Although most salamanders have four legs, the aquatic salamander resembles an eel. It lacks hind limbs and
has very tiny forelimbs. Explain how
limbless salamanders evolved according to Darwin's theory of natural selection.
Check this site for your answer.
http://bioweb.cs.earlham.edu/9-12/evolution/HTML/theory.html
Create a 7- to 10-slide PowerPoint® presentation that describes environmental benefits
and challenges of urbanization. In your own words, include descriptions of two 1996
award winners, discussing how they overcame one of the challenges mentioned in your
presentation.
According to Darwin's theory of natural selection, limbless salamanders may have evolved through a process called "adaptive evolution." This process typically occurs over a long period of time and involves several steps:
1. Variation: Within a population of ancestral salamanders, there is always genetic variation. This means that some salamanders may have slightly different characteristics than others, including variations in limb development.
2. Environmental Factors: The environment plays a crucial role in shaping the evolution of organisms. In the case of aquatic salamanders, the absence of legs becomes advantageous for their specific way of life. Having long, snake-like bodies allows them to move more efficiently through water, making it easier for them to catch prey and avoid predators.
3. Selective Pressure: Over time, environmental factors create selective pressure on the population. In the case of salamanders, those individuals with longer bodies and reduced or absent limbs would have a higher chance of survival and reproduction in water-based habitats. This is because their body shape provides them with a competitive advantage for obtaining resources and avoiding predators compared to salamanders with fully developed limbs.
4. Reproduction and Inheritance: As the limbless individuals successfully reproduce and pass on their genetic traits to their offspring, the genes responsible for limb reduction become more prevalent in the population. This process, known as natural selection, leads to the gradual evolution of the limbless salamander.
5. Time and Persistence: The evolution of limbless salamanders is a result of cumulative changes over a long period of time. It is important to note that not all salamanders will evolve in this manner. The limbless adaptation is specific to the aquatic environment and has only happened in lineages that have faced selective pressures favoring limb reduction.
Overall, natural selection, driven by the interaction between genetic variation and environmental pressures, has likely played a significant role in the evolution of limbless salamanders, allowing them to become well-adapted for their aquatic lifestyle.