Bio 1108 - Unit 2

Ecology

study of relationships of organisms to one another (biotic factors) and the environment (abiotic factors)

biotic + abiotic factors with organisms produce

ecosystems

abiotic factors (organism with environment)

determine the type and number of speices that live in region → leads to biomes

Terrestrial biomes are

characterized by the plants present

Primary production

the synthesis of organis compunds from CO2

• sunlight and precipitation explain most of global variation

High plant diversity =

high animal diversity

Similar biomes on differen continets

leads to convergent evolution in plants (EX. succulent)

In aquatic system

differences in nutrient availibility drive variation in primary production. Ex. oxygen, and sunlight

• coastal waters are more productive

1st law of thermodynamics

amount of avalible energy is infinite

2nd lay of thermodynamics

explains that energy loss is a problem for biological organisms (entropy)

Autotrophs (Producers)

carry out primary production → transform energy and chemicals to a useable form

Consumers

eat food produced by primary production and pass it up through the tropic pyramid

Dead organisms produce

detritus

Decomposer of detritivors

consume detritus → breaks down organic compunds and return them back into the environment

Trophic(relating to nutrition) Pyramids

view into trophic levels as a function of the amount of energy at each level

Trophic level

an indivisuals place in the food web based on it’s distance from the energy input into the system

Biofeochemical cycles…

link the abiotic and biotic componets of every ecosystem

Chemicals Cycles in an ecosystem

cycles includes organsims and non-living componets

• reservoirs are critical (carbon and nitrogen cycle)

Carbon Cycle

how carbon moves throughout an environment

Bacteria and Archea are critical to many ecosystems

• have greater duversuty in ways of acquiring energy and carbon

• often make up the primary producers and consuer in ecosystems in “harsh”/”extreme” environments

Bacteria and Archea can

transform chemical from forns that most organisma cannot use to froms that most organisms can use

• ex. nitrogen cycle

• some plants cultivate nitrogen fixing bacteria in special root nodes

Competition

arises from needed but limited resources.

Ecological niches

species role + physical requirements

• what they do and where they occur

Fundamental niche

full range of conditions and resources that a speices can live within

• climate condition, food resources etc

• theoretical maximum

Realized niche

the ACTUAL range that species can occupy

• product of competition with other speices (biotic)

• reduces interspeices comeptition

Competitive exclusion

prevents 2 speices from occupying that same niche at the same time

• animals may be forces to move from their fudamental niches to a realized niche

Resources partitioning

(reduces competition) - similar species diverging (in response to competitive exclusion)

• results: overlap between closely related groups is minimalize

Think: sympatric speciation, day and night (temporal).

Community

composed of local populations of multiple species that my interact with one another

Antagonistic interactions

can shape a species’ ecological niche

Predation (one of antagonistic interations)

consumer (predator) eats anothr consumer (prey)

• has possiblity to overexploit prey and drive extinction

The risk of predation are mitigated by:

• prey adaptation

• big population size in comparison

• prey variety

Predators shape communities

• directly

• influencing competition amoung prey

Herbivory (antagonistic)

producer (typically plants and other photosynthetic auto trophs) eaten by consumer

• herbivores generally need to eat nore (plants have less nutrition/not easy to digest)

  • exert similar population affects on plants that predetors do prey

How plants prevent/mitigate herbivory

• thorns, latex, chemical toxins, mutualisms with other predators (ex. bullhorn acacia)

Parasitism (antagonistic)

benefit by living in close association at the cost of their host’s fitness

• usually does not kill: reduces fitness

  • pathogentic diseases are parasitic relationships

Mutualism

benefits BOTH participants

• benefits include: access to nutrients, shelter, heling reproduction, protection from predators

Symbiosis

Mutualism’s important implications for species evolution and communities

• tight evolutionary relationships

Commensalism

• in the middle of parasitism and mutualism (spectrum)

  • one species benefits while the other is unaffected.

Parasitism, commensalism and mutualism are

not fixed and can evolve into different interactions

• further study will often show full spectrum of species interations (ex. oxpecker birds + herbivore: thought to be mutalism but is more parasitic)

Aspergillus fungi

growth is usually small and harmless but can turn into serious infection in immunocompromised people

Charater Displacement

• evidence of past competition

Biodiversity

can refer to:

• genetic sequences

• species

• phylogenetic groups

• communities

• Ecosystems

  • each can be quantified in diff. ways

People often refrence species/taxonomic measures as:

look at slides

Keystone species

• have stronger influence on communities than other speices

  • often through predation or altering abiotic enviornment

    • when it alters physical ecosystem: ecosystem engineer

Ecosystem engineer

When a speices alters the physical ecosystem.

Climate and other abiotic factors

also influence species interations

Ex. In the Artic, changing climate: distributiong of snowy owls, foxes anf lemmings to move north (more cold) → changes in species interations occur

Ecological succession

represents a predictable series of changes a community goes through following distrubances.

• physical disturbances have effect of communities independent of their densities

  • most environments: some disturbance is necessary to maximize species diversity

abiotic and biotic factors

influecne th edistribution of populations → influcence evolutionary trajectory

Populations

made up by 3 things:

• size

• range

• density

Affects on population

• survival

• mortality

• migration

birth and immigraton increase

mortality and migration decrease

Constant Per Capita Growth Rate r o]Over Time

(dN/dt)/N = r

Exponetial Growth Equation

N_t= N₁(1+r)^t

Competiton (intraspecific and interspecific)

limits population growth

Carrying Capacity

Finite resources limits population growth past a certain point

Population equation with carrying capacity

dN/dt = r[K-N/K]N

Density Independent

abiotic factors - cannot regulate population size consistently

Density Dependent

biotic factors -