APES Ch5

apex predators

top predator that control populations below it

How are trophic levels without apex predators affected?

become unbalanced

species diversity

species richness and evenness

species richness

number of dif species

species (abundance) evenness

number of individuals within each of those species

Where is species richness greatest and why?

closest to equator

• stable year round climate

• like tropical rainforest (high in productivity) --> more energy from sun (photosynthesis) to support more organisms

• higher competition with more energy

Can species diversity differ within an area?

Yes; ecotone can have more diversity than in neighboring areas bc slightly dif microclimate

ecotone

overlapping biomes

niche structure

looks at how many niches, how they resemble/differ, how species interact/overlap

Law of Competitive Exclusion

2 species that compete for exact same resources cannot stably coexist

resource partitioning

using limited resource at dif time/place

native species

normally live and thrive in a particular community

nonnative species

migrate, deliberately/accidentally

invasive species

nonnative and displace native by outcompeting them

indicator species

serve as early warnings of damage to a community or ecosystem

keystone species

help determine types and numbers of other species in community --> helping to sustain it

foundation species

can create and enhance habitats that can benefit other species in community

Why are amphibians vanishing?

• habitat loss (draining wetlands) and fragmentation

• prolonged drought/climate change

• pollution

• increase in UV rays

• parasites

• viral/fungal disease

• overhunting

• natural immigration

symbiosis

2 species closely interacting with each other

intraspecific competition

"within" competing with own species

interspecific competition

"between" competing with another species

predation

regulates population size

• predator consume prey

• strengthen population by removing weak

What does natural selection favor for predation?

adaptations that help predators find pray and adaptations that help prey avoid predators

How do some prey escape predators?

• armor

• camouflage

• chemicals

• mimicry

parasitism

(+-) parasite feeds off of / harms host but doesn't kill right away

What does natural selection favor for parasitism?

adaptations for parasites to exploit host and adaptations for host to defend against parasites

endoparasite

parasite from within

ectoparasite

parasite from the outside

mutualism

(++) both species cooperate and both benefit

commensalism

(+0) 1 species benefits, other not affected

interference competition

when 2+ organisms directly try to limit access to a resource

exploitation competition

when 1 group uses a resource faster than another, indirectly limits resource

social parasitism example

when a cricket pretends to be an ant, hides his scent, lives in ant's home, gets fed

brood parasitism example

cowbirds and cuckoos: lays eggs in another species' nest

What can reduce the amount of competition when niches overlap?

divergent evolution

divergent evolution

evolutionary process where a beneficial adaptation can "displace" an older 1

inertia / persistence

ability of system to resist disturbances
- seen mostly in climax community

constancy

keeps population level stable

resilience

describe ecosystem's ability to recover after disturbance

What does having many different species do to sustainability?

appears to increase sustainability

intermediate disturbance hypothesis

fairly frequent, moderate disturbances produce greatest diversity

theory of island biogeography

bigger = more diverse
small = less resources --> higher extinction rate
farther from mainland = less diverse, less immigration

ecological succession

gradual change in species composition of given area

What do new conditions allow?

allow 1 group of species in a community to replace other groups

primary succession

establishment of communities in lifeless areas where there's no soil

• several centuries to thousands of yrs to produce soil

• physical weathering (wind/water/ice)

• lichen / mosses secrete acids

secondary succession

communities develop in places containing soil / sediment
- disturbances: forest fire, natural disasters, logging, mining, farming, fallen trees

How are food webs early in succession?

simple

pioneer species

a fast-responding fast-growing species

• first to colonize a new area

• can tolerate wide range of temperatures / conditions

• generalist

climax community

community go through stages until stable point

• reset by another disturbance

• always changing / recovering

Is succession orderly and can you predict if an area will become a climax community?

not orderly and can't predict

population

group of organisms of same species living in particular place at same time

population size

number of individuals

population density

number of individuals per area or volume

dispersion

spatial distribution of individuals in a population

clumped dispersion

individuals clustered together --> most common

even (uniform) dispersion

evenly separated individuals --> intraspecific competition
- scarce, evenly distributed resources

random dispersion

location of individuals independent of others

age structure

how fast population grows / declines depends on this

preproductive age

not mature enough to reproduce

reproductive age

those capable of reproduction

post productive age

those too old to reproduce

What happens is a population majority is post productive age?

population declines in future

How does a population increase?

births and immigration

population change formula

(birth + immigration) - (death + emigration)

How does a population decline?

deaths and emigration

natality

birth rate

mortality

death rate

immigration

individuals of population move in

emigration

individuals of population move out

population dynamics

how these factors change due to environmental stresses

biotic potential

population's capacity for growth

What determines carrying capacity?

biotic potential and environmental resistance

intrinsic rate of increase (r)

rate of growth with unlimited resources

What does a high intrinsic rate of increase mean?

• many offspring

• reproduce early in life

• reproduce often

• short generation time

environmental resistance

factors that limit population growth

carrying capacity (k)

max population an area can sustain without being degraded

factors that limit carrying capacity:

tendency to grow exponentially (biotic potential) and tendency to not grow exponentially (limit growth) (environmental resist)

exponential model

• doesn't take into account limiting factors

• only accurate prediction short period of time

• describes a population that increases rapidly after only a few generations

logistic model

• move closer to carrying capacity (k)

• accounts for limiting factors

• birth/death rates nit constant

What happens if a population exceeds carrying capacity?

population crash

Solutions to exceeding carrying capacity:

move, switch habitats, decrease in size

density dependent factors

dependent on density of population
ex: food shortage, disease

density independent factors

population reduced by factor not dependent on population size
ex: natural disasters

stable population curve

fluctuates slightly above and below carrying capacity

irruptive population curve

explodes and then crashes to more stable level

cyclic (boom and bust) population curve

fluctuates regularly

irregular population curve

erratic changes (possible due to drastic changes to habitat)
ex: insect populations in severe winters

top-down

predators hunt and kill prey, keeping prey population stable

bottom-up

prey are food source that determine predator population

asexual reproduction

reproduction without exchanging genetic material
- offspring exact genetic copies (clones)

sexual reproduction

reproduction with exchange of genetic material

disadvantages to sexual reproduction:

• males not give birth (females need to produce 2 offspring to replace parents)

• increase chance of genetic defects

• courtship / mating rituals can be costly (energy)

advantages to sexual reproduction:

• genetic diversity

• offspring protection

opportunists

reproduce rapidly when conditions are favorable or new niche opens up
ex: pioneer species

survivorship curves

show how likely an organism is to survive at dif times in its life

type 1

late loss --> more likely to die late in life
ex: humans or elephants

type 2

constant loss --> probability of dying not change throughout life
ex: some birds and squirrels

type 3

early loss --> probability of dying is high when young but high probability of living to old age if survive
ex: sea turtles, insects, oak trees

r strategist

• species that produce many "cheap" offspring

• little / no parental care

• small, short-lived adults

• reach reproductive age rapidly

• type 3 survivorship

k strategist

• species that produce few "expensive" offspring

• lengthy parental care

• high ability to compete

• reproduce later in life

• low ability to adapt to change compared to r strategists

• type 1 and 2 survivorship