Ensatina_ring Drosophila-phylogeny DSC_0068 fig2 Iris-brevicaulis-14 iris_fulva_red What is species? How do species arise? divizna sedmikraska vlci mak sitta6 Eurasian nuthatch (Sitta europea) soupalek1 common treecreeper (Certhia familiaris) Sitthia eurofamiliaris x Mechanisms maintaining species integrity European herring gull (Larus argentatus) File:Larus argentatus ad.jpg zafferano Larus argentatus map.svg http://www.avibirds.com/migration/Lesser%20Black-Backed%20Gull.jpg lesser black-backed gull (L. fuscus) http://gull-research.org/heuglini/tomtams/image001.jpg File:Larus argentatus ad.jpg zafferano Antics: species unstable and highly variable ´ ´ ´ wild-boar-bharatpur-2006 Velbloud sparrow Are species real entities? nominalists: no universals and abstract objects (= only words), only particulars exist eg. William of Ockham, popular in France in the 1700s (young Buffon and Lamarck), Darwin species are human abstractions, artificially dividin natural continuum Buffon_1707-1788 lamarck DARWIN http://stendhalgallery.com/wp-content/uploads/2011/01/Occam.jpg http://www.evolution-textbook.org/content/free/figures/22_EVOW_Art/04_EVOW_CH22.jpg according to Darwin classification of organisms to a large extent arbitrary: realists: only universals are real, particulars are derived, random, variable, and ephemeral eg. Plato https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSJZThrm_-t2BSSUAnCo6Zk4Duhbjjb08evwlqu2piCF76 t8NxD species really exist in nature New Guinea tribes: Karam people ® almost identical discrimination of bird species with western taxonomists (but bats considered as birds) Rofaifo people ® only two names for mammals (small = Hunembe, big = Hefa); cassowary considered as a mammal ´ human brain same in aborigines and professional taxonomists free hybridization within species ´ rare between species Problem: definition should be both universal and operational Typological (essentialist) concept Plato´s world of ideas: assumption of existence of limited number of types (universals) species composed of idividuals having the same essence variability strongly limited, results from imperfekt expression of the idea each species separated from others by sharp boundary constant in time ´ sexual dimorphism https://c2.staticflickr.com/4/3023/2359172254_2782bb7438_b.jpg http://www.datosfreak.org/site_media/upload/dimorfismo-sexual-gusano-marino-bonellia-viridis.jpg Bonellia viridis angler (Lophius piscatorius) http://nd06.jxs.cz/826/118/00ef7ca184_96071968_o2.jpg male http://butterfliesofamerica.com/images/Papilionidae/Papilioninae/Papilio_polyxenes_stabilis/04-SRNP -36235-DHJ308688.jpg ´ polymorphism, different ontogenetic stages http://openi.nlm.nih.gov/imgs/512/40/1570757/1570757_pbio.0040303.g001.png Heliconius spp. Ranitomeya imitator http://www.backyardnature.net/pix/b-swal-c.jpg Papilio polyxenes ´ sibling species, cryptic species Drosophila persimilis/ D. pseudoobscura http://www.cb.iee.unibe.ch/unibe/philnat/biology/zoologie/cb/content/e7117/e7119/e7978/e8450/detail _Pipistrellebats.jpg https://earthlingnature.files.wordpress.com/2012/03/drosophila.jpg Pipistrellus pipistrellus/P. pygmaeus http://www.mun.ca/biology/scarr/Fut_15_03_treecreeper_variation2.gif Certhia brachydactyla/C. familiaris Typological species still in nomenclatorial practice: type specimen = holotype, type series, type locality barcoding http://dnabarcodingcourses.com/wp-content/uploads/2013/03/barcode_upc_dna_2013_300.png http://thumbs.ifood.tv/files/image/80/37/562097-barcode-of-life-unlocked.jpg http://www.museunacional.ufrj.br/mndi/Aracnologia/pdfliteratura/ICZN%20at%20500%20dpi.jpg http://ecx.images-amazon.com/images/I/51m1P65APpL._SL500_SY344_BO1,204,203,200_.jpg Biological species concept (BSC) T. Dobzhansky, H. Muller, J. Huxley, E. Mayr species as gene pools, reproductive communities reproductively isolated from others no constant, „essential“ characters Ernst-Mayer E. Mayr Ernst Mayr (1942): Ernst-Mayer free mating free mating X reproductive barrier Species are groups of interbreeding natural populations that are reproductively isolated from others such groups. https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcShg-b_d8EgB4ZxncVzYOrKxllM-ZPkCYlFVLlWxP7mvar RV7XWew http://fc02.deviantart.net/fs15/i/2007/019/b/8/Tigon_by_FirstLight75.jpg liger tigon Limitations and problems of biological species: only sexual organisms problems in allopatry („potential“ hybridization) Þ auxiliary morphological and genetic criteria (degree of divergence ~ degree of reproductive isolation) problems in palaeontology – populations are not contemporary hybridization between „good“ species (Bombina bombina ´ B. variegata) auxiliary criteria (DNA sequences) bombina%20variegataSM B.bombina http://www.evolution-textbook.org/content/free/figures/22_EVOW_Art/06_EVOW_CH22.jpg http://swbiodiversity.org/imglib/seinet/Fagaceae/Quercus-gambelii-P-web-N3.jpg http://oaks.of.the.world.free.fr/Q.grisea2.jpg Quercus gambelii Q. grisea grisea + gambelii = syngameon Reproductive barriers 1. Prezygotic A) pre-copulatory: partners do not meet: seasonal (temporal) eg. fireflies, crickets Gryllus pennsylvanicus (autumn) ´ G. veletis (spring) springfieldcricketsmalefemale formerly reproductively isolating mechanisms = RIM ... today we prefer the term reproductive barriers (RIM imply „in order to“)! Reproductive barriers ecological (habitat): Viola arvensis (chalk soils) ´ V. tricolor (acidic soils), hybrids limited to neutral or weakly acidic soils Viola arvensis File:Viola tricolor.jpg 1. Prezygotic A) pre-copulatory: partners meet but do not mate: ethological, behavioral, sexual signals: - acoustic mediterranea lacewing (Chrysoperla) lucasina johnsoni carnea zastrowi arabica 680420 Edible_frog_calling frog-calling-03 Chrysoperla%20carnea Reproductive barriers 1. Prezygotic A) pre-copulatory: partners meet but do not mate: ethological, behavioral, sexual signals: - acoustic - chemical - light File:GluehwuermchenImWald.jpg firefly´s track drosophila-male Reproductive barriers Reproductive barriers 1. Prezygotic A) pre-copulatory: partners meet but do not mate: ethological, behavioral, sexual signals: - acoustic - chemical - light - behavioral (eg. wedding dances) black-necked-stilt-919rnpn 5125133DaINJZeLMW_ph jeremy%20cranes 3364676015_eb38a25bb6 red-crowned crane (Grus japonensis) great bustard (Otis tarda) grey-crowned crane (Balearica regulorum) black-necked stilt (Himantopus mexicanus) Western-Grebe-(mating-dance)-brian-currie western grebe (Aechmophorus occidentalis) SkalMatkaJetelLucni Ctrap%2Bpoll5 kolibrik Chiloglottis formicifera #2 473px-Ophrys_apifera_flower2 signals: - acoustic - chemical - light - behavioral (eg. wedding dances) - different pollinators in plants Reproductive barriers 1. Prezygotic B) post-copulatory: partners mate but without transfer of gametes: mechanical: - especially plants; in animals shape of genitalia 378-02-MinkBaculum-Lg cat_baculum_4012b_876 8000-walrus-penis baculum-manedwolf mink fox cat walrus (fossil: 1,2 m and recent: 56 cm) 378-05-RaccoonBaculum-Lg racoon File:WalrusOosik.jpg os penis Reproductive barriers 1. Prezygotic B) post-copulatory: transfer of gametes occur but without fertilization: gametic incompatibility external fertilization: esp. marine invertebrates (mollusks, echinoderms) internal fertilization: eg. Drosophila – sperm cannot survive in spermatheca of females of other species plants: pollen tube grows through style Reproductive barriers 2. Postzygotic inviability of F1 hybrids sterility of F1 hybrids reduced viability or fertility of F2 or backcrosses = hybrid dysgenesis Haldane´s rule: http://media-1.web.britannica.com/eb-media/05/46505-004-5ED4FC78.jpg When in the F1 offspring of two different animal races one sex is absent, rare, or sterile, that sex is the heterozygous (heterogametic) sex.*) *) Drosophila type – males (XY); Abraxas type – females (WZ) Drosophila pseudoobscura ´ D. persimilis Haldane´s rule explains Large X effect: genes having large impact on postzygotic reproductive isolation are usually located on X chromosome dominance theory (Muller 1940, 1942; Orr 1997): males – both dominant and recessive alleles of X-linked genes females – only dominant alleles http://www.evolution-textbook.org/content/free/figures/22_EVOW_Art/11_EVOW_CH22.jpg Rate of prezygotic isolation between allopatric species is similar to rate of postzygotic isolation ... ... prezygotic isolation between sympatric/parapatric species arises more rapidly both sympatric and allopatric sympatric allopatric Recognition species concept Hugh E.H. Paterson (1985) empasizes shared fertilization system rather than isolation: specific mate recognition system (SMRS) courtship, timing of mating, choice of condition, coloration, endocrine system, shape of copulatory organs, gametic compatibility, … reproductive isolation as a byproduct Evolution and the Recognition Concept of Species: Collected Writings Concepts related to biological species: Cohesion species concept Alan R. Templeton (1989) empasizes mechanisms maintaining morphological stability of populations cohesion mechanisms: gene flow, stabilizing selection, ontogenetic constraints, reproductive isolation aplication also to asexual organisms, possibility of interspecific hybridization templetonpict Concepts related to biological species: Evolutionary species concept attempts for vertical species concepts George Gaylord Simpson (1961): phyletic speciation, chronospecies asexual organisms temporal perspective biological species is a part of it Edward O. Wiley (1978): „A species is a lineage of ancestral descendant populations which maintains its identity from other such lineages and which has its own evolutionary tendencies and historical fate.“ contrary to Simpson´s concept Wiley admits only cladogenesis, ie. splitting speciation http://www.pbs.org/wgbh/evolution/library/06/2/images/l_062_02_l.jpg http://ww1.prweb.com/prfiles/2006/07/06/0000408657/DrEdWileyDirectorRASO.jpg emphasis on diagnostic criteria ® but which ones? Þ primary inference of phylogeny (synapomorfies) Phylogenetic species = smallest monophyletic group distinguished by a shared derived trait Phylogenetic species concept A B1 B2 C X RI origin of reproductive barrier biological species A biological species B Relation of biological and phylogenetic species: A B1 B2 C X RI origin of synapomorfy phylogenetic species C phylogenetic species B Relation of biological and phylogenetic species: SPECIATION geography: allopatric allopatric (isolation) peripatric allo-parapatric (reinforcement) sympatric parapatric (no isolation) sympatric mechanism: drift selection sexual selection hybridisation polyploidisation genetic elements: genes vs. chromosomes (stasipatric speciation) Allopatric speciation geographic isolation advancing divergence: mutation, drift, selection, sexual selection reproductive barriers as a byproduct original population geographic barrier incompatibility mutation drift selection Þ divergence http://nd04.jxs.cz/004/069/b83f433a8a_73299543_o2.jpg Dobzhansky-Muller model: muller fund0236 2084_Bateson-William W. Bateson T. Dobzhansky H. Muller aabb aAbb aaBb A-b compatible 2 genes: AAbb aaBB AABB A-B incompatible a-B compatible large population allopatric speciation usually slow (exceptions: sexual selection, genetic conflict) arms race in ancestral population subpop. 1 subpop. 2 secondary contact incompatible! genetic conflict: ongoing arms race Joelle.jpg J. Goüy de Bellocq Wasimuddin hybrids co-speciation (parasite-host): Peripatric speciation (founder-effect speciation) Mayr: founder effect island organisms, peripheral isolates (extinction-recolonisation) genetic revolution Þ rapid speciation http://www.privateislandsonline.com/content/listings/1086/cimage_ef6415ad37-thumbb.jpg https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcSMDUfsnHdLjhOEVixkYoGAc5PHXU13VFOalu13WccvvEj GuZNU founder-flush model: Drosophila colonisation of a novel environment – no selection Þ rapid divergence http://rice.bio.indiana.edu:7082/images/Drosophilidae/Drosophila_capnoptera_m/Drosophila_capnoptera .jpg Interlaced fingers, braid, fingerloop braiding, twist together Allo-parapatric speciation (reinforcement speciation) initial geographic isolation reproductive isolation incomplete ® secondary hybrid zone secondary hybrid zone A. R. Wallace, R. A. Fisher, T. Dobzhansky selection against hybrids Þ formation of prezygotic barrier ® strenghtening of isolation (reinforcement) = Wallace´s effect selection against hybrids http://www.evolution-textbook.org/content/free/figures/22_EVOW_Art/11_EVOW_CH22.jpg faster isolation in contact allopatric pairs both sym/parapatric and allopatric pairs Reinforcement clines ABP Reinforcement clines urine Both female and male preference show reinforcement in the zone centre Þ prezygotic barrier probably contributes to reproductive isolation Vošlajerová Bímová et al. (2011) Parapatric speciation environmental gradient Þ genetic gradient Þ primary hybrid zone different selection in the two parts Þ genetic divergence even with gene flow ecotone A A A A A a a a a a a Sometimes difficult to distinguish allopatric and parapatric speciation: ring species worldmap Larus Ensatina Phylloscopus ring species: European herring gull (Larus argentatus) and lesser black-backed gull (L. fuscus) File:Larus argentatus ad.jpg zafferano http://gull-research.org/heuglini/tomtams/image001.jpg http://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/Ring_species_seagull.svg/2000px-Ring_speci es_seagull.svg.png ring species: greenish warbler (Phylloscopus trochiloides) ddwesterncwarbler8 mn_birdevolution phytri001-2 image ring species: Ensatina_ring eexanthopticabr306 ensatina_eschscholtzii_2 Ensatina e. xanthoptica Ensatina e. klauberi Ensatina eschscholtzii ring species: 2N Sympatric speciation Polyploidisation 2N ® 4N 2N ´ 4N = 3N 4N aneuploid hybrids Arabidopsis thaliana ´ A. arenosa ® A. suecica Sympatric speciation Host shift apple magot (Rhagoletis pomonella): hawthorn ® 1866 apple ® ca. 1960 cherry tree peer, rose, plum etc. assortative mating, genetic differences, different incubation period (seasonal isolation) absence of postzygotic mechanisms R. pomonella Final overview: allopatric peripatric Rate of speciation: allopatric speciation usually slow rapid speciation and adaptive radiation: Darwin´s finches fruit flies in Hawaii cichlids in African lakes Adaptivni radiace.jpg Great Rift Valley – Viktoria, Malawi, Tanganyika; Viktoria: 400 000 years, 17 300 – drying, 14 700 re-creation; molecular clock: ancestor of cichlids – 100 000 years http://www.evolution-textbook.org/content/free/figures/22_EVOW_Art/32_EVOW_CH22.jpg Cameroon: Barombi Mbo (4,2 km2) – 11 species, Bermin (0,6 km2) – 9 cichlid species, monophyletic origin, absolute isolation, ancestor – 10 000 years http://farm8.staticflickr.com/7171/6694731825_36b72aa837_z.jpg http://www.frontiersinzoology.com/content/figures/1742-9994-1-5-1-l.jpg http://4.bp.blogspot.com/-WrAUYMUl3mk/UJL_mJ9iZzI/AAAAAAAAAKk/DWeAzctqXWU/s1600/PA094538.JPG Barombi Mbo Bermin Paralel speciation habitat shift role of natural selection role of sexual selection (cichlids)