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Evolution of fish to tetrapods. The basic body plan has been phylogenetically constrained. Most terrestrial vertebrates have a body plan that consist of four limbs. The phylogenetic inertia hypothesis suggests that this body plan is observed, not because it happens to be optimal, but because tetrapods are derived from a clade of fishes (Sarcopterygii) which also have four limbs.
The phyllosoma larva of spiny lobsters has a long planktonic life before metamorphosing into the puerulus stage, which is the transitional stage from planktonic to a benthic existence. [ 3 ] [ 4 ] Despite the importance of larval survival to predict recruitment, not much is known about the biology of phyllosoma larvae. [ 5 ]
Müller demonstrated that crustaceans shared the Nauplius larva, identifying several parasitic species that had not been recognized as crustaceans. Müller also recognized that natural selection must act on larvae, just as it does on adults, giving the lie to recapitulation, which would require larval forms to be shielded from natural selection ...
Biological constraints are factors which make populations resistant to evolutionary change. One proposed definition of constraint is "A property of a trait that, although possibly adaptive in the environment in which it originally evolved, acts to place limits on the production of new phenotypic variants."
Polypodium spends most of its life inside the oocytes of acipenseriform fishes. In infected oocytes, Polypodium develops from a binucleate cell into an inside-out planuliform larva and then into an elongate inside-out stolon; the epidermal cell layer is located internal to the body and the gastrodermis is located externally.
There is some doubt as to whether the lepospondyls form a phylogenetic unit at all, or is a wastebin taxon containing the padamorphic forms and tadpoles of other labyrinthodonts, notably the reptile-like amphibians, or even very small primitive amniotes with reduced skulls.
Marine larval ecology is the study of the factors influencing dispersing larvae, which many marine invertebrates and fishes have. Marine animals with a larva typically release many larvae into the water column, where the larvae develop before metamorphosing into adults.
Phylogenetic comparative methods (PCMs) use information on the historical relationships of lineages (phylogenies) to test evolutionary hypotheses. The comparative method has a long history in evolutionary biology; indeed, Charles Darwin used differences and similarities between species as a major source of evidence in The Origin of Species .