Speciation, Adaptive Radiation, & Extinction PDF

Speciation, adaptive radiation, and extinction 9:42 am  What processes shape evolutionary trees? Why more species here than here? today 31...

Speciation, adaptive radiation, and extinction 9:42 am  What processes shape evolutionary trees? Why more species here than here? today 31 41 Why did lots of species Why did so appear here? many species go extinct at the same What caused time? this extinction? time How do we get new species? 21 9:42 am 11 What is a species?  What is a species? 9:42 am 9:42 am  time Mating Female 9:42 am Male  Gene 1 Mating Female 9:42 am Male  Gene 2 Mating Female 9:42 am Male  Gene 3 Mating Female 9:42 am Male  Gene 1 Mating Female 9:42 am Male  Gene 2 Mating Female 9:42 am Male  Gene 3 Mating Female 9:42 am Male  Gene 1 Gene 2 Gene 3 9:42 am  Gene 1 Gene 2 Gene 3 9:42 am  Gene 1 Gene 2 9:42 am Gene 3  speciation 9:42 am  Allopatric External barrier separates populations Populations diverge genetically 9:42 am  Allopatric (founder event) Small population becomes isolated Rapid evolution due to non- random sample of genes, different environment, etc. 9:42 am  Sympatric No geographic barrier Populations may differ in habitat, behaviour, adaptation Assortative mating may lead to genetic divergence 9:42 am  What processes shape evolutionary trees? Why more species here than here? today Why did lots of species Why did so appear here? many species go extinct at the same What caused time? this extinction? time How do we get new species? What is a species? 9:42 am  What is an “adaptive”radiation? Galápagos finches 9:42 am  Random speciation 3 species 3 species 9:42 am 21  Non-random speciation 1 species 5 species Why has this group speciated more? 9:42 am 22  Possible causes of adaptive radiations Key innovations Environmental changes (new habitats) Ecological changes (new opportunities) 9:42 am  Ray--finned fishes Near TJ, Eytan RI, Dornburg A et al. (2012) Resolution of ray-finned fish phylogeny and timing of diversification. Proceedings of the 9:42 am National Academy of Sciences USA,  Key facts about bony fish Single most species-rich vertebrate group Third whole genome duplication Buoyancy using swim bladder Innovations in jaw structure Protruding upper jaws Secondary jaws (pharyngeal jaws) 9:42 am  Swim bladder (lung equivalent) 9:42 am  Shark vs. piranha 9:42 am  Examples of fish variation 9:42 am  Many fish have a “kinetic skull” Mammalian skulls are mostly fused bone, lower jaw moves Many bony fish skulls have multiple moving parts 9:42 am 9:42 am 9:42 am  Jaw protrusion 9:42 am  Sling-jaw wrasse 9:42 am  Pharyngeal jaws "second set" of jaws contained within fish’s throat distinct from the primary, oral jaws modified gill arches to manipulate and help with Fraser GJ, Hulsey CD, Bloomquist RF, Uyesugi K, Manley NR, Streelman JT (2009)An ancient gene network is co-opted for teeth on old and new jaws. PLoS Biology, 7, e1000031. 9:42 am swallowing prey  Eel jaws 9:42 am  How to eat without hands? How to crush tough prey? Meyer A (1990) Ecological and evolutionary consequences of the trophic polymorphism in Cichlasoma citrinellum (Pisces: Cichlidae). Biological Journal of the Linnean Society, 39, 279–299. Map of life: Pharyngeal jaws in teleost fish 9:42 am  New habitats 9:42 am  Insular giants and dwarfs Large animals often evolve small “dwarfs” Small animals often evolve large “giants” mainland island 9:42 am  Giant tortoises Lonesome George (died June 2012) 9:42 am 9:42 am  Meiolania platyceps (Lord Howe Island) Giant horned turtles Meiolania dates back to Cretacteous Fossils found on several Pacific Islands and Australia Species on Vanuatu hunted to extinction 3000 years ago 9:42 am  Komodo dragon 9:42 am 9:42 am  Cambrian Explosion Nearly all major animal phyla appear in Cambrian rocks (545 to 525 million years ago) Many weird and wonderful creatures appear suddenly in the fossil record 9:42 am 44  Nemiana > Sea anenome? Algal? < Spriggina Annelid Worm? Arthropod? Cyclomedusa > Benthic Polyp 1-5 mm in diameter 9:42 am 45 9:42 am 46 9:42 am 47  Hallucigenia’s head and the pharyngeal armature of early ecdysozoans Martin R. Smith & Jean-Bernard Caron Nature 523, 75–78 (02 July 2015) doi:10.1038/nature14573 9:42 am 48  What caused the “explosion” Environmental changes Developmental changes Ecological changes 9:42 am 49  Environmental changes Increase in oxygen levels (may have finally reached level to support large animals) Snowball Earth (hypothesis that Earth iced over before 650 Mya) 9:42 am 50  Developmental explanations (HOX genes) Regulate development of segmentation in animals 9:42 am 51  Ecological changes Evolution of eyes leading to predation Arms race between predators and prey 9:42 am 52  What processes shape evolutionary trees? Why more species here than here? today Why did lots of species Why did so appear here? many species go extinct at the same What caused time? this extinction? time How do we get new species? What is a species? 9:42 am  Ordovician-Silurian 443 Mya ice sheet Late Devonian 359 Mya marine 75% Permian 248 Mya multiple 96% Triassic-Jurassic 200 Mya Cretaceous- Tertiary 65 Mya impact 9:42 am 9:42 am 9:42 am 9:42 am  Ordovician-Silurian 443 Mya ice sheet Late Devonian 359 Mya marine 75% Permian 248 Mya multiple 96% Triassic-Jurassic 200 Mya Cretaceous- Tertiary 65 Mya impact Anthropocene 9:42 am Now human  The sixth mass extinction (the Anthropocene) 9:42 am  Lost giants (megafauna) 9:42 am  Meiolania platyceps (Lord Howe Island) Giant horned turtles Meiolania dates back to Cretacteous Fossils found on several Pacific Islands and Australia Species on Vanuatu hunted to extinction 3000 years ago 9:42 am  Varanus priscus (Megalania) 9:42 am  Canis dirus (Dire wolf) 9:42 am  Wooly mammoth 9:42 am  What caused the extinction of the megafauna? Human hunting of megaherbivores (causing extinction of predators as well) Climate change (end of ice age) Disease (from humans and/or associated animals) Second-order predation (humans kill predators, prey overpopulation then collapse) 9:42 am 9:42 am  Late surviving mammoths Most megafauna extinct by Mammoths still on St. Paul 12,000 years bp* 6,500 years bp Great pyramid of Giza 4600 bp 9:42 am *bp = “before present” where present = 1950 9:42 am  What processes shape evolutionary trees? Why more species here than here? today Why did lots of species Why did so appear here? many species go extinct at the same What caused time? this extinction? time How do we get new species? What is a species? 9:42 am  De-extinction (is extinction forever?) 9:42 am 9:42 am 9:42 am 9:42 am  Should we bring them back? 9:42 am  Genetic ghosts 9:42 am 9:42 am 9:42 am  Hobbits! 9:42 am  1%-4% of DNA in Eurasians comes from Neanderthals 9:42 am 9:42 am  Things to know/think about What is a species? Modes of speciation Why more species here than here? today Radiations, how to recognise them, and possible causes (key Why did innovations, environmental, lots of species Why did so many developmental, ecological) appear here? species go What How many mass extinctions? time caused this extinction? extinct at the same time? Anthropocene (human How do we get influence and other causes) What is a new species? species? De-extinction 9:42 am