Allopatric & Sympatric Speciation | A-level Biology | OCR, AQA, Edexcel

[@inktothedarkness5469]

This video is done very well. Im going to recommend it to my class this week because it explains everything we will need for the exam in just a short amount of time. Thank you for making this video!

[@launchpadlearn]

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[@Ariat1913]

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[@amnashaikh-sl1qi]

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[@ChsonlineOrgUkinternetschool]

Great content

[@launchpadlearn]

Thank you! 😊

[@AlevelStudent-c1y]

For sympatric speciation, there isn’t any geographic barrier between the 2 populations so wouldn’t they experience the same selection pressures?

[@amishadas2634]

Sympatric speciation is rare firstly. (In allopatric) Selective pressures don’t CAUSE genetic mutations, but if an organism experiences a random genetic mutation, and a geographical selective pressure is added which happens to make that organism better adapted to survive, natural selection occurs in each group, in which one group experiences genetic variation from the other group due to the different selective pressures forcing particular characteristics to be passed on to offspring (as the organisms with the mutation are more likely to survive until reproductive age than others in that population), which may not necessarily be an advantageous characteristic to have for the group experiencing a DIFFERENT geographical pressure. Sympatric speciation is the disruption of gene flow between a species, but this time it could be caused by one individual wanting to mate at night. That individual will most likely always die because the random mutation which caused them to experience this change in behaviour isn’t advantageous. However, if a mutation occurs within more than one organism which causes them to mate at night, there will no longer be any gene flow between group one (night-time maters) and group two (day-time maters). They are all experiencing the same selective pressures GEOGRAPHICALLY but despite that, the two groups will eventually form two different species. Night-time maters will never reproduce with Day-time maters, eventually a mutation will occur and natural selection will happen in one group, and not the other, or different pressures will be added to the day-time group (e.g too much sunlight). As the two groups evolve, even if you tried to continue gene flow between them, and put the day-time and night-time maters in the same place at the same time to mate, they wouldn’t be able to as they are now too genetically different and it PHYSICALLY wouldn’t work, confirming that they are now two species not one. If however, before any natural selection was experienced in group 1 or 2, you put them together same time same place, they WOULD be able to reproduce successfully to produce fertile offspring, and they will no longer develop into 2 species as the continuation of gene flow shares the alleles between them. The selective pressure is now the time in which they want to mate, so if that is removed, which it more easily can be than a geographical pressure (mountain), they won’t form two different species. This is why it is so rare.

[@remkenyon]

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[@mylessinclair9132]

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[@levitatingmonkeys9544]

nice intro vid!

[@youdonknowme2471]

Amazing

[@launchpadlearn]

Thank you! Cheers!

[@dungabernalex466]

Thanks

[@launchpadlearn]

You're welcome!

[@NephilimFree]

What evolutionists refer to as speciation is not evolutionary change. It does not develop new anatomical features and therefore does not move an organism towards become a different kind of organism. It amounts to mere variation, often produced by phenotypic plasticity. It is not a pro0dfuict of mutation. It is a product of gene expression. Speciation is the opposite of evolutionary change in that it causes a continuous loss of genetic information by making genes recessive and eventually turned off permanently, unable to be expressed. Evolution, if it could have been true, would require the opposite - a continuous input of new information, which mutation is incapable of producing. There are over 50,000 varieties of spiders in the world. All of them are spiders. There are an estimated 4,300 species of horse and deer flies in the world. All of them are flies. There are about 17,500 varieties of butterflies in the world. All of them are butterflies. There are over six thousand varieties of lizards in the world and come in a variety of sizes. All of them are lizards. There are over 100 varieties of deer in the world. All of them are deer. There are over 100 varieties of chicken in the world. All of them are chickens. There are over hundreds varieties of cat in the world including Lion, Tiger, Cheetah, Lynx, Bobcat, Jaguar, Puma, Leopard, African Wildcat, etc. All of them are cats. The list goes on and on. Richard A. Richards, The Species Problem: A Philosophical Analysis, Cambridge University Press, 2010, 236pp., $89.00 (hbk), ISBN 9780521196833. ndpr.nd.edu/news/29700-the-species-problem-a-philosophical-analysis/ The Species problem and the Value of Teaching the Complexity of Species, Carl Chung www.nabt.org/websites/institution/File/pdfs/american_biology_teacher/2004/066-06-0413.pdf Evolutionary History and the Species Problem, Robert J. O’Hara, Center for Critical Inquiry in the Liberal Arts and Department of Biology, University of North Carolina at Greensboro rjohara.net/cv/1994-az Problems Inherent in the Species Concepts and Possible Work-Arounds www.uni-koeln.de/~aeb25/species2.html "The species problem is the set of questions that arises when biologists attempt to define what a species is. Such a definition is called a species concept; there are at least 26 recognized species concepts." ttps://en.wikipedia.org/wiki/Species_problem Species problem en.wikipedia.org/wiki/Species_problem "What are species? Perhaps no other issue in comparative or evolutionary biology has produced quite so much disparate opinion as this simple question" - Steve Jones, leading geneticist "What are species? Perhaps no other issue in comparative or evolutionary biology has produced quite so much disparate opinion as this simple question" - Niles Eldredge, nobel Prize winning scientist, evolutionist “When we descend to details, we cannot prove that a single species has changed; nor can we prove that the supposed changes are beneficial, which is the groundwork of the theory [of evolution].” Charles Darwin, The Life and Letters of Charles Darwin, Vol. 1, p. 210. "Within the period of human history we do not know of a single instance of the transformation of one species into another one... It may be claimed that the theory of descent is lacking therefore in the most essential feature that it needs to place the theory on a scientific basis. This must be admitted." - T H Morgan, evolutionist, Evolution and Adaptation, Quoted in Why I Believe, 57 "And let us dispose of a common misconception. The complete transmutation of even one animal species into a different species has never been directly observed either in the laboratory or in the field.” - Dean H. Kenyon, Professor of Biology, San Francisco State University, affidavit presented to the U.S. Supreme Court, No. 85-1513, Brief of Appellants, prepared under the direction of William J. Guste Jr., Attorney General of the State of Louisiana, October 1985, p. A-16. Kenyon has repudiated his earlier book advocating evolution. “... no human has ever seen a new species form in nature.” Steven M. Stanley, The New Evolutionary Timetable (New York: Basic Books, Inc., 1981), p. 73. "My attempts to demonstrate Evolution by an experiment carried on for more than 40 years have completely failed." - Bacteriologist Dr. Nils Heribert-Nilsson “We found no evidence that these things are related. The rate at which genetic reproductive barriers arise does not predict the rate at which new species form in nature,” ... “If these results are true more generally - which we would not yet claim but do suspect - it would imply that our understanding of species formation is extremely incomplete because we’ve spent so long studying the wrong things, due to this erroneous assumption that the main cause of species formation is the formation of barriers to reproduction.” Rabosky, University of Michigan biologist and a colleague are questioning the long-held assumption that genetic reproductive barriers, also known as reproductive isolation, are a driving force behind speciation. www.sciencedaily.com/releases/2013/09/130902162536.htm “Although the vast majority of research in evolutionary biology is focused on adaption, a general theory for the population-genetic mechanisms by which complex adaptations are acquired remains to be developed.” Proceedings of the National Academy of Sciences of the U.S., “Scaling expectations for the time to establishment of complex adaptations”, September 7, 2010, doi:10.1073/pnas.1010836107 “Dr Eric Bapteste, an evolutionary biologist at the Pierre and Marie Curie University in Paris, said: 'For a long time the holy grail was to build a tree of life. We have no evidence at all that the tree of life is a reality.' Dr Rose said: 'The tree of life is being politely buried - we all know that. What's less accepted is our whole fundamental view of biology needs to change.'” “Charles Darwin's tree of life is 'wrong and misleading', claim scientists”, January 22, 2009, Telegraph UK Online. www.telegraph.co.uk/science/4312355/Charles-Darwins-tree-of-life-is-wrong-and-misleading-claim- scientists.html “It is not necessarily easy to 'see' macroevolutionary history; there are no firsthand accounts to be read. Instead, we reconstruct the history of life using all available evidence: geology, fossils, and living organisms.” “Understanding Evolution” by the University of California Museum of Paleontology and the National Center for Science Education, “What is macroevolution?” evolution.berkeley.edu/evolibrary/article/0_0_0/evo_48 “The fact that all the individual species must be stationed at the extreme periphery of such logic [evolutionary] trees merely emphasized the fact that the order of nature betrays no hint of natural evolutionary sequential arrangements, revealing species to be related as sisters or cousins but never as ancestors and descendants as is required by evolution.” [emphasis in original] - Denton, p. 132.

[@ivegotbadtaste9181]

It must suck to leave such a long comment and still be wrong. Also google how mutations work and examples you'll be surprised.

[@NephilimFree]

@@ivegotbadtaste9181 If you ever graduate from self-proclaimed keyboard hero to the real world and think you can demonstrate you are right and refute me, I debate anyone willing to try.

[@ivegotbadtaste9181]

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[@nameofuser5743]

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[@ot38years2]

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