‘Islands in the Sky’ - Tepuis
• Guayana Shield centered in southern Venezuela • 1.2 X 106 m2 • sandstone table mountains of Roraima Formation
Autana, 1300 m
‘Islands in the Sky’ - Tepuis
• Roraima Formation - Precambrian, highly leached sandy marine sediments laid down 1.5 - 1.8 billions years ago
• Roraima Formation uplifted during formation of Atlantic in Cretaceous Roraima, 2723 m Autana, 1300 m • tepuis formed with erosion of major river systems (Orinoco) – vicariance? • tepuis are resistant (quartzite) mesas
Kukenán, 2650 m Neblina, 3014 m
1 ‘Islands in the Sky’ - Tepuis ‘Islands in the Sky’ - Tepuis
• tepuis basis for Sir Arthur Conan Doyle’s “The Lost • tepuis basis for opening scene of Arachnophobia World”
• actually home to one of the world’s largest set of plant “carnivores”
Heliamphora - sun pitcher Canaima National Park
‘Islands in the Sky’ - Tepuis ‘Islands in the Sky’ - Tepuis
• Pantepui - biogeographic province proposed by the Phelps for high • Pantepui - biogeographic province proposed by the Phelps for high elevation “island” portion over 1500 m elevation “island” portion over 1500 m • characterized by a combination of extreme conditions: cool weather, heavy rainfalls, dense clouds, strong winds, high solar radiation, and extremely infertile substrates
Pantepui
2 ‘Islands in the Sky’ - Tepuis
• Pantepui - biogeographic province proposed by the Phelps for high elevation portion over 1500 m • Distinctive biota
Tepui vireo Rana Tepui manakin
Redbanded fruiteater
Asteraceae
Tepui Flora Tepui Flora
• Pantepui - island like species/area relationship Riki Olivares - M.S. thesis
Do the tepuis function as islands?
P < 0.0001 Ricarda Riina M.S. thesis (2003)
Log Summit Area
3 Tepui Flora Tepui Flora •Pantepui - island like endemism • Floristic relationships among tepuis Overall plant richness and endemism Pantepui Shield Pantepui Single tepui • Is there a biogeographical taxa endemics endemics endemics pattern? Families 156 2 0 0 – vicariance formed by river erosion? Genera 626 80 23 13 (4%) (2%) Species 2447 1517 1034 617 (42%) (25%)
Riki Olivares - M.S. thesis Vicki Funk - Smithsonian
Tepui Flora
Cluster Analysis based on floristic composition Guayana Shield - pantepui area
eastern tepuis
western tepuis
4 Tepui Flora
Guayana Shield - pantepui area • positive significant (P = 0.001) correlation between the floristic distance matrix and the among-tepuis geographic distance matrix (Mantel Test)
eastern tepuis
western tepuis
‘Islands in the Sky’ - Paramo, Afroalpine
• convergent biome types across high elevation areas of the tropics • depending on elevation, often occur as ‘islands’
5 ‘Islands in the Sky’ - Paramo, Afroalpine ‘Islands in the Sky’ - Paramo, Afroalpine
• South American paramo and East African afroalpine (‘Ethiopian’) • ecology is harsh and unvarying: ‘winter by night, summer by day’ best studied floristically as islands
‘Islands in the Sky’ - Paramo, Afroalpine ‘Islands in the Sky’ - Paramo, Afroalpine
• Convergent life forms occur in both areas as a response to • Convergent life forms occur in both areas as a response to these ecological conditions these ecological conditions Hypericum (sclerophyll) Afroalpine
Erica Dendrosenecio (Asteraceae) Lobelia (Lobeliaceae) (sclerophyll)
Viola (cushion)
Acaena (rosette) tussock grass
6 ‘Islands in the Sky’ - Paramo, Afroalpine Radiation in Andean Puya (Bromeliaceae) • Convergent life forms occur in both areas as a response to Rachel Schmidt Jabaily these ecological conditions Paramo
Puya (Bromeliaceae)
Espeletia (Asteraceae) Puya raimondii, Ancash, Peru
Radiation in Andean Puya Radiation in Andean Puya “mapping” on latitude & (Bromeliaceae) (Bromeliaceae) elevation on DNA tree Direction of latitudinal and elevation shifts?
latitude elevation
Jabaily&Sytsma 2013
7 Radiation in Andean Puya ‘Islands in the Sky’ - Paramo, Afroalpine (Bromeliaceae) • Biogeography of afroalpine flora – adaptive radiation of Dendrosenecio Relative rates of movements (Asteraceae)
in latitude and elevation ! !
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! !
Jabaily&Sytsma 2013 !
‘Islands in the Sky’ - Paramo, Afroalpine ‘Islands in the Sky’ - Paramo, Afroalpine
• Biogeography of afroalpine flora – adaptive radiation of Dendrosenecio • Biogeography of afroalpine flora – adaptive radiation of Dendrosenecio (Asteraceae) Which pattern? 1. Inter-island dispersal followed by (Asteraceae) Which pattern? 1. Inter-island dispersal followed by elevation shifts elevation shifts 2. Multiple dispersals from similar • Convergence of species adapted 2. Multiple dispersals from similar to similar elevations! elevations Mt. Kenya elevations Mt. Kenya
8 species adapted to 4 life zones (in color)
Eric Knox
root
Phylogeny superimposed on biogeography
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