Ecology Flashcards
~Ecology
● Study of the interactions of organisms with their physical environemtn and wth each other
~Population
● Group of individuals of one species living in one area who have the ability of interbreeding and interacting with each other
~Community
● Consists of all the organisms living in one area
~Ecosystem
● Includes all the organisms in a given area as well as the abiotic (nonliving) factors with which they interact
~Abiotic factors
● Nonliving and include temperature, water, sunlight, wind, rocks, and soil
~Biosphere
● Global ecosystem
~Size
● The toal number of individuals in a population and is represented by N
~Density
● Number of individuals per unit area or volume
● Scientists use sampling techniques to estimate the number of organisms living in one area
~Mark and recapture
● One sampling technique
● Organisms are captured, tagged, and then released
● The same process is repeated and the a formula is used for hte collected data
● N = (number marked in first catch) x (total number in second catch) / (number of recaptures in second catch)
~Dispersion
● The pattern of spacing of individuals within the area the population inhabits
● The most common pattern of dispersion is clumped (fish)
● Some spread in a uniform pattern (platns may secrete toxins that keep away other plants that would compete for limited resources)
● Random spacing occurs in the absence of any special attractions or repulsions (forest)
~Survivorship/mortality curves
● Show the size and composisiton of a population
● Three tyeps
~Type I survivorship curve
● Show organisms with low death rates in young and middle age and high mortality in old age
● There is a great deal of parenting, which accounts for the high survival rates of the young
● This is characteristic of humans
~Type 2 survivorship curve
● Describe a species with a death rate that is constant over the life span
● Describes the hydra, reptiles, and rodents
~Type 3 survivorship curve
● Show a very high death rate among the young but then shows that death rates decline for those few individuals that have survived to a certain age
● Characteristic of fish and invertebrates that release thousands of eggs, have external fertilization, and have no parenting
~Age structure diagram
● Shows the relative numbers of individuals at each age
~Zero population growth
● The number of people at each age group is about hte same and the birth rates and the death rates are about equal
~Biotic potential
● Maximum rate at which a population could increase under ideal conditions
● Different populations have different biotic potentials, which are influenced by several factors
~Exponential growth
● The population has no predatin, parasitism, or competition
● No immigration or emigration and is in an environment with unlimited resources
● Characteristic of a population that has been recently introduced into an area
~Carrying capacity (K)
● Limit to the number of individuals that can occupy one area at a particular time
● Each particular environemnt has its own carrying capacity around which the population size oscillates
● Changes as the environemntal conditions change
~Limiting factors
● Factors that limit population growth
● Density-dependnet and density-independent
~Density-dependent factors
● Those factors that increase directly as the population dnsity increases
● Include competition for food, the buildup of wastes, predation and disease
~Density-independent factors
● Those factors whose occurrence is unrelated to the population dnsity
● include earthquakes, storms, and naturally occurring fires and floods
~R-strategists
● Opportunistic ● Reproduce rapidly when the environemnt is uncrowded and resources are vast ● Many young population ● Little or no parenting ● Rapid maturation ● Reproduce once ● Ex) insect
~K-stategists
● Live at a density near the carrying capacity (K) ● Few young ● Intensive parenting ● Slow maturation ● Reproduce many times ● Ex) mammals
~Species richness
● The number of different species in the community
~Relative abundance
● The proportion of different species within a community
~Diverse communities
● More productive because they are more stable and survive for longer periods of time
● Better able to withstand adn recover from environemntal stresses such as drought or an incursion by invasive species
~G.F. Gause
● Developed the competitie exclusion principle after studying the effects of interspecific competition in a laboratory setting
● When he cultured two species separately, each population grew rapidly and then leveled off at the carrying capacity
● When he put the two cultures together, one species had the advantage and dorve hte other species to extinction
● He stated that two species cannot coexist in a community if they share a niche (use the same resources)
~Resource partitioning
● If two species inhabit the same niche and therefore compete for resources, one of the species will evolve through natural selection to exploit different resources
~Character displacement
● Occured on the Galapagos Islands
● Finches evolved different beak sizes through natural selection and were able to eat different kinds of seeds and avoid competition
● Divergence in body structure
~Predation
● One animal eating another animal or animals eating plants
● For their protection, animals and plants have evolved defenses against predation
~Active defenses
● Animals have evolved active defenses such as hiding fleeing or defending themselves
● Very costly in terms of energy
~Passive defenses
● Animals have also evolved passive defenses such as cryptic coloration or camouflage that make the prey difficult to spot
~Aposematic coloration
● Very bright, often red or orange, coloration of poisonous animals as a warning that possible predators should avoid them
~Bastesian mimicry
● Copycat coloration where one harmless animal mimics the coloration of one that is poisonous
● One example is the viceroy btterfly which is harmless but looks very similar tot he monarch butterfly, which stores poisons in its body from the milkweed plant
~Mullerian mimicry
● Two or more poisonous species, such as the cuckoo bee and hte yellow jacket, resemble each other and gain an advantage from their combined numbers
● Predators learn more quickly to avoid any prey with that appearance
~Herbivory
● Interaction in which an organism eats part/s of a plant or alga
● They have special adaptations for gazing the right plant body or flower, such as specialized teeth or a modified digestive system
● Platns have evolved spines and thorns and chemical poisons such as strychnine, mescaline, morphine and nicotine to fend off attack by animals
~Symbiosis
● When two ro more species live in direct and intimate contact with each other
● Can be helpful, harmful or neutral
~Mutualism
● Symbiotic relationship where both organisms benefit
● An example is the bacteria that live in the human intestine and produce vitamins
~Commensalism
● Symbiotic relationship where one organism benefits and one is unaware of the other organism
● Barnacles that attach themselves to the underside of a whale benefit by gaining access ot a variety of food osurces as the whale swims into different areas
- In addition, the whale is unaware of hte barnacles
~Parasitism
● Symbiotic relationship where one organism, the parasite, benefits while the host is harmed
● A tapeworm in the human intestine is an example
~Facilitation
● Organisms can have positive effects on the survival and reproduction of toher species without livign in direct and intimate contact with them
● Ex) Black rush Juncus gerardi, which makes the soil more hospitable for other species in New England slat marshes
- it helps prevent salt buildup int he soil by shading the soil surface and reducing evaporation
~Gross primary productivity (GPP)
● Amount of light energy that is converted to chemical energy by photosynthesis per unti time
~Net primary productivity (NPP)
● Equal to the GPP minues the energy used by producers for their own cellular respiration
~Food chain
● Pathway along which food is transferred from one trophic or feeding level to another
● Energy, in the form of food, moves from the producers to the herbivores to the carnivores
● Only about 10% of the energy stored in any trophic level is converted to organic matter at the next trophic level
~Food pyramid
● A good model to demonstrate the interaction of roganisms in the food chain and hte loss of energy is the food pyramid