What is the difference between a homologous structure and an analogous structure? Give an example
of each.
A homologous structure refers to anatomical structures that have a similar origin and structure in different species, indicating a common evolutionary ancestor. These structures may or may not have the same function in different species. For example, the forelimbs of mammals, such as humans, bats, and whales, all have the same basic bone structure, consisting of a humerus, radius, ulna, carpals, metacarpals, and phalanges. Despite having different functions (e.g., walking, flying, swimming), these forelimbs are considered homologous because they share a common ancestor and have a similar underlying structure.
An analogous structure, on the other hand, refers to anatomical structures that have similar functions or appearances in different species but do not share a common ancestry or underlying structure. These structures evolve independently in different species due to similar environmental pressures or adaptations. For example, the wings of birds and the wings of insects both serve the purpose of flying, but their underlying structures and evolutionary origins are completely different. Bird wings are modified forelimbs, whereas insect wings are extensions of the exoskeleton. Therefore, bird wings and insect wings are considered analogous structures.
Rephrase it in prek.
A homologous structure means that certain body parts look the same in different animals, even if they do different things. For example, humans, bats, and whales all have arms with the same bones inside, even though they use their arms for different things.
An analogous structure means that certain body parts do the same thing or look the same in different animals, but they are not made the same way. For example, birds and insects both have wings that help them fly, but their wings are made differently.