This review suggests that the ecology and patchy global distribution of seasonally dry tropical forest (SDTF) has distinctively structured the evolutionary history and biogeography of woody plant groups that are confined to it. SDTFs have few widespread woody plant species causing high β-diversity between separate areas of forests. These separate areas contain geologically old, monophyletic clades of endemic plant species that often have geographically structured intraspecific genetic variation. These patterns of diversity, endemism, and phylogeny indicate a stable, dispersal-limited SDTF system. SDTF species tend to belong to larger clades confined to this vegetation, exemplifying phylogenetic niche conservatism, and we argue that this is evidence that the SDTF is a metacommunity (biome) for woody plant clades. That phylogenetic, population genetic, biogeographic, and community ecological patterns differ in woody plants from tropical rain forests and savannas suggests a hypothesis that broad ecological s...

/pdf/woody-plant-diversity-evolution-and-ecology-in-the-tropics-1l6d6hxe5y.pdf

Woody Plant Diversity, Evolution, and Ecology in the Tropics: Perspectives from Seasonally Dry Tropical Forests

Recent phylogenetic studies have revealed the major role played by the uplift of the Andes in the extraordinary diversification of the Neotropical flora. These studies, however, have typically considered the Andean uplift as a single, time-limited event fostering the evolution of highland elements. This contrasts with geological reconstructions indicating that the uplift occurred in discrete periods from west to east and that it affected different regions at different times. We introduce an approach for integrating Andean tectonics with biogeographic reconstructions of Neotropical plants, using the coffee family (Rubiaceae) as a model group. The distribution of this family spans highland and montane habitats as well as tropical lowlands of Central and South America, thus offering a unique opportunity to study the influence of the Andean uplift on the entire Neotropical flora. Our results suggest that the Rubiaceae originated in the Paleotropics and used the boreotropical connection to reach South America. The biogeographic patterns found corroborate the existence of a long-lasting dispersal barrier between the Northern and Central Andes, the “Western Andean Portal.” The uplift of the Eastern Cordillera ended this barrier, allowing dispersal of boreotropical lineages to the South, but gave rise to a huge wetland system (“Lake Pebas”) in western Amazonia that prevented in situ speciation and floristic dispersal between the Andes and Amazonia for at least 6 million years. Here, we provide evidence of these events in plants.

/pdf/tracing-the-impact-of-the-andean-uplift-on-neotropical-plant-k945bj8xgu.pdf

Tracing the impact of the Andean uplift on Neotropical plant evolution

The linking of North and South America by the Isthmus of Panama had major impacts on global climate, oceanic and atmospheric currents, and biodiversity, yet the timing of this critical event remains contentious. The Isthmus is traditionally understood to have fully closed by ca. 3.5 million years ago (Ma), and this date has been used as a benchmark for oceanographic, climatic, and evolutionary research, but recent evidence suggests a more complex geological formation. Here, we analyze both molecular and fossil data to evaluate the tempo of biotic exchange across the Americas in light of geological evidence. We demonstrate significant waves of dispersal of terrestrial organisms at approximately ca. 20 and 6 Ma and corresponding events separating marine organisms in the Atlantic and Pacific oceans at ca. 23 and 7 Ma. The direction of dispersal and their rates were symmetrical until the last ca. 6 Ma, when northern migration of South American lineages increased significantly. Variability among taxa in their timing of dispersal or vicariance across the Isthmus is not explained by the ecological factors tested in these analyses, including biome type, dispersal ability, and elevation preference. Migration was therefore not generally regulated by intrinsic traits but more likely reflects the presence of emergent terrain several millions of years earlier than commonly assumed. These results indicate that the dramatic biotic turnover associated with the Great American Biotic Interchange was a long and complex process that began as early as the Oligocene–Miocene transition.

https://www.pnas.org/content/pnas/112/19/6110.full.pdf

Biological evidence supports an early and complex emergence of the Isthmus of Panama

The Neotropical region (tropical America) is the most species rich region on Earth. Several causes have been proposed to explain this extraordinary biodiversity, which may be very roughly classified into two major categories: 'biotic' (e.g. soil adaptations; biotic interactions with pollinators, dispersers and herbivores; niche conservatism; dispersal ability) and 'abiotic' (e.g. time; rainfall, temperature and area; mountain uplift; hydrological changes). In this paper we review the evidence for each of these postulated causes of diversification and provide general directions towards further testing. We highlight the need of more well-sampled and dated phylogenies and urge increased inter-disciplinary collaboration.

/pdf/why-are-there-so-many-plant-species-in-the-neotropics-55smu7d993.pdf

Why are there so many plant species in the Neotropics

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8339.2012.01235.x

A new subfamilial and tribal classification of the pantropical flowering plant family Annonaceae informed by molecular phylogenetics

Aim We test biogeographical hypotheses regarding the origin of Andean-centred plant groups by reconstructing phylogeny in the short-branch clade (SBC) of Annonaceae, and estimating the timing of diversifications in four apparently Andean-centred genera: Cremastosperma R.E.Fr., Klarobelia Chatrou, Malmea R.E.Fr. and Mosannona Chatrou. The SBC includes species distributed in both the Old and New World tropics. A number of the Neotropical genera display 'Andean-centred' distribution patterns, with high species richness on both sides of the Andes mountain range. In particular, we test whether these groups could have originated on the South American continent during the time frame of the Andean orogeny [from c. 23 Ma (Miocene) to the present]. Methods Chloroplast DNA sequences were used to reconstruct phylogeny in related Annonaceae taxa plus outgroups, under maximum parsimony and Bayesian inference. The markers rbcL, trnL-trnF and psbA-trnH were sampled for 96 accessions to test the monophyly of each of the genera, and thus whether they might be para- or polyphyletic with respect to related groups distributed across Amazonia. To determine the sister groups of the four genera, the additional markers matK, ndhF, trnT-trnL, trnS-trnG and atpB-rbcL were sampled for 23 of the 96 accessions. Molecular dating techniques (nonparametric rate-smoothing; penalized likelihood; Bayesian inference) were then applied to estimate the age of the crown group of each genus and the age of their sister groups. Results Monophyly was confirmed in Cremastosperma, Malmea and Mosannona. The monotypic genus Pseudephedranthus Aristeg. was found to be nested within Klarobelia, the species of which otherwise formed a monophyletic group, and a South American-centred (SAC) clade was identified. The SAC clade comprises all the SBC genera distributed in South America and generally to a limited extent into Central America, but not those endemic to Africa, Asia and Central America. Age estimations for clades within the SBC were no older than around 60 Myr; those for the crown groups of Cremastosperma, Klarobelia, Malmea and Mosannona fell largely within the last 10–20 Myr. Main conclusions The distribution patterns of Cremastosperma, Klarobelia, Malmea and Mosannona are not the arbitrary result of the definition of para- or polyphyletic groups. We infer the presence of a common ancestor of the four genera in South America, but not by vicariance of an ancestral population on Gondwana. The age estimations, instead, may suggest that the SAC clade originated in South America by dispersal across the Boreotropics. Although the strength of this test was limited by imprecision in the molecular dating results, the ages of crown groups of the four genera suggest that diversifications occurred within the time frame of the orogeny of the Northern Andes

‘Andean‐centred’ genera in the short‐branch clade of Annonaceae: testing biogeographical hypotheses using phylogeny reconstruction and molecular dating

We present revisions of the Neotropical genera Ruizodendron and Pseudephedranthus (Annonaceae). Ruizodendron includes a single species R. ovale. Pseudephedranthus now comprises two species, with the description of the new species P. enigmaticus sp. nov. extending the range of the genus beyond the Upper Rio Negro region of Brazil (Amazonas) and adjacent Venezuela (P. fragrans), to include Guyana, Suriname, and the Brazilian state of Para. An overview is provided of current revisions of Neotropical Annonaceae genera that will aid in accessing proper species information for this frequently encountered tropical rain forest family.

https://phytokeys.pensoft.net/lib/ajax_srv/article_elements_srv.php?action=download_pdf&item_id=13773

Revisions of Ruizodendron and Pseudephedranthus (Annonaceae) including a new species and an overview of most up-to-date revisions of Neotropical Annonaceae genera.

Jessica Oosterhof

Papers

‘Andean‐centred’ genera in the short‐branch clade of Annonaceae: testing biogeographical hypotheses using phylogeny reconstruction and molecular dating

Revisions of Ruizodendron and Pseudephedranthus (Annonaceae) including a new species and an overview of most up-to-date revisions of Neotropical Annonaceae genera.