Natural and Sexual Selection in Frogs

Natural and Sexual Selection in Frogs

According to the Darwinian theory of natural and sexual selection, organisms undergo variations and mutations in order to possess significant traits for their survival in a specific ecosystem. Such adaptations increase the survival and reproduction rates thus maintaining their existence in an ecological niche. Moreover, the variations are inheritable hence making the future generations to survive. However, in the case of reproductive isolation, new species are likely to form. Sexual selection inhibits overproduction of unfit species’ generation since only organisms with the best fitness compete successfully for mates either in intrasexual or intersexual selection. For instance, the bullfrog has unique phenotypic adaptations that enable it to survive on the competitive land and aquatic niches.

Since amphibians live partly on land and water, the bullfrogs have different leg lengths which help them in their movements with the fittest bullfrog having the desirable characteristics and optimum length. Irschick & Higham (2016) affirm that due to the effect of natural selection, some of the bullfrogs underwent phenotypic reproduction hence the variation in the leg characteristics of the bullfrogs. Some of the bullfrogs have muscular, long legs with webbed feet which provide desired traits for both swimming and jumping. However, others lack the webbed feet characteristic thus they become competitively weak.

According to Darwin, the strongest organic being will live while the weak will die, therefore, the bullfrogs with desirable movement traits have more rates of survival and reproduction than the others.

Additionally, for a bullfrog to be the most competitive, the size and length of the tongue is a key consideration. Significantly, long tongues help in hunting insects which are at a distant. In this context, big bullfrogs have long and sticky tongues than the small bullfrogs thus making them better in hunting. Therefore, with time the frogs with small-sized tongue will eventually be phased out due to competition for resources. All in all, Darwin states that natural selection only eliminates or maintains but does not create (Thomé & Carstens, 2016).

On the other hand, Bullfrogs, just as other frogs, have sexual selection techniques which help them overcome the competition of mates. For instance, extensive research concludes that male frogs which have longer and louder croaking attract the female mates faster than those exhibiting softer and shorter croaking sounds (Irschick & Higham, 2016). Such sexual selection trait makes them more intrasexual competitive. Moreover, their female counterparts exhibit a high sensory characteristic in their auditory system thus enabling them to notice the low-frequency croaks of the larger males. According to Darwin, males are prone to an open competition whereby the ablest male won’t be prevented from existing.

Additionally, sexual dichromatism among the frogs, such as bullfrogs, is a sexual selection trait which determines the probability of either a female or male frog getting the most desirable mate. Sexual dichromatism in frogs can either be ontogenetic or dynamic and varies among different species. According to Rojas (2017), in this case male or female frogs become brighter increasing their chances of being noticeable. Since evaluation of potential mates in frogs is based on coloration, in most cases the brightest mates end up being selected for breeding and non-breeding periods. Therefore, breeding chances of the disadvantaged group decrease leading to their extinction. As Darwin said, the emergence of new species leads to other species becoming rarer hence extinction.

In conclusion, the phenotypic variations and adaptations of the bullfrogs are very significant for their survival. The difference in the amalgam of traits makes them more fit for their survival in their respective ecological niches. Although natural selection produces the organisms which are fit for a certain ecosystem, sexual selection only promotes the chances of mate acquisition through the development of enhanced sexual traits. Moreover, natural selection has led to the modification of organisms to keep up with the changing climate as well as the extinction of several species globally.

References

Irschick, D. J., & Higham, T. E. (2016). Animal athletes: an ecological and evolutionary    approach. Oxford University Press.

Rojas, B. (2017). Behavioural, ecological, and evolutionary aspects of diversity in frog colour       patterns. Biological Reviews, 92(2), 1059-1080.

Thomé, M. T. C., & Carstens, B. C. (2016). Phylogeographic model selection leads to insight        into the evolutionary history of four-eyed frogs. Proceedings of the National Academy of    Sciences, 113(29), 8010-8017.