Discussion Questions on Ecology - Paper Example

Why top predators are so rare and green plants so common in terrestrial ecological communities

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This occurrence is best explained through an analysis of the food chains. The green plants are so common mainly because of their source of food. Green plants are producers as they use sunshine to make their food. Sunshine is available in plenty in a terrestrial community, hence the plants tend to be widespread (Pelini et al., 2015). Herbivores are next in the chain as they feed on these green plants. Due to their sources of food, they also tend to be more in number compared to those at the higher end of the food chain. However, they are less when compared to the producers. The carnivores, which are the top predators, feed on the herbivores. The number of carnivores is also less compared to the source of food. Basically, each time an orgasm is eaten, the amount of energy in its food resource tends to decrease (Pelini et al., 2015). Therefore, by the time the top predators consume a meal, the energy resource available will be minimal. This means that only a few predators will be supported. An example of a top predator is the Lion and the green plant is the grass.

Two Groups of Organisms That Do Not Fit the Biological-Species Concept

A biological species concept refers to a set of organisms which can potentially interbreed. The two organisms which do not fit in the biological species concept are the Larus gulls and the Greenish warbler. These species showcase unusual and valuable sexual situations. The Larus gulls species interbreed in a ring around the Arctic Circle. The European herring gull is found primarily in Great Britain and Ireland. It can hybridize with the American herring gull, which is found in North America. The latter species can hybridize with East Siberian herring gull, which can also hybridize with another species and so on (Pereira & Wake, 2015). Eventually, two species which cannot hybridize end up together in one place. These are the lesser black-backed gulls and herring gulls.

As for the Greenish warblers, two distinct forms coexist in central Siberia. One is found in the East and the other in the West. Due to their extreme difference, they cannot interbreed. The chain of populations encircling the Tibetan Plateau at the South featured this species with chains that differ from one to the other (Pereira & Wake, 2015). This is what connects these two species.

These two groups of organism best fit in the ring species concept. This is because the population encircles an area of unsuitable habitat (Pereira & Wake, 2015). In one location, two distinct organisms coexist without actually interbreeding, however, there is a species in a different location which can interbreed with one of these. These are two different species whose genes cannot allow for a successful breeding. However, as the ring progressing with time, the traits of one of the species changes gradually as a result of the influences of intermediate populations. With time a new organism is born bearing the traits of the second species.

How Adaptive Radiations Develop

Adaptive radiation refers to an event where a lineage of organisms rapidly diversifies, with every new lineage producing different adaptations. Different factors may trigger this occurrence, but each tends to be as a response to an opportunity (Bock, 2004). One of the factors features a key adaptation that occurs to enable an organism to exploit new resources. This opens up a lot of opportunities for adaptive radiation to take place. For instance, beetle radiations were triggered by the adaptation which was meant to enable it to feed on flowering plants. Release from competition or vacated niches may also cause adaptive radiations to occur. Species that invade islands may experience adaptive radiations when competition on the island is minimized. On the contrary, when the competition is stiff, a lineage may find it impossible to split into new forms or diversify. For example, when dinosaur extinction occurred, the niche was vacated and left open for the mammals to radiate into the positions in the food web.

Why there is no single overall measure of biodiversity

Biodiversity pluralism is mainly based on the argument that there are many different definitions of biodiversity, hence many different ways to value it (Bock, 2004). Therefore, the value of a decision maker is the one which will determine the measure of biodiversity. Just as the values of different people vary from one to other, so will the value of biodiversity. Basically, it is as a result in the availability of different definitions and theories.

Microevolution and Macroevolution

Microevolution refers to the change in species within a single population, while Macroevolution refers to a variety of species (Bock, 2004). Although the mode of evolution is similar, the difference is merely on the scale that the evolution impacts. For instance, microevolution examples may occur when two dogs mate to produce a new breed. Macroevolution example may be described in how all fish descended from an invertebrate animal. Considering these examples, it is evident that biological species concept is the one which has had a greater influence on the rise of biodiversity.

References

Bock, W. J. (2004). Species: the concept, category and taxon. Journal Of Zoological Systematics & Evolutionary Research, 42(3), 178-190. doi:10.1111/j.1439-0469.2004.00276.x

Pelini, S. L., Maran, A. M., Chen, A. R., Kaseman, J., & Crowther, T. W. (2015). Higher Trophic Levels Overwhelm Climate Change Impacts on Terrestrial Ecosystem Functioning. Plos ONE, 10(8), 1-10. doi:10.1371/journal.pone.0136344

Pereira, R. J., & Wake, D. B. (2015). Ring species as demonstrations of the continuum of species formation. Molecular Ecology, 24(21), 5312-5314. doi:10.1111/mec.13412