Unit 1 + 2 Review Book Flashcards
(28 cards)
Ecosystems
Ecosystem is a system of interconnected elements: a community of living organisms and its environment
Includes both biotic (living) and abiotic (nonliving) components
Ecosystems are the result of the biotic and abiotic components interacting
Biotic components - life - require resources to flourish, and the availability of those resources influences the interaction between species and their interactions their environments
Over time, the most fundamental interaction between ecosystems is that of evolution – which produces life as we know it
Organisms
A species is defined as agroup of organisms that ar capable of breeding with another – and incapable of breeding with other species.
As you may recall, individual organisms that are better adapted for their environment will live and reproduce, ensuring that their genes are part of their population’s next generation.
This si what Charles Darwin meant by evolutionary fitness.
Natural selection
When a habitat (an organism’s physical surroundings) selects certain organisms to live and reproduce and others to die, that population is said to be undergoing natural selection.
In natural selection, beneficial characteristics that can be inherited are passed down to next generation, and unfavorable characteristics that can be inherited become less common in the population.
Any cause that reduces reproductive success (fitness) in a portion of the popular is selective pressure, and these are what drive natural selection.
It is important to remember that natural selection acts upon a whole population, not on an individual organism during it lifetime.
What changes during evolution is the total genetic makeup of apopulation, or gene pool, and natural selection is one of the mechanisms by which evolution operates.
The other way evolution operates is genetic drift.
Genetic Drift
Genetic drift is the accumulation of changes that occur as a result of random chance.
For example, in a population of owls there may be an equal chance of a newly born owlet having long talons or short talons, but due to random breeding variances, a slightly larger number of long-taloned owlets are born.
Over many generations, this slight variance can develop into a larger trend, until the majority of owls in that population have long talons.
These breeding variances could be a result of a chance event — such as an earthquake that drastically reduces the size of the nesting population one year.
Small populations are more sensitive to the effects of genetic drift than large, diverse populations.
When a population displays smal-scale changes over a relatively short period of time, micro-evolution has occurred.
Macroevolution refers to lage-scale patterns of evolution within biological organisms over a long period of time.
Just as new species are formed by natural selection and genetic drift, other species may become extinct.
Extinction
Extinction occurs when a species cannot adapt quickly enough to environmental change and all members of the species die.
Biological extinction is the true extermination of a species.
There are no individuals of a biological extinct species left on the planet (for example, the dodo bird or passenger pigeons).
Ecological extinction occurs when there are so few individuals of a species taht this species can no longer perform its ecological function (ex. Alligators in the Everglades in the 1960s or wolves in Yellowstone before the re-introduction in he last decade).
Commercial or economic extinction is when a few individuals exist, but the effort needed to locate and harvest them is not worth the expense (ex. Groundfish population of Grand Banks of Maritimes of Canada).
Relationships Between Species
A group of organisms of the same species is called a population, and when populations of different species occupy the same geographic area, they form a community.
Every species within the community has an ecological niche.
A species’ niche is described in the total sum of a species’ use of the biotic and abiotic resources in its environment.
The niche describes where the species lives, what it eats, and all of other resources the species utilizes in an ecosystem.
Another term you should know for the exam is habitat – a habitat in the area or environment where an organism or ecological community normally lives or occurs.
Species can be generalist or specialist.
Specialist Vs. Generalist
A specialist is on ethat has a narrow niche and can only live in a certain habitat.
General species has a broad niche, highly adaptable, and can live in varied habitats.
Specialist species tend to have an advantage when their environments are relatively unchanging, while generalist species have the advantage in habitats that undergo frequent change.
Types of competition, resources
Some species interact quite a bit with other members of their population; for example, some animals form herds, while other species are loners – like bears.
The reasons for these different levels of sociability are largely competition, predation, and a general need to exploit the resources of the environment.
Competition arises when two individuals – of the same species or of different species – are competing for resources in the environment.
When the two individuals competing are of the same species, called interspecific competition, when they are different species, called interspecific competition.
Resources that are competed for can be food, air, shelter, sunlight, and various other factors necessary for life.
Competitor who is “most fit” eventually wins and obtains the resource.
The others are eliminated by competition.
When two different species in a region compete and the better adapted species wins, this phenomenon is called competitive exclusion
Ecological niches, resource partitioning
Gause’s principle states that no two species can occupy the same niche at the same time and that the species that is less fit to live in the environment will relocate, die out, or occupy a smaller niche
When a species occupies a smaller niche than it would in the absence of competition, this compromised niche is called its realized niche (the niche it would have if there were no competition is known as its fundamental niche)
Direction competition can also be avoided in the case of resource partitioning, which occurs when different species use slightly different parts of the habitat, but realy on the same resource.
Migration, competition between plants
Many types of species engage in both short and long term migration, for reasons including food and water availability, temperature changes, mating opportunities and safety from predation.
This means that a given species might be part of several different communities at different times, and might fill a given niche in each of those communities only some of the time
Competition between plants is much more subtle than between animals and occurs much more slowly, but plants do compete for sunlight and for gound space, they even produce chemicals that inhibit other plant’s growth
Biomes
Land environments are separated into biomes based on factors such as climate geology, soils, topography, hydrology, and vegetation
Transitional area where two ecosystems meet ha a name - ecotones
Ecozones - smaller regions within ecosystems that share similar physical features
Aquatic Life Zones
Equivalents of biomes in aquatic environments
Aquatic ecosystems are categorized primarily by the salinity of their water – freshwater and saltwater ecosystems fall into separate categories
Freshwater Biomes
In all natural bodies of water, layers of water exist that vary significantly in temperature, oxygen content, and nutrient levels
These layers are affected differently by seasonal changes and other disturbances, and this also contributes to how they are categorized
In freshwater, the layers are the epilimnion, which is the uppermost and thus the most oxygenated, layer; and the hypolimnion, which is the lower colder, and denser layer
The demarcation line between these two layers, at which the temperature shifts dramatically, is the thermocline
The layers of freshwater bodies may also be categorized differently, according to the types of organisms that can live in theme
Layers of freshwater bodies
littoral zone, limnetic zone, profundal zone, benthic zone
Littoral zone
begins with very shallow water at the shoreline, plants and anime that reside in the littoral zone receive abundant sunlight, also includes turtles, frogs, and other species that travel back and forth from water to land, the end of this zone is defined as the depth at which rooted plant stop growing
limnetic zone
surface of open water; the region that extends to the depth that sunlight can penetrate, organisms that are residents in this zoen tend to be shorltlived and rely on sunlight, photosynthesizing phytoplankton use it directly, and they provide energy to zooplankton, insects, and fish
profundal zone
the depths, water that is too deep for sunlight to penetrate, because the profundal zone is aphotic (a place where light cannot reach), photozynthesizing plants and animals cannot live here; instead organisms adapted to little light, colder temperatures, and less oxygen reside in this less populated zone
Benthic zone
surface and sub-surface layers of the river, lake, pond, or streambed, haracterized by very low temperatures and low oxygen levels and inhabited by organisms that live on, in , or below the sediment surface, including bottom feeders, scavengers, and decomposers (inluding microorganisms such as bacteria and fungi)
Estuary
A sight where the “arm” of the sea extends inland to meet the mouth of a river
Often rich with many different types of plant and animal species, because the freshwater in these areas usually has a high concentration of nutrients and sediments
The waters in estuaries are usually quite shallow, which menas that the water is fairly warm and that plants and animals in these locations can receive significant amounts of sunlight
Subcategories of estuarine environments that you should know for the exam include saltwater marshes, mangrove forests, inlets, bays, and river mouths
Some of Earth’s most important ecologically diverse ecosystems are wetlands
Areas on the shores of fresh bodies of water, wet inaldn habitats fed only by rainwater, and ehemeral (seasonally temporary) water bodies
Types of wetlands include marshes, swamps, bogs, prairie potholes (which exist seasonally), and floodplains (which occur when excess water flows out of the anks of a river and into a flat valley
Mangrove Swamps
Coastal wetlands (areas of lands voered in freshwater, saltwater, or a combination) found in tropical and subtropical regions, and they are threatened by activities such as shrimp aquaculture and the degradation of the Western coastlines
Mangroves are characterized by trees, shrubs, and other plants that can grow in brackish tidal waters and are often located in estuaries
In North America, mangrove swamps are found from the southern tip of Glorid song the entire Gulf Coast to Texas; Florida’s southwest coast supports one of the largest mangrove swamps in the world
Huge diversity of animals are found in mangrove swamps
Because estuarine swamps are constantly replenished with nutrients transported by freshwater runoff from the land, they support a bursting population of bacteria, other decomposers, and filter feeders
Also sustain billions of worms, protozoa, barnacles, oysters, and other invertebrates, which in turn feed fish and shrimp, which support wading birds, pelicans, and the US endangered crocodile
Mangroves are important because they function as nurseries for shrimp and recreational fisheries, exporters of organic matter to adjacent coastal food chains, andenormous sources of nutrients valuable to plants, wildlife, and ecosystem function, physical stability also helps to prevent shoreline erosion, shielding inland areas from severe damage during hurricanes and tidal waves
The World’s Oceans
Certain landforms that lief off coastal shores are known as barrier islands
Because barrier islands are created by the buildup of deposited sediments, their boundaries are constantly shifting as water moves around them
These spits of land are generally the first hit by offshore storms, and they are important buffers for the shoreline behind them
In tropical waters, a very particular type of barrier island called a coral reef is quite common
These barrier islands are formed from a community of living things
The organisms responsible for the creation of coral reefs are cnidarians, which secrete a hard, calciferous shell; these shells provide homes and shelter for an incredibly diversity of species, but they are also extremely delicate and thuse veryvulnerable to physical stresses as well as changes in light intensity, water temperature, ocean depth, and pH
The increase in ocean temperatures and dissolved CO2 due to climate change is resulting in more acidic waters resulting in coral bleaching
Coral bleaching occurs when acidic conditions cause the coral to expel the colorful algae which provided them with food
Like freshwater bodies, oceans are divided into zones based on changes in light and temperature
Coastal zone
Consists of the ocean water closes to land
Usually defined as being between the shore and the end of the continental shelf (the edge of the tectonic plate)
Life thrives here due to abundant sunlight and oxygen and the proximity of the sediment surface, allowing for varied niches
In addition, coastal zones border and extend into estuaries, beaches, and marshes, which have their own varied populations of organisms adapted to their conditions
Euphotic zone
The photic, upper layers of water
The euphotic zone is the warmest region of ocean water; this zone also has the highest levels of dissolved oxygen
Much like the limnetic zone in freshwater biomes, it supports algae as well as fish
Algae in marine biomes supply a large portion of the Earth’s oxygen, and also take in carbon dioxide from the atmosphere
Since most red light is absorbed in the top 1 meter of water, and blue light doesn’t usually penetrate deeper than 100 meters, photosynthesizers have adapted mechanisms to address the lack of visible light
How deep the euphotic zone extends depends on the turbidity of the water in a given area
