Givnish et al. 2004 (Article) Pitcairnia

Ancient vicariance or recent Long-distance Dispersal? Inferences about phylogeny and South American–African disjunctions In Rapateaceaeand Bromeliaceae based on ndh f Sequence data

Author(s):—T.J. Givnish, K.C. Millam, T.M. Evans, J.C. Hall, J.C. Pires, P.E. Berry & K.J. Sytsma

Publication:—Int. J. Plant Sci. 165(4 Suppl.): 35–54. (2004)

Abstract:—Rapateaceae and Bromeliaceae each have a center of diversity in South America and a single species native toa sandstone area in west Africa that abutted the Guayana Shield in northern South America before the Atlanticrifted. They thus provide ideal material for examining the potential role of vicariance versus long-distancedispersal in creating amphiatlantic disjunctions. Analyses based on ndh F sequence variation indicate thatRapateaceae and Bromeliaceae are each monophyletic and underwent crown radiation around 41 and 23Ma, respectively. Both exhibit clocklike sequence evolution, with bromeliads evolving roughly one-third moreslowly than rapateads. Among rapateads, the divergence of west African Maschalocephalus dinklagei from itsclosest South American relatives implies that Maschalocephalus resulted via long-distance dispersal 7 Ma, notancient continental drift; only its sandstone habitat is vicariant. Rapateads arose first at low elevations in theGuayana Shield; the earliest divergent genera are widespread along riverine corridors there and, to a lesserextent, in Amazonia and the Brazilian Shield. Speciation at small spatial scales accelerated 15 Ma with theinvasion of high-elevation, insular habitats atop tepuis. Among bromeliads, Pitcairnia feliciana diverges littlefrom its congeners and appears to be the product of long-distance dispersal ca. 12 Ma. Brocchinia / Ayensua andthen Lindmania are sister to all other bromeliads, indicating that the Guayana Shield was also the cradle of the bromeliads. Three lineages form an unresolved trichotomy representing all other bromeliads: (1) Till-andsioideae, (2) Hechtia , and (3) a large clade including remaining genera of Pitcairnioideae and allBromelioideae. The last includes a clade of pitcairnioid genera endemic to the Guayana and Brazilian Shields;a xeric group ( Abromeitiella / Deuterocohnia / Dyckia / Encholirium / Fosterella ) from southern South Americaand the southern Andes, sister to Pitcairnia ; and Andean Puya , sister to Bromelioideae, with many of the latternative to the Brazilian Shield. Both Rapateaceae and Bromeliaceae appear to have arisen at low elevations inthe Guayana Shield, experienced accelerated speciation after invading dissected mountainous terrain, andundergone long-distance dispersal to west Africa recently. Bromeliad acquisition of key adaptations to drought(e.g., CAM photosynthesis, tank habit, tillandsioid leaf trichomes) 17 Ma appears to have coincided with andhelp cause the centripetal invasion of drier, more seasonal regions beyond the Guayana Shield, resulting ina wider familial range and dominance of the epiphytic adaptive zone. Geology, past and present climate, andproximity to South America help account for both families occurring in nearly the same area of Africa. Wepresent a new classification for Rapateaceae, including a new tribe Stegolepideae, a new subfamilyMonotremoideae, and revisions to tribe Saxofridericieae and subfamily Rapateoideae

Keywords:—adaptive evolution, historical biogeography, penalized likelihood