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?