there is zero population growth |
| biotic potential is seldom reached in in natural populations due to... | limiting factors (density-dependent and density-independent) |
| density-dependent factors | predation, disease/parasites, competition, territoriality, sunlight, physiology |
| density-independent factors | weather, natural disasters, human activities |
| limiting factors determine the carrying capacity (k) of an environment... | maximum number of individuals a particular environment can support indefinitely |
| life-history strategies | based on a species' reproductive traits and the carrying capacity of their environment |
| r-strategists (growth) | high growth rate, large # of offspring, rapid mutation, small body size, unpredictable environments, many asexually reproduce, many only reproduce once in lifetime |
| k-strategists (carrying capacity) | population near or at carrying capacity, few offspring, slow maturation, often care for young, larger in size, stable environments, most reproduce more than once |
| life tables and survivorship | summarize the probability that an individual will survive and reproduce in any given year over the course of its lifetime |
| life table | data on number of individuals alive in each particular age class (cohort) |
| survivorship | the proportion of offspring produced that survive on average to a particular age |
| life tables are used to plot survivorship... | probability that a given individual in a population will survive to a particular age; plot log of surviving individuals against age/life span |
| type 1 survivorship curve | survivorship of young, live most of life expectancy (large mammals etc); usually k-strategists |
| type 2 survivorship curve | relatively constant death rate throughout life span (rodents, large fish and birds, etc) |
| type 3 survivorship curve | many young, most of which die early in life (sea turtles, frogs, trees, invertebrates, etc); usually r-strategists |
| human population growth | does not currently show density effects that typically characterize natural populations; in natural populations, per capita population growth rate decreases with population size, whereas global human population growth rate has a positive relationship |
| doubling time | time needed for a population to double in size; 70/rate of increase in % |
| demographic transition | movement from high birth and high death rate to low birth and death rates |
| age structure | proportion of individuals in each age-group |
| ecological footprint | land and water used by a nation for the consumption and wastes of its population; US has a greater footprint than its ecological capacity |
| overpopulation and overconsumption... | richest countries (20% of world) use 86% of world resources |
| 4 major types of interspecific interactions | competition, predation, parasitism, symbiosis |
| competition | intraspecific, interspecific, interaction is negative for both types; competition leads to species having an ecological niche |
| intraspecific | same species (fighting, etc) |
| interspecific | 2 different species |
| ecological niche | role in the ecosystem (herbivore, carnivore, producer, etc) its tolerance limits (soil pH, humidity) requirements for shelter, nesting sites etc |
| competitive exclusion principle (Gause 1934) | if two species compete directly for a limited resource, one species will eliminate the other from that resource ; "complete competitors cannot coexist" |
| fundamental niche | full spectrum of resources potentially available to an organism |
| realized niche | resource actually available to an organism |
| competition may also lead to... | resource partitioning |
| resource partitioning | slight difference in niches; reduces competition among coexisting species |
| character displacement | tendency for two species to diverge in characteristics and resource use |
| allopatric populations | closely related species that are geographically separate |
| sympatric populations | geographically overlapping, likely to see character displacement |
| predation (consumption of prey species by predator species) | beneficial only for predator; predator may conceal self to avoid notice by prey or may attract prey; predator and prey species coevolve; predator/prey interactions result in population cycles |
| plants are "prey species" too... | chemical toxins, physical defenses (thorns, thistles, spines); herbivores have unique adaptations that allow them to eat and/or digest certain plants |
| mammalian herbivores | cattle, sheep, deer, water buffalo |
| invertebrate herbivores | grasshoppers, beetles, caterpillars, snails, sea urchins |
| cryptic coloration | advertise unpleasant attributes |
| apposematic coloration | divert attention; playing dead; living in groups; mobbing predator; decorate self using environment; disruptive coloration; weaponry (fight back) |
| Mullerian mimicry | several well-protected species resemble each other (many species) |
| Batesian mimicry | unprotected species resembles a harmful species (one species) |
| parasitism | one species benefits, other is harmed; if parasite causes disease and/or death to the host= pathogen; tapeworm, heartworm (endoparasite); tick, flea (ectoparasite); social parasite (cowbird) |
| symbiosis | close, generally long-term associates between two or more species |
| mutualism | both species benefit; fungi and roots of plants; flowering plants and pollinators |
| commensalism | one benefits, other is unaffected; epiphytes on tropical trees; bird resting in tree; shark and remora |
| communities | all living organisms in an area |
| disturbance | event that changes a community, removes organisms from it, and alters resource availability |
| natural activity | storm, fire, flood |
| human activity | logging, urbanization |
| intermediate disturbance hypothesis | moderate disturbances can create opportunities for greater species diversity |
| ecological succession | community development over time, gradual change in plant and animal life in an area, especially after a disturbance |
| pioneer community | initial colonizers of area, usually r species |
| climate community | most stable and diverse, characterize the region |
| primary succession | occurs in a newly formed, often lifeless area (begins with soil formation) |
| secondary succession | occurs in a disturbed area, faster than primary because soil already exists |
| eutrophication | due to nutrient enrichment, resulting in increased plant and/or algal growth...decomposers multiply, use up most of oxygen; water quality declines, lake may eventually be filled by plants/soil; occurs naturally over thousands of years; accel. by human use |
Created by:
Leah.mazur