Search results
Results from the WOW.Com Content Network
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 ]
Put another way, when evolution is considered to be guided by developmental constraints or by phylogenetic constraints, it is orthogenetic. [10] Some researchers [who?] consider Croizat as one of the most original thinkers of modern comparative biology, whose contributions provided the foundation of a new synthesis between earth and life sciences.
The idea of a tree of life arose from ancient notions of a ladder-like progression from lower into higher forms of life (such as in the Great Chain of Being).Early representations of "branching" phylogenetic trees include a "paleontological chart" showing the geological relationships among plants and animals in the book Elementary Geology, by Edward Hitchcock (first edition: 1840).
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. [36] [34]
They are inferences based on patterns of relationship among taxa inferred in a phylogenetic analysis of extant organisms and/or fossils. [1] The last universal common ancestor (LUCA) is the most recent common ancestor of all current life on Earth, estimated to have lived some 3.5 to 3.8 billion years ago (in the Paleoarchean). [2] [3] [note 1]
In today's puzzle, there are eight theme words to find (including the spangram). Hint: The first one can be found in the top-half of the board. Here are the first two letters for each word:
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."