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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.
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."
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 ...
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.
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
It has been called a "universal phylogenetic tree in rooted form". [1] This tree and its rooting became the subject of debate. [50] [b] In the meantime, numerous modifications of this tree, mainly concerning the role and importance of horizontal gene transfer for its rooting and early ramifications have been suggested (e.g. [54] [49]).
A particularly strict form of evolutionary systematics has been presented by Richard H. Zander in a number of papers, but summarized in his "Framework for Post-Phylogenetic Systematics". [ 13 ] Briefly, Zander's pluralistic systematics is based on the incompleteness of each of the theories: A method that cannot falsify a hypothesis is as ...
The effects of anhydrobiosis, gamma ray and heavy-ion irradiation on the nuclear DNA and gene expression of these larvae were studied by Gusev et al. [31] They found that larval DNA becomes severely fragmented both upon anhydrobiosis and irradiation, and that these breaks are later repaired during rehydration or upon recovery from irradiation ...