relationships of floras (& faunas) · relationships of floras (& faunas) southern...
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Relationships of Floras (& Faunas)
Knowledge of earth and organism histories now permit closer examination ofrelationships of disjunct floras and faunas.Will examine four importantexamples of floristic relationships (Southern Hemisphere temperate, SouthernHemisphere tropics, the Wallace Line, and Eastern Asian - Eastern NorthAmerican temperate).
There are other “simple” tools toevaluate floristic and faunisticrelationships besides thoseinvolving phylogenetics andearth history as just discussed
A common method is to simplycompare different regions interms of % similarity at aspecific taxonomic level — ashere with families of mammalsand flowering plants
However, families, or any othertaxonomic rank, are not usuallyequivalent in age
Relationships of Floras (& Faunas)
Mt. Kenya
Floristic relationships among the afroalpineregions of the East African mountains wereassessed by looking at species in common
Relationships of Floras (& Faunas)
Mt. Kenya
Pairwise similarity (shared species) between nineafroalpine regions. Total number of species for eachmountain shown in parenthesis and endemics inbold.
Relationships of Floras (& Faunas)
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Mt. Kenya
Spatial distribution of nine mountains (A) andcluster diagram showing floristic relationships basedon Jaccard’s coefficient of similarity (B)
Relationships of Floras (& Faunas) Southern Hemisphere Temperate Flora
Interesting contrast between the floras of the southern hemisphere temperate andtropical floras. [The northern hemisphere continents are far more affected byrecent glaciation events, so their distribution patterns are far more complex].
35 species of trees and shrubs, evergreen and deciduous, restricted to SouthAmerica, New Zealand, Australia, Tasmania, New Caledonia, New Guinea,and fossilized in Antarctica
Nothofagaceae
Absent from Africa! — “odd continent out”
Southern Hemisphere Temperate Flora
Connections between South America and Australasia pronounced:
Nothofagaceae
• Subg. Nothofagus — South America• Subg. Fuscospora — S. Am., N. Zeal., Tasmania• Subg. Lophozonia — S. Am., N. Zeal., Tasmania, Austr.• Subg. Brassospora — New Caledonia, New Guinea
Southern Hemisphere Temperate Flora
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Most recent molecularcladogram of Nothofagus; nowthere appears to be 3 lineageswithin Nothofagus that showindependent Gondwananvicariance with S. Americasplitting first
Southern Hemisphere Temperate Flora
Proteaceae BanksiaProteaRoupala
Proteaceae comprise 1700 species of woody plants placed in 79 generapredominantly of the southern hemisphere. The family, unlike Nothofagaceae,occurs in south Africa and Madagascar, and extends into southern China.
The 16 genera from Africa are endemic and comprise only 3 lineages. Incomparison, South America and Australasia share roughly half of the genera incommon. All tribes within the latter two areas are shared.
Africa — “odd continent out”!
Southern Hemisphere Temperate Flora
Restionaceae comprise 520 species of grass-like plants placed in 58 generapredominantly of the southern hemisphere.
Askidiosperma — RestionaceaeCape Region
Southern Hemisphere Temperate Flora
Restionaceae comprise 520 species of grass-like plants placed in 58 generapredominantly of the southern hemisphere.
The 350 species from Africa are unique and belong only to 11 genera of theRestio group. In contrast, South America and Australasia share many generaincluding some species. Africa — “odd continent out”!
Fynbos, S. Africa — Restionaceae
Southern Hemisphere Temperate Flora
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Why is Africa the “odd continent out” when it comes to the temperate southernhemisphere flora?
Three reasons:
Proteaceae
Nothofagaceae
Restionaceae
Southern Hemisphere Temperate Flora
Estimates in millions of years BP when migration routes between land masses were broken or made.
made
broken
1. All three continents separated from Gondwana at about 100-110 mya in theearly Cretaceous, but South America and Australia linked with temperateAntarctica until about 50 mya (and via small water passages until 27 mya)
Southern Hemisphere Temperate Flora
Positions of Labrador, Africa, and Australia in the Triassic (200 mya) and at the present
2. Africa drifted further north and experienced greater climatic change throughthis latitudinal journey. Greater extinction of temperate biota; which is nowrestricted to small area of south Africa.
Temperate floraTriassic
Temperate floraPresent
Southern Hemisphere Temperate Flora
Estimates in millions of years BP when migration routes between land masses were broken or made.
made
broken
3. Africa made secondary contact with temperate Eurasia around 17 mya; longcontact further differentiated the temperate flora of Africa relative to SouthAmerica and Australia
Southern Hemisphere Temperate Flora
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Are all southern hemisphere disjunct patterns to beexplained by vicariance (i.e., continental drift)?
We can get information about continents, therelationships of organisms or clades, but we stillhave little knowledge about timing of events or aclock.
Southern Hemisphere Temperate FloraContinents, Clades, and Clocks
Taxon A
Taxon B
Taxon C
Maximum likelihood treewith different rates alongeach branch
α1
α2
α3
α4
Taxon A
Taxon B
Taxon C
Rate smoothed tree
β1
β2
β3
β4
Biogeographical interpretation
Area B
Area CArea A
15 myaTaxon A
Taxon B
Taxon C
Fossil calibrated tree
∗
Million yrs ago102030
∗
Example of Fuchsia with an Old World - NewWorld disjunction: introducing the idea ofcontinents, clades, and clocks
Southern Hemisphere Temperate Flora
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Hemsleyella (apetalous, 14 spp)
Quelusia – 8 spp SE Brazil, 1 S Andes
Sect. Fuchsia - 62 spp
South American sectionsCentral American
sections
Ellobium – F.splendens
Encliandra – F. thymifolia
Schufia – F. arborescens
Section Skinnera – New Zealand
Fuchsia excorticata &bellbird pollinator
… and TahitiF. cyrtandroides
Raven 1972
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Berry et al. 1990
Fossil pollen sites of Fuchsia in Australasia(Oligocene to Miocene)
Diporites
Berry et al. 1990; Sytsma et al. 1991; Sytsma & Smith 1992
Fuchsia ML tree based on 4 genes[Berry et al. 2004]
Penalized likelihood rate smoothedusing 41 mya separation date forCircaea and Fuchsia based onMyrtales wide analysis
Old world Fuchsiadivergence dated at 32mya, consistent witholdest Australian fossils(30 mya)
Fuchsia ML tree based on 4 genes[Berry et al. 2004]
Penalized likelihood rate smoothedusing 41 mya separation date forCircaea and Fuchsia based onMyrtales wide analysis
Old world Fuchsiadivergence dated at 32mya, consistent witholdest Australian fossils(30 mya)
Radiation of NewZealand Fuchsia dated at20 mya
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F. procumbens F. cyrtandroides
F. excorticata
Separation of Tahitianand New Zealandspecies also estimatedat 10 mya based oncpDNA restriction siteanalysis [Sytsma et al.1991]
Fuchsia ML tree based on 4 genes[Berry et al. 2004]
Explosive radiation ofsect. Fuchsia dated at 20mya, consistent withinitial orogeny of theAndean mountains and oftheir pollinators
Southern Hemisphere Tropical Flora
Numbers of shared families between the three tropical floristic regions
The floristic relationships among the three southern hemisphere continents arequite different when one examines the tropical floras.
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Numbers of shared families between the three tropical floristic regions
First point is that there are a large number of pantropical families — indicatingtropical connections throughout the Cretaceous
Southern Hemisphere Tropical Flora
Gondwanan separation began near the early Cretaceous (135 mya), but there wasstill considerable tropical connections for another 40 my as shown below
94 mya
Southern Hemisphere Tropical Flora
For example, tropical America and Africa were still close at around 90 mya eventhough temperate regions had separated 30+ my earlier
Southern Hemisphere Tropical Flora
Distribution of Monimiaceae - a basalangiosperm family
Siparuna
Flowering plants are first seen at theearliest Cretaceous, and many majorlineages are already seen at 95 mya
Thus, early (“primitive”) families areoften pantropical in distribution
Southern Hemisphere Tropical Flora
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Gyrocarpus jacquiniAsian tropics
Flowering plants are first seen at theearliest Cretaceous, and many majorlineages are already seen at 95 mya
Thus, early (“primitive”) families areoften pantropical in distribution
. . . or even genera of thesefamilies!
Distribution of Gyrocarpus - a genusfrom the basal angiosperm familyHernandiaceae
Southern Hemisphere Tropical Flora
Numbers of shared families between the three tropical floristic regions
Second, Africa is not the “odd continent out” — in fact, it appears that SouthAmerica seems less related in its tropical flora to either Africa or AustralAsia.
vs.
Southern Hemisphere Tropical Flora
African - Australasian Distributions
Distribution of Pittosporaceae
Many families show the African - Australasiandistribution pattern. Why?
1. A relatively continuous tropical land arcexists across the northern Indian Ocean andthrough the Malay Archipelago - assistsmigration
Many families show the African - Australasiandistribution pattern. Why?
1. A relatively continuous tropical land arcexists across the northern Indian Ocean andthrough the Malay Archipelago - assistsmigration
2. India, Africa, and Australia all rafted up tomake contact with the Eurasian plate atdifferent times - facilitates mixing
African - Australasian Distributions
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Adansonia digitataAdansonia grandidieri Adansonia gregorii
The baobab (Adansonia -Malvaceae) disjunct patternhas been shown to be due tolong distance dispersal
LDD
African - Australasian Distributions Southern Hemisphere Tropical Flora
Numbers of shared families between the three tropical floristic regions
Third, 12 families shared only between South America and Africa may notindicate shared biota . . .
?
Third, 12 families shared between South America and Africa may not indicateshared biota . . .
although Croizat argued that this Generalized Track indicated an ancestral biota
Southern Hemisphere Tropical Flora Vochysiaceae: 8 genera, 210 spp. all American except 3 spp.
Gondwanan vicariance or dispersal?
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Myr
tace
ae
Long distance dispersal ofVochysiaceae to Africa!South America and Africa hadalready separated for 60 my.
Molecular cladogram of Vochysiaceaeand relatives rate smoothed with threefossil calibrations (Sytsma et al. 2004)
Rapateaceae - characteristic family of theGuayana Shield
Auyuan tepui
Is the African Mascolocephalus a vicariad with closest GuayanaShield relatives, or a product of long distance dispersal?
Rapateaceae - . . . and one genus from theAfrican Man Shield
Rate smoothed with PL using8 fossils in an across monocotsurvey (Givnish et al. 2004)
(error bars for age estimates)
Rapateaceae 3-gene ML tree
Long distancedispersal to Africa!African speciesdivergence is 8-6 my
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1 species of Pitcairnia in west Africa -vicariance or dispersal?
Bromeliaceae (pineapples) is an Americanfamily
Rate smoothed with PL using8 fossils in an across monocotsurvey (in press)
Bromeliaceae 3-gene ML tree
Long distance dispersalto Africa! Africanspecies divergence is15-13 mya
Pitcairnia felicianaderived from Andeanclade
South American - west African Disjuncts
Vochysiaceae - water dispersed
Rapateaceae - bird (mud) dispersed
Bromeliaceae - ? dispersed
Cactaceae - bird dispersed
Humiriaceae - water dispersed
Cactaceae
The majority of the 12 familiesshowing this repeated pattern can notbe examples of vicariance, but rathertrans-oceanic dispersal at differenttimes
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Rhipsalis horrida
Rhipsalis baccifera
Rhipsalis — fleshy fruitedand bird dispersed
Cactaceae
South American - west African Disjuncts South American - west African Disjuncts
Pantropical distribution of Malpighiaceae
Boreotropics Hypothesis
An alternative to Gondwananvicariance or transoceanic dispersalhas been proposed for severalfamilies that are largely tropical butalso have northern temperate lineages
Phylogenetic analysis of these familiesindicate that the northern lineages are basalor primitive and not derived as previouslysuspected
Boreotropics Hypothesis
Boreal - Laurasia
• and migrated to the tropics in two or three separate lineages
Tropics
• these families likely originated in Laurasia (not Gondwana)
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Southern Hemisphere Faunal Relationships
Does vicariance explain patterns of animal distributions? Certainly for oldlineages such as Reptilia and for Marsupial vs. Placental Mammals.
Mesosaurus - Permian freshwater reptile
Does vicariance explain patterns of placental mammal distributions? Longcontroversy on how South American and African placentals are related.
?
?
?
?
?
capybara
paca
agouti
brocket deer
armadillo
pygmy hippo
chevrotain
royantelope
duiker
pangolin
Southern Hemisphere Faunal Relationships
64 mya 90 mya - separation of tropical South America and Africa
135 mya - separation of Gondwana
Major radiations of placental mammals occurred after Gondwanan separationand split of tropical South America and Africa
Southern Hemisphere Faunal Relationships
Relationships in placental mammals exist only within a continent and similaritiesbetween South America and Africa are a striking case of convergence.
capybara
paca
agouti
brocket deer
armadillo
pygmy hippo
chevrotain
royantelope
duiker
pangolin
Southern Hemisphere Faunal Relationships
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64 mya 90 mya - separation of tropical South America and Africa
135 mya - separation of Gondwana
A major surprise in the last few years using DNA sequences has been therecognition of a biogeographically defined lineage of African mammals with nodefining morphological features — Afrotheria
Southern Hemisphere Faunal Relationships
The lineage Afrotheria has beenevolving in isolation for 85 my andincludes quite divergent and onceconsidered totally unrelated mammals
Southern Hemisphere Faunal Relationships
Representatives of the six orders comprising the Superorder Afrotheria— a striking case of divergence within a lineage
African forestelephant
Aardvark
Eastern treehyrax
Golden-rumpedelephant shrew
Streaked tenrec
Dugong, sea cows
Southern Hemisphere Faunal Relationships