Competitive exclusion principle

"Direct competition between different species almost always produces a winner and a loser- and the losing species dies out," or is forced to migrate to another ecosystem which can support them (Levine, 2010). This is the competitive exclusion principle. This principle says that two species that need the same resources cannot survive together in the same habitat. One organism will eventually die off, thus, called.

Parasitism

In biology/ecology, parasitism is a non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the host. Traditionally parasite (in biological usage) referred primarily to organisms visible to the naked eye, ormacroparasites (such as helminths). Parasites can be microparasites, which are typically smaller, such as protozoa, viruses, andbacteria. Examples of parasites include the plants mistletoe and cuscuta, and animals such as hookworms.

Unlike predators, parasites typically do not kill their host, are generally much smaller than their host, and will often live in or on their host for an extended period. Both are special cases of consumer-resource interactions.^[4] Parasites show a high degree of specialization, andreproduce at a faster rate than their hosts. Classic examples of parasitism include interactions between vertebrate hosts and tapeworms,flukes, the Plasmodium species, and fleas. Parasitism differs from the parasitoid relationship in that parasitoids generally kill their hosts.^[5][6][7]

Parasites reduce host biological fitness by general or specialized pathology, such as parasitic castration and impairment of secondary sex characteristics, to the modification of host behavior. Parasites increase their own fitness by exploiting hosts for resources necessary for their survival, e.g. food, water, heat, habitat, and transmission. Although parasitism applies unambiguously to many cases, it is part of a continuum of types of interactions between species, rather than an exclusive category. In many cases, it is difficult to demonstrate harm to the host. In others, there may be no apparent specialization on the part of the parasite, or the interaction between the organisms may remain short-lived.

 

Parasitism is a relationship in which one organism (the parasite) benefits while the other(the host) is harmed. This is a positive, negative relationship. (Campbell)(Dionne L Rice Jr)

The parasite usually lives on or inside the other organism.

For example, mosquito is a parasite, feeding on a human while transferring the disease called Malaria. Other examples would be ticks or fleas that live off of many large mammals. Similarly, head lice are an example of parasitism because they feed on blood from the humans head.

In Colorado, the pine bark beetle is a common parasite. The pine beetles lays its eggs in the pine trees, and then when the babies are born, they eat the layers of the tree which stops the tree from growing.

Symbiosis (from Greek συμβίωσις "living together", from σύν "together" and βίωσις "living") is a close and often long-term interaction between two different biological species. In 1877 Albert Bernhard Frank used the word symbiosis (which previously had been used to depict people living together in community) to describe the mutualistic relationship in lichens.^[3] In 1879, the Germanmycologist Heinrich Anton de Bary defined it as "the living together of unlike organisms."

The definition of symbiosis has varied among scientists. Some advocated that the term "symbiosis" should only refer to persistent mutualisms, while others thought it should apply to any type of persistent biological interaction (in other words mutualistic,commensalistic, or parasitic). After 130 years of debate, current biology and ecology textbooks now use the latter "de Bary" definition or an even broader definition (where symbiosis means all species interactions), with the restrictive definition (where symbiosis means mutualism only) no longer used.

Some symbiotic relationships are obligate, meaning that both symbionts entirely depend on each other for survival. For example, many lichens consist of fungal and photosynthetic symbionts that cannot live on their own. Others are facultative (optional): they can, but do not have to live with the other organism.

Symbiotic relationships include those associations in which one organism lives on another (ectosymbiosis, such as mistletoe), or where one partner lives inside the other (endosymbiosis, such as lactobacilli and other bacteria in humans or Symbiodinium incorals). Symbiosis is also classified by physical attachment of the organisms; symbiosis in which the organisms have bodily union is called conjunctive symbiosis, and symbiosis in which they are not in union is called disjunctive symbiosis.

Endosymbiosis is any symbiotic relationship in which one symbiont lives within the tissues of the other, either within the cells or extracellularly. Examples include diverse microbiomes, rhizobia, nitrogen-fixing bacteria that live in root nodules on legumeroots; actinomycete nitrogen-fixing bacteria called Frankia, which live in alder root nodules; single-celled algae inside reef-buildingcorals; and bacterial endosymbionts that provide essential nutrients to about 10%–15% of insects.

Ectosymbiosis, also referred to as exosymbiosis, is any symbiotic relationship in which the symbiont lives on the body surface of the host, including the inner surface of the digestive tract or the ducts of exocrine glands. Examples of this include ectoparasitessuch as lice, commensal ectosymbionts such as the barnacles that attach themselves to the jaw of baleen whales, and mutualistectosymbionts such as cleaner fish.

Mutualism

Hermit crab, Calcinus laevimanus, with sea anemone.

Mutualism or interspecies reciprocal altruism is a relationship between individuals of different species where both individuals benefit. In general, only lifelong interactions involving close physical and biochemical contact can properly be considered symbiotic. Mutualistic relationships may be either obligate for both species, obligate for one but facultative for the other, or facultative for both. Many biologists restrict the definition of symbiosis to close mutualist relationships.

A large percentage of herbivores have mutualistic gut flora that help them digest plant matter, which is more difficult to digest than animal prey. This gut flora is made up of cellulose-digesting protozoans or bacteria living in the herbivores' intestines. Coral reefs are the result of mutualisms between coral organisms and various types of algae that live inside them. Most land plants and land ecosystems rely on mutualisms between the plants, which fix carbon from the air, andmycorrhyzal fungi, which help in extracting water and minerals from the ground.

An example of mutual symbiosis is the relationship between the ocellaris clownfish that dwell among the tentacles of Ritteri sea anemones. The territorial fish protects the anemone from anemone-eating fish, and in turn the stinging tentacles of the anemone protect the clownfish from its predators. A special mucus on the clownfish protects it from the stinging tentacles.

A further example is the goby fish, which sometimes lives together with a shrimp. The shrimp digs and cleans up a burrow in the sand in which both the shrimp and the goby fish live. The shrimp is almost blind, leaving it vulnerable to predators when outside its burrow. In case of danger the goby fish touches the shrimp with its tail to warn it. When that happens both the shrimp and goby fish quickly retreat into the burrow. Different species of gobies (Elacatinus spp.) also exhibit mutualistic behavior through cleaning up ectoparasites in other fish.

Another non-obligate symbiosis is known from encrusting bryozoans and hermit crabs that live in a close relationship. The bryozoan colony (Acanthodesia commensale) develops a cirumrotatory growth and offers the crab (Pseudopagurus granulimanus) a helicospiral-tubular extension of its living chamber that initially was situated within a gastropod shell.^[24]

One of the most spectacular examples of obligate mutualism is between the siboglinid tube worms and symbiotic bacteria that live athydrothermal vents and cold seeps. The worm has no digestive tract and is wholly reliant on its internal symbionts for nutrition. The bacteria oxidize either hydrogen sulfide or methane, which the host supplies to them. These worms were discovered in the late 1980s at the hydrothermal vents near the Galapagos Islands and have since been found at deep-sea hydrothermal vents and cold seeps in all of the world's oceans.

There are also many types of tropical and sub-tropical ants that have evolved very complex relationships with certain tree species.

Mutualism and endosymbiosis

During mutualistic symbioses, the host cell lacks some of the nutrients, which are provided by the endosymbiont. As a result, the host favors endosymbiont's growth processes within itself by producing some specialized cells. These cells affect the genetic composition of the host in order to regulate the increasing population of the endosymbionts and ensuring that these genetic changes are passed onto the offspring via vertical transmission (heredity).

Adaptation of the endosymbiont to the host's lifestyle leads to many changes in the endosymbiont–the foremost being drastic reduction in its genome size. This is due to many genes being lost during the process of metabolism, and DNA repair and recombination. While important genes participating in the DNA to RNA transcription, protein translationand DNA/RNA replication are retained. That is, a decrease in genome size is due to loss of protein coding genes and not due to lessening of inter-genic regions or open reading frame (ORF) size. Thus, species that are naturally evolving and contain reduced sizes of genes can be accounted for an increased number of noticeable differences between them, thereby leading to changes in their evolutionary rates. As the endosymbiotic bacteria related with these insects are passed on to the offspring strictly via vertical genetic transmission, intracellular bacteria goes through many hurdles during the process, resulting in the decrease in effective population sizes when compared to the free living bacteria. This incapability of the endosymbiotic bacteria to reinstate its wild type phenotype via a recombination process is called as Muller's ratchet phenomenon. Muller's ratchet phenomenon together with less effective population sizes has led to an accretion of deleterious mutations in the non-essential genes of the intracellular bacteria.^[28] This could have been due to lack of selection mechanisms prevailing in the rich environment of the host

Commensalism

Commensalism is a relationship in which one organism benefits from another organism that is not affected. This is a positive, neutral relationship. (Campbell)

For example, a small fish called the Pilot Fish follows underneath a shark and when the shark eats something the pilot fish eats the scrap pieces of the shark original kill.(Blue Planet BBC Documentary 2001).

Commensalism, in ecology, is a class of relationships between two organisms where one organism benefits from the other without affecting it. This is in contrast with mutualism, in which both organisms benefit from each other, amensalism, where one is harmed while the other is unaffected, and parasitism, where one benefits while the other is harmed. The word "commensalism" is derived from the word "commensal", meaning "eating at the same table" in human social interaction, which in turn comes through French from the Medieval Latin commensalis, meaning "sharing a table", from the prefix com-, meaning "together", and mensa, meaning "table" or "meal".Originally, the term was used to describe the use of waste food by second animals, like the carcass eaters that follow hunting animals, but wait until they have finished their meal.

Commensalism, in biology, is a relation between individuals of two species in which one species obtains food or other benefits from the other without either harming or benefiting the latter. The commensal (the species that benefits from the association) may obtain nutrients, shelter, support, or locomotion from the host species, which is substantially unaffected. The commensal relation is often between a larger host and a smaller commensal; the host organism is unmodified, whereas the commensal species may show great structural adaptation consonant with its habits, as in the remoras that ride attached to sharks and other fishes. Both remora and pilot fishfeed on the leftovers of their hosts’ meals. Numerous birds feed on the insects turned up by grazing mammals, while other birds obtain soil organisms stirred up by theplow. Various biting lice, fleas, and louse flies are commensals in that they feed harmlessly on the feathers of birds and on sloughed-off flakes of skin from mammals

Another example is of a birds nest in a tree. The bird is benefitting because the tree is giving the bird shelter and the tree is not getting anything in return.

Similarly, the transparent shrimp benefits from a reef because it hides within it (camouflaging), but the coral is not affected.

Additionally, the relationship between an infectious disease and its carrier, an animal such as a mosquito, could be classified as commensalism because the mosquito is unaffected by the presence of the disease, but the mosquito transfers it to a host in which the disease can reproduce or spread more easily to others.

Lecture 10. Ecological succession.

"Often, the host species provides a home and/or transportation for the other species." (www.Biology-Online.org) The whale and barnacles are a perfect example of this. "Barnacles are crustaceans that have jointed legs and shells of connected overlapping plates. Instead of crawling after food, they glue themselves to rocks, ships, pillings, abalones, and maybe even whales and wait for food to wash by." (Oracle, 2000). The barnacles attach themselves to the whale. This way, the barnacle can get food faster. This does not affect the whale so he does not take the barnacle off.

 

 

1.Atmosphere – the main components of the biosphere.

2. Atmosphere, its qualitative and quantitative composition.

3.Ecological disaster zone of Kazakhstan.

Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction,

The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community. The ʺengineʺ of succession, the cause of ecosystem change, is the impact of established species upon their own environments. A consequence of living is the sometimes subtle and sometimes overt alteration of one's own environment.

It is a phenomenon or process by which an ecological community undergoes more or less orderly and predictable changes following a disturbance or the initial colonization of a new habitat. Succession may be initiated either by formation of new, unoccupied habitat, such as from a lava flow or a severe landslide, or by some form of disturbanceof a community, such as from a fire, severe windthrow, or logging. Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession, whereas succession that follows disruption of a pre-existing community is called secondary succession.

Succession was among the first theories advanced in ecology. The study of succession remains at the core of ecological science. Ecological succession was first documented in the Indiana Dunes of Northwest Indiana which led to efforts to preserve the Indiana Dunes. Exhibits on ecological succession are displayed in the Hour Glass, a museum in Ogden Dunes.