The extinction of one animal species and its ecosystem effects

Extinction and the Ecosystem

The ability of a species to survive the extinction of another depends on its ability to adapt. Omnivores fair better than those with a limited range of food. When a single food source disappears from the environment, it can more easily find another suitable food source. More highly specialized members of the ecosystem will not be able to substitute food as those that can eat a variety of food. The extinction of a single food species will quickly follow the elimination of their major food source. This research will support the thesis that non-random species loss will have a more devastating effect on the community and than random species loss.

Research Methods and Extinction

Non-random species loss is the result of human managerial practices and other humanly controllable events. At this time, research into species loss depends on computer simulation as the basis for its theory. This has the advantage of allowing researchers to manipulate variables to precise standards (Drake, p. 1). However, it can be argued that this type of study does not represent real world scenarios. This is one of the difficulties of research in the extinction of any plant or animal species. The only real-world studies that can be performed are those where an actual extinction is taking place. However, in this research scenario, the researcher does not have the ability to manipulate variables, as in the computer simulation (Drake, p. 1). This creates a dilemma in the study of species within ecosystems.

In a computer simulation, Schlapper, Pfister, and Schmid, (p. 13) examined the potential effects of non-random species loss on grassland productivity. In this study, the researches set up an environment with 15 species. They exposed this population to 2-years of high-intensity management that resulted in the extinction phase of many species. After the extinction phase, they exposed the plot to 2 years of low intensity management, which comprised the restoration phase. This allowed the recolonization of neighboring plots under different management schemes.

Some unexpected results came from this experiment. For instance, during the extinction phase, species in a monoculture environment had lower extinction probabilities than those in a mixed community (Schlapper, Pfister, and Schmid, (p. 13). One of the more significant findings of this research is that species that were more productive during the extinction phase were different than those that predominated during the restoration phase. Inconsistency between in recolonization from neighboring communities was also observed (Schlapper, Pfister, and Schmid, p. 13).

This research was supported by stochastic models of population growth and decline. In populations that are randomly fluctuating a lack of empirical evidence makes it difficult to predict population rises and declines (Drake, p. 1).To examine how the repopulation process occurs means an examination of those that are responsible for spreading the seeds. It is important for humans to understand these dynamics, as the disruption of these processes can have an impact on society (Sekerciosglu, Daily, and Ehrlich, p. 18043). Birds play an important role in the repopulation of plants. Birds provide a service to the plant community by spreading seeds from one place to another (Sekerciosglu, Daily, and Ehrlich, p. 18043). Declines in bird populations can lead to a decline in plant species as a result.

The Example of Plants and Avian Species

When one considers the interconnectedness of plant and bird species, they seldom consider the role of scavengers. However, scavengers also play an important role in the extinction or growth of a species in an ecosystem. Scavengers help to recycle nutrients and get them into the soil (Sekerciosglu, Daily, and Ehrlich, p. 18045). In 1997, there were 35,00 to 50,000 cases of rabies, which happened to coincide with a decline in the vulture population (Sekerciosglu, Daily, and Ehrlich, p. 18045). This decline was not random chance, but was due to the presence of disease-infested carcasses lying around in villages. The decline of bird species at the present time is alarming, Approximately 78% of threatened bird species are in decline on a global basis (Sekerciosglu, Daily, and Ehrlich, p. 18045).

In addition to spreading seeds, some birds play a direct role in plant pollination, such as the Cape fynbos (Sekerciosglu, Daily, and Ehrlich, p. 18045). This bird pollinates specific plants. This bird species is highly specialized, making the possibility of others taking its place unlikely (Sekerciosglu, Daily, and Ehrlich, p. 18045). Without pollination from birds, many plant species will also go into rapid decline as well. There has been surprisingly little research into the connection between plant and avian extinction. However, the studies that were conducted demonstrated the interdependence of the two. The extinction of plant species will mean the loss of food sources for many birds. Likewise, the extinction of bird species will accelerate or implement the decline of plant species through the loss of seeding and pollination mechanism.

The interdependence of bird and plant populations can have an impact on humans as well. In areas where the plant population has been depleted through overharvesting, birds play an important role in the restoration of the area. There has been considerably more research conducted on the effects of the disappearance of birds on declines in the plant population as well. However, there have been even fewer studies on the widespread consequences of the disappearance of fish on fish eating or scavenging bird species.

Populations of bacteria oscillate in the laboratory. They move between growth responses and extinction (Lin et al., 2004). Scavengers also help to prevent the spread of disease to nearby human communities by forcing them. They also reduce the costs of restoration in communities with depleted soil by spreading species to these areas (Sekerciosglu, Daily, and Ehrlich, p. 18045). As one can see, the disappearance of birds can have a devastating effect on human populations as well.

Scavenging species are typically highly specialized in the types of food that they eat (Sekerciosglu, Daily, and Ehrlich, p. 18045). However, due to the limited number of studies on these ecosystems, it is not known whether a decline in these species would have a top-down or bottom-up effect on reductions in nutrient deposition. One the key points that was not addressed in the literature about the reduction of scavenger species was the effects of reductions in scavenger species on insect populations that are responsible for the further decomposition of nutrients in the soil. Some of these species, such as worms also provide food for species responsible for seed dispersal as well. The circle of interdependence of species is highly complex and we have only just recently begun to discover many interactions that were previously unknown.

When we talk about declines in bird or plant populations, it is difficult to make the distinction in what is meant by diversity and complexity. Diversity means the number of different species within an area. The complexity of the ecosystem relates how interconnected these species are on one another (Williams and Martinez, p. 1). In a complex ecosystem, extinctions have a greater impact than in ecosystems where species are more independent. Complex ecosystems might not be necessarily diverse, making it less likely that a replacement species will perform the job of an extinct species.

Conclusions

There are many reasons why a species may become extinct. Overharvesting of species is often blamed as the single reason for species extinction. However, it is unlikely that overharvesting alone is responsible for species extinction, as the costs of finding the last of a species is high (Courchamp, et al., p. 1). However, there is also a connection between the rarity of a species and its desirability as a fashion object. As a species becomes rarer, it will become more desirable as a fashion statement. As the species becomes more valuable, it might outweigh the costs of hunting the last of a species. This is referred to as the Allee effect (Courchamp, et al., p. 1). In this way, a species might go extinct as they become more rare and pricey on the open market.

In order to understand the extent and severity of the current crisis that we are facing regarding the rapid decline in bird species, we must look to past extinction events. Geochemical analysis is often used in conjunction with paleontological data in order to examine past extinctions more closely (Martin, 2007). Fossil evidence analyzed in this manner demonstrates that increasing oxygen levels increases the number of species as well. As oxygen levels decrease, the number of species in the fossil record decreases as well (Martin, 2007).