The well-known high species richness of the tropical forests is not uniform through its different regions; Africa is species-poor when compared to Southeast Asia and the Neotropical region. One of the hypotheses for differences between the richness in the Neotropics and Africa points to the importance of recent speciation in the Neotropics. This is considered in particular in Andean-centred taxa that probably diversified in response to the opportunities for speciation offered by the final uplift of the tropical Andes (during the past c. 25 million years [Ma] to the present, with higher rates on the past 10 Ma to the present). The aim of this thesis is to test this hypothesis in the genus Renealmia L.f. (Zingiberaceae), an Andean centred lineage (c. 64 Neotropical spp.) that also occurs in Africa (c. 17 spp.). A taxonomic account of the Colombian species (c. 32; the country with the most species) is presented, and three species new to science were discovered and are described in an updated revision. I designed a new approach for obtaining nuclear phylogenetic markers for estimating species-level phylogenies using transcriptomes for recent diversification that could be applied to samples from herbarium specimens. I generated de-novo transcriptomes for two Renealmia species and a relative in the subfamily Alpinioideae that were combined with data available in repositories to target low copy number and potentially orthologous genes with short introns. I obtained sequence data for eight introns (ranging from 219 to 924 bp) and an rRNA (ITS1 & ITS2) marker for 40 species and at least one marker for 64 species, comprising a total of 137 accessions of which 67.9%(93) were sampled from herbarium specimens. Gene and species-trees were estimated for the genus. I found that most of the subgroups based on morphological characters are supported by the molecular data but a possible combination of incomplete lineage sorting (related to recent radiations or large population sizes) and/or introgression through hybridisation makes difficult to solve the relationships among these subgroups. Finally I estimated and compared diversification rates of the Neotropical and African lineages using dated phylogenies based on the trees estimated. I used available and customized methods that take into account incomplete taxon sampling, the uncertainty in the phylogenetic relationships and the stochasticity inherent to diversifications processes. Differences in diversification rates between Africa and the Neotropics indicate increased speciation attributable to the Andean orogeny in the Neotropical lineages of Renealmia.

Deformation of the Eastern Cordillera, as a double-verging thrust belt that separates the Magdalena Valley from the Llanos Basin, is a defining moment in the history of the northern Andes in South America. Here we examine the age and depositional setting of the youngest stratigraphic unit in three sectors of the Eastern Cordillera: (i) the Santa Teresa Formation (western flank), (ii) the Usme Formation (southern central axis), and (iii) the Concentración Formation (northeastern central axis). These units were deposited prior to the main Neogene deformation events. They represent the last preserved record of lowland conditions in the Eastern Cordillera, and they are coeval with a thick syn-orogenic deposition reported in the Llanos Basin and Magdalena Valley. Based on palynological data, we conclude that the upper Usme Formation was deposited during the Bartonian-earliest Rupelian? (Late Eocene-earliest Oligocene?); the Concentración Formation was deposited during the Late Lutetian-Early Rupelian (Middle Eocene to Early Oligocene), and the upper Santa Teresa Formation was accumulated during the Burdigalian (Early Miocene). These ages, together with considerations on maximum post-depositional burial, provide important time differences for the age of initial uplift and exhumation along the axial zone and western foothills of the Eastern Cordillera. The switch from sediment accumulation to erosion in the southern axial zone of the Eastern Cordillera occurred during the Rupelian-Early Chattian (Oligocene, ca 30 to ca 26 Ma), and in the northeastern axial zone occurred prior to the latest Chattian-Aquitanian (latest Oligocene-Early Miocene ca 23 Ma). In contrast, in the western flank, the switch occurred during the Tortonian (Late Miocene, ca 10 Ma). In addition, we detected a marine transgression affecting the Usme and Concentración formations during the Late Eocene; coeval marine transgression has been also documented in the Central Llanos Foothills and Llanos Basin, as evidenced by the similarity in floras, but not in the western foothills. Our dataset supports previous sedimentological, geochemical and thermochronological works, which indicated that (i) deformation in the Eastern Cordillera was a diachronous process, (ii) the sedimentation along the axial zone stopped first in the south and then in the north during the Oligocene, (iii) depositional systems of the axial zone and central Llanos Foothills kept partly connected at least until the Late Eocene, and (iv) Miocene strata were only recorded in adjacent foothills as well as the Magdalena and Llanos basins.

Controls on denudation in the eastern Bolivian Andes are evaluated by synthesis of new and existing denudation estimates from basin-morphometry, stream - powered fluvial incision, landslide mapping, sediment flux, erosion surfaces, thermochronology, foreland basin sediment volumes, and structural restorations. Centered at 17.5 °S, the northeastern Bolivian Andes exhibit high relief, a wet climate, and a narrow fold- thrust belt. In contrast, the southeastern Bolivian Andes have low relief, a semi-arid climate, and a wide fold-thrust belt. Basin -morphometry indicates a northward increase in relief and relative denudation. Stream-power along river profiles shows greater average incision rates in the north by a factor of 2 to 4. In the south, profile knickpoints with high incision rates are controlled by fold-thrust belt structures such as the surface expressions of basement megathrusts, faults, folds, and lithologic boundaries. Landslide and sediment-flux data are controlled by climate, elevation, basin morphology, and size and show a similar trend; short -term denudation-rate averages are greater in the north (1- 9 mm/yr) than the south (0.3-0.4 mm/yr). Long-term denudation-rate estimates including fission track, basin fill, erosion surfaces, and structural restorations also exhibit greater values in the north (0.2-0.8 mm/yr) compared to the south (0.04-0.3 mm/yr). Controls on long-term denudation rates include relief, orographic and global atmospheric circulation patterns of precipitation, climate change, glaciation, and fold-thrust belt geometry and kinematics. The denudation synthesis supports two conclusions: 1) denudation rates have increased towards the present 2) an along-strike disparity in denudation (greater in the north) has existed since at least the Miocene and has increased towards the present. Denudation rates and controls suggest that Bolivian mountain morphology is controlled by both its orientation at mid-latitude, and the feedbacks between uplift, kinematics, orographic effects on precipitation, glaciation, and the increased erosion that accompanies orogenesis.