TOPIC 10.3 GENE POOL & SPECIATION
INTRO http://dbou9h1pp5ks6.cloudfront.net/wp-content/uploads/2015/12/08183701/baby-macaque.jpg Recall that a species is a 2 group of organisms that has the potential to produce fertile offspring. Populations are made of a multiple members of the same species in the same area (reproducing). ------------ *Sometimes members of different species can breed, however their offspring are sterile (i.e. mule)
https://www.pathwayz.org/node/image/url/ahr0chm6ly9plmltz3vylmnvbs9psmrzqxqwlnbuzz8x U1: A gene pool consists of all the genes and their different alleles present in an interbreeding population. The gene pool of a interbreeding population is the whole of all the genes and their alleles. Members that reproduce contribute to the pool of the next generation. 3 Gene Pool
http://www.pnas.org/content/105/17/6350/f3.large.jpg U1: A gene pool consists of all the genes and their different alleles present in an interbreeding population. Having a diverse gene pool is important for a species survival. Since the environment is always changing, which traits result in the highest fitness can vary over time. Lack of diversity = vulnerability. 4 Gene Pool
http://jeb.biologists.org/content/204/18/3151 U2: Evolution requires that allele frequencies change with time in populations. In order for evolution to occur in a population, the frequency of alleles must change over time. Recall that evolution is the cumulative change of a populations heritable characteristics. 5
https://gcbias.files.wordpress.com/2013/09/onesnp.png Skills S1: Comparison of allele frequencies of geographically isolated populations. Online databases can be used to compare allele frequencies in populations that are geographically separated. For example, you can use the Allele Frequency Database hosted by Yale. 6
https://upload.wikimedia.org/wikipedia/commons/thumb/8/80/selection.svg Applications A1: Identifying examples of directional, stabilizing and disruptive selection. Alleles that increase fitness are more likely to be passed on to subsequent generations. Environmental factors act selectively on phenotypes, which results in natural selection. There are three patterns of selection: Directional Stabilizing Disruption 7
https://i1.wp.com/gregladen.com/wordpress/wp-content/graphics/stabilizingselection.jpg Applications A1: Identifying examples of directional, stabilizing and disruptive selection. Stabilizing Selection Environmental factors apply pressure, which removes extremities of certain traits. For example, High/low birth weight 8 Stabilizing Selection Promotes health of offspring and mother Number of eggs Promotes survival of offspring
https://upload.wikimedia.org/wikipedia/commons/thumb/c/cd/directional_selection_%28left%29.svg/2000px-directional_selection_%28left%29.svg.png Applications A1: Identifying examples of directional, stabilizing and disruptive selection. Directional Selection Environmental factors apply pressure, which causes the population to move towards an extreme. 9 Directional Selection For example, Color (e.g. peppered moths) Beak Type (e.g. finches) Organism size (e.g. horses)
https://i1.wp.com/gregladen.com/wordpress/wp-content/graphics/stabilizingselection.jpg Applications A1: Identifying examples of directional, stabilizing and disruptive selection. Stabilizing Selection Disruptive Selection Environmental factors apply pressure, which removes intermediates of a trait. This is typically seen in high-density populations For example, Pea pod color Rabbit fur color 10
https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2012/colour-morphs-3-columns-3.jpg U3: isolation of be temporal, behavioral or geographic. The process of speciation results in a wide diversity of life forms on Earth. This speciation is often the result of various forms of isolation. 11
http://embed.wistia.com/deliveries/d89443027b2bf88c1065ea96a9cbbc2173cf30cf.jpg U3: isolation of be temporal, behavioral or geographic. is an important part of natural selection and evolution. In 12 reproductive isolation, barriers prevent species from producing fertile offspring. This prevents gene flow between populations
http://geology.com/articles/east-africa-rift/figure2.jpg U3: isolation of be temporal, behavioral or geographic. Prezygotic barriers are those 13 that prevent either members from mating or that prevent fertifilization from occurring. Types of prezygotic barriers include: Geographical Temporal Behavioral
http://www.fullfrontalanatomy.com/bio3/standard_docs/resources/campbell/chapter_14/b_jpeg_images/14_labeled_images/14_08geographic-l.jpg U3: isolation of be temporal, behavioral or geographic. Geographic isolation occurs when populations of a species are separated by a geographic barrier. This can include mountains, bodies of water, rifts, etc. While separated the evolve separately. 14 Geographic
https://calendar.google.com/calendar/render#main_7%7cweek U3: isolation of be temporal, behavioral or geographic. Geographic isolation was the reason Darwin observed such diversity amongst the Galagagos Islands. Since species on different islands were unable to mate, over time they evolved differently 15 Geographic
http://media.springernature.com/full/springer-static/image/art%3a10.1186%2f1471-2148-11-194/mediaobjects/12862_2011_1803_fig1_html.jpg U3: isolation of be temporal, behavioral or geographic. Similar variations can be seen on land as well. For example, this map shows the variety of Ensatina species that emerged California as a result of being geographically separated. 16 Geographic
https://s3.amazonaws.com/user-media.venngage.com/801250-72cd70b952d51b60f92c80155e26dc7b.jpeg U3: isolation of be temporal, behavioral or geographic. Temporal isolation occurs when the reproductive systems species 17 mature at different times. Although one group is able to reproduce, the other is not physically prepared. These crickets are an example: Temporal
https://wildlifepreservation.ca/2016/wp-content/uploads/2015/06/fowler-american.jpg U3: isolation of be temporal, behavioral or geographic. The American toad (left) mates in the early summer while the 18 Fowler toad (right) mates in late summer. As a result, the two toads are temporally isolated and do not reproduce. Temporal
http://en.hitachikaihin.jp/wp-content/uploads/2014/01/flower-calendar2.jpg U3: isolation of be temporal, behavioral or geographic. Plants can also experience temporal isolation. For example, if two 19 species bloom at different times then they will not be able to fertilize each other. This chart shows some blooming times: Temporal
http://www.lolwot.com/wp-content/uploads/2016/03/10-surprising-bird-mating-rituals-youve-never-heard-of-3.jpg U3: isolation of be temporal, behavioral or geographic. Behavioral isolation occurs between populations when groups have incompatible mating practices. This can include songs, mating rituals and even a change in pheromones. 20 Behavioral
https://s-media-cache-ak0.pinimg.com/originals/48/a1/be/48a1bee58fbfa7ce1240c50f5a7bec4a.jpg U3: isolation of be temporal, behavioral or geographic. For example, male fireflies 21 attract females of the same species by flashing their light in a specific pattern. Females only respond to patterns of their own species, which prevents them from mating with other species. Behavioral
https://upload.wikimedia.org/wikipedia/commons/c/cd/animal_diversity_october_2007.jpg U4: Speciation due to divergence of isolated be gradual. Speciation is the formation of 22 new species that occurs during the course of evolution. It is the result of changes in isolated populations and is the source of biological diversity on Earth. There are two main types: Speciation Allopatric Sympatric
http://ksuweb.kennesaw.edu/~jdirnber/bio2108/lecture/lecevolution/24_labeled_images/24_14hybrzoneovertime_4-l.jpg U4: Speciation due to divergence of isolated be gradual. Allopatric speciation is the most common form of speciation. It occurs when populations are geographically isolated. As a result, genes no longer flow between the populations. 23 Speciation
http://ksuweb.kennesaw.edu/~jdirnber/bio2108/lecture/lecevolution/24_labeled_images/24_14hybrzoneovertime_4-l.jpg U4: Speciation due to divergence of isolated be gradual. Speciation Over time, the genetic makeup 24 of the differ as a result of natural selection their respective environments. Selection and genetic drift can act differently on the groups eventually resulting in new species. Although once related, the new species are unable to reproduce with each other.
http://ksuweb.kennesaw.edu/~jdirnber/bio2108/lecture/lecevolution/24_labeled_images/24_14hybrzoneovertime_4-l.jpg U4: Speciation due to divergence of isolated be gradual. Sympatric speciation occurs 25 when populations of species in a habitat become reproductively isolated. Unlike allopatric, in sympatric speciation the populations still inhabit the same area. This most often is the result of polyploidy. Speciation
http://www.motherofahubbard.com/wp-content/uploads/2013/06/floweranatomy.jpg U4: Speciation due to divergence of isolated be gradual. Sympatric speciation is rare, but occurs more often in plants as they are able to easily self-fertilize. Polyploidy animals must find a mate with similar ploidy which is difficult. 26 Speciation
https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/haploid%2c_diploid_%2ctriploid_and_tetraploid.svg Applications A2: Speciation in the genus Allium by polyploidy. Polyploidy occurs when offspring are produced with an abnormal number of chromosomes. This is the result of errors occurring in meiosis. 27 Polyploidy These individuals are not able to mate with normal diploid members since the chromosome count doesn t much. As a result they are reproductively isolated.
https://2.bp.blogspot.com/-xzmdctmw7nc/vwgub8g3fli/aaaaaaaaigi/xfiqvxdpbwkn6xpawyrndvrclcszxpa7w/s1600/allium%2bekimianum.jpg Applications A2: Speciation in the genus Allium by polyploidy. Polyploidy For example, polyploidy is a common event in the Allium genus, which includes onions, leeks, garlic and chives. This results in many similary but reproductively isolated populations. Many species reproduce asexually, so polyploidy may provide some sort of advantage. 28
https://www.nature.com/article-assets/npg/nature/journal/v485/n7400/images/nature11050-f1.2.jpg U4: Speciation due to divergence of isolated be gradual. The rate of speciation can vary, especially when the availability of new habitats allows adaptive radiation to occur. 29
https://mrkubuske.files.wordpress.com/2014/03/puncgrad.jpg U4: Speciation due to divergence of isolated be gradual. In the theory of gradualism, 30 species descended from a common and gradually change over time. Small changes accumulate over time, which results in the formation of new species. However, transition fossils are rarely found, making it difficult to support this rate of change. Gradualism
https://upload.wikimedia.org/wikipedia/commons/thumb/6/69/punctuated-equilibrium.svg/1200px-punctuated-equilibrium.svg.png U5: Speciation can occur abruptly. In punctuated equilirium, new species change the most when they diverge from the parent species. After that, few changes in the species are observed 31 Punctuated Equilibrium
https://www.pathwayz.org/node/image/url/ahr0chm6ly9plmltz3vylmnvbs9pcdbyc1hilnbuzw== U5: Speciation can occur abruptly. This model of speciation is supported by sudden changes observed in the fossil record. The record typically consists of species that suddenly appear and then remain unchanged until their extinction 32 Punctuated Equilibrium
REVIEW 1. Define gene pool. 33 2. Define directional, disruptive and stabilizing selection. 3. Outline behavior, temporal and geographical isolation, providing an example of each. 4. Define speciation. 5. Outline polyploidy and its role in speciation. 6. Differentiate between gradualism and punctuated equilibrium.
VIDEOS Speciation: An Illustrated Introduction https://www.youtube.com/watch?v=8yvedqrc3xe CrashCourse Speciation: Of Ligers & Men https://www.youtube.com/watch?v=2oklkmrblou CrashCourse Natural Selection https://youtu.be/atftyfboc_m?t=464 Gradualism vs Punctuated Equilibrium https://www.youtube.com/watch?v=qsjifxihknk Trilobites and Punctuated Equilibria https://www.youtube.com/watch?v=9uqpckwuhru 34