divergent evolution

Examples of divergent evolution in the following topics:

• Convergent Evolution

  • Convergent evolution occurs in different species that have evolved similar traits independently of each other.
  • This phenomenon is called convergent evolution, where similar traits evolve independently in species that do not share a recent common ancestry.
  • Convergent evolution describes the independent evolution of similar features in species of different lineages.
  • Convergent evolution is similar to, but distinguishable from, the phenomenon of parallel evolution.
  • The opposite of convergent evolution is divergent evolution, whereby related species evolve different traits.

• Gene Duplications and Divergence

  • Gene duplications create genetic redudancy and can have various effects, including detrimental mutations or divergent evolution.
  • Gene duplication is believed to play a major role in evolution; this stance has been held by members of the scientific community for over 100 years.
  • These changes in gene frequency can contribute to divergence.
  • Divergent evolution is usually a result of diffusion of the same species to different and isolated environments, which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics through genetic drift and natural selection.Divergent evolution can also be applied to molecular biology characteristics.
  • Both orthologous genes (resulting from a speciation event) and paralogous genes (resulting from gene duplication within a population) can be said to display divergent evolution.

• Processes and Patterns of Evolution

  • The evolution of species has resulted in enormous variation in form and function.
  • Sometimes, evolution gives rise to groups of organisms that become tremendously different from each other.
  • When two species evolve in diverse directions from a common point, it is called divergent evolution.
  • Such divergent evolution can be seen in the forms of the reproductive organs of flowering plants which share the same basic anatomies; however, they can look very different as a result of selection in different physical environments and adaptation to different kinds of pollinators .
  • These physical changes occur over enormous spans of time and help explain how evolution occurs.

• Early Human Evolution

  • Modern humans and chimpanzees evolved from a common hominoid ancestor that diverged approximately 6 million years ago.
  • Evidence from the fossil record and from a comparison of human and chimpanzee DNA suggests that humans and chimpanzees diverged from a common hominoid ancestor approximately 6 million years ago.
  • In years past, when relatively few hominin fossils had been recovered, some scientists believed that considering them in order, from oldest to youngest, would demonstrate the course of evolution from early hominins to modern humans.
  • This chart shows the evolution of modern humans and includes the point of divergence that occurred between modern humans and the other great apes.

• Evolution of Reptiles

  • Dinosaurs and pterosaurs diverged from early amniotes and dominated the Mesozoic Era.
  • Soon after the first amniotes appeared, they diverged into three groups (synapsids, anapsids, and diapsids) during the Permian period.
  • The Permian period also saw a second major divergence of diapsid reptiles into archosaurs (predecessors of crocodilians and dinosaurs) and lepidosaurs (predecessors of snakes and lizards).
  • Pterosaurs had a number of adaptations that allowed for flight, including hollow bones (birds also exhibit hollow bones, a case of convergent evolution).

• Evidence of Evolution

  • The evidence for evolution is compelling and extensive.
  • Embryology, the study of the development of the anatomy of an organism to its adult form, provides evidence for evolution as embryo formation in widely-divergent groups of organisms tends to be conserved.
  • Over time, these species diverge evolutionarily into new species that look very different from their ancestors that may exist on the mainland.
  • DNA sequences have also shed light on some of the mechanisms of evolution.
  • Explain how the fossil record has aided in the development of the theory of evolution

• Evolution of Mammals

  • The evolution of mammals passed through many stages since the first appearance of their synapsid ancestors in the late Carboniferous period.
  • Since Juramaia, the earliest-known eutherian, lived 160 million years ago in the Jurassic, this divergence must have occurred in the same period.
  • The relatively new techniques of molecular phylogenetics have also shed light on some aspects of mammalian evolution by estimating the timing of important divergence points for modern species.
  • Although mammary glands are a signature feature of modern mammals, little is known about the evolution of lactation.
  • Most study of the evolution of mammals centers, rather, around the shapes of the teeth, the hardest parts of the tetrapod body.

• Evolution of Amniotes

  • The early amniotes diverged into two main lines soon after the first amniotes arose.
  • The diapsids diverged into two groups, the Archosauromorpha ("ancient lizard form") and the Lepidosauromorpha ("scaly lizard form") during the Mesozoic period .
  • This chart shows the evolution of amniotes.

• The Evolution of Craniata and Vertebrata

  • This suggests that the cephalochordates first diverged from urochordates, and that vertebrates subsequently diverged from the cephalochordates.

• Evolution of Viruses

  • The evolution of viruses is speculative as they do not fossilize; biochemical and genetic information is used to create virus histories.
  • This phylogenetic tree of the three domains of life (Bacteria, Archaea, and Eukarya) attempts to identify when various species diverged from a common ancestor.