Ecology Exam 2

Population

a group of individuals of the same species that vary in size over space and time

Populations are dynamic

variation in distribution and abundance over their geographic range

species are limited in distribution and abundance by

habitat susceptibility, historical factors, and dispersal

distribution

geographical area where individuals of a species occur

abundance

number of individuals in a given area

population ecology

study of how and why population abundance changes in space and time

genet

reproductive units with same genotype

ramets

physiological independent reproductive unit

relative population

number of individuals in one time period or place relative to another

absolute population

actual population abundance

Mark recapture formula

N=(M x C)/R

types of populations estimates

area counts (quadrats, mark recapture, line transects, citizen science, eDNA, etc.)

dispersion

spatial arrangements of individuals in a population

regular distribution

individuals are evenly spaced throughout environement

Random dispersion

individuals are randomly spaced

Clumped dispersion

individuals are clumped together (occurs in natural populations)

Specialist

eats highly specific diet made up of an abundant resource with a high handling time

generalist

eats a highly varied diet with lower

the Wallace line is an example of

Continental drift effect on species diversity

relictual distributions

occurs when the range of a formerly widespread species is constricted or fragmented

dispersal factors

relictual distribution, migration, contineteal drift, dispersal limitations (islands)

metapopulaiton

a set of spatially isolated populations linked to one another through dispersal

blinking lights metaphor in relation to metapopulations

populations will move and go locally extinct, blink lights in a space represent a population’s existence or extinction

Levin’s metapopulation formula

dp/dt=cp(1-p)-ep

Levin’s p represents

proportion of patches occupied

Levin’s c represents

patch colonization rate

Levin’s e represents

patch extinction rate

Assumptions for levin’s model

infinite number of identical patches, all patches have equal chances of colonization and extinction

if e/c<1

the population will persist

if e/c>1

all populations will go extinct

rescue effect

high rates of immigration from a nearby patch can protect small populations from extinction

Case study for e/c

spotted owls are at high risk of extinction due to habitat fragmentation, barred owls have monopolized on this fragmentation

urchin distribution is dependent on

sea otters

Bottom up control

increased nutrients cause eutrophication, leading to mass die-offs

top-down control

top predators control the abundance of populations

trophic species interactions

due to feeding

nontrophic species interactions

competition and facilitative

competition

two or more species overlap in the use of limiting resources

commensalism

one species benefits, another is neither harmed nor benefiting

mutualism

both species benefit

amensalism

one species is unaffected and another is harmed ex. elephants walking

Predation

parasitism, carnivory, and herbivory: individuals of one species kill/consume individuals of another species

optimal foraging theory for generalists v. specialists

encounter rate v. handling time balance: carnivores will have a low encounter rate + handling time = eat everything; herbivores have high encounter rate and handling time=specialization (koalas)

mechanisms for predation

finding: search, ambush, trap

capture: poison, burst of speed, mimicry, etc.

animal mechanisms for predator avoidance

physical features (armor), warning features, mimicry, crypsis (camouflage), behavioral adaptation

landscape of fear is an example of behavioral adaptation

deer become afraid of roadways with the release of wolves, leading to safer roadways

plant mechanisms for predation prevention

structural defenses (thorns), chemical defenses, produce a lot of offspring, induced defenses (compensation growth + increasing existing defenses)

Lotka-Volterra Predator Prey relationship formula for prey

dN/dt=rN-aNP

rN in Lotka-Volterra pred-prey formula

population growth rate x prey population

-aNP

capture efficiency x prey pop x pred pop

Lotka-Volterra Predator Prey relationship formula for pred

dP/dt= baNP-mP

baNP in pred-prey formula

energy gain from prey

-mP in pred-prey

mortality rate x pred pop = starving pred

predator and prey isoclines and subsequent pop cycles

prey isoclines: r/a=P, prey decrease if P>r/a, increase if P<r/a, predator isocline: H=m/ba, pred decrease if N<m/ba

how can removing a predator impact community

removing top pred can decrease community diversity

#of parasitic species on earth

more than 50%

parasites are typically

specialists and feed on one or two host species

microparasite, macroparasite, parasitoid, hyperparasite

small, large, and parasitic as a baby, parasite of a parasite

ectoparasites v. endoparasites

ecto live on surface of host, endo live inside host → ectoparasites and vectors for endos

defenses against parasites

symbiotes (microbiome), vertebrate immune system, use plant biochemical defenses (eat plants or be plant)

red queen hypothesis: evolutionary arms race

species must constantly evolve to maintain fitness against evolving opposing species leads to coevolution

parasites

adapt to the most common host genotype

what stops an arms race

trade offs- parasites that trade virulence for high transmittance,