Source: Mader and Windelspecht. 2012. Essentials of Biology.
Ecology
Ecological Leves of the Biological Levels of Organization
-- study of relationships (interaction) between organisms and the environment -- both living and non-living (including energy flow, and nutrient recycling).
-- levels of ecology: Population ecology, Community ecology, Ecosystem ecology, Biosphere ecology
These notes takes an ecosystem approach, but ecology has a hierarchical nature -- including studies of individuals of the same species living in the same place at the same time (population ecology), multiple populations living together and interacting (community ecology), complex interactions over small or large different geographic regions -- including both living organisms and the abiotic world -- including studying energy flow and nutrient cycling (ecosystem ecology), and the whole planet (biosphere).
Terms
The map above illustrates the major biomes on Earth -- a grouping of globally distributed terrestrial or aquatic ecosystems, defined by climate and geology -- with distictive fauna and flora. Climate and geology has changed during the evolutionary history of Earth, and therefore also fauna and flora in particular areas.
Migration of human populations thousands of years ago. (Source: http://www.globalchange.umich.edu/gctext/Inquiries/Inquiries_by_Unit/Unit_5.htm. )
Human Evolutionary Tree. (Source: Old version of Biology by Sylvia Mader.)
Climate change affects ecosystems, which change the distribution of organisms, affecting the factors that we call "selective pressures". When humans migrated out of Africa the biomes were about the same as today. One must go further back in time to see major changes. Human evolution is an example of how local climate change played an importan role in human evolution -- in eastern Africa -- where natural selection favored genetic traits that made us to the species we are today. (See Learning Resource 09) or the Human Origins web page at California State University, Fullerton (link to the right).
Continental Drift. When continents move to differen latitudes on the planet, the climate change -- and thereby the ecosystems on the affected continents.
Earth 555 million years ago. (Source: Click on the figure.)
Earth today. (Source: Click on the figure.)
Earth 200 million years ago. (Source: Click on the figure.)
(Source: Click on the figure.)
Continental Drift. Alfred Wegner proposed that all present day continents were once part of a single continent (Pangaea). Over time, these continents drifted apart. The idea is based on based on; 1) the near perfect fit of the continents (especially along the Atlantic, 2) Common glaciation in the southern landmasses (South America, Africa, Madagascar, India, Australia, and Antarctica), 3) Similarities in rocks and fossils on continents separated by oceans.
(Source: Click on the figure.)
Human Evolutionary Tree. (Source: Old version of Biology by Sylvia Mader.)
Life forms living in different land mass over the last 560 million years. Plate tectonics makes oceans open and close, mountains rise and fall and continents collide or move apart. When these supercontinents slowly break up, separating landmasses evolution move faster, forming new species which colonize the new habitats. A tectonic plate, can move a continent from a tropical to a polar latitude, where the organisms will experience new patterns of competition and changing ecosytems.
Town Hall Meeting reminder...
Teach Both Sides Addendum: Continental Drift is just a theory?? Alternative ideas?
This is a very important message from the former Bishop...
For the record:
The "other side" want "the Great "Biblical" Flood to be taught in school. This instructor does not agree with that -- of course, but I for one am willing to at least provide some "CRITICAL THINKING" material about it -- hence the assignment called "Town Hall Meeting".
Streamed live on Feb 4, 2014
Is creation a viable model of origins in today's modern, scientific era? Leading creation apologist and bestselling Christian author Ken Ham is joined at the Creation Museum by Emmy Award-winning science educator and CEO of the Planetary Society Bill Nye.
Let the discussion continue in the Town Hall. Now back to ecology and the real world...
Ecosystems
Biotic Structure (living parts of the environment)
Abiotic Structure (non-living parts of the environment)
BIOTIC STRUCTURE
Categories of Organisms
Feeding Relationships
(We will ignore the non-feeding relationships -- usually covered in Community ecology)
CATEGORIES OF ORGANISMS
Ecological pyramid of organisms (Source: http://www.vtaide.com/png/foodchains.htm)
Producers
Consumers
A. Producers
All ecosystems (with a few exceptions) must have an input of energy from the sun!
SUN >>>> ORGANISMS (dead or alive) >>>> HEAT
First Law of Thermodynamics: (Law of conservation of energy) Energy can neither be created nor destroyed. It may change from one form to another, but the energy in a closed system remains constant.
Second Law of Thermodynamics:When energy is transferred, there will be less energy available at the end of the transfer process than at the beginning -- ultimately forming heat. (This is also commonly referred to as increase of entropy.)
1.Energy is a "one way process". Energy flows one-way through an ecosystem, with less and less available useful energy after each "exchange" (e.g., when an animal eat a plant or another animal -- see "food chain").
e.g., Food chains (lose available energy as heat)
Producer >>> Consumer >>> Another consumer
2.In living systems only producers (Autotrophs -- plants, algae, cyanobacteria) can make use of the sunlight, so a food chain must always start with a producer ("plant"). In real life all "food chains" link to form complex "food webs"
Eventually, by time, all energy will be converted to heat (ultimately that will destroy the universe...)
Organisms that can use energy from the sun directly: Autotrophs -- self-feeders
def. Autotrophs: organisms capable of producing its own food from inorganic materials & sunlight.
In ecological terminology these are called: Producers
- Photosynthesis
def. Producers: organisms that obtain energy from sunlight by photosynthesis
def. Photosynthesis: the conversion of light energy to chemical energy (stored in glucose produced) from carbon dioxide and water.
Organisms that cannot use the sun directly -- must feed on something: Heterotrophs
def. Heterotrophs: organisms incapable of producing its own food, and therefore depend directly or indirectly on producers to
meet their food requirements.
In ecological terminology these are called: Consumers
def. Consumers: organisms that obtain energy by feeding on the tissues of other organisms.
- - - - - - - - - - - - - - -
Various kinds of consumers:
General types:
def. Herbivores: animals feeding on plants.
def. Carnivores: animals feeding other animals.
def. Omnivores: animals feeding both on plants and other animals.
def. Decomposers: organisms that use dead organic matter as a source of energy (organisms whose feeding actions results in decay or rotting of organic material (mainly fungi and bacteria).
def. Scavengers: animals that feed on food left by other animals.
def. Parasites: Ecological relationship between two organisms where only one organism benefits, by deriving nourishment from the other, without killing it (at least not immediately) but usually doing harm to it.
FEEDING RELATIONSHIPS
A. Food Chains (Interconnecting paths of energy flow)
Producers and consumers are connected by food chains.
(usually in 3 or 4 links)
def. Food chains: A sequence of organisms that feeds on one another, resulting in a flow of energy from a producer through a series of consumers (flow of energy as each one feeds upon the next).
ii. Detrital Food Chain (Energy from dead organic matter):
Decomposer (producer of detritus) - Detritus feeder - Carnivores
fungus - earthworm - beetle
soil bacteria - earthworm - beetle
B. Trophic Levels (Feeding levels in a food chain) Each step in a food chain is known as a trophic level ("FEEDING LEVEL")
A trophic level is composed of all organisms that feed at a particular link in a food chain.
def. Trophic levels: a step (feeding level) in the flow of energy through an ecosystem (Organisms that photosynthesize are at the first trophic level, organisms that feed on first trophic level organisms are at the second level.)
1st trophic level:Producers -- AUTOTROPHS
algae
2nd trophic level:Herbivores (primary consumer) -- HETEROTROPHS
small fish
3rd trophic level:Primary carnivores(secondary consumer) -- HETEROTROPHS
big fish
Blackpoll Warbler, migration route... Click on the figure for source.
D. Energy Flow Through Ecosystems
Energy flows into the food webs of ecosystems from an outside source -- usually the sun.
Energy flow is a one-way system and leaves ecosystems as
1. waste(dead tissue, urine, feces) 2. heat(metabolic heat generated by the organisms)
The amount of useful energy flowing through the food web (consumer trophic levels) declines at each energy transfer.
(Each time energy passes from one trophic level to the next, 90% of the energy is lost as
-- heat, or waste.
E. Ecological Pyramids
Ecosystems usually have a larger producer base -- more 'plants'
Only about 90% of the energy of one trophic level is NOT available at the next trophic level. An ecosystem can be illustrated a a pyramid. A pyramid is broad base, necessary to support the upper levels of the structure.
i. Energy Pyramid -- Energy losses between trophic levels result in pyramids based on amount of energy available.
ii. Number Pyramid
-- Energy losses between trophic levels result in pyramids based on number of organisms that can feed at each level. (Some exceptions exist.)
iii. Biomass Pyramid
-- Energy losses between trophic levels result in pyramids based on biomass (dry weight of a collection of designated organisms).
Ecological pyramid of organisms (Source: http://www.vtaide.com/png/foodchains.htm)
At each level of the pyramid there is a 90% loss of energy:
Producer - Herbivore - Carnivore (or Omnivore)
grass - cow - human
ABIOTIC STRUCTURE
Biotic factors: living parts of the environment Abiotic factors: nonliving part of the environment
i. Climate (rain, temperature, wind, light) ii. Chemistry (minerals, pH, salinity) iii. Topography (physical barriers) iv. Environmental events (fire, volcanic eruptions)
ECOLOGICAL SUCCESSION (Community change over time)
def. Succession: Gradual changes in the structure of a community, due to some abiotic change, ultimately leading to a climax community.
- - - - - - - - - - - - - - -
def. Primary succession: Ecological succession to a climax ecosystem in an area that has not been occupied before (e.g., rock face).
def. Secondary succession: Ecological succession to a climax ecosystem in an area that has been occupied before (e.g., an area that has been cleared).
def. Climax community: Last stage of succession, a relatively stable long-lasting community of organisms.
def. Climax ecosystem: An ecosystem with a climax community, the last stage in ecological succession. (An ecosystem in which populations of all organisms are in balance with each other and with existing abiotic factors. The biomes are climax ecosystems for their particular areas.)
def. Pioneer species: Early colonizer of barren or disturbed habitats that usually has rapid growth and high dispersal rate.
def. Fire climax ecosystems: Ecosystems that depend on the recurrence of fire to maintain balance.
def. Aquatic succession: Ponds and lakes gradually filled in and invaded by the surrounding land ecosystem.
def. Immediate disturbance hypothesis: moderate disturbance is required for a high degree of community diversity.
--- CLIMAX VEGETATION
Ecological communities change over time. In primary succession a new community form where no community previously existed (e.g. a new island, or bare rock after a volcanic event -- the first species to invade is called a pioneer species); in secondary succession the types of species change after a disturbance in the area (e.g. after a forest fire, or agriculture), with some soil and life remaining.
Succession often leads to a climax community, which is a community that remains fairly constant as long as climate does not change or a major disturbance does not occur. The climax community is often a type of forest.
Source: Mader and Windelspecht. 2012. Essentials of Biology.
BIOMES
Source: Mader and Windelspecht. 2012. Essentials of Biology.
Present day biomes. (Source: Mader, Biology.)
A. Biomes (Terrestrial size communities)
A biome is characterized by the climax vegetation adapted to living under certain environmental conditions.
The distribution of the biomes can be described as bands going east - west along the latitudinal gradients of the planet. However, there is no definite demarcation but rather a gradual change from one biome to another. Also, the bands are irregular, affected by altitude (mountains) which change the climate expected at certain latitudes (mainly temperature and rainfall).
Some biomes are more productive than others -- the Tropical rainforest and Coral reefs are the two most productive biomes/ ecosystems.
END OF NOTES!
(Source: Dr. Nilsson's old lecture notes. Permission given in 2001 by McGraw-Hills then sales representative, Don Grainger, to use the picture online on lecture notes.)