Which evidence supports the theory that fish and mammals involved from the same ancestor?
There is substantial evidence supporting the theory that fish and mammals evolved from the same ancestor. Here are some key pieces of evidence:
1. Fossil record: Fossils of early fish-like creatures, such as Tiktaalik and Panderichthys, show features that are intermediate between fish and land-dwelling animals like tetrapods (four-limbed vertebrates). These transitional fossils provide evidence for the evolutionary transition from fish to land-dwelling animals, which eventually gave rise to mammals.
2. Genetic similarities: Comparative analysis of the genomes of various organisms, including fish and mammals, has revealed striking similarities in their genetic makeup. These similarities suggest a common ancestry and provide evidence for evolutionary links between these groups. For example, the Hox genes responsible for body axis development are highly conserved in both fish and mammals.
3. Developmental similarities: Comparative embryology reveals similar developmental patterns and structures between fish and mammals. They both exhibit pharyngeal arches, which form the jaws and gill arches in fish and evolve into various structures in mammals, such as the jawbones, inner ear bones, and throat cartilages. This shared developmental pattern indicates a common ancestry.
4. Molecular evidence: Comparative studies of proteins and other molecules have shown that fish and mammals share many similarities at the molecular level, further supporting their common ancestry. Molecular phylogenetic analyses, which compare DNA or protein sequences, consistently place fish and mammals in the same evolutionary tree.
5. Vestigial structures: Both fish and mammals possess vestigial structures that have lost their original function but continue to exist as remnants of ancestral traits. Examples include the pelvic bones in whales and dolphins, remnants of hindlimbs from their terrestrial ancestors, and the presence of gill slits in embryonic stages of mammals, which reflect the shared ancestry with fish.
These lines of evidence, when considered collectively, strongly support the theory that fish and mammals evolved from a common ancestor.