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