An adaptive trait is a characteristic that has evolved in a population of an organism that provides a functional advantage. This trait is developed from the ancestors to their descendants. Over time most organisms have evolved to help them survive in their different environments. At times, genetically, other species can evolve to develop a similar characteristic to help them stay. An example of a common adaptive trait common for more than one species is fins in whales and turtles.
Modern whales have tail flukes, extended flippers, and dorsal fins, and they live in oceans and the sea. However, it is believed that their ancestors walked on land millions of years ago (Gross, 2020). Whales are mammals just like human beings, and paleontologists have found fossil evidence of whale-like creatures with legs. These creatures are believed to have favored eating plants on water’s edges and could hide from danger in shallow water. With time the whales moved into being semi-aquatic life as they spent more time in the water, and eventually, their bodies adapted to life under waters by learning to swim. (Harris). Apart from their nose moving to the top of their head, the whales evolved to form fins. Their front legs became flippers forming two pectoral fins, and they developed a flat tail called a caudal fin. Although not all, some whales evolved dorsal fins that help them stabilize the whale’s body as it swims. This evolution results from genetic mutation, as some genes are reported to have been lost while evolving to aquatic life. It is believed that the reason for evolution from land to marine animals was in search of food.
Modern-day turtles are fully aquatic fresh and saltwater species. However, turtles were land-dwelling reptiles with limps to walk millions of years ago. Over 100 million years ago, turtles evolved from dwelling in the land to being semi-aquatic animals and eventually became fully aquatic life (Evers, 2018). In present-day turtles, their limps and claws grew to form flippers (fins). Present-day sea turtles have long flippers to help them steer their body efficiently in water. The evolution was driven by the breaking up of ancient supercontinents and the isolation of oceans and their currents. As a result of genetic mutation, the old turtles evolved into the present-day turtles that live aquatic life (de Salva et al., 2020)
A homologous trait is a structure that evolves in the living organism that has common ancestors. In contrast, an analogous characteristic is a structure that develops independently in different living organisms with similar or the same functions (Watling, 2020). The adaptive trait in both whales and sea turtles of fins is analogous. Both organisms are of different species, i.e., whales are mammals while sea turtles are reptiles. They have both evolved to have fins to perform the same function, making them possible for aquatic life.
Convergent evolution is how two species develop a similar feature despite not sharing common ancestry. In contrast, divergent evolution occurs when two organisms with common ancestry evolve into two different species. An example of divergent evolution is Bat and Mouse, which share the exact origin but have evolved to have wings in bats and paws in mice. An example of convergent evolution is in the marine life in the case of whales and turtles(Cordero et al., 2018). The two organisms have different ancestry but have evolved to have similar features, i.e., the fins to help them survive in their new aquatic environment.
Gross, M. (2020). Step changes in evolution. Retrieved from https://www.sciencedirect.com/science/article/pii/S0960982219316926
Harris Tom. (n.d). How Whales Work. Retrieved from com/mammals/baleen-whale.htm”>https://animals.howstuffworks.com/mammals/baleen-whale.htm
Cordero, G. A., Liu, H., Wimalanathan, K., Weber, R., Quinteros, K., & Janzen, F. J. (2018). Gene network variation and alternative paths to convergent evolution in turtles. Evolution & Development, 20(5), 172-185. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1111/ede.12264
da Silva Ramos, E. K., Freitas, L., & Nery, M. F. (2020). The role of selection in the evolution of marine turtles mitogenomes. Scientific reports, 10(1), 1-13. Retrieved from https://peerj.com/articles/4386/
Evers, S. W. (2018). The early evolution of sea turtles (Doctoral dissertation, University of Oxford). Retrieved from https://ora.ox.ac.uk/objects/uuid:197f0461-a847-4b76-ab2a-d0fa1c4a8309
Watling, L. (2020). A classification system for crustacean setae based on the homology concept. In Functional morphology of feeding and grooming in Crustacea (pp. 15-26). CRC Press. Retrieved from 1201/9781003079354-2/classification-system-crustacean-setae-based-homology-concept-les-watling“>https://www.taylorfrancis.com/chapters/edit/10.1201/9781003079354-2/classification-system-crustacean-setae-based-homology-concept-les-watling