ECOLOGY - Frontier Central School District · 2018-08-08 · 6 Mutualism is a symbiotic relationship in which both the host and the symbiont benefit Types: • Resource-resource interactions

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ECOLOGY

Table of Content

Biotic and Abiotic Factors ….............................................................. 2

Ecological Succession ….............................................................. 3

Energy Flow in Ecosystem ….............................................................. 4

Interspecific Interactions ….............................................................. 5

Levels of Organization in Ecology ….............................................................. 6

Terrestrial and Aquatic Biomes …............................................................. 7

Quiz …............................................................ 13


Biotic and Abiotic Factors of the Environment Biotic factors are all the living organisms that inhabit an environment. Abiotic factors are the nonliving parts of an organism’s environment. Important Abiotic Factors 1. Temperature

• Cells may rupture if the water they contain freezes at temperatures below 0oC. • Proteins of most organisms denature at 45 oC. Denaturation refers to the disruption of the

secondary and tertiary structure of proteins. • Few organisms can maintain a sufficiently active metabolism at extreme temperatures.

2. Water • Availability varies dramatically among habitats. • Aquatic organisms face problems of water balance if their intracellular osmolarity do not match

that of the surrounding water. • Terrestrial organisms encounter the constant threat of desiccation.

3. Sunlight • Sunlight provides energy that drives nearly all ecosystems. • Shading by a forest canopy makes competition for light in the understory intense. • Intensity and quality of light limit the distribution of photosynthetic aquatic organisms. • Photoperiod is a more reliable indicator for cueing seasonal events than temperature (e.g.

flowering and migration) 4. Wind

• Amplifies the effects of environmental temperature on organisms by increasing heat loss due to evaporation and convection (the wind-chill factor) It refers to the combined effect of evaporation, convection and wind speed on organisms.

• Has substantial effect on the morphology of plants by inhibiting the growth of limbs. 5. Rocks and Soil

• Physical structure, pH and mineral composition of rocks and soil limit the distribution of plants and animals that feed upon them.

• Affect water chemistry. • Determine the types of organisms that can attach or burrow in the intertidal zones and seafloors.

6. Periodic Disturbances • Catastrophic disturbances like fires, hurricanes, tornadoes, and volcanic eruptions can devastate

biological communities. • Can introduce succession.


Ecological Succession Ecological succession is the orderly natural change and species replacement that take place in the communities of an ecosystem. This occurs in stages; different species at different stages create conditions that are sustainable for some organisms, while unsustainable for others. Succession can take decades, or even centuries, for one type of community to completely succeed another. Primary Succession

Lava flowing from the mouth of a volcano is hot; it destroys everything in its path. However, it forms new land when it cools it. This colonization of new sites by communities of organisms is called primary succession. The first species in the area are called pioneer species. After some time, primary succession slows down, and after many changes in species composition, the community becomes fairly stable. This stable, mature community that undergoes little or no change in species is called a climax community. Secondary Succession Secondary succession refers to the sequence of community changes that takes place after a community is disrupted by natural disasters or human actions. During secondary succession, like in primary succession, the community of organisms inhabiting an area gradually changes. However, the difference of secondary succession is that it occurs in areas that previously contained life and on land that contains soil. Therefore, the pioneer species involved in the two successions are different, but the same climax community will be reached in areas with similar climate. Secondary succession takes less time than primary succession because soil is already present. Causes of Succession

1. Autogenic succession is caused by the alteration in soil nutrients and pH due to an organism’s activities. Example: Large trees serve as shade to the developing forest floor that is disadvantageous to the light-requiring species. Thus, shade-tolerant species will inhabit the area)

2. Allogenic changes is induced by external environmental causes and not by the vegetation. Example: Soil changes due to erosion, leaching or the deposition of silt and clays can change the nutrient content and water interactions in the ecosystems.

3. Climatic factors, such as significant changes in temperature and precipitation will cause changes in ecological communities. Example: At the end of the ice age, the climate became warmer therefore succession took place. The tundra biomes and bare glacial till deposits went through succession and became mixed deciduous forest.


Energy Flow in Ecosystems Food chain is the pathway of energy transfer in the different trophic levels of the ecosystem.

Producers • The trophic level that ultimately supports all others. • Consist of autotrophs, which are photosynthetic

organisms that use solar energy to produce sugars and other organic compounds.

• These products of photosynthesis (sugars and other organic compounds) fuel cellular respiration and are used as building material for growth.

Consumers

• Consist of heterotrophs that directly or indirectly depend on photosynthetic products of the producers.

1. Primary consumers: herbivores that eat plants or

algae 2. Secondary consumers: carnivores that eat

herbivores 3. Tertiary & quaternary consumers: carnivores

that eat other carnivores Decomposers

• Consist of detritivores. • Derive their energy from detritus or organic waste

such as feces or fallen leaves and remains of dead organisms from other trophic levels

A general energy flow scenario


Interspecific Interactions Predation refers to an interspecific interaction wherein a predator (an organism that pursuits other organisms) eats its prey (the organism that is assaulted).

Types: • True predation. A true predator kills and eats another organism, which results to the death of

the prey. Predators may hunt actively for prey, or ambush predators by sitting and waiting until the prey is within their reach.

• Grazing. In this case, the grazing organisms may or may not kill their prey. An example of this is the zooplankton that feeds on phytoplankton. The zooplankton may eat only a small portion of the phytoplankton’s body. This, nevertheless, may cause the phytoplankton’s demise.

• Parasitism. A symbiotic relationship in which the symbiont (parasite) benefits at the expense of the host by living either within the host (endoparasite) or outside the host (ectoparasite).

• Parasitoidism. Parasitoids are organisms that inhabit their host. They eat their host, leading to the host’s death.

Competition happens when two or more species in a community rely on a similar but limited resource.

Types:

• Interference Competition exists when there is actual fighting over resources. • Exploitative Competition is the consumption or use of similar resources.

Commensalism is a symbiotic relationship in which the symbiont benefits but the host is neither helped, nor harmed.

Types:

• Phoresy occurs when the symbiont attaches itself to the host for transportation purposes. This can either be obligate or facultative (i.e., induced by environmental conditions). • Inquilinism takes place when the symbiont lives on the host (e.g. birds living on trees). • Metabiosis this is an indirect dependence wherein the organism B uses something created by

organism A, but only after organism A dies (e.g. hermit crabs use gastropod shells to protect their bodies).


Mutualism is a symbiotic relationship in which both the host and the symbiont benefit

Types: • Resource-resource interactions. A trading of resources exists. (e.g. mycorrhizal associations

between plant roots and fungi, with the plant providing carbohydrates to the fungus in return for primarily phosphate but also nitrogenous compounds).

• Service-resource relationships. A resource is traded for a service (e.g. pollination wherein the nectar or pollen, or food resources, are traded for pollen dispersal, a service).

• Service-service relationships. A service is traded for another form of service (e.g. anemones and the fish protect each other from predators).

Interaction Effect on Species 1 vs. Effect on Species 2

Effects on Population Density

Predation (+/-) The interaction is beneficial to one species but detrimental to the other.

Competition (-/-) The interaction is detrimental to both species. Commensalism (+/0) One species benefits from the interaction, while the

other is unaffected. Mutualism (+/+) The interaction is beneficial to both species.

Levels of Organization in Ecology The main levels of organization in Ecology are as follows:

1. Individual is any living organism that is limited by the environmental abiotic factors.

2. Population is a group of organisms of one species that interbreed and live in the same place at the

same time. 3. Community is a collection of interacting populations. 4. Ecosystem is made up of the interactions among the populations in a community and the

community’s physical surroundings, or abiotic factors. 5. Biosphere is the whole area of the Earth inhabited by living organisms. It is the collection of all

ecosystems on Earth.


Terrestrial and Aquatic Biomes Biomes are the world’s major communities; they are classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment. Terrestrial Biomes Tropical forests

• Found near the equator, where photoperiod and temperature are nearly constant.

• Most species live in rich terrestrial biomes.

Savanna

• Tropical grassland with scattered trees. • Precipitation varies greatly between wet and dry

seasons.

Deserts

• Arid biomes • Extreme in temperature • Very low precipitation


Chaparral

• Consists of scrublands, usually found along coastlines. • Encounters mild, rainy winters and long, hot, dry

summers.

Temperate Grasslands

• Present in relatively cool climates with nutrient-rich, deep soils.

• Periodic fires and drought inhibit the growth of woody shrubs and trees.

Temperate Deciduous Forests

• Occur in mid-latitudes, wherein sufficient moisture supports the growth of large, broad-leaf deciduous trees.


Taiga

• Consists of dense, coniferous forests. • Long, old, snowy winters and short summers.

Tundra

• Occurs in the northernmost limits of plant growth at high latitudes.

• Growth of plant forms is limited by cold temperature and wind to a low shrubby or mat-like morphology.

Aquatic Biomes


Lakes

• Classified on the basis of their nutrient content and productivity. • Euphoric lakes are nutrition-rich. • While oligotrophic lakes are nutrient-poor.

• Temperate lakes turn over twice a year, mixing oxygen and nutrients that were stratified as a result of the thermocline.

Rivers and streams

• Comprised of freshwater communities that change significantly from the source to the final destination (ocean or lake).

• Upstream areas contain organisms associated with clear water, cool temperatures, and rocky substrates.

• Downstream organisms can tolerate murkier water and warmer temperatures.

Wetlands

• Range from having periodically flooded to permanently saturated soil.

• Contain hydrophytes or adapted plants, which can grow in water or soil, and are periodically anaerobic.

• They can either be freshwater wetlands or marine wetlands.


Estuary

• The transition zone between a river or stream and the ocean, into which it empties.

• Large fluctuations in salinity occur. • Supports an abundance of both aquatic and semi-aquatic

organisms.

Rocky Intertidal Zone

• A vertically stratified biome found on ocean shorelines. • Periodically inundated by seawater. • Organisms in the uppermost zone, which are frequently

exposed to air and sun, continually adapt to prevent desiccation and overheating.

Coral Reefs

• Found in nutrient-rich and warm tropical waters. • Skeletons of coral animals form complex structures

among which a diverse number of invertebrates and fishes live.


Oceanic Pelagic Zone

• Includes most of the open ocean. • Phytoplankton and zooplankton occupy the upper layers.

Benthic Zone

• The ocean bottom below the pelagic zone. • Occupied by communities of organisms called benthos,

which subsist largely on detritus than “rains” down from the pelagic zone.


QUIZ

ECOLOGY I. Fill in the Blanks.

The five levels of organization in ecology are as follows: 1. 2. 3. 4. 5. Few organisms can maintain a sufficiently active metabolism at extreme ______________. Intensity and quality of __________ limit the distribution of photosynthetic aquatic organisms. ________ and ________determine the types of organisms that can attach or burrow in the intertidal zones and seafloors. Stable, mature community that undergoes little or no change in species is called a _________________. ____________________ refers to the sequence of community changes that takes place after a community is disrupted by natural disasters or human actions. ____________________ is caused by alteration in the soil nutrients and pH due to organism’s activities. These products of ____________ (sugars and other organic compounds) fuel cellular respiration and used as building material for growth ____________ derive their energy from detritus or organic waste such as feces or fallen leaves and remains of dead organisms from other trophic levels.


Interaction Effect on Species1 vs.

Effect on Species 2 Effects on Population Density

Predation (+/-) The interaction is beneficial to one species but detrimental to the other.

____________ (+/+) The interaction is beneficial to both species. Commensalism (+/0) One species benefits from the interaction, while the

other is unaffected. ____________ (-/-) The interaction is detrimental to both species.

____________ are the world’s major communities, classified according to the predominant ____________ and characterized by adaptations of organisms to that particular environment. II. Identify the following terrestrial and aquatic communities:

_________________________


____________________

_____________________


________________________

III. Essay. Differentiate primary and secondary succession.

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ECOLOGY - Frontier Central School District · 2018-08-08 · 6 Mutualism is a symbiotic relationship in which both the host and the symbiont benefit Types: • Resource-resource interactions