Zoology Test 1 Community Ecology

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Ecosystem

Back 1

a natural unit consisting of all plants, animals and micro organisms in an area functioning together with all the non living physical factors of the environment.

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Ecology

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the scientific study of the distribution and abundance of living organisms and how the distribution and abundance are affected by interactions between the organisms and their environment.

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Community ecology

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a subdiscipline of ecology which studies the distribution, abundance, demography, and interactions between coexisting populations. Interactions between populations, determined by specific genotypic and phenotypic characteristics, is the primary focus of community ecology.

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Population ecology

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autecology, is a major sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment.

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Define the concept of a community as used in ecology. Give examples of five different communities.

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an assemblage of organisms that are associated in a common environment and interact with each other in a self sustainingand self-regulating relation

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Coevolution

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the correlated evolution of two apparently independent entities. This could be two interacting proteins with correlated amino acid mutations on their interacting surfaces (although it is debateable whether this actually happens). Co-evolution can also be the mutual evolutionary influence between two species. Each party in a co-evolutionary relationship exerts selective pressures on the other, thereby affecting each others' evolution. Co-evolution includes the evolution of a host species and its parasites, and examples of mutualism evolving through time.

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Competition

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when food or space are in limited supply and members of the same or different species interfere with each other's use of the limited resources. (pg 790 zoology)

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Interspecific competition

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a form of competition in which individuals of different species vie for the same resource in an ecosystem (e.g. food or living space). The other form of competition is intraspecific competition, which involves organisms of the same species.

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Intraspecific competition

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members of the same species vie for the same resource in an ecosystem (e.g. food, light, nutrients, space).

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What is sexual competition?

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competing for mating rights

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Explain the competitive exclusion principle (Gause's experiment). Why is this principle
important in ecology?

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the competitive exclusion principle, sometimes referred to as Gause's Law of competitive exclusion or just Gause's Law, is a theory which states that two species competing for the same resources cannot stably coexist. Either of the two competitors will always have an advantage over the other that leads to extinction of the second competitor or an evolutionary shift of the inferior competitor towards a different ecological niche. As a consequence, competing related species often evolve distinguishing characteristics in areas in which they coexist. This aids in mate recognition, thus maintaining each species' superiority in exploiting slightly different ecological niches.

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Niche

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All environmental conditions that permit members of a species to survive and multiply. (zoology pg 790)

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Fundamental niche

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Fundamental niche - all environmental conditions that the species can potentially tolerate.

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Realized niche

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subset of potentially suitable conditions that an animal actually experiences.

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What happens when two different species have exactly the same niche?

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they compete

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What is resource partitioning? What is the connection between resource partitioning and the niche concept?

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process by which natural selection drives competing species into different patterns of resource use or different niches.

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What is the difference
between predation and parasitism?

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predators obtain energy by killing, and parasites usually allow the host to live.

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Explain the concept of an evolutionary armsrace. Use the toxic newts as an example

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Animals undergoing coevolution are competing fiercly which is the selective pressure for natural selection. Prey are evolving defenses to evade or otherwise defeat the predator and the predator is evolving ways to deal with the preys defenses. The newts are highly poisonous and most predators cannot eat them, except for a particular species of garter snake, the snake is highly resistant to the poison. The more resistant to the poison however the slower they move.

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What is aposematic coloration?

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warning coloration markings that make a dangerous, poisonous, or foul-tasting animal particularly conspicuous and recognizable to a predator. Examples include the yellow and black stripes of bees and wasps, and the bright red or yellow colours of many poisonous frogs and snakes.

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Batesian Mimicry

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named after Henry Walter Bates, an English naturalist whose work on butterflies in the Amazon rainforest (including The Naturalist on the River Amazons) was pioneering in this field of study. In this type of mimicry the mimic sends signals similar to the model, but does not share the attribute that makes it unprofitable to predators (e.g. unpalatability).

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Mullerian mimicry

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Two or more species have very similar warning or aposematic signals and both share genuine anti-predation attributes (e.g. being unpalatable).

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What is the connection between biodiversity and predation?

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Predation is a force for biodiversity.

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Define the concept of keystone predator and be able to explain their role in the community

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A species that has a disproportionate effect on its environment relative to its abundance. The sea otter is a keystone species, due to its effect in keeping the sea urchin population down, which keeps them from eating the roots of the kelp which is vital to the kelp forests.

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Symbiosis

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the living together of 2 organisms in a community. Symbionts always benefit, hosts may benefit or be unaffected, or may be harmed. 3 forms are: mutualism, commensalism, and parasitism.

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Parasitism

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Relationship between 2 organisms where one organism, usually the physically smaller of the two (the parasite) benefits and the other (the host) is harmed.

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commensalism

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a relationship where one individual lives close to or on another and benefits and the host is unaffected.

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mutualism

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2 different species derive benefit from their association and in which the association is necessary to both.

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Explain the phenomenon of mutualism with the help of the interactions between the Bull's Horn Acacia tree and the Pseudomyrmex ants.

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The ants, Pseudomyrmex ferruginea, are obligate on these species; they cannot exist without the trees. The trees barely exist without the ants; they do poorly and lose in competition to other plants. A thorn is colonized by a single queen who chews a hole near the tip. Inside the thorn she will lay 15 to 20 eggs. As the colony grows, the ants inhabit other thorns. The colony becomes aggressive and protects the acacia when its population has reached about 400 members. The ants drive out other ant colonies and kill any insects browsing on the tree.

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Describe the relationship between Leafcutter Ants and fungi as an example of mutualism.

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Leaf cutter ants cut leaves and chew them into a paste that they feed to a fungus they grow. The fungus breaks down the toxins in the leaves and produces sugars and stuff the ants eat. There is a mold that will grow in the fungus killing it but the ants grow a colony of bacteria, that produce antibiotics, on their own bodies and distribute the antibiotics around killing the mold.

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Primary succession

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one of two types of ecological succession of plant life, and occurs in an environment in which new substrate, Devoid of vegetation and usually lacking soil, is deposited (for example a lava flow). (The other type of succession, secondary succession, occurs on substrate that previously supported vegetation before a disturbance destroyed the plant life.) In primary succession pioneer plants like mosses and lichen plus algae and fungus plus other abiotic factors like wind and water start to "normalize" the habitat, creating conditions nearer the optimum for vascular plant growth; pedogenesis or the formation of soil is the most important process. These pioneer plants are then dominated and often replaced by plants better adapted to less austere conditions, these plants include vascular plants like grasses and some shrubs that are able to live in thin soils that are often mineral based. A good example of primary succession takes place after a volcano has erupted. The barren land is first colonized by pioneer plants which pave the way for later, less hardy plants, such as hardwood trees, by facilitating pedogenesis, especially through biotic acceleration of weathering and the addition of organic debris to the surface regolith.

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Secondary succession

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he series of community changes which take place on a previously colonized, but disturbed or damaged habitat. Examples include areas which have been cleared of existing vegetation (such as after tree-felling in a woodland) and destructive events such as fires.