Transcript bio100--eastside-owens valley-lect 1--f09-

What is Natural History?
• the study of the natural environment
with an emphasis on identification,
formation/origin of physical features,
life-history, distribution, abundance,
and inter-relationships.
– It often and appropriately includes an
Aesthetic component.
The Natural Environment—Ecosystems
• An interacting unit of living and non-living
components.
– Non-living things (abiotic)—the physical
environment
• Water, temperature/heat, sunlight, wind/air, soil/minerals,
nutrients (found in air, water, & soil) etc…
– Living Things (biotic)
• Plants, animals, fungi, microbes
• All the living things of an area = community
Major Ecosystem Interactions
• Nutrient uptake, transfer, and recycling.
• Energy production, transfer, and loss
• Resources and physical conditions
determine what and where living things are
found and in what numbers.
• Ecological Succession
• Symbiosis: very/unusually close relationships among organism
How do living things get their food
(trophic levels)
• Producers (autotrophs)—they make their own through
photosynthesis.
– Use energy of sun to combine nutrients (from soil,
water, air) to make food (and other molecules)
– plants, algae, some bacteria
• Herbivores—they eat producers
• Carnivores—eat herbivores
Consumers (i.e., animals)
• Decomposers: eat the dead and detrius.
– Bacteria, fungi, other microbes
Energy Flow
• The energy needed for life originates from
the sun.
• Is captured by plants (and other
producers)
• Is passed from one organism to another
as they eat (or decompose) one another
• A little energy is lost at each transfer so
the amount of energy diminishes from one
organism to another.
Another example of a food web
Trophic levels are color coded.
Nutrient/Chemical Cycles
• All the nutrients and molecules an organism
needs are obtained from the surrounding
physical environment (air, water, soil, or another
living thing)
• They pass from one organism to the next
• Are returned to the environment through waste
products or decomposition of the dead.
• Nutrients are thus made available for use again.
CARBON CYCLE — carbon passes from physical environement to producers (e.g., plants)
to animals, to another animal (etc.) and returns to the physical env through waste and
decomposition (of dead).
Tolerance Ranges
• For every physical aspect of the
environment and for every substance
used by an organism :
– (e.g., temperature, water, wind, minerals, nutrients, pH,
etc):
– There is a minimum amount needed and a
maximum amount that can be tolerated.
– Between the minimum needed and maximum
tolerable is the “tolerance range)
Tolerance range
a simple schematic
too dry
Tolerance range
for the grass to
survive
there is enough to meet the grasses
needs, but not too much
too wet
for the grass to
survive
water
wet
dry
Competitive Exclusion
• Two species sharing the same niche
cannot co-exist forever
– because they directly compete (for resources which
reduces the amount of resources that either species successfully obtains)
– The species that is the better competitor (in a
given environment) will exclude the other
specie from existing in that same location 
this is competitive exclusion
The brown barnacle competitively excludes the gray barnacle from the lower
area even though the gray barnacle could tolerate that area
Distribution of Living Organisms across the
landscape is determined by a combination of (things
are where they are because):
• Physical factors
– specifically availability and tolerance of
physical factors
• Competition
• Predation
• Dispersal
– has the organism been able to get to an area
from its existing range
THE CENTRAL IMPORTANCE OF PLANTS
• Plants cannot move (animals can).
– Thus they are reflective of the physical conditions at a
particular area.
• They form the base of the food chain
– Biologically available energy and nutrients originate
from plants
• The type of plants in a location influences
the type of animals at that same location
– Via habitat structure and food availability (type and
amount)
• Ecosystems/communities are usually
identified by the plants groups they posses.
HOW PLANTS WORK
• OBTAINING ENERGY
• OBTAINING RESOURCES
• REPRODUCTION
HOW PLANTS OBTAIN ENERGY
• Plants make their own food with photosynthesis.
– H20 + CO2
sunlight
C6H1206 + O2
Glucose/sugar
• Glucose sugar is used as source of energy and
as a building material for most everything else
the plant needs and is made of.
• Non-photosynthetic organism get all of their
carbon and by eating plants (directly or
indirectly)
How plants obtain resources
• Obtaining water:
– from soil (except aquatic plants) by roots.
– lose water through leaves, but some water loss is
required to move it.
– roots get it, leaves lose it.
• Obtaining Sun:
– Leaves
• Obtaining carbon dioxide:
– from leaves pores called stomata, but letting CO2 in
allows water to exit.
PLANT REPRODUCTION
• Sexual Reproduction (flowers, cones, spores, etc)
• Since plants can’t move:
– their sperm needs to disperse to eggs
• animal pollinators, wind, or water)
– offspring (seeds and spores) need to disperse
away from parents
• by animals, wind, water, or “explosive propulsion”
• Asexual (roots, stem base, runners, fragments)
– Alternative reproduction includes self-fertilizing and
vegetative propagation (cloning).
Abiotic (non-living) factors affecting
the distribution of organisms
• Temperature
• Water
Large Scale
• Sunlight
• Wind
• Soil Conditions
– pH
– salt content/salinity
– sandy
– tightly packed
– organic content
Small Scale
All Organisms Face the Same
Problems
• How to get energy and nutrients (including
water).
– These are obtained from the environment
• How to cope with/respond to the physical
environment (e.g., heat, cold, wind)
• How to ____ with other organisms.
• How to reproduce.