Macro n megaevolution

of 25

Please download to get full document.

View again

All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
25 pages
0 downs
1. Macroevolution And Megaevolution Submitted to: Dr.Fakhar Un Nisa Class: BS-IV Roll no: 329 Semester: 7th Department of Zoology 2. WWW.PLANETAYURVEDA.COM Macroevolution…
  • 1. Macroevolution And Megaevolution Submitted to: Dr.Fakhar Un Nisa Class: BS-IV Roll no: 329 Semester: 7th Department of Zoology
  • 2. WWW.PLANETAYURVEDA.COM Macroevolution And Megaevolution Microevolution Definition: Micro evolution is the change in alleles frequency that occur within time through evolution.this change is due to four different processes: •Mutation •Selection(artificial or natural) •Gene flow •Genetic drift
  • 3. Macroevolution And Megaevolution Macroevolution Definition: Macroevolutionary studies focus on change that occurs at or above the level of specie. •An example of macroevolution is the appearance of feathers during the evolution of birds from theropod dinosaurs.
  • 4. An Example of Macroevolution Macroevolution And Megaevolution •genus of Equidae, Equus
  • 5. Pattern of Macroevolution Macroevolution And Megaevolution we can think of patterns as "what happened when" All of the changes, diversifications, and extinctions that happened over the course of life's history are the patterns of macroevolution. General patterns that recur across the tree of life: •Stasis •Character change •Lineage-splitting •extinction
  • 6. Macroevolution And Megaevolution Biological Species Concept Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups. •Breeding behavior can be real or potential, if two species come together and breed then there was only one species. •Breeding behavior in nature can be different than in captivity.
  • 7. Macroevolution And Megaevolution How do new species arise?How do new species arise? Speciation is the development of a new species through evolution. Evolution within a species means a change in that population’s allele frequency. When two populations are separated their allele frequency changes. Since they no longer have migration between the populations, two separate species develop. There are many ways to separate two populations besides geographically.
  • 8. Macroevolution And Megaevolution Allopatric Speciation •Allopatric means ‘of other countries’ When geographical barriers divide a population, followed by the development of mechanisms in the separated populations that prevent interbreeding. •Geographical isolation is the most important factor in starting speciation. •Physical or behavioral changes develop that will keep the two species isolated from interbreeding.
  • 9. Macroevolution And Megaevolution Reproductive Isolation Any factor in nature that prevents interbreeding between individuals of the same or closely related species. Extrinsic isolating mechanism – outside of the organisms in question Geographic isolation is extrinsic Intrinsic isolating mechanism – internal characteristics that prevent interbreeding Differences in anatomy, physiology and behavior
  • 10. Macroevolution And Megaevolution Intrinsic Reproductive Isolating Mechanisms •Ecological •Temporal •Behavioral •Mechanical •Gametic
  • 11. Macroevolution And Megaevolution Ecological Isolation When two species have different habitats they will rarely have contact. •Lions prefer open grassland, tigers prefer forest Temporal Isolation Two species that share the same habitat but do not mate within the same time frame. •Two populations of the same species of plant release their pollen at different times of the year.
  • 12. Macroevolution And Megaevolution Behavioral Isolation Even if populations are in contact and breeding can occur, they must choose to mate. Such a choice is based on specific courtship and mating displays.
  • 13. Behavioral Isolation These albatrosses are behaviorally isolated from other bird species by their elaborate, species- specific courtship behavior.
  • 14. Macroevolution And Megaevolution Mechanical Isolation Reproductive organs differ in size or shape or other feature. •Different species of Alpine Butterfly look similar but have different reproductive organs.
  • 15. Macroevolution And Megaevolution Gametic Isolation Even if mating occurs, offspring may not result if there are incompatibilities between sperm and egg, or between sperm and the female reproductive tract.
  • 16. Macroevolution And Megaevolution Any speciation that does not involve geographic separation. e.g.Sympatric Speciation in fruit flies •Only 6% of flies interbreed •Conduct courting, mating, laying eggs in their specific type of tree •In transition to being two separate species •Mutation or combination of rare alleles •allowed flies to smell the apple trees Sympatric speciation
  • 17. Macroevolution And Megaevolution Parapatric Speciation •Populations in contact along a common border giant velvet worm blind velvet worm
  • 18. early reptile pterosaur chicken bat porpoise penguin •Change from body form of a common ancestor •Produces homologous structures Macroevolution And Megaevolution Morphological Divergence human
  • 19. Macroevolution And Megaevolution Morphological Divergence
  • 20. Macroevolution And Megaevolution Morphological Divergence body wall (exoskeleton) strong membrane (extension of wall) wing veins
  • 21. Macroevolution And Megaevolution Adaptive Radiations of Mammals
  • 22. Macroevolution And Megaevolution Megaevolution Definition: The term "megaevolution" is used for great changes. A list was prepared by John Maynard Smith and which he called The Major Transitions in Evolution.On the 1999 edition of the list they included: •Replicating molecules: change to populations of molecules in protocells. •Independent replicators leading to chromosomes. •RNA as gene and enzyme change to DNA genes and protein enzymes.
  • 23. Megaevolution •Bacterial cells (prokaryotes) leading to cells (eukaryotes) with nuclei and organelles •Asexual clones leading to sexual populations •Single-celled organisms leading to fungi, plants and animals •Solitary individuals leading to colonies with non- reproducing castes (termites, ants & bees) •Primate societies leading to human societies with language
  • 24. Megaevolution The Cambrian radiation example When it was first described, the Cambrian fossil Opabinia was thought to be unrelated to any known phylum. Later discoveries have shown it to be closely related to the ancestors of arthropods. The Cambrian organism Marrella, was clearly an arthropod, but with features not seen in modern organisms Dickinsonia, an organism of the Ediacaran Period that precedes the Cambrian, whose affinity is still unknown.
  • Related Search
    We Need Your Support
    Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

    Thanks to everyone for your continued support.

    No, Thanks