ecology lec 5 defs Flashcards
Reproductive Strategies-Asexual reproduction
organisms produce offspring that are clones of the parent (bacteria, some insects (wasps, bees, ants) , some plants-not flowers, some algae)
Reproductive Strategies-Sexual reproduction
organisms reproduce via 2 parents offspring are a combination of genetic material from both parents; increases genetic diversity (mammals (see K selected) and flowering plants (angiosperms)
Reproductive Strategies-2 different strategies
r & K selection
r-selection
The two evolutionary “strategies” are termed r-selection, for those species that produce many “cheap” offspring and live in unstable environments and K-selection for those species that produce few “expensive” offspring and live in stable environments.
r-selected species
species with a capacity for a high rate of population increase; many, small, no parental care, high mortality early in life, maturity = early, environment = unstable (cheap/uncomplicated offspring
r-selected species examples
1) algae/bacteria, 2) pest organisms insects, rodents, & weeds. 3) Fish & frogs
K-selected species
species that tend to reproduce late in life, but spend more time caring for their offspring; few, large offspring, parental care, low mortality early in life, environment = stable (expensive/complicated offspring), maturity=late.
K-selected species example
1) primates humans 2) elephants 3) whales 4) extinction long times between generations & low reproductive rates Polar bears, rhino, sharks.
How are populations regulated
some are stable, some are cyclic
stable population pattern
A stable population fluctuates slightly above and below carrying capacity and is characteristic of many species living under fairly constant environmental conditions. e.g. tropical rain forests where avg temp & rainfall vary little from year to year
cyclic population patterns
Cyclic fluctuations occur over a regular time period, generally a multiple year cycle. e.g. sync and hare whose populations generaly rise & fall in 10 year cycles.
top-down regulation
these populations are controlled by the feeding level above them (usually predators BUT can be parasites, predators or competitors ). abundances of organisms at lower trophic levels can be strongly affected
bottom-up regulation
these populations are controlled by the feeding level (trophic level) below them (usually food or nutrients). Remember organism is part of a larger community which controls its ability to grow or shrink. Bottom-up controls arise from near the bottom of the food web, below the trophic level in question. Exp. Plants = nutrients,water sunlight (give fertilizer to bulk up nutrient content) abiotic factors
mutualism
an interaction between two organisms of different species that is beneficial for both organisms (e.g. honeybee and flower honeybee gets food (nectar and pollen) and the flower gets pollinated (reproduces). Oxpeckers & rhinoceros -
mutalism examples
exp1: combine nutrition and protection:oxpeckers - eat parasites (ticks/flies) from rhinoceros. oxpeckers make noises warning the larger animals predator approch. exp2: clownfish, live sea anemones, tenetacles sting/paralyze fish. gain protection and feed on detritus lef from anemones meal. clownfish protect anemones predators/parasites
commensalism examples
epiphytic plant in tree | birds nesting trees, barnacles on whales
commensalism
an interaction between two organisms that is beneficial for one organism and neutral for the other organism (e.g. epiphytic plant that lives on a branch of a tree in the rainforest it benefits by being closer to the sun and away from the ground; the tree is unaffected)
competition
an interaction between two organisms that is detrimental for both organisms (two hyenas fighting over the carcass of a dead animal; or a hyena and a turkey vulture fighting over the carcass of a dead animal). Conflict arises due to using same limited resource in the same ecosystem.
exp of limited resource that cause competition
space, water (eucaplytus tree steals), light (rainforest), nutrients, food, nesting sites , mates
predation
interaction between in which one organism of one species (predator) feeds on organism of another species (prey). an organism killing and eating another organism (the prey. Beneficial for one organism and detrimental for the other organism. e.g. lion eating an antelope OR wolf eats elk )
examples predation
wolf eating elk | lion eating antelope | croccodile eating wildebeest
parasitism
interaction between species in which one organism called parasite, preys on another organism called host by living on or in the host. an organism feeds on another organism, but rarely kills it –beneficial for one organism and detrimental for the other organism (e.g. mosquito)
exp parasitism
A flea is a parasite on a coyote. The flea benefits by drinking the coyote’s blood, but the coyote, by losing blood and acquiring discomfort and potential disease, is harmed. 2) mosquito feeds on blood, possible giving diseases to human.
inter-specific competition
two individuals from different species that are competing for the same limited resource (food, water, light, nutrients, space , nesting)
