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Baleen Whales

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Baleen Whales Main Points 1) Diversity, Phylogeny, and Systematics -- Infraclass Metatheria continued -- Orders Diprotodontia and Peramelina -- Infraclass Eutheria -- Orders Lagomorpha through Cetacea 2) The Great American Interchange -- dispersal versus vicariance -- example: recent range expansion of nine-banded armadillos 3) Evolution of body size on islands -- the island rule -- example: sloth evolution in the Caribbean 4) Terms: syndactyly, placenta, saltatorial, myrmecophagy, folivory, dispersal, vicariance, island rule, cursorial, ruminant, cecum, Cetartiodactyla, fusiform, echolocation, baleen Pre-reading: Monday 17 Sep = Sykes et al 2014, MacLeod 2014 Wednesday 19 Sep = NA 1 Order Diprotodontia: kangaroos, wallabies, phalangers, possums, wombats spotted cuscus Taxonomy: 117 species Distribution: Australasian red kangaroo hairy-nosed wombat koala 2 Order Diprotodontia: kangaroos, wallabies, phalangers, possums, wombats Taxonomy: 117 species Distribution: Australasian Characteristics: --diprotodont teeth --syndactyly 3 Order Peramelina: bandicoots Taxonomy: 21 species Distribution: Australasian rabbit-eared bandicoot Eastern barred bandicoot 4 Order Peramelina: bandicoots Taxonomy: 21 species Distribution: Australasian Characteristics: -- hind limbs specialized for hopping (convergent with rabbits) -- have placenta, in addition to marsupium rabbit-eared bandicoot Eastern barred bandicoot 5 Subclass Theria, Infraclass Eutheria 6 Subclass Theria, Infraclass Eutheria 7 Order Lagomorpha: hares, rabbits, pikas Taxonomy: 80 species Distribution: cosmopolitan, except Australasia Characteristics: -- incisors grow continuously -- saltatorial with hind limbs longer than forelimbs black-tailed jackrabbit American pika mountain cottontail 8 9 Order Rodentia: rodents Taxonomy: about 2500 species Distribution: cosmopolitan Characteristics: -- incisors grow continuously throughout life -- skull and jaw musculature adapted for gnawing naked mole rat capybara Lord Derby’s anomalure 10 Order Cingulata: armadillos Taxonomy: 21 species Distribution: Neotropical, 1 species Nearctic Characteristics: -- bony plates on head and body -- myrmecophagous fairy armadillo screaming hairy armadillo giant armadillo 11 The Great American Interchange • Joining of Nearctic and Neotropical zoogeographic regions roughly 3 MYA -- many Nearctic taxa migrated southward; few Neotropical taxa migrated northward -- mass extinctions of Neotropical metatherians 12 Recent range expansion by the nine-banded armadillo • Northward expansion of 10 1972 km/year since 1940s 1994 nine-banded armadillo 13 Taulman and Robbins 1996 Recent range expansion by the nine-banded armadillo • Northward expansion of 10 1972 km/year since 1940s • Ultimately might be limited by rainfall (to the west) and temperature (to the north) 1994 Red = 2009 distribution Pink = predicted future distribution 14 Taulman and Robbins 1996 Historical biogeography—dispersal vs. vicariance • Dispersal (biogeographic context) = migration across preexisting geographic barriers after their removal. 15 Historical biogeography—dispersal vs. vicariance • Dispersal (biogeographic context) = migration across preexisting geographic barriers after their removal. 16 Historical Biogeography—dispersal vs. vicariance • Vicariance = formation of geographic barriers across preexisting geographic ranges 17 Historical Biogeography—dispersal vs. vicariance • Vicariance = formation of geographic barriers across preexisting geographic ranges 18 Order Pilosa: true anteaters and sloths Taxonomy: 10 species Distribution: Neotropical giant anteater common Hoffman’s silky anteater two-toed sloth 19 Order Pilosa: true anteaters and sloths Characteristics: -- incomplete zygomatic arches -- no enamel on cheek teeth -- myrmecophagous (anteaters) or folivorous (sloths) silky anteater two-toed sloth giant anteater 20 Evolution of gigantism and dwarfism -- island rule = on islands, the tendency for small species to increase in size (gigantism), and large species to decrease in size (dwarfism), over evolutionary time scales pygmy sloth (~3 kg) brown-throated sloth (~7 kg) 21 Evolution of gigantism and dwarfism pygmy sloth (~3 kg) brown-throated sloth (~7 kg) 22 Discussion question: come up with a hypothesis for the island rule. What does your hypothesis predict? pygmy sloth (~3 kg) brown-throated sloth (~7 kg) 23 Evolution of gigantism and dwarfism 24 Anderson and Handley 2002 Evolution of gigantism and dwarfism island wood mouse (35 g) wood mouse (15 g) 25 Order Artiodactyla: even-toed ungulates Taxonomy: 220 species Distribution: cosmopolitan, excepting Australasia Characteristics: -- cursorial or aquatic -- weight borne on 3rd and 4th digit musk deer -- many with ruminant stomach or cecum river hippopotamus bactrian camel bighorn sheep 26 Discussion question: Wong describes the history of how artiodactyls (and hippos in particular) were discovered to be ancestral to whales. To you, what was the most convincing piece of evidence for this? 27 Discussion question: Wong describes the history of how artiodactyls (and hippos in particular) were discovered to be ancestral to whales. To you, what was the most convincing piece of evidence for this? fossil whale pronghorn fossil whale 28 29 30 31 32 33 34 35 36 Cetartiodactyla 37 Order Cetacea: whales, dolphins, porpoises Taxonomy: 10 families, 78 species Distribution: Oceanic, rivers of Neotropical and Oriental Characteristics: -- fusiform body with modified forelimbs and vestigial hind limbs -- posterior migration of external nares 38 Suborder Odontoceti: toothed whales Taxonomy: 6 families, 67 species Distribution: Oceanic, rivers of Neotropical and Oriental regions Characteristics: -- single narial opening -- homodont dentition -- echolocation orca and harbor porpoise baiji narwals 39 Suborder Mysticeti: baleen whales Taxonomy: 4 families, 11 species Distribution: Oceanic (no rivers) gray whale Characteristics: -- two narial openings -- baleen blue whale bowhead whale 40.
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