Although most salamanders have four legs, the aquatic salamander shown below resembles an eel. It lacks hind limbs and has very tiny forelimbs. Propose a hypothesis to explain how limbless salamanders evolved according to Darwin's theory of natural selection.
To propose a hypothesis for the evolution of limbless salamanders according to Darwin's theory of natural selection, we need to consider the principles of variation, heritability, and differential reproductive success.
Hypothesis: Limbless salamanders evolved through natural selection due to adaptation to an aquatic lifestyle.
Explanation: According to Darwin's theory, individuals within a population exhibit natural variation. In salamanders, this variation could include differences in limb development. Some individuals may have slight variations resulting in smaller or rudimentary limbs, while others may have more developed limbs.
In an aquatic environment, having limbs might not confer a significant advantage or might even be a hindrance for certain activities, such as swimming or moving through narrow spaces. Individuals with smaller or rudimentary limbs may have had an increased ability to navigate through aquatic habitats more efficiently. This initial advantage allowed them to access new ecological niches and resources that were not available to their fully limbed counterparts.
Furthermore, the heritability of these limb variations becomes important for the hypothesis. Individuals with smaller limbs would pass on their genetic traits to their offspring, increasing the likelihood of offspring also having reduced limb development. Over generations, the frequency of these genetic traits for reduced limb development would increase in the population.
Differential reproductive success is a critical component of natural selection. If limbless salamanders had an advantage in their aquatic habitat, they would have better survival rates and reproductive success compared to fully limbed individuals. This successful reproduction of limbless individuals would result in their genetic traits becoming more predominant in the population over time.
Therefore, through the mechanisms of natural variation, heritability, and differential reproductive success, the hypothesis proposes that limbless salamanders evolved due to the selection for adaptations advantageous to an aquatic lifestyle.