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Ecology
Population + Comuunity Ecology
| Question | Answer |
|---|---|
| Population | A group of individuals of one species that live in the same area |
| Density | Number of individuals per unit of area or volume |
| Spacing/dispersion types (3) | Clumped: ex. for cooperation Uniform: ex. individuals staying in their own territories Random: ex. dandelions |
| Demography | The study of how the statistics of populations and how they change over time |
| Cohort | Group of individuals of the same age, selected for study |
| Factors affecting density | Per capita birth rate (b=#births/population size) Per capita death rate (m=#deaths/population size) Per capita rate of increase (r=b-m) |
| Survivorship curves | Graph illustrating the number of individuals of a cohert that are expected to be alive at a given age |
| Carrying capacity (k) | Maximum population size that a particular enviroment can support. Determined by reasources + enviromental factors |
| Traits the determine the rate of increase | Age when reproduction starts Frequency of reproduction Number of offspring per reproductive event |
| R-selection | Short lifespan with few reporductive events and large offspring per event |
| K-selection | Long lifespan with several reproductive events and small offspring per event |
| Homeostatic capability | Ability to change reproduction rate in response in response to enviromental conditions (only in k-selected species) |
| Density dependent factors (in population growth) | competition for reasources, predation, toxic waste accumulation, territoriality, disease, decreased reproduction |
| Density independent factors (in population growth) | drastic enviromental events (ex. flood, drought, earthquake, human caused disasters) |
| Life history | The schedule/pattern of reproduction and survival of an organism (and the traits that influence it) |
| Exponential growth | Population is increaseing/individuals are reproducing at their maximum rate. Reasourses are unlimited (J shaped curve on graph) |
| Logistic growth | Population increases quickly until it begins to level off as it nears the carrying capacity (k). (S shaped curve on graph) |
| Semelparity vs iteroparity | Semelparity: organism reproduces only once before dying Iteroparity: organism reproduces multiple times during its life |
| What defines the geographical boundries of a population? | Natural boundries like rivers or mountains |
| How would population ecologists estimate density for sessile + mobile organisms? | Mobile: mark-recapture method. Organisms in a population are caught/marked/released, then marked/unmarked counted again later Sessile: squares are randomly placed in the population + organisms are counted. Average is calculated and used to get density |
| 4 factors that contribute to changes in population size | birth rate, death rate, immigration, emigration |
| What per capita values would mean an increasing vs decreasing population? When would the population growth equal 0? | Increasing: (r>0) Decreasing: (r<0) Population growth would equal 0 when births/deaths + immigration/emigration are equal |
| List an example of exponential growth in natural populations. Why are there so few? | Exponential gorwth happens when a population is in a reasource rich envioment. ex. bacteria in a petri dish. There are so few becuase eventually the carrying capacity will be reached. (less reasouces, disease, etc) |
| Habitat (definition) | An organism's home. The type of place it lives, its physical + chemical characteristics |
| Niche (definition) | An organism's role. The use of all biotic and abiotic reasources from the enviroment by an organism. ex. beavers build dams, fungi are decomposers |
| What are interspecific interactions? | The relationships between different species in the same habitat |
| Competition (symbols + description) | (-/-) competition is always negative (time/energy wasted) |
| Competitive exclusion | When 2 populations of similar species compete for the same reasources, one is eliminated |
| Reasource partioning | Different niches allow similar species to coexist within a community (avoiding competition) It might couses a species realized niche to be differnt from its fundemental niche |
| Herbivory (symbols + description) | (+/-) Species that eats plants |
| Parasitism (symbols + description) | (+/-) Parasites benefit from host, getting nutriunts + protection. Host is harmed |
| Mutualism (symbols + description) | (+/+) Both organisms benefit from relationship ex. bees + flowers |
| Predation (symbols + description) | (+/-) One species eats the other |
| Character displacement | Evolution of differences in morphology and reasource use as a result of competition. It makes reasource partitioning possible. ex. 2 bird species compete for same reasouce, beak size changes over time in each species |
| Adaptions of predators | fast movement, acute senses, camouflage and mimicry, claws/teeth/fangs, poisons/toxins |
| Adaptions of prey | camouflage, bright warning colors, imitation of a harmful/unpalatable species, resemblance between unpalatable species |
| What is symbiosis? | Any long term relationship between 2 species, can be harmful, benificial or neutral (includes parasitism, mutualism + commensalism) |
| Why are commensal interactions difficult to document in nature? | Becuase the "neutral" organism rarely is actually neutral, and will be affected in a neg/pos way, if only slightly |
| What are primary producers? | Autotrophic organism that are using photosynthesis to produce energy |
| What are primary/secondary/tertiary comsumers? | primary consumers eat producers (herbivores) secondary eat primary and tertiary eat secondary (food chain) organisms at the top of the chain will have no natural predators |
| Detritivores definition | heterotrophic organisms that ingest + breakdown dead organic matter interally (ex. earthworms) |
| Describe the pattern of energy/nuitriunt flow in an ecosystem | Energy flows from the sun to primary producers to the consumers (some lost as heat). Nutrients get recylced- organisms die, get broken down then get reabsorbed into the soil which plants can then use (+ repeat) |
| What is a food web? | Interconnected food chains showing the differernt roles organsims have in an ecosystem, and the energy transfer between them. More complex then a food chain. |
| What is a food chain? | Linear chain showing how energy transfers when one organism eats another. |
| Food web vs chain | Food chain is 1 path showing how energy flows, a web is many interconnected food chains. Food webs are more realistic |
| What do arrows represent in food chains + webs? | Web: arrows point towards the organism that eats it Chain: arrows point towards the organism it eats |
| Trophic effiency defintion | The percentage of energy (10%) contained in a level that is used to produce new biomass in the higher level |
| Why is the transfer of energy between 1 trophic level to the next inefficient? | Much energy is lost as heat (respiration) and some is lost during digestion as well |
| Why would a tertiary consumer organism be more vulnerable to extinction then a primary consumer organism? | There is a smaller population of tertiary consumers, and they are highly dependent on the lower trophic levels for reasources |
| Commensalism (symbols + description) | (+/0) One organism benefits, the other neither benefits nor gets harmed (neutral) |
| decomposers definition | organisms that break down dead organic matter externally (ex. fungi) |
| biomass defintion | Any organic material from organisms (plants + animals) that can be used for energy (ex. wood, alegae, etc) |
Created by:
every_august
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