NS201 Final Exam

4 common ways of knowing

empiricism, science, deductive reasoning, + inductive reasoning

empiricism

evidence gathered from sense + experiences

science

process of acquiring knowledge abt natural world

deductive reasoning

logical thinking that gets conclusion based on general principle or law; top down, test hypotheses or apply general theories to specific situations

inductive reasoning

logical thinking that gets conclusion using related observations; bottom up, formulate hypotheses + theories

deductive vs inductive reasoning

top down vs bottom up

hypothesis

testable question/statement that is supported/rejected by experimental data

variables

quantity or aspect of experiment that is changed or fixed

continuous vs categorical

measured on numerical scale vs discrete categories

independent vs dependent

changed to see if it has an effect vs measured to see if it’s related

confounding variable

extra variables that might influence independent + dependent variables, must control for them

confirmation bias

tendency to search for, interpret, favor, + recall info in a way that confirms one’s prior beliefs; vaccine + health literacy, vaccine positive/negative more likely to select headline that aligns w/ their belief

observer bias

systematic variation b/t true value + value actually observed by observer; healthcare providers round up/down blood pressure, could be influenced by bias/beliefs + differ b/t providers

sampling bias

research samples over or under represent certain groups; study participants over or under represented by age, gender, race, or other demographic factor

publishing bias

studies w/ negative findings are less likely to be submitted to and/or published in scientific journals; drug treatment trials w/ negative results are not published, making drug seem more effective than it is

how to mitigate bias

consider + test alternative hypotheses, blind/double-blind studies, careful sampling methods, multiple observers, publish negative results

biological species concept

a species taxon as a group of organisms that can successfully interbreed + produce fertile offspring

latitudinal gradient in biodiversity

biodiversity tends to decrease as latitude increases (less species the further toward a pole you go)

endemic species

species native to only one geographical location

biodiversity hotspots

geographical areas containing a high number of endemic species

ecology

study of relationships b/t living organisms + their environment, drives evolutionary responses

organisms

single individual of a species

populations

group of interbreeding organisms that are member of the same species living in the same area @ the same time

communities

all the different plant + animals species + interactions among these species

ecosystems

communities of biotic factors + their abiotic counterparts

biosphere

all ecosystems on earth

abiotic factors that limit species ranges

water, climate, light, salinity, pH, + minerals/nutrients

biotic factors that limit species ranges

predation, competition, disease + parasitism, + allelopathy (plant chemical warfare)

lvls @ which we study ecology

organism, population, community, ecosystem, + biosphere

conspecific

organisms that are all members of the same species

population sampling methods

direct count, quadrat, transect, mark re-capture, index of relative abundance

direct counts

not sampling, count every single individual in population, easy if measuring small population or animals are large + in open area, must mitigate observer bias

quadrats

define sampling area + count individuals w/in border, snails, must mitigate sampling + observer bias

transects

go in a straight line thru sampling area + only count w/ in defined area, elephant census, must mitigate sampling + observer bias

mark re-capture

capture first sample, count total # of animals, capture second sample, count # of marked + unmarked animals; marked animals in second sample / total caught in second sample = marked animals in first sample / total population size

indices of relative abundance

compare b/t 2 environments over time; traps, fecal pellets, vocalization frequency, catch per fishing effort, dens/nests in defined area

indirect indices

useful for when observing organisms is difficult, not an absolute count; count # of dens or deer droppings

demography

statistical study of population changes over time; birth rates, death rates, + life expediencies

what determines population size

birth rates, death rates, + immigration/emigration rates

population parameters

r = b-d, r = population growth rate, b = birth rate, d = death rate

basic exponential growth model

describes population growth in an idealized, unlimited environment

r > 0

population grows

r < 0

population declines

r = 0

population remains constant

Malthus’ view on human population growth

upper bound, growth is limited by factors like war, famine, natural disasters, etc

carry capacity

K, maximum population size the environment can support, determined by limiting factors; space, food, competition, disease, etc

logistic growth model

describes population that grows to carrying capacity

logistic growth curve

S-shape, bacteria growth

exponential growth curve

J-shape, population in new environment or rebound following catastrophic event that reduced population size

positive density dependent

growth of population is positively impacted due to density; herd protection, predator detection, + dilution effect

negative density dependent

growth of population is negatively impacted due to density; crowding/stress, over consumption, predators, competition, + disease

density independent factors

factors that influence majority of a population regardless of population density

life history

series of events over a lifetime, how resources are allocated for growth, maintenance, + reproduction; reproductive characteristics, life-history switchpoints, aging, length of life

life history trade offs

compromise b/t 2 or more factors, cannot have it all; high investment in small # of offspring, lower investment in larger # of offspring, reproduce early vs reproduce later

fecundity

potential reproductive capacity of an individual w/ in a population

semelparity

organism reproduces only once b/4 dying, adaptation to unpredictable environments w/ low survival in adulthood; explosive breeding, salmon, wheat

iteroparity

reproduce multiple times thru/out life, predictable environments; all birds + virtually all mammals

iteroarity vs semelparity

iteroparity = few offspring thru/out lifetime w/ high investment, semelparity = boom + bust

r-selection

many offspring, smaller offspring, low or no parental care, high morality, short life span, rapid + early reproduction

K-selection

fewer offspring, larger offspring reproduce later, live longer, greater parental care, more competition

boom + bust cycles

favorable conditions allow sharp increase in population, depletion of nutrients causes decline in population

community

all the different plant + animal species + interactions among these species

intraspecific interactions

interactions w/in one species, competition for mates

interspecific

interactions b/t different species, predator + prey

trophic structure

feeding relationships b/t organisms in a community

food chain

shows energy flow b/t trophic lvls w/ in one individual in each trophic lvl

food web

shows energy flow b/t trophic lvls w/ many food chains combined; organisms can consume @ multiple trophic lvls

trophic lvls

lvl in food web that represents role of individual organisms; producer, primary consumer, secondary consumer, tertiary consumer, apex predator

energy pyramid

visual representation of how energy is lost b/t trophic lvls, only 10% of energy is passed to next trophic lvl, burning of energy b/t lvls causes loss of energy

fundamental niche

set of resources that a species can utilize in the absence of competition + other biotic interactions

realized niche

species actual usage of resources after competition + other interactions

competition

interaction b/t organisms that is over resource that both need, occurs bc there are not enough resources for all species

competitive exclusion

one species excludes another from a limited resource or habitat

resource partitioning

differentiation of ecological niches, may evolve to specialize on different resources

non-symbiotic mutualism + commensalism vs symbiosis

symbiosis is sustatined, mutualism + commensalism aren’t necessarily long-term

symbiosis

close + long term biological interaction of 2 different organisms

obligate

type of symbiotic relationship in which 2 different organisms absolutely need each other to survive

facultative

2 different organisms rely on each other but do not absolutely need each other to survive

mutualism

reciprocal altruism, both species benefit from relationship

commensalism

one species benefits + the other is unaffected

parasitism

one organism lives inside another organism, causing the host harm

trophic cascade

indirect control that a top predator exerts on lower, non-adjacent trophic lvls

keystone species

organism that keeps everything in balance, if removed, has disproportionately large effect on the ecosystem, not always top predator; wolves in yellowstone, starfish on rocky intertidal, krill

Paine’s removal experiment on rocky intertidal

Paine removed starfish from some areas, left them in others; in areas w/o starfish, mussels dominated + out competed all other species; in areas w/ starfish, diversity of species was maintained

dominant species

species w/ largest population in community, they exert force on the system

foundation species

ecosystem engineers, modify the environment, greatly affecting its overall structure; beaver, coral

invasive species

non-native species whose introduction causes harm, or is likely to cause harm to the ecosystem, economy, and/or human health

how introductions of invasive species occurs

some are natural, colonization, agriculture, horticulture, aquaculture, accidental transport, + biological control

what makes invasive species successful

absence of natural predators, reproduction, dispersal, physiological tolerance for adverse conditions, good competitors, better suited to taking advantage of disturbed habitat compared to native species, very difficult to remove once established

trait-mediated indirect interactions

interactions that occur bc of predator effects on prey rather than prey density, predators can induce morphological, physiological, behavioral, + life history changes

examples of trait-mediated indirect interactions

avoiding carnivores detract from foraging, allow plants to grow more; indirect effect on plants is due to change in herbivore behavior

trait-mediated indirect interactions vs density-mediated interactions

direct = predator eats prey, reducing their population size, indirect = w/ fewer herbivores in the community, plants grow more

succession

progressive, sequential change in community composition overtime

primary succession vs secondary succession

new land colonized by livings things vs recovery of land

stages of primary succession

new land is create or exposed → pioneer species colonize new area, breaks down rock into soil, organic material is added as they die → grasses further enrich soil → intermediate species are able to grow, grasses turn into trees + shrubs → climax community

stages of secondary succession

soil, seeds, + roots left behind after disturbance → pioneer species (annual plants + grasses) → intermediate species (shrubs, then pines, oak + hickory) → climax community

climax community

final or stable community in a successional series, self-perpetuating + in equilibrium w/ physical + biotic environment

Lamarck’s theory of evolution

use it or lose it, organisms change from simple to complex, evolution is a natural process

wrong w/ Larmarck’s theory

implies that animal makes conscious decision to change while it’s actually environmental pressures causing them to change

general history of Darwin

collected tons of specimens + observations, studied finches @ Galapagos islands (noticed different in beak sizes), noticed how fossils were much larger than animals @ his time, wrote “I think” + tree model