Life 320 exam 3

commensalism

one species benefits the other is unaffected

ex:hermit crab and shell

amensalism

one species is harmed and the other is unaffected

ex: penicillium

mutalism

both species benefit

ex:aphids and ants

exploitation

one organism benefits at a cost to another

communities

interactions of populations

predation

A biological interaction where one organism, the predator, hunts, kills, and consumes another organism, the prey, for food.

ex:seal and shark

parasitism

organism feeds on host, many times till death

ectoparasitism

live on or adjacent to host

ex:bed bugs

endoparasitism

live in host

ex: cymothoa exigua

herbivory

animal consuming primary producer

Grazing

under herbivory, consuming part of grasses herbs and algae

Browsing

under herbivory, consuming wood vegetation

Parasatoids

consume host, but does not kill until ready to mature

detritvores

consume dead organisms

coprophagy

eating feces or dung

competition

two or more species interact for one or more resources -/-

indirect competition

indirectly competing over resource

ex: lion vs hyena over zebra

adaptions to avoid consumption

• chemically: spray fluid

• Physically: spines

• Psychologically

• hide

• run

• become unpalatable

Adaptions for consumption

• find:visual and chemical

  • herbivores: eyes side head horizontal aligned pupils

• capture: chase

• Eat: tear apart, swallow, digest

herbivore

what digestive system longer, herbivore or carnivore

tannis

released during chewing, bind to proteins and inhibitt digestion

terpenoids

Terpenoids are a diverse group of organic compounds found in plants. They are responsible for the distinct aromas and flavors in fruits, flowers, and herbs. OILS, LATEX, RESIN

Nitrogen compounds

morphine, nicotine, lignin, cyanogenic glycosides

constant herbivory

affects the distribution and abundance of plants

ex:elk grazing without wolves

insect outbreaks

can cause defoliations

ex:pine beatle

biocontrol

using organisms to control other species (can introduce species that take over)

ex:cactus as a fence→ bugs to eat cactus

coevolution

The reciprocal evolutionary influence between two or more species, where changes in one species lead to adaptations in the other species over time.

Pairwise coevolution

between species or populations

diffuse coevolution

between guilds or trophic levels

guild

group of species that exploit the same resource in the same way

Charles Mode

Mathematical ecologist that predicted genetic oscillations like predator-prey

red queen hypothesis

evolutionary arms race, evolutionary responses go back and forth, no one really gets an advantage

Host-virus coevolution

European rabbits and myxoma virus, 90% mortality, explosive

David Pinmentel host-parasitoid system

limited by intraspecific competition. The rapid rate of evolution which occurred was the most important aspect of the experimental parasite-host populations. Within eight generations in a 16-cell system, reproductive capacity of the parasite declined 40 per cent. In 20 generations in a 30-cell system, reproductive capacity of the parasite declined 68 per cent. Such important qualitative changes in the parasite and host populations influenced the population characteristics of the systems to some degree.

plant-insect coevolution

herbivorous insects drive natural selection for plant defenses

Plant defenses select for behaviors or detoxification mechanisms

sympatric/Sympatry

Living in the same region (SAME)

allopatry/ allopatric

living separated from each other (OTHER)

Character displacement

coevolution among competitors

trophic mutualism

partners specialized in complementary ways to obtain energy and nutrients

Defensive mutualism

one partner receives food while the other protects against herbivores/predators/parasties

dispersive mutualism

pollination and seed dispersal

ruminants

bacteria live in rumen in digestive tract and decompose cellulase

Aposematism

warning coloration denoting noxious chemicals. Accumulate chemicals from external sources

Crypsis

mimicking some part of the environment

• coloration

• structure

• movement

chromatophores

color changing

ambush predator

blend into the environment to get prey

Batesian Mimic

non harmful modeling as harmful

~octopus playing as lion fish

Mullerian Mimic

group of unpalatable species that resemble each other

ex:stripes of bee

Wasmannian mimic

mimic organism it lives with

ex: mimic social insect species to live in their space and protection

~common in insect species

agressive mimic

mimic has characteristics of prey model

ex: flashes mating pattern of other species to attract

Vavilovian mimic

weeds that mimic crop species

Poop mimic

mimicing poop

ex: dung beatle and seed that looks like poop

brood parasitism

eggs laid in other nests where nesting bird accepts them and cares for their upbringing, often kicking out other baby birds

ex: brown headed cowbirds

Lynx-Hare

classic example of predation

Ex in class questionable because two data sets are used from different locations

really affected by:

• hare populations oscillate areas where no lynx

• hare pop influenced by available food and predators

• Hare fecundity affected by stress

  • Hunting pressure

Gause Culture butterflies

bottles with refuge and no refuge for prey + immigration

=absence of refuges and immigration, both prey and predator extinct

=two could only coexist with complex dynamics of immigration

Huffaker mites and oranges

rubber balls and oranges

most arrangements= extinction

needed complex arrangement with special barriers to predators so two coexist= spatial mosaic of suitable habitats enables coexistance

Sustained oscillations

Lotka-Volterra Model

R=prey pop size

r=exponential growth rate

P= pred pop size

RP=# pred-prey interactions

c=capture efficiency

cRP= overall capture rate

a=assimilation efficience

acRP=predator birth rate

dP= externally imposed death rate

equilibrium pred: r/c equilibrium prey: d/ac

Oscillation time=2pi sqrt rd

prey isocline

know pred isocline and put together circle

Lotka Volterra model dynamics

CYCLES natural part of model

extinction possible for high rates of capture

equilibrium are UNSTABLE=no constant population size

Cycle is neutrally stable

Predator-Prey Stability

stability in these =reduced oscillation

Reduce amplitude

• reduced predator efficiency/prey escape

• External density-dependent constraints on either predator or prey

• Alternate food sources for predator

• Refuge for prey at low densities

• Reduced lag between prey abundance and predator response

L-V model more realistic

Spatial realism (metapopulation, immigration to predator free)

More sophisticated ways to think about feeding (multiple prey items)

SIR model

Susceptible, infected recovered

r= transmission rate

a=recovery rate

S initial<a/r = epidemic die out

small a/r = slow recover, fast transmission

threshold phenomenon: virulence/persistence tradeoff

S (SIR)

Susceptible individuals: capable of contraction

vaccination can reduce # of susceptible

I (SIR)

Infected: have the disease and can give it to other S individuals

R (SIR)

Resistant: can non longer acquire the disease

Competition

use or defense of a resource by one individual that reduces that availability of that resource to other individuals

intraspecific competition

comp among the same species

interspecific competition

comp among different species

lower resource levels

Superior species survive at ____

David Tilman

author defines resources as

• something that can be consumed and have its amount reduced (food)

• consumers use resources for maintenance & growth

• when its availability is reduced, biological processes are affected, reducing population growth

Nonrenewable

Can’t regenerate. Space

renewable

regenerate.

external: sunlight

direct internal: prey

indirect internal regeneration: nutrients released during decomp. important in nature

limiting resource

resource that restricts growth. Often co-limitation by multiple resources

Competition exclusion principle

two species can’t coexist indefinitely on the same limiting resource

(same space for same resource)

ex: separate from each other grow similar in space, but together one outcompete in a space

logistic growth

intraspecific competition

Volterra’s Competition model

coexistence occurs when a<1 (inter weaker than intra)

• when species not competing for resource at the same time/place/way

a=interspecific

COMPETITION VARIES DEPENDING ON THE SYSTEM

Evidence for light competition

• forest canopies

  • tall growth

  • broad leaves

  • vertical leaf orientation

nutrient competition

• deep roots

• symbiotic fungi

• nutrient storage

exploitation competition

indirect competition through mutual effects on shared resources

interference competition

consumers profitable defend resources through antagonistic behaviors

Allelopathy

release of chemicals to affect the outcome of competition

ex:sage brush release compounds reducing seed growth and germination

Muller shrub

small animals live under shrubs and forage close yielding ring around (not allelopathy)

Connell barnacles

two compete for same space. Removing one allows other to grow there, but with the other there can’t grow

Sea stars lower tide predator (Paine)

asymmetric competition

competitors co-exist locally, but on different microhabitats

superior competitor for resources is almost always limited by some other factor

• environmental stress

• predators

Organism absent or rare

• competition

• who the comp is

• what is resource

• removal of competition

• adding resources

Community ecology

study of a unit that arises from the interaction of populations

community

assemblage of species that live in the same place

close community

coevolution among members is prominent

Clements

holistic concept

community is a super organism whose functioning can only be appreciated when it is considered as an entire entity

Clements

Clements Community Vegetation grows in community groups

• Vegetation grows in community groups that are cohesive and distinct

• “Holistic concept” a community is a superorganism whose functioning can only be appreciated when it is considered as an entire entity.

• The functions of various species are connected like parts of the body, and have evolved to enhance interdependent functioning.

• “Closed community” where coevolution among members is prominent

Gleason Community

• Community is a fortuitous association of species whose adaptations and requirements enable them to live together under the physical and biological conditions that characterize a particular place.

• “Individualistic concept” that organization is absent above the species level

• “Open community” where coevolution is uncommon & diffuse

individual concept

organization is absent above the species level

Gleason

Open community

coevolution is uncommon and diffuse

Gleason

ecotone

Transition zone between two different ecosystems where species from both ecosystems coexist and interact. Ecotones have higher biodiversity and unique species adapted to the unique conditions found in this zone. They play a crucial role in supporting ecological resilience and facilitating the movement of species.

Whittaker

PUTS CLEMENTS VIEWS to REST

• species are independently distributed, not in groups as predicted by Clements

• Ecotones

• We still name communities by their dominant vegetation, but recognize that plants and animals are widely, independently distributed

Graph Theory

set of nodes and edges that connect nodes

each species=node

interactions=edges

Simple graph no loops (like cannibalism or decomposers of own species)

path=sequence of nodes connected by edges that do not have a node appear more than once

Food Chain

path in the food web that has as its end nodes one that is a producer and one that is a consumer that is not prey to another node

keystone species

exert strong control on community composition and function

ex: sea urchin, sea otter, kelp forest

HSS hypothesis

earth is green because carnivores depress the populations of herbivores that would otherwise eat all the plants

ex:lakes ~ sea algae daphnia fish bigger fish

Top-down

ARGUE AGAINST: food webs much more complex

Top-down control

predators exert control on levels below

ex:zooplankton+chlorophyll+ w/ w/out fish