enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Speciation - Wikipedia

    en.wikipedia.org/wiki/Speciation

    The fact that the lines remain parallel with the time axis illustrates the unchanging appearance of each of the fossil species depicted on the graph. During each species' existence new species appear at random intervals, each also lasting many hundreds of thousands of years before disappearing without a change in appearance.

  3. Molecular evolution - Wikipedia

    en.wikipedia.org/wiki/Molecular_evolution

    The genome-wide amount of recombination is directly controlled by the number of chromosomes, with one crossover per chromosome or per chromosome arm, depending on the species. [ 31 ] Changes in chromosome number can play a key role in speciation , as differing chromosome numbers can serve as a barrier to reproduction in hybrids.

  4. Genetic isolate - Wikipedia

    en.wikipedia.org/wiki/Genetic_isolate

    A genetic isolate is a population of organisms that has little to no genetic mixing with other organisms of the same species due to geographic isolation or other factors that prevent reproduction. Genetic isolates form new species through an evolutionary process known as speciation. All modern species diversity is a product of genetic isolates ...

  5. Lists of organisms by population - Wikipedia

    en.wikipedia.org/wiki/Lists_of_organisms_by...

    More than 99 percent of all species, amounting to over five billion species, [7] that ever lived on Earth are estimated to be extinct. [8] [9] Estimates on the number of Earth's current species range from 10 million to 14 million, [10] of which about 1.2 million have been documented and over 86 percent have not yet been described. [11]

  6. Macroevolution - Wikipedia

    en.wikipedia.org/wiki/Macroevolution

    Charles Darwin first discovered that speciation can be extrapolated so that species not only evolve into new species, but also into new genera, families and other groups of animals. In other words, macroevolution is reducible to microevolution through selection of traits over long periods of time. [ 31 ]

  7. Population genetics - Wikipedia

    en.wikipedia.org/wiki/Population_genetics

    Population genetic models can be used to identify which populations show significant genetic isolation from one another, and to reconstruct their history. [52] Subjecting a population to isolation leads to inbreeding depression. Migration into a population can introduce new genetic variants, [53] potentially contributing to evolutionary rescue.

  8. Microevolution - Wikipedia

    en.wikipedia.org/wiki/Microevolution

    Migration into or out of a population may be responsible for a marked change in allele frequencies. Immigration may also result in the addition of new genetic variants to the established gene pool of a particular species or population. There are a number of factors that affect the rate of gene flow between different populations.

  9. Rate of evolution - Wikipedia

    en.wikipedia.org/wiki/Rate_of_evolution

    The rate of evolution is quantified as the speed of genetic or morphological change in a lineage over a period of time. The speed at which a molecular entity (such as a protein, gene, etc.) evolves is of considerable interest in evolutionary biology since determining the evolutionary rate is the first step in characterizing its evolution. [1]