Greater Antilles

Food Web Structure and Basal Resource Utilization along a Tropical Island Stream Continuum, Puerto Rico

March, JG, and CM Pringle. 2003. Food web structure and basal resource utilization along a tropical island stream continuum, puerto rico. Biotropica 35 (1) (MAR): 84-93.

Tropicals treamf ood webs are thought to be based primarilyo n terrestriarl esources( leaf litter) in small forested headwatesrt reamsa nd algalr esourceisn largerw, iders treamsI. n tropicali slands treamst, he dominantc onsumeras re often omnivorousfr eshwatesrh rimpst hat consumea lgae,l eaf litter,i nsects,a nd others hrimpsW. e useds tablei sotope analysist o examine( 1) the relativei mportanceo f terrestriaal nd algal-basedfo od resourcest o shrimpsa nd other consumersa nd determine( 2) if the relativeim portanceo f thesef ood resourcecs hangeda longt he streamc ontinuum. We examined8 15N and 813Cs ignatureos f leaves,a lgae,m acrophytesb, iofilm,i nsects,s nails,f ishes,a nd shrimpsa t threes ites (300, 90, and 10 m elev.)a longt he Rio EspirituS anto,w hichd rainst he CaribbeanN ationalF orestP, uerto Rico. Isotopes ignatureos f basalr esourcews ered istincta t all sites.R esultso f two-source6 13Cm ixingm odelss uggest that shrimpsr eliedm oreo n algal-basedca rbonr esourcetsh an terrestrialldye rivedr esourceas t all threes itesa longt he continuum.T his studys upportso therr ecentf indingsi n tropicals treamsd, emonstratintgh ata lgal-basedre sourceas re very importantt o streamc onsumers,e ven in small forestedh eadwaters treams.T his study also demonstratetsh e importanceo f doing assimilation-baseadn alysis( i.e., stablei sotope or trophicb asis of production)w hen studying food webs.

Bivergent thrust wedges surrounding oceanic island arcs: Insight from observations and sandbox models of the northeastern Caribbean plate

ten Brink U, Marshak S, Granja JL (2009) Bivergent thrust wedges
surrounding oceanic island arcs: insights from observations and
sandbox models in the north-eastern Caribbean plate. Geol Soc
Am Bull 121:1522–1536

At several localities around the world, thrust belts have developed on both sides of oceanic island arcs (e.g., Java-Timor, Panama, Vanuatu, and the northeastern Caribbean). In these localities, the overall vergence of the backarc thrust belt is opposite to that of the forearc thrust belt. For example, in the northeastern Caribbean, a north-verging accretionary prism lies to the north of the Eastern Greater Antilles arc (Hispaniola and Puerto Rico), whereas a south-verging thrust belt called the Muertos thrust belt lies to the south. Researchers have attributed such bivergent geometry to several processes, including: reversal of subduction polarity; subduction-driven mantle fl ow; stress transmission across the arc; gravitational spreading of the arc; and magmatic infl ation within the arc. New observations of deformational features in the Muertos thrust belt and of fault geometries produced in sandbox kinematic models, along with examination of published studies of island arcs, lead to the conclusion that the bivergence of thrusting in island arcs can develop without reversal of subduction polarity, without subarc mantle fl ow, and without magmatic infl ation. We suggest that the Eastern Greater Antilles arc and comparable arcs are simply crustalscale bivergent (or “doubly vergent”) thrust wedges formed during unidirectional subduction. Sandbox kinematic modeling suggests, in addition, that a broad retrowedge containing an imbricate fan of thrusts develops only where the arc behaves relatively rigidly. In such cases, the arc acts as a backstop that transmits compressive stress into the backarc region. Further, modeling shows that when arcs behave as rigid blocks, the strike-slip component of oblique convergence is accommodated entirely within the prowedge and the arc—the retrowedge hosts only dip-slip faulting (“frontal thrusting”). The existence of large retrowedges and the distribution of faulting in an island arc may, therefore, be evidence that the arc is relatively rigid. The rigidity of an island arc may arise from its mafi c composition and has implications for seismic-hazard analysis.

Historical phytogeography of the Greater Antilles

Historical Phytogeography of the Greater Antilles
Alan Graham
Vol. 55, No. 4 (Sep. - Dec., 2003), pp. 357-383

An understanding of the phytogeographic history of a region depends upon an adequate fossil record to reveal migrational histories and the timing and direction(s) of introductions and extinctions, and to augment or circumvent undue reliance on molecular clocks. It further depends upon an accurate phylogeny of the taxa to establish real patterns of geographic affinities (phylogeography), and a relatively detailed geologic history to assess the relative roles of dispersal and vicariance in populating the islands. For the Greater Antilles new information is slowly emerging on the plant fossil record through study of new floras such as the Eocene Saramaguaca´n palynoflora from Cuba, and more is potentially available from the middle Oligocene San Sebastian megafossil flora of Puerto Rico that has not been revised since the early 1900s. Phylogeographic studies and area cladograms are still meager for plants, but data from various animal groups are providing a context for the general biotic history of the Antilles. Perhaps the area of greatest advance is being made in achieving an adequate plate tectonic model for the Caribbean region. There is now some convergence toward a mobilist model that depicts a Cretaceous volcanic island arc that extended from the Mexico/Chortis block in the north to Ecuador in the south, and gradually moved through the developing portal between North and South America to collide with the Bahamas Platform in the middle Eocene. Throughout this 70-million-year history there was an immensely complex pattern of collision/separation and submergence/emergence that provided opportunity both for vicariance and dispersal in the migration, evolution, and speciation of the flora of the Greater Antilles.
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