Final answer:
Homoplasy is the convergence of similar traits in unrelated species often due to similar environmental conditions, as opposed to homologous traits, which stem from a shared ancestry. Examples include the wings of insects versus those of birds and bats, where the former are analogous structures evolved independently, while the latter are homologous.
Step-by-step explanation:
Homoplasy refers to a phenomenon where similar traits evolve independently in unrelated species due to similar environmental pressures, rather than shared ancestry. In contrast, homologous traits originate from a common ancestor, suggesting a close evolutionary relationship between the species that possess them. Therefore, the convergence of traits in unrelated species, often caused by living in similar ecosystems or facing similar challenges, is what defines homoplasy.
An example of homoplasy can be seen in the wings of bats and birds compared to the wings of insects. While all these creatures have wings that allow for flight, the wings of birds and bats are homologous structures as they share a common vertebrate ancestor with similar bone structures. In contrast, insect wings have evolved separately and have a different structural and embryonic origin, making them analogous structures.
To decipher the phylogeny of organisms, scientists must determine if the traits in question are homologous or analogous. Morphological, biochemical, and genetic traits that are shared across species and trace back to a common ancestor are used to reconstruct evolutionary histories — these are homologous traits. Conversely, traits that arise independently in different lineages due to adaptation to similar environments are not inherited from a common ancestor and are known as analogous traits, a result of homoplasy.