Relationships of Floras (& Faunas) · Relationships of Floras (& Faunas) Southern Hemisphere...

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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


Mt. Kenya

Floristic relationships among the afroalpineregions of the East African mountains wereassessed by looking at species in common


Mt. Kenya

Pairwise similarity (shared species) between nineafroalpine regions. Total number of species for eachmountain shown in parenthesis and endemics inbold.


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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


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Most recent molecularcladogram of Nothofagus; nowthere appears to be 3 lineageswithin Nothofagus that showindependent Gondwananvicariance with S. Americasplitting first


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”!


Restionaceae comprise 520 species of grass-like plants placed in 58 generapredominantly of the southern hemisphere.

Askidiosperma — RestionaceaeCape Region


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


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Why is Africa the “odd continent out” when it comes to the temperate southernhemisphere flora?

Three reasons:

Proteaceae

Nothofagaceae

Restionaceae


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)


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


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


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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


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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)


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]


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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First point is that there are a large number of pantropical families — indicatingtropical connections throughout the Cretaceous


Gondwanan separation began near the early Cretaceous (135 mya), but there wasstill considerable tropical connections for another 40 my as shown below

94 mya


For example, tropical America and Africa were still close at around 90 mya eventhough temperate regions had separated 30+ my earlier


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


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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



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.


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


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


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


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


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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


The lineage Afrotheria has beenevolving in isolation for 85 my andincludes quite divergent and onceconsidered totally unrelated mammals


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


Relationships of Floras (& Faunas) · Relationships of Floras (& Faunas) Southern Hemisphere...

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