Biologist uses different terms to describe evolution based on the available information. Speciation which is a term describing the formation of new species can be termed a complex technical term considering the level of information and arguments raised by a biologist in respect to the subtypes of speciation. We know that species are formed by various process which somewhat might be difficult to ascertain. It is also defined as the "evolution of genetically distinct populations maintained by reproductive isolation in the case of sexual taxa" (Bolnick & Fitzpatrick)
This form of macroevolution comes into play via hybridizing or crossbreeding in some situations. Sympatric and allopatric speciation is some of the few common types of speciation that has undergone various forms of evaluation and research. There are different opinion regarding each of the speciation especially as regards to their setup and how other fundamental factors influence the outcome of each of the speciation. In recent times, studies and reviews have raised several forms of arguments against the actual existence of all these types of speciation. The influence of environmental changes and build-up was also highlighted to be a factor of concern in the development of each of the types of speciation listed. The paper will review four different articles and the respective views of those articles on the sympatric and allopatric speciation. The present evidence according to those articles will be deduce and compared. Their findings will then be synthesized to collect the evidence based information that will allow us to understand the two types of speciation.
Bolnick & Fitzpatrick (2005) article showed that there is an extensive critique against the existence of sympatric speciation in natural populations. The critique showed that there is little evidence regarding the sympatric speciation. However, the authors highlighted some of the factors that have prevented the biologist from actually establishing the true status of the sympatric speciation. Bolnick and Fitzpatrick also demonstrate the occurrence of sympatric speciation by stating the need to rule out alternative hypothesis such as allopatry. It also shows that there are two major evidences that support the existence of sympatric speciations. The first evidence is that which states that sister species in an isolated environment makes the secondary contact unlikely.
The second evidence is that which believes speciation mechanism occurring easily is that of sympatry when compared to all other types of speciation. These two evidences do not support the frequency of the sympatric speciation in the natural environment. However, the Fitzpatrick and Turelli in another paper also argued against the existence of any evidence favoring the frequent sympatric speciation. This paper strongly showed that geographic factor which is one of the strongest determinants for both allopatric and sympatric speciation is not for sure a constant factor. Can we then say that this argument or findings are true? If this is true, both types of speciation will then be invalid in the natural setting.
The only speciation type supported by the result of their research is the allopatric which they believed created some forms of overlap among the species pair. Fitzpatrick & Turelli (2006) strongly pointed towards the fact that there is a phylogenetic signal from all studied species supporting a form of overlap and also making the existence of other groups of speciation to be classified as an inconclusive group.
Another aspect of the present evidence scenario is in the area of the evolutionary phenomenon relating to the ecology and evolutionary biology. This phenomenon also reflects different changes occurring with the ecological communities that described changes that occur in relations with the various forms of species. This describes those that overlapped and those that do not. The idea relates to the term described as the 'ecological character displacement'. This ecological character displacement has now become a controversial issue within the biologist. The perception of the speciation in terms of the ecological character displacement relates to the fact that biologist now believes that the sites of the sympatry and allopatry should not differ. This is viewed in term so the sites for food, climate and other environmental factors that believed to influence the speciation.
Stuart & Losos (2013) described ecological character displacement in another perspective in terms of sympatry and allopatry speciation. Their views differ from that of the Dayan & Simberloff (2005) which creates morphological and phenotypic differences as an important factor that must exist in relations to speciation. Stuart and Losos revealed that for a two species be considered to have a form of exaggerated divergence in sympatry, such species must show some form of similar resource use while allopatry need to show some form of phenotype similarity in allopatry. This information has some direct and indirect implication on the views presented by Bolnick & Fitzpatrick that was raised earlier stating a difficulty in counter-displacing the occurrence of sympatric speciation in natural populations. The exaggerated divergence stated by Stuart & Losos to have a similar relationship in terms of species interactions.
It is important to note as stated by the Stuart and Losos that no field experiment will perfectly control every factor that tend to influence the evolution in nature. It is better to have the understanding of the dynamics of the ecological and evolutionary process. These dynamics such as depletion of competition and natural selection are very important in predicting by the several other theories. The causes of the phylogenetic distance and range of overlap are also distinct. As stated by the Dayan & Simberloff (2005), the majority of the studies conducted in relation with ecological character displacement relating to speciation tend support the proposed hypothesis. Those studies were conducted ranging from their impact on plants to vertebrate. However, there are still several issues that are still being considered to require research. Some of these studies are pointed to consider the size of the ecological communities.
Much that has been said regarding the comparative estimate of the frequency of sympatric and allopatric speciation are not fully evidence based considering the findings of the reviewed studies. Bolnick & Fitzpatrick (2007) study showed that sympatric speciation might not have been found to exist in the form of the natural population, the theoretical models described showed that the sympatric speciation is possible in principle. It is said that this theoretical models are made up of magic traits that helps influence the mating patterns and ecological fitness of the species that are involved in the sympatric speciation in the natural population.
Work Cited
Bolnick, D. & Fitzpatrick,M. Sympatric Speciation: Models and Empirical Evidence. Annual Review of Ecology, Evolution, and Systematics. 2007. 38: 459-89
Dayan, T. & Simberloff, D. Ecological and community-wide character displacement: the next generation. Reviews and Syntheses. Ecology letters (2005). 8: 875-894.
Fitzpatrick, B. & Turelli, M. The geography of mammalian speciation: mixed signals from phylogenies and range maps. Evolution, 60(3), 2006, pp.601-615.
Stuart, Y. & Losos, J. Ecological character displacement: glass half full or half empty?. Opinion. Trends in Ecology & Evolution. July 2013, Vol. 28, No 7.
