For over 2000 years a single idea has changed both societal and scientific perception of the world and its inhabitants. Primarily evolution by natural selection is a concept developed by Charles Darwin to explain fundamental factors on populations existence. Darwin eluded that, “all living species are descendants of ancestral species and are different from the present-day organisms as a result of cumulative changes in positive characteristics of the population over a period” (Darwin, 2004). Perhaps, the most exciting part of this theoretical concept is how scientist shifts the prevailing view of natural populations from supernatural creation to by-products of an evolution process: natural selection. Therefore, the essay aims to explore the ideological concepts of Darwin’s theory towards defending the evolution process.
The Origin of Species
Darwin’s concept of species existence revolves around two ideas; Evolution explaining the diversity and unity of life as well as Natural selection to provide an insight into the adaptive mechanism of evolution. The analogy of this concept is that life is like a tree with branches emerging from a common point, in the process some branches died off (extinction) while other branches survive and multiple resulting to present-day diversity. Therefore, based on observation and inference the key conclusive points to the ideology include;
Overpopulation
Overproduction is a crucial part of natural selection. Biologically, overproduction results to more offspring by the subsequent generations than the environment can support. Therefore, this mechanism results in the identification and isolation of only individuals with specific characteristics to compete favorably for the available resources (Bonner, 1988). The surviving species must reach maturity and pass these traits to the next generation. Darwin at the Island of Galapagos in South America while studying inheritance among finches, he noted there were thirteen different types though similar but had different beak variation (Darwin, 2004). Darwin observed that after the 1977 drought on the Island, finches overproduced to compete for the limited resources. As a result, the birds with strongest and bigger beaks that could feed on any available food seed had an increased survival rate compared to small-beaked birds whose population radically declined thus dying without passing their genes to the next generation. Although most studies point to the overpopulation as a means of increasing chances of survival, the maturity and passing of traits to the offspring are closely linked to natural selection of “fit” organisms.
Adaptation
The concept of adaptation is derived from the natural selection evolutionary theory of increased survivorship and successive reproduction among organisms. According to Darwin, a group of species could acquire a given trait and share the characteristic over the period over time making it common among the population. These new traits could be elaborate or inconspicuous. For example, when Darwin discovered 11-inch nectar-producing tube, he conclusively said there would be a moth with 11-inch proboscis to feed on the tube. “Over 50 years later, scientists discovered Xanthopan morganii praedicta that had 12-inch proboscis feeding on the Darwin’s discovered orchid” , (Ospovat, 1995). The concept explains the importance of the interconnected relationship of plants and animals where one feature in the other is complimented by the other party to result in a mutually beneficial relationship. However, the understanding of this concept is directly linked to the association of both plants and animals interact with the environmental influence through the natural selection process.
Natural Selection
According to this concept, Darwin eluded to nature or environmental situation is the ultimate indicator of individuals’ survival. This process dictates that organisms with suited inherited traits that equip them to survive the natural changes than other individuals will grow to maturity and produce offspring with the new characteristics to sustain the environment (Bowler, 2009).
The evidence to elaborate the role of natural selection in evolution has been documented by the discovery of “peppered” moths around the industrial cities in England. The studies document the color variation among these insects from Dark to light body coloration. The 19th-century industrial revolution led to burning of coal in many furnaces that subsequently led to the killing of lichen on trees as well as bark darkening (Bowler, 2009). These environmental changes are associated with a natural selection process where dark-colored moths characteristically were difficult to identify and isolate on dark tree barks by predator birds (Darwin, 2004). Therefore, as the birds concentrated on light-colored moths, the dark individuals had an opportunity to live long and reproduce. As the environmental condition continued to favor more dark moths, their population progressively become common contributing 98 percent of the species population by 1895 (Darwin, 2004). Comparatively, environmental conservation interventions from the 1950s aimed at reducing air pollution significantly resulted in the reduced emission of sooty smoke in the atmosphere (Darwin, 2004). As a result, there was reduced heavy soot on the buildings, trees, and environment. The subsequent changes resulted to the lighter environment as lichens grow back and buildings are cleaned thus a new trend was documented when they survival rate of the light colored moths started to increase and subsequently become common compared to the dark-colored moth's varieties. Alternatively, natural selection of good traits is eluded to condition rise of new species a process referred to as “speciation.”
Speciation
According to Darwin’s theoretical perspective, natural selection resulted in the acquisition of favorable traits accumulation in a species over many generations and lost of “bad” traits over the time (Darwin, 2004). The accumulation of the new changes will eventually become common among a population thus resulting in a new species. Although Darwin introduced the concept of speciation, he spent most of his time focusing on how species populations were becoming adapted to their environments through natural selection, but not how the adaptation processes were leading to speciation. Evolutionary biologists have makes two understanding of these concepts in relation to Darwin’s natural selection. The biological explanation states speciation results from the way different organisms exploits their natural resources in each ecological niche (Ospovat, 1995). Therefore, the disruptive selection makes individuals falling between the niches less fit thus are eliminated leading to two distinct species from the same evolutionary line. On the other hand, sexual isolation explains that: isolated reproduction leads to the adaptation of different groups to their environment thus over time, through divergent evolution the differences increase resulting to the formation of new species (Keller, 1999). Accordingly, a new understanding of genetic biology will expound on the issue as new species being a result of the prevented exchange of genes among populations during isolation (Keller, 1999). However, Darwin was not privileged to understand the concept of genetic inheritance, and he introduced the idea in the analysis of species traits and the variation of these characteristics among different species. The idea is known as genetic variation among modern evolutionary biologists.
Genetic Variation
Darwin denoted that individual species had a characteristic variation from different perspectives, body-color, wings, mode of feeding to the tiniest issues such as eye color. In his studies, Darwin concentrated on the effect of the environment through a process he referred to as natural selection. The new trait variation suitable for survival will spontaneously rise and make the individual more competitive for resources and subsequent dominance due to a high number of populations reaching maturity. Darwin’s theoretical perspective was unable to account for the mechanism leading to the variation or how it was inherited. For example, the question of how natural selection would give rise to sterile workers often observed in social insects (Ratnieks, Foster, & Wenseleers, 2011). Considerably, this population of social animals is always stabilized in all generations despite their inability to reproduce. Moreover, this individual despite being sterile was observed to be consistently different from their fertile parents (Ratnieks et al 2011). Therefore, the introduction of Mendelian genetic towards giving an understanding of inheritance and variations among different species in revelation to Darwin’s theory of natural selection resulted to neo-Darwinian synthesis that enlightened the mechanism of acquiring and passing inherited genetic compositions to the next generation (Marshall, McNamara, & Houston, 2011). However, theoretical perspectives considerably factored the role of competition on influencing the new characteristics of a species.
Competition
The process of competition is viewed as a major contributor to Darwin’s theory of natural selection. The increasing number of a given species individual ultimately result in severe competition due to same needs requirements at any time (Keller, 1999). Suggestively, the completion among coexisting species of same family members is unlikely to affect the population as their needs may vary. Moreover, it is often easy to note that these individuals explore different ecological niches. However, Darwin noted competition as a limitation of living space and food among given species individuals thus leading to struggle to survive among the species (Darwin, 2004). The growth of a population with unlimited access to resources will experience exponential growth as the community survives to reproduce equally. However, the density-dependent population as eluded to by Darwin, the population growth is governed by the resources available thus resulting in individual performance importance on their phenotypic variation to facilitate the advantage needed (Bonner, 1988). Thus, subsequently, implicates that natural selection process of the individual species where individuals with better phenotypic characteristics have an opportunity to reach maturity and dominate the environmental niche.
Conclusion
The evolution theory according to Charles Darwin is a pioneering concept to understanding the interrelation of organisms and their environment. According to the idea, organisms must evolve to access all the ecological niches in relation to prevailing environmental changes. These processes include overproduction, adaptation, natural selection, speciation, genetic variation and competition consistently creating a natural balance of populations. Through these stages, organisms better equipped are selected and their traits inherited while those with “bad” features are eliminated. Although Darwin experience difficulty in explaining the mechanisms of inheritance or the intrinsic evidence of variation among populations of same species, genetic experimentations by Mendel gives an insight to the concepts of variations and offspring trait inheritance as eluded to by Darwin.
References
Bonner, J. T. (1988). The evolution of complexity by means of natural selection. Princeton University Press.
Bowler, P. J. (2009). Darwin's originality. science, 323(5911), 223-226.
Darwin, C. (2004). On the origin of species, 1859. Routledge.
Keller, L. (1999). Levels of selection in evolution. Princeton University Press.
Marshall, J. A., McNamara, J. M., & Houston, A. I. (2011). The state of Darwinian theory. Behavioral ecology and sociobiology, 65(3), 417-420.
Ospovat, D. (1995). The development of Darwin's theory: Natural history, natural theology, and natural selection, 1838-1859. Cambridge University Press.
Ratnieks, F. L., Foster, K. R., & Wenseleers, T. (2011). Darwin's special difficulty: the evolution of “neuter insects” and current theory. Behavioral ecology and sociobiology, 65(3), 481-492.
