Search results
Results from the WOW.Com Content Network
Allochronic speciation (also known as allochronic isolation, or temporal isolation) is a form of speciation (specifically ecological speciation) arising from reproductive isolation that occurs due to a change in breeding time that reduces or eliminates gene flow between two populations of a species.
Turbulence and vortices play a much larger role in insect flight, making it even more complex and difficult to study than the flight of vertebrates. [18] There are two basic aerodynamic models of insect flight. Most insects use a method that creates a spiralling leading edge vortex.
This model implies a progressive increase in the effectiveness of the wings, starting with parachuting, then gliding and finally active flight. Still, lack of substantial fossil evidence of the development of the wing joints and muscles poses a major difficulty to the theory, as does the seemingly spontaneous development of articulation and ...
Dosage compensation is the process by which organisms equalize the expression of genes between members of different biological sexes. Across species, different sexes are often characterized by different types and numbers of sex chromosomes .
How the Snake Lost Its Legs: Curious Tales from the Frontier of Evo-Devo is a 2014 book on evolutionary developmental biology by Lewis I. Held, Jr. The title pays homage to Rudyard Kipling 's Just So Stories , [ 1 ] [ a ] but the "tales" are strictly scientific, explaining how a wide range of animal features evolved, in molecular detail.
The mediaeval great chain of being as a staircase, implying the possibility of progress: [1] Ramon Lull's Ladder of Ascent and Descent of the Mind, 1305. Alternatives to Darwinian evolution have been proposed by scholars investigating biology to explain signs of evolution and the relatedness of different groups of living things.
The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous , whereas homologous structures or traits have a common origin but can have dissimilar functions.
The Cretaceous saw the rise of more modern birds with a more rigid ribcage with a carina and shoulders able to allow for a powerful upstroke, essential to sustained powered flight [citation needed]. Another improvement was the appearance of an alula, used to achieve better control of landing or flight at low speeds [citation needed].