Biology Ii: Final - Ch. 52 Intro To Ecology And The Biosphere

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What is Ecology?

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Greek = oikos, home
- Study of interactions between organisms and environment

Q's to ask:
- factors limiting geographic distribution?
- How do variations in their food supply or interactions w/ other species, such as pathogens affect size of pop?

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Ernest Haeckel (1869)
Definition of Ecology

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Total relations of the animal to both its organic and inorganic environment

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Avila's Favorite Definition of Ecology

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Charles Krebs (1972)

- Scientific study of the interactions that determine the distribution and abundance of organisms

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Levels of Ecological Orgnization

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- Individual: biological entity with a unique genotype, capable of growth, maintenance, and reproduction (ie, productions of more such entities)

- Population: group of individuals of the same species living in a certain area at a certain time.

- Community: Assemblage of individuals of diff species living in certain area at a certain time.

- Ecosystem: A biological community plus all of the abiotic factors influencing and being influenced by that community

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What is the most significant influence on distributions of organisms on land and ocean?

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A: Climate - long term prevailing weather conditions in a given area
- Four physical factors: Temp, precipitation, sunlight, and wind

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What is: Macroclimate?

What is: Microclimate?

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- Macroclimate: patterns on global, regional, and landscape level

- Microclimate: very fine localized patterns, such as those encountered by community of organisms that live in the microhabitat beneath a fallen log.

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Climate Latitude

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Latitude is main determinant of climate; incidence of solar radiation
- Global atmospheric circulation patterns
- Temperature and precipitation
- Ocean currents
- Regional Influences: (altitude and topography) & (Proximity to lakes and oceans)

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Global Climate Patterns
- what are global climate patterns determined largely by?

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- input of solar E and Earth's movement in space

> Sun warms atmosphere, land, and water
> warming establishes temp variations, cycles of air and water movement
> Evap of water causes dramatic latitudinal variations in climate

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Climate patterns can be modified by many factors, including? (3)

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- seasonal variation in climate
- large bodies of water
- mountain ranges

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Seasonality

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- earths axis of rotation, and revolving around the sun cause seasonal cycles in middle to high latitudes
- changes: day length, solar radiation, temp

- belts of wet & dry air on either side of equator move slightly north & south w/ changing angle of the sun > producing wet and dry seasons 20 degrees north & south latitude, where many tropical deciduous forests grow
- seasonal wind patterns alter ocean currents, causing upwelling of cold water from deep ocean layers, which stimulates grown of surface dwelling phytoplankton.

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Bodies of water

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- Ocean currents heat or cool overlying air masses that pass over land
- Coastal regions are generally wetter than inland areas of same latitude - supports rain forest ecosystem.
- large lakes moderate climate of nearby land
- hot day, air over land heats up rises, drawing cool breeze from water > vice versa at night, cooling water and warming up land.

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Mountains

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- influence air over land
1) cool air comes inland from water, moderating temp near shore
2) air encounters mountains flows upward, cools at higher altitudes, releases rain and snow
3) less moisture left in air, leeward side therefore has little precip. Rain shadow can create a desert.

- Can also affect amt of sunlight. South-facing slopes rec'v more sun than north facing.
- this can also affect species of plants.

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Biomes

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Major regions characterized by
- vegetation: terrestrial biomes
- PHysical conditions - aquatic biomes

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Climate and Terrestrial Biomes

- What is one way to highlight the importance of climate on the distribution of biomes?

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- Construct a Climograph: annual mean temp and precipitation in a particular region.
- Factors other than mean Temp and Precep also play a role in determining where biomes exist
> some areas may rec'v reg precip, some areas have distinct wet and dry seasons.
- also Abiotic characteristics may affect mineral nutrient availability (bedrock in an area), which may affect what kind of vegetation may grow.


- terrestrial biomes show strong latitudinal patterns in where they are found.

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General Features of Terrestrial Biomes

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- most named for major physical or climatic features and for their predominant vegetation.

- also characterized by microorganisms, fungi, and animals adapted to that particular environment.

- Terrestrial biomes grade into each other, without sharp boundaries - area is called Ecotone (may be wide or narrow)

- Vertical layering is a feature, shapes and sizes of plants define layering
- eg) forests, layers from top to bottom consist of upper canopy, low-tree layer, shrub understory, ground layer or herbaceous plants, forest floor (litter layer) and root layer

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Disturbance and Terrestrial Biomes

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- Disturbance is an event such as a storm, fire, human activity that changes a community, removing organisms from it and altering resource availability

- result of disturbances, biomes often exhibit extensive patchiness, w/ several diff communities represented in a single area.

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Exploring Terrestrial Biomes

- Different types of Biomes

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1) Tropical Forest
2) Desert
3) Savanna
4) Chaparral
5) Temperate Grassland
6) Northern Coniferous Forest
7) Temperate broadleaf forest
8) Tundra

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Aquatic Biomes

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- Characterized by their physical environment
- less latitudinal variation

- Ecologists distinguish between freshwater and marine biomes on basis of physical and chemical diff.
- Marine biomes have salt concentrations that avg 3%
- Freshwater biomes have less than 0.1% salt concentrations

- Water evaporated from oceans provides most of the planet's rainfall, and ocean temp have a major effect on the global climate and wind patterns
- Marine algae and photosynthetic bacteria supply a substantial portion of world's 02 and consumes large amts of atmospheric C02.

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Zonation in Aquatic Biomes

- Photic Zone / Aphotic Zone
- Pelagic Zone
- Abyssal Zone
- Benthic Zone

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- Aquatic biomes are physically and chemically stratified vertically and horizontally.
- light absorbed by water itself and by photosynthetic organisms, so its intensity decreases rapidly w/ depth

- Photic Zone: upper layer where there is sufficient light for photosynthesis
- Aphotic Zone: little light penetrates
- Pelagic Zone: photic and aphotic zones together make up Pelagic Zone.

- Abyssal Zone: deep in aphotic zone, part of ocean 2,000-6,000m below surface
- Benthic Zone: bottom of all aquatic biomes (deep or shallow). Made up of sand and organic and inorganic sediments
> made up of communities or organisms called Benthos
> food source is dead organic matter called Detritus, which "rains" down from productive surface waters of photic zones.

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Zonation in Aquatic Biomes

- Thermocline
- Turnover

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- Thermocline: layer of abrupt temp change, separates the uniformly warm upper layer from uniformly cold deeper waters.

- Turnover: temperate lakes undergo semiannual mixing of their waters, as a result of temp change. Exchanges oxygenated rich water from surface to bottom, and nutrient rich bottom water to the top.
> essential for survival and growth of organisms at all levels

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Exploring Aquatic BIomes

- Types of Aquatic biomes

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1) Lakes
2) Wetlands
3) Streams and Rivers
4) Estuaries
5) Inertidal Zones
6) Oceanic Pelagic Zone
7) Coral Reefs
8) Marine benthic Zone

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Biotic Interactions

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- Apart form physical conditions (temp, precip, winds, exposure, pH, salinity, sunlight, oxygen concentration, etc) species distribution is limited (partially determined) by interactions among species:
> competition
> Predation
> Mutualism

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52.4 Interactions between organisms and the environment limit the distribution of species

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- species distributions are a consequence of both ecological and evolutionary interactions through time

- Differential survival and reproduction of individuals that lead to evolution occur in ecological time

- Through natural selection, organisms adapt to their environment over time frame of many generations, in evolutionary time.
(eg: galapagos finches)

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What do ecologists focus on when finding out: where, why species occur, and what factors determine distribution?

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Ecologists focus on both biotic and abiotic factors that influence the distribution and abundance of organisms

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52.4 Interactions between organisms and the environment limit the distribution of species
Dispersal And Distribution

- factor that contributes to global distribution of organisms?

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Dispersal greatly contributes to distribution of organisms.
- Dispersal is the movement of individuals or gametes from their area of origin or centres of high pop density.
- biogeographer may study why there are no kangaroos in N.A
- dispersal of organisms is critical to understanding role of geographic isolation in evolution, as well as broad patterns of species distribution today

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Population Ecology

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- Species distribution, partly determined by how fast individuals can reproduce, how many survive, and whether they disperse far away or not
- These are pop processes, and are determined by:
> fecundity
> survival / mortality
> growth rates
> patterns of spatial distribution

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52.4 Interactions between organisms and the environment limit the distribution of species

Natural Range Expansions and Adaptive Radiation

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- Importance of dispersal is most evident when organisms reach new area they didn't exist previously
(eg, cattle egret, orginated in africa, then went, S.A, then N.A
- long distance dispersal can lead to adaptive radiation, rapid evolution of an ancestral species into new species that fill many ecological niches

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52.4 Interactions between organisms and the environment limit the distribution of species

Species Transplants

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- Intentional or accidental transplants of the species to areas it previously was absent
(determines if dispersal limits distribution)

- Successful transplants, species must survive and reproduce sustainably.

- if successful, can conclude that potential range of species is larger than actual range
(species could live in areas, it currently doesn't)

- new intro'd species can disrupt communities and ecosystems
- ecologists document the outcome when a species has been transplanted for other reasons: introduce new game animals or predators of pest species, or when a species has been accidentally transplanted.

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52.4 Interactions between organisms and the environment limit the distribution of species

Biotic Factors

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- Do biotic factors limit distribution of species?
- Negative interactions w/ predators or herbivores restrict ability of a species to survive and reproduce.
(sea urchin and Limpet vs. Seaweed growth)

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52.4 Interactions between organisms and the environment limit the distribution of species

Abiotic Factors

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- abiotic factors: temperature, water, oxygen, salinity, sunlight, or soil might limit species distribution

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52.4 Limiting Species Distribution

Abiotic Factor: Temperature

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- Temp has effect on biological processes
- Most organisms function best w/in a specific range of environmental temperature.
- Temp outside range may force abnormal energy expenditure, regulating internal temp.

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52.4 Limiting Species Distribution

Abiotic Factor: Water and Oxygen

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- Species living at seashore or in tidal wetlands can dry out as the tide recedes
- Terrestrial organisms can possibly dry out, distribution of terrestrial species reflects their ability to obtain and conserve water

- Water affects oxygen availability in aquatic environment and in flooded soils
- Oxygen diffuses slowly in water, its concentration can be low in certain aquatic systems, soils, limiting cell respiration
- 02 concentrations can be low in deep waters, and in flooded wet land soils.
- mangroves and other trees have specialized roots that project above water and help root system obtain oxygen
- Surface waters of streams are well oxygenated because of rapid gas exchange

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52.4 Limiting Species Distribution

Abiotic Factor: Salinity

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- Salinity affects the water balance of organisms through osmosis
- most aquatic organisms are restricted to either fresh or saltwater, by their limited availability to osmoregulate
- most terrestrial organisms excrete salts through special glands, or through urine and feces.
- salt flats and other high salinity habitats have few species of plants or animals

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52.4 Limiting Species Distribution

Abiotic Factor: Sunlight

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- affect photosynthesis, too little can limit distribution of photosynthetic species
- Treetop shading makes competition for light intense between seedlings on the forest floor.
- In water, every meter of water depth selectively absorbs about 45% of red light, and 2% blue light
- More photosynthesis in water happens near the surface.

- Too much light can increase temp. stress in animals and plants that are unable to avoid light or to cool themselves through evap.
- At high elevations, sun can damage DNA and proteins because air is thin, absorbing less UV radiation.
- UV Radiation + other abiotic stress presents trees surviving at high altitude.

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52.4 Limiting Species Distribution

Abiotic Factor: Rocks and Soil

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- In terrestrial environments: the pH, mineral composition, and physical structure limit distribution

- pH can limit distribution directly: through extreme acidic or basic conditions
- pH limit indirectly: by affecting the solubility of nutrients and toxins.

- In water, rocks and soil that make up the riverbed can affect water chemistry, which influences resident organisms.
- The structure of the substrate determines the organisms that can attach to it or burrow into it.