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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.
In population genetics, gene flow (also known as migration and allele flow) is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent allele frequencies and therefore can be considered a single effective population.
Zugunruhe is borrowed from German; it is a German compound word consisting of Zug, "move, migration," and unruhe (anxiety, restlessness). The word was first published in 1707, when it was used to describe the "inborn migratory urge" in captive migrants. [4]
The experiment continues to this day, and is now the longest-running (in terms of generations) controlled evolution experiment ever undertaken. [citation needed] Since the inception of the experiment, the bacteria have grown for more than 60,000 generations. Lenski and colleagues regularly publish updates on the status of the experiments. [42]
Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryonic development , wound healing and immune responses all require the orchestrated movement of cells in particular directions to specific locations.
Wildebeest migrating in the Serengeti. Migration, in ecology, is the large-scale movement of members of a species to a different environment.Migration is a natural behavior and component of the life cycle of many species of mobile organisms, not limited to animals, though animal migration is the best known type.
Migration of cells is free toward and away on the axis of the concentration gradient; Detected responses are the results of active migration of cells; Despite the fact that an ideal chemotaxis assay is still not available, there are several protocols and pieces of equipment that offer good correspondence with the conditions described above. The ...
Objections to evolution have been raised since evolutionary ideas came to prominence in the 19th century. When Charles Darwin published his 1859 book On the Origin of Species, his theory of evolution (the idea that species arose through descent with modification from a single common ancestor in a process driven by natural selection) initially met opposition from scientists with different ...