What is a phylogenetic species concept?
The phylogenetic species concept defines a species as a group of organisms that shares a common ancestor and can be distinguished from other organisms that do not share that ancestor. As an analogy, the phylogenetic species concept asserts that on the tree of life, species are the distal twigs. This contrasts with the biological species concept, which asserts that organisms are of the same species if they can interbreed successfully.
What is comparative embryology?
Comparative embryology is the scientific study of the similarities in structure between the embryos of various species that suggest a possible link to a common ancestor. Early developmental patterns are collated and compared to investigate the likely relationships among evolved organisms.
How do homologous structures support evolution?
Homologous structures, such as the fins of whales and the hands of monkeys, demonstrate that while a species may use structures for different purposes, the species shared a common ancestor. By definition, homologous structures refer to those that were derived from ancestrally similar structures. The natural world is full of examples of homologous structures, which the theory of natural selection predicts should be the case.
What do all mollusks have in common?