Transcript 204FinalSG_AA_W05

- Population: individuals of same species in same general area. Has
geographic boundaries and population size. Key traits: density (individuals
per unit of area or volume) and dispersion (uniform, clumped, random).
- Demography: studies changes in population size.
Births and immigration (+); deaths and emigration (-).
- Life histories: affect reproductive output and survival rate, thus population
growth. Trade-offs between survival and reproduction. Semelparity (big-bang
reproduction), iteroparity (repeated reproduction).
- Population growth: exponential (J-shaped, idealized, occurs in certain
conditions) and logistic (S-shaped. little more realistic, carrying capacity).
K-selection. Density-dependent selection.
r-selection. Density independent selection.
- Density-dependent changes in birth and death rates usually slow
down population growth rate. Natural populations are characterized
by instability due to interaction of biotic and abiotic factors. In some
populations they result in regular boom-and-bust cycles.
-Human population growth, age pyramids, ecological footprint.
CHAPTER 52: pages 1151-1153, 1156-1171
Study Guide
1- Understand all the concepts in the guide, do not memorize the
examples.
2- Read the pages in the book to look at other examples and further
understand the concepts.
3- Study the answers to questions written by students and discussed
in class
Community. All the organisms of all the species inhabiting an area.
Plant communities apparently determined by chance occurrence of
species with similar requirements. Unclear in animal communities.
The properties and structure of a community are defined by its species
composition and the interactions between the species.
Interspecific Interactions
Competition: -/Predation (includes herbivory and parasitism): +/Mutualism: +/+ (obligatory or facultative= facilitation)
Commensalism: +/0
Key in shaping communities: competition, predation and mutualism.
Species interactions involved in determining trophic structure, dominant and
keystone species, and community control. All affect community structure.
Trophic structure. Feeding relationships between organisms. Food
chain, trophic levels and food web. Food webs have few trophic levels:
energetic and dynamic stability hypotheses.
Dominant species. Control in community due to abundance.
Keystone species. Control in community due to ecological role.
Community organization.
Bottom-up model. Changes in community structure controlled by
bottom trophic levels (competition and available food).
Top-down model. Changes in community structure controlled by
upper trophic levels (predation).
Communities are dynamic, constantly changing, due to disturbance.
Humans are the greatest agents of disturbance.
Ecological succession- Transitions in species composition over ecological
time.
Primary succession- It begins in a virtually lifeless area where soil has yet
not formed.
Secondary succession- Occurs where an existing community has been
cleared by some disturbance that leaves the soil intact.
CHAPTER 53: pages 1174-1191
Ecosystem. All the organisms living in a community AND the abiotic factors
with which they interact.
Ecosystem Dynamics
1- Energy flow
Primary production
gross and net
aquatic (light and nutrients).
terrestrial (climate and nutrients).
Secondary production
gross and net
production and trophic efficiencies
biomass and number pyramids
green world hypothesis.
2- Matter (chemical) cycling
Biogeochemical model.
Water, carbon, nitrogen.
Role of decomposers.
Vegetation regulation.
CHAPTER 54: pages 1198-1214
What is conservation biology?
Levels of biological diversity (biodiversity). genetic, species,
ecosystem diversity.
Why preserve biodiversity?
Where preserve biodiversity? Terrestrial and marine biodiversity hotspots.
Biodiversity loss and poverty are linked problems. How to
preserve biodiversity?
What are the major threats to biodiversity?
Habitat destruction and fragmentation: farming.
Introduced species.
Overexploitation.
Other human impacts: climate change
CHAPTER 55: pages 1224-1229
- Is a forest or grassland considered a uniform distribution?
- When calculating population sizes, do you count migratory species?
- Do we know the carrying capacity of the world for humans?
- When determining human population growth, do the only consider natural death
or all causes?
- In the barnacle example, are you saying that Balanus is better suited to the
environment and that if desiccation was not a problem at the higher water level,
they would force out the Chthamalus?
- Assuming two species occupy the same ecological niche, why couldn’t they both
co-exist assuming they were equally fit?
- Wouldn’t ash and other material be nutrient-rich and counted as soil, therefore
making it secondary succession?
- What happens to the rest of the light energy if only 1% is used?
- How would omnivores be classified in consumer nomenclature?
- If organic and inorganic materials are only recycled, where are they from?
- Is there any way to artificially produce photosynthesis to limit CO2?
- If we need 2,000 calories per day and maybe half go out as feces, does that
mean that we use only 10 calories for growth per day?