ECOL 182R Evolution 3 Lecture Notes: Speciation
ECOL 182R Evolution 3 Lecture Notes: Speciation ECOL 182R
U of M
Popular in Introductory Biology II
Popular in Science
This 12 page One Day of Notes was uploaded by Jenna Pimentel on Friday January 30, 2015. The One Day of Notes belongs to ECOL 182R at University of Arizona taught by Bonine, Hunter, Martinez in Spring2015. Since its upload, it has received 244 views. For similar materials see Introductory Biology II in Science at University of Arizona.
Reviews for ECOL 182R Evolution 3 Lecture Notes: Speciation
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 01/30/15
12615 From the end of Thursday s lecture Leaves of a white oak Quercus alba Not all variation is geneticallybased Some is environmentallybased meaning that genes are the same but their expression changes in different Grown 1 sun environments Example of environmentallybased variation 1 Another example cactus flower has ability to store water for a long period of time Average height of a man in the Netherlands Andrew Frank and Andrew are brothers Frank lifts weights at the gym all the time Andrew doesn t Ifwe measure muscle mass Frank has more 1850 5 ft 4 12 inches Will Frank have children with bigger muscles than Andrew willlt W Why or why not environmentallybased Why the difference Can a Ifthere is a population of exercisers eg Spartans ofancient trait be in uenced by both Greece will their offspring be stronger than those in a populati genes and environment of philosophers Why or why not environmentallybased 3 genetic difference L Review Population a group of potentially interbreeding individuals ofthe same species ie coexisting in the same place and time Today Speciation A How do new species form B H d I t 7 Species a group of individuals capable of OW oes ISO a lOn occur interbreeding and reproductively C Why does divergence continue isoiated from other groups D Why do groups vary in rates of speciation Redwinged blackbird Agelaius phoeniceus W mm l 12615 Species a group of individuals capable of Species a group of individuals capable of interbreeding and reproductiver interbreeding and reproductively isolated from other groups isolated from other groups This is caued the biological species concept Redwinged blackbird Agelaius phoeniceus Redwinged blackbird Agelaius phoeniceus 7 8 Species may consist of several populations 3 a group of individuals capable of all capable of interbreeding but irelL interbreeding and reproductively or never actually having the opportunity isolated from other groups I Eastern l u s 39 39 V I gt h l Calif I 14 I L 39 39 g X 7 Redwinged blackbird Tricolored blackbird Agelaius phoeniceus I Agelaius tricolor Two different populations of Agelaius phoeniceus 9 10 Problem who actually interbreeds Problem who actually interbreeds 1 We rarely watch We use clues from morphology but it can be tricky 1 We rarely watch We use clues from morphology but clues can deceive Same species Or different species same C T A I A x a Nil r39 W I 1 male I 39tIA IILII yunmma p 11 I l l t 12 WWW 2 Problem who actually interbreeds 1 We rarely watch We use clues from morphology but clues can deceive do DNA sequencing C 13 V Problem who actually interbreeds 2 People can M some species to interbreed that in nature don t quotcamaquot camel and llama hybrid via arti cial insemination 15 Problem who actually interbreeds 8 Some organisms never have sex to begin with Some bacteria protists fungi 12615 Problem who actually interbreeds People can fog some species to interbreed that in nature don t A liger Problem who actually interbreeds Should we consider camas and ligers species Why or why not Problem who actually interbreeds The more we know eg species ranges morphology genetic information behavior the more con dent we can be 12615 HOW DO NEW SPECIES FORM species But old Inc 19 They diverge from existin HOW DO NEW SPECIES FORM 2 critical processes 0 Isolation separation 0 Genetic divergence and A reproductive Time isolation 4 Genetic distance gt One way Species formation in 3 easy steps 1 One species is separated into two populations by a barrier 2 each population adapts to a new habitat diverges genetically i ifquot 3Whenifthe populations y overlap again they no I longer interbreed 21 HOW DO NEW SPECIES FORM 2 critical processes 0 Isolation 0 Divergence One interbreeding group Become iSOIated in 2 subgroups Become more amp more different If recontact occurs can t or 7 won t interbreed HOW DO NEW SPECIES FORM 2 critical processes x HOW amp WHY 0 Separation 0 Genetic divergence and reproductive isolation How Does Separation Occur A One population breaks into 2 separate groups We ll lookat 2 ways this happens 4 Genetic distance gt Time 12615 Allopatric speciation involves A39 one pOpUlatlon breaks 39nto 2 distance and a geographic barrier separate groups 77 V l 1Allopatric speciation a physical barrier arises that prevents interbreeding Allopatric means different countriesquot thought to be the usual start to speciation 25 Example allopatric speciation due to the formation ofthe Grand Canyon r quot White tailed antelope squirrel North Rim Harris s antelope squirrel South Rim and south Ancestor dispersed to Galapagos Islands 28 Island populations then lost contact with each other A One population breaks into 2 A One population breaks into 2 separate groups separate groups 2 Sympatric speciation 0 phySical 2 Sympatric speciation m physical barrier arises interbreeding between barrier arises interbreeding between groups stops for another reason groups stops for another reason 7 Sympatry means same country 29 30 5 Two types of sympatric speciation 1 multiplication Of chromosome number Polyploids have multiple sets of chromosomes HOW OSpontaneous duplication of chromosomes auto polyploidy we ll describe this one 0Combination of parents chromosome in offspring when 2 species successfully mate 12615 Unreduced gamete with 6 chromosomes Why can t polyploids interbreed with individuals like their normal parents Example diploid normal tetraploid 4 copies mm Ha loid ametes h 223528 L 44 am g39 e r39se t Migtr IV o gametes that are not completely Rll p l m haploid nor each chromosome completely di loid p 33 33332 33330 tetraploid can quot4quot r 32131123 become a new i equot quot e iiza ion ka39YP YPeS may f rtltv A g 3331333 specres only If mph lg 1333 th 3y mate with cquoti ii l swquotquot ot1er tetraploid Selffertilization most common in plants V l 32 Autopolypoidy multiplication of chromosome number CONSEQUENCE 0 If polyploid offspring can mate with each other but not with individuals like their diQIOid parents they have become different species In this one case there is no isolation step and genetic divergence is instantaneous 34 Autopolypoidy Very common in major plant group Angiosperms quotII What plant co ee Different species have 22 44 66 or 88 chromosomes 2 4 6 or 8 sets 35 Some polyploid species are big beautiful and successful uunniasl 1 Look at Figs 278a and 279 in text Diplnid 36 12615 2 Second type of sympatric speciation due Another type of sympatric speciation to temporal isolation separation in time Example Hawthorn fruit fly 0 native to US 0 attracted to fruit smell 0 lay eggs in fruit Hawthorn fruit fly 0 native to US 0 attracted to fruit smell 0 lay eggs in fruit led some flies to be attracted to Apples introduced amp lay eggs on apple to US in 1623 instead 38 APlt Hawthorn Numbers of Fruit Time of Summer Hawthorn and apples set frUIt at differenttimes Natural U S eciation U selection on the timing ofthe life cycle of apple flies has J caused these ies to emerge early before hawthorn ies These mate 9 39 These mate Flles become separated In time 39 with each other with each other 40 HOW DOES ISOIatlon OCCUF How Does Isolation Occur B After initial separation groups B After initial separation groups Become reproductiver isolated become Reproductiver isolated from each other from each other they don t mate or don t make fertile offspring when they do 4 Genetic distance gt 42 Time 4 1 nnnnnnnnnnnnnnnn m y 7 Reproductive Isolating Mechanisms 1 Prezygotic barriers occur before zygote formation 6 3 What s a zygote Diploid cell formed by two haploid cells L 12615 Barriers to Reproduction 1 Prezygotic barriers occur before zygote forms a Barrier in space or time Individuals never meet autumn Rhagoletis pomonella summer Reproductive Isolating Mechanisms 1 Prezygotic barriers occur before zygote formation b Behavioral isolation females won39t accept mating Reproductive Isolating Mechanisms b Behavioral isolation Many animal species have Elaborate courtship rituals Evolve generally as adaptations that allow evaluation of mates but also serve to discriminate against the wrong species VIDEOCIark s Grebe Oregon USA 46 Reproductive Isolating Mechanisms 2 Postzygotic barriers occur after zygote formation Norway rat a Hybrid inviabilitv hybrid zygotes don t develop or die before birth Reproductive Isolating Mechanisms 2 Postzygotic barriers occur after zygote formation b Hybrid sterility hybrids survive but are sterile mule sterile offspring of horsedonkey WWW 8 12615 1 Natural selection may reinforce reproductive isolating 2 critical processes mechanisms 0 Isolation 0 Divergence HOW DO NEW SPECIES FORM Closely related jumping spider males have but why do speCIes dIverge speciesspeci c SO MUCH colors amp dances Video 49 50 1Natural selection may reinforce Reinforcement continued Often behaviors that reproductive isolating mechanisms keep species apart eg courtship behaviors are more di erent when the Species are in sympatry than Eg elaborate plumage courtship in birds Video when they re In all Gastrophyne arolinensis l r x Gastrophyne olivacea What parts of the two toads range is f allopatry 39 3 which is 39 Bird of paradise species wild plumage courtship sympatry dances 51 r K iiiiiiiiiii is Reinforcement continued The frequencies of the mating calls ofthe two species are different and the frequency ofthe mating call of G carolensis is lower in areas that are sympatric with G olivacea Why reinforcement 3 w MM Hybrids are produced that are not as t as 5000 v 4500 Gastrophryne olivacea EN quot Why do E54000 YOU They may even be inviable 53500 think E I I 0 300 th395 395 Therefore there IS selection for even more reproductive isolation 00 39 Allopatry Allopatry Gastrophyrne carolinenss 5 3 9 Why do species diverge so much Reinforcement and 2 Once isolated species adapt to local conditions Bud eaters Vegetarian nch Q Insect eaters Small tree nch 039 ANCESTOR FlNCH Medium tree nch What different conditions might these nches be adapting to Large tree nch Mangrove nch Woodpecker nch Q 55 Warbler nch 12615 10 I Speciation A How do new species form B How does separation occur C Why does divergence continue Key concepts 1 What are some of the problems with determining species by looking at who interbreeds Using clues from morphology can be tricky People can force species to interbreed that don t normally in interbreed in nature ome organisms never have sex to begin with 2 What are the two important processes involved with the formation of new species lsoationseparation one population breaks into 2 separate groups Genetic divergence reproductive isolation populations adapt to new habitat and become so different they no longer interbreed 3 What is the difference between allopatric and sympatric speciation W at are two methods by which sympatric speciation can occur Allopatric form of separation where a physical barrier preve quotdifferent country Sympatric form of separation where there is no physic between groups stops for another reason quotsame coun Ier interbreeding 4 How can plants doubling their chromosome co t autopolyploidy cause instant speciation Polyploid offspring can mate with eac become a different species N no is l h r but not other diploids so they have ers to reproduction Postzygotic barriers or time individuals never meet behavioral isolation females won t acc 39ng many animal species have elaborate courtship rituals Postzygotic hybrid invia ity hybrid zygotes don t develop or die after birth hybrid sterility hybrids survive b are sterile 5 What are examples of prezy ti Prezygotic barrie in sp 6 Why might natural selection reinforce reproductive isolation between two new species Hybrids are produced that are not as fit as either pure species may even be inviable 7 Understandbe able to define Species and how it differs from population a group of individuals capable of interbreeding reproductivey isolated from other groups species consist of many populations Biological species concept the concept that a species is a group of individuals capable of interbreeding and is reproductivey isolated from other groups Allopatric speciation that involves a physical barrier preventing Sympatric speciation that involves no physical barrier interbreeding between species stops for another reason Polyploidy having more than twice the basic haploid number of chromosomes Autopolyploidy multiplication of chromosome number common in Angiosperms Diploid containing two sets of chromosomes 1 from each parent Haploid containing a single set of unpaired chromosomes Tetraploid containing four sets of chromosomes Triploid containing three sets of chromosomes Zygote diploid cell resulting from the fusion of two haploid gametes fertilized Reproductive isolation when gene flow is prevented between two populations of the same species Prezygotic reproductive isolating mechanism that occurs before zygote formation Postzygotic reproductive isolating mechanism that occurs after zygote formation Reinforcement of species reproductive isolation behaviors that keep species apart