Biology & Geology 100
• Introduction to key biological concepts• Background for tomorrow’s field trip
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.– Living Things (biotic)
• Plants, algae, animals, fungi, microbes• All the living things of an area = community
– Non-living things (abiotic)—the physical environment• Water, temperature/heat, sunlight, wind/air, soil/minerals,
nutrients (found in air, water, & soil) etc… – Created by geological (sometimes astronomical) factors
The Natural Environment = Ecosystems:An interacting unit of living and non-living components
Abiotic = non-living• Sunlight & Heat• Air• Water• Earth
(minerals/soil)
Physical Factors
Biotic = living• Animals• Plants• Algae• Microbes
Biological Factors
Homage to Geology
• Geological forces creates diversity in landscape and abiotic variability
• Variation in the physical landscape habitat diversity habitat diversity biological diversity– opportunity for different forms of life to evolve
and co-exist
Major Ecosystem Interactions
• Energy production, transfer, and loss• Nutrient movement• Tolerance • competition • predation• Symbiosis• Ecological Succession
Energy Transfer = food chains/webs
Producers:--Plants--algae
Herbivores carnivores
consumers
Decomposers:--fungi--bacteria
Food Webs = energy and nutrient movementSun = initial source of energy
Interactions and flow within an ecosystem
Nutrient Cycling: an example showing interactions between physical environment and living things
• nutrients pass from one organism to the next through feeding and are then cycled back through the ecosystem
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 rangea simple schematic
waterwet dry
too wet for the grass to survive
too dry for the grass to surviveTolerance range
there is enough to meet the grasses needs, but not too much
CompetitionCompetition for:• Food• Shelter• Light• water• space• Mates
Competition happens:• Between individuals of same
species• Between different species
– Competitive exclusion• Influences where organisms
are located
Competitive Exclusion• Two species that compete for the same resources in the
same way cannot coexist long term
– The species that is the better competitor (in a given environment) will exclude the other specie at that location this is competitive exclusion
Tolerance range + Competitiona simple schematic
waterwet dry
Limit due to competition = competitive exclusion
too dryTolerance range for “grass”
Limit due to tolerance
Bush is better competitor in this area; excludes grass
Predation• One thing eats another (e.g., one consumer eats another)
• Energy and nutrient acquisition
seal
Distribution of Living Organisms:across the landscape is determined by a combination of
(things are where they are because) the following
• Physical factors – specifically tolerance to physical factors and
availability of abiotic resources
• Competition• Predation• Dispersal
– has the organism been able to get to an area from its existing range
Common Factors Determining Distribution (i.e., where things are found)
Found in this range
• Intolerant (too much)• Predation• Out competed
• Intolerant (too little)• Predation• Out competed
Also dispersal: is the organism or its offspring able to get to an area. If the organism is incapable of reaching an area (or has not yet reached an area) then it won’t be found there.
• Intolerant (too much)• Predation• Out competed
• Intolerant (too little)• Predation• Out competed
barrier to dispersal (no lizards here)
Major Ecosystem Interactions• Symbiosis: very/unusually close relationships among organism
Symbiosis• Particularly close relationships between two or more
organisms– Often (but not always) refers to situation when one
organism lives in or on another organism
• Mutualism
• Commensalism
• Parasitism
Host (bigger) Symbiot (smaller)
x x
• Adaptation:– A characteristic that makes an organism better suited to
its environment • better able to tolerate, compete, be a predator or escape
predation, and reproduce
Our Goal = biologically interpret/assess
1. Why is this place the way it is; why are the things that are here, here?
2. What can I tell about this place from what I see?
Niche• The role an organism plays in its environment• How an organism “makes its living”.• All the ways a species uses its physical
environment/resources and all its interactions with other living things.
• Examples of what a niche contains:– What it eats– When it eats– How it gets food– What eats it– When is it active– What wastes does it put back into the environment– What resources it needs (nutrients, space, shelter, etc)
Terrestrial Environments:it all begins with plants
Terrestrial Environments:it all begins with plants (or some other producer)
THE CENTRAL IMPORTANCE OF PLANTS (and many producers)
• They form the base of the food chain
• Plants cannot move (animals can).– they are reflective of the physical conditions at a particular area.
• The type of plants in a location influences the type of animals at that same location
• Terrestrial ecosystems/communities are usually identified by the plants groups they posses.
What is a community
• A group of species that grow together in sites that are environmentally similar
• They exist together because:– they have similar tolerance ranges– They inhabit different niches
• Don’t compete too directly
HOW PLANTS WORK• Water (from soil) + CO2 (from air) + Sunlight Sugars
• This happens mostly in leaves
photosynthesis
HOW PLANTS WORK pt 2• Plants loose water through leaves• They have to lose water to move water.
– necessary to get water to leaves for photosynthesis– But too much water loss is bad
photosynthesis
Water loss
Leaves are compromises between:
HOW PLANTS REPRODUCE• plants do it with animals or the wind…or water
How Plants Work• Seeds (with embryo) are dispersed
Asexual Reproduction in Plants:some plants do it by themselves
Plant Reproduction:asexual v. sexual
ASEXUAL• Fast• Cheap/low energy• Easy
BUT• Produces offspring that are
identical to parent
SEXUAL• Slower• Takes more energy• More risky
BUT• Produces variable offspring
that could be better adapted to current or future conditions
Abiotic (non-living) factors affecting the distribution of plants & plant communities
• Temperature
• Water
• Sunlight
• Wind
• Soil Conditions
– pH
– salt content/salinity
– sandy
– tightly packed
– organic content
– Slope aspect
Large Scale
Small Scale
Water Availability
Productive Temperature
Photosynthesis and Growth
Right temp and water amount photosynthesis food growth and reproduction
“productivity”
Within a zone, there is further fine scale variation based on:• small scale differences in water
– (creeks, ponds, slope aspect, etc…)– create Riparian zones
• temperature – (depressions, slope aspect)
• sunlight – (clearings, slope aspect, canopy shading)
• soil – (pH, sandy, gravelly, salinity, mineral, organic, nutrient levels, etc..)
• wind – (exposed or protected)
Increasing Altitude =• Decreasing Temperature (~3 deg. F per 1000’)• More rain/water (precipitation, but….)• Shorter growing seasons
Hotter
Colder
Slope Aspect: North v. South
Slope Aspect: east v. west
Chaparral Biome
Mediterranean Climate & Chaparra Biome• Mid-latitude (30 deg), coastal regions
• Sea level – ~5500’
• Seasonal precipitation– Precipitation 8-20”, mostly in winter (Dec – Mar)– Prolonged period of drought (~Apr-Nov) – Rain/precipitation highly variable from year to year.
• Seasonal Temperatures– long dry summers 80-100+ F– spring, winter, fall cool– winters moderately cold in coastal regions, but higher elevation can
experience frost and small amounts of snow
In more coastal regions:• Santa Ana winds in summer (hot and dry)• fog, mist, marine layer in some seasons
Common Communities of the Mediterranean Climate in So.CA• Sage scrub
– Closer to coast, lower elevations– 8-10” of rain per year, but with moderate temperatures– sub-shrub dominant– drought deciduous– frost intolerant– Types
• Coastal• Inland• succulant
• Chaparral (true/hard chaparral)– More inland, higher elevations– Wetter (~15-20” of rain)– shrub dominant– Generally evergreen dominant– frost tolerant – snow tolerant– Types:
• Lower v. Upper v. maritime v. desert• Chamise v. mixed
• Oak woodland• Riparian
– Mesic community in canyon bottoms (and where water is more abundant)• Grassland• Conifer Forest
Hwy 2 Field trip
• Changes with altitude• Changes with slope aspect• Changes due to localized water availability—
i.e., permanent water/streams• Effects of fire?
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