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Also called functionalism. The Darwinian view that many or most physiological and behavioral traits of organisms are adaptations that have evolved for specific functions or for specific reasons (as opposed to being byproducts of the evolution of other traits, consequences of biological constraints, or the result of random variation). adaptive radiation The simultaneous or near-simultaneous ...
Under conditions of stress such as crowding and high temperature, L2 larvae of some free living nematodes such as Caenorhabditis elegans can switch development to the so-called dauer larva state, instead of going the normal molts into a reproductive adult. These dauer larvae are a stress-resistant, non-feeding, long-lived stage, enabling the ...
Even if there is a gene flow between two populations, strong differential selection may impede assimilation and different species may eventually develop. [34] Habitat differences may be more important in the development of reproductive isolation than the isolation time.
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.
Regeneration, many different unrelated species can grow new limbs, tail or other body parts, if body parts are lost. [204] [205] The statocyst is a balance sensory receptor independently found in different organisms like: some aquatic invertebrates, including bivalves, [206] cnidarians, [207] echinoderms, [208] cephalopods, [209] and ...
Both structures appear during some stage of embryonic development but are not always obvious in the adult form. [51] Because of the morphological similarities present in embryos of different species during development, it was once assumed that organisms re-enact their evolutionary history as an embryo.
Adventitious root s may develop from node s of prostrate stems of some plant species, or from the hypocotyl rather than from the radicle of a germinating monocotyledon. adventive Introduced accidentally [13] (usually referring to a weed). aerial Of the air; growing or borne above the surface of the ground or water. [15] aestivation
The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to parallel evolution , which occurs when two independent species evolve in the same direction and thus independently acquire similar characteristics; for instance, gliding frogs have evolved in parallel from ...