Patterns of Evolution
Why Humans are Subject to Pressures of Natural Selection
Human beings differ in their reproduction capacity thus making them prone to natural selection just like other living organisms. For instance, a generation reproduces more members than the habitat can sustain consequently increasing unhealthy competition thus struggle for existence. (Braithwaite & Baxter, 2006). Additionally, humans also differ in height, weight, eye color, strength and intellectual capacity, which signify effects of natural selection. Humans often change and adapt to their new environments in order to meet their needs thus explaining natural selection. During the prehistoric period, for example, early humans settled in different parts of the world thus adapting to new surroundings with different climate, food, predators and disease thus giving rise to racial differences through natural selection (Fichman, 2004).
Examples
There are numerous examples of convergent evolution. Among them include the birds’ and bats’ wings, which appear similar both in structure and in appearance. An ichthyosaur, a porpoise and a shark remarkably resemble due to their streamlined body, yet they are from very different origin.
In divergent evolution, organisms from the same ancestor accumulate differences over time both structurally and physically thus resulting to the formation of two or more different species. Examples are the finches that have developed beaks to fit to the type of food available in particular ecological niches.
In adaptive radiation, members of a species will tend to adapt to their environment in many ways. Examples are Darwin’s finches, which, due to the absence of other birds in Galapagos, they adapted to different ecological niches that were adapted by different families (Losos, 2009).
Co-evolution, conversely, happens in two different organisms that are interdependent whereby when one evolves, it leads to the evolution of the other. This may be seen in flowering plant and their pollinators (mainly birds and insects). In example, Darwin foresaw the presence of a certain moth in Madagascar due to the type of flowers that were there.
Implication of Divergent Evolution for future
As effects of divergent evolution, human beings will have migrated to various locations of the world. On the other hand, the general population of human beings will increase significantly thus leading to scarcity of resources. Additionally, this will eventually lead to unhealthy competition among the human population consequently leading to their death.
References
Braithwaite, D. & Baxter, L. (2006). Engaging theories in family communication: multiple
perspectives. London, LDN: Sage Publication Ltd Press.
Fichman, M. (2004). An elusive Victorian: the evolution of Alfred Russel Wallace. Chicago, IL:
The University of Chicago Press.
Losos, J. (2009). Lizards in an evolutionary tree: ecology and adaptive radiation of anoles. Los
Angeles, LA: University of California Press.
