Species vs. Human Predator

Katelyn Lutes

October 14, 2010.

Since the evolution of the human race, all of humanity has manipulated the external environment of the world. The use of resources, living or inanimate has been essential to the development and success of the various cultures and lifestyles of the global population. The vicious cycle of consumption present in humanity has been destructive, and detrimental to many species of animal and plant life.

Evolution constantly alters all organisms through natural selection. Natural selection is the theory of the gradual adaptation of a species caused by altering environmental factors. These factors, including predators, alter visible and invisible traits (Futuyma 2004). Ultimately, the most advantageous trait prevails, benefiting the species. Humanity plays a very large role in evolution, as one of the largest predators. Typically, large populations of one specific type of species are targeted, and exploited. This forces the population to try to rapidly change their characteristics and adapt to the sudden demand.

In a study conducted by Chris Darimont et al., 40 human predator systems and 29 species were used to observe if any obvious visible or physical changes occurred to the organisms in question. To ensure the reliability of the results, Darimont took 475 different estimates of the data collected. The results proved that the targeted organisms rapidly change in terms of body size and life history traits. Almost all species that were targeted by humans averagely decreased their body size by aproximately 20%, while life history averagely decreased by aproximately 25%. The information observed is essential in understanding more about the speed that species can alter their genetic traits. In many cases, the species are targeted solely because of the visible traits that they have. This can cause them to alter their physical characteristics. For instance, humanity is interested in the coloured feathers of a specific bird species to make a product. This species has birds that vary in feather colour, either white or grey. The product can only contain white feathers, and therefore the grey are useless. Mass harvesting of specific birds with only white feathers occurs. Since the birds of this targeted group have been harvested to the point that their population cannot survive, there are no individuals to pass down the genes to create white feathered birds. Visibly, it is more advantageous to be a grey bird, so successive populations of this species of bird will be dominated by mainly grey birds. This is the process of natural selection intensified by human predator interference. Regeneration of the population is nearly impossible, as humanity continues to develop new technology to capture the species.

The rapid physical changes of organisms that have been targeted by human predators also provide implications on their surrounding environment. Human preditors cause more rapid changes than natural predators, which species are accustomed to. Population growth is severely altered when a species is targeted. If this species is a type of plant, surrounding herbivore populations that require the plant for survival are now in food deficit and are at risk of dying unless they adapt themselves. This places the whole ecosystem out of balance. In the same way, if a herbivoire species is targeted and unable to adapt is removed from an ecosystem, the plant life that it consumed will fluctuate. These examples are outlining the ripple effect. Because the world can be viewed as one large ecosystem, rather than many small ones operating it, it is evident that all organisms rely on one another. Mnay other closely linked species may not be able to adapt themselves to the changes of the environmental conditions. Human predators have endangered this species as well.

Throughout the course of history, humans have hunted many animals, plants and organisms into extinction either for resources or for sport. One classic example is the Dodo Bird. The Dodo Bird was an African bird, unable to fly (a picture of this bird can be seen to the left of the text). Characteristically, it had small wings, a hooked beak and great plumage. It had no natural predators until humans invaded their environment and made survival impossible (Roberts and Solow 2003). In this way, humans indirectly caused the extinction of the animal, and could not alter its genetic information rapidally enough to prevail.

Sustainability and moderation are key elements that can eliminate the problem of human predators and the need for species to alter their visible traits rapidally. Without the constant, strong threat to the species, populations can have time to regulate, and compensate for the amount harvested. Ensuring this is able to happen is a key point in maintaining populations.

Works Cited

Futuyma, Douglas. "Natural Selection: How Evolution Works". 2004. http://www.actionbioscience.org/evolution/futuyma.html

Roberts, David L., Solow, Andrew R. "Flightless Birds: When did the Dodo Become Extinct?". 2003 http://www.nature.com/nature/journal/v46/n6964/full/426245a.html

Darimont, C. T., Carlson, S. M., Kinnison, M. T., Paquet, P. C., Reimchen, T. E., Wilmers, C. C. "Human predators outpace other agents of trait change in the wild". PNAS. (2008)