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Phylogenetic inertia or phylogenetic constraint refers to the limitations on the future evolutionary pathways that have been imposed by previous adaptations. [ 1 ] Charles Darwin first recognized this phenomenon, though the term was later coined by Huber in 1939. [ 2 ]
A wild-caught cyphonautes, likely of Membranipora, from a plankton sample taken in Coos Bay, Oregon. A cyphonautes is a larva of an ectoproct or bryozoan.It is triangular in profile with a heavily ciliated band called the corona at the base of the triangle and a sense organ at the apex (cypho-, bent; nautes, sailor).
A few species from other phyla; the nemertean pilidium larva, the larva of the phoronid species Phoronopsis harmeri and the acorn worm larva Schizocardium californicum, do not depend on Hox genes in their larval development either, but need them during metamorphosis to reach their adult form.
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."
Each is a member of one of three monophylitic clades. All tunicate larvae have the standard chordate features, including long, tadpole-like tails. Their larva also have rudimentary brains, light sensors and tilt sensors. [28] The smallest of the three groups of tunicates is the Appendicularia. They retain tadpole-like shapes and active swimming ...
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 bracketing is a method of inference used in biological sciences. It is used to infer the likelihood of unknown traits in organisms based on their position in a phylogenetic tree. One of the main applications of phylogenetic bracketing is on extinct organisms, known only from fossils, going back to the last universal common ancestor ...
Orthogenesis is a term used by Croizat, in his words "... in a pure mechanistic sense", [8] which refers to the fact that a variation in form is limited and constrained. [9] Croizat considered organism evolution as a function of time, space and form. Of these three essential factors, space is the one with which biogeography is primarily concerned.