Andean Uplift Research Articles

First Miocene fossils of Vivianiaceae shed new light on phylogeny, divergence times, and historical biogeography of Geraniales

The origin of Geraniales (approximately 900 species in three families: Geraniaceae, Melianthaceae, and Vivianiaceae) is traced back to the Cretaceous of Gondwana, yet their geotemporal history is largely unknown because of a limited fossil record and incomplete phylogenies. In the present study, we provide the first fossil record of Vivianiaceae and a highly resolved molecular phylogeny for all extant Geraniales genera. Our results support the hypothesis that five (instead of three) families should be recognized in the order Geraniales: Francoaceae A. Juss. (Francoa, Greyia, Tetilla), Geraniaceae Juss. (Erodium, Geranium, Monsonia, Pelargonium), Hypseocharitaceae Wedd. (monogeneric), Melianthaceae Horan. (Bersama, Melianthus), and Vivianiaceae Klotzsch (Balbisia, Rhynchotheca, Viviania). The four major lineages (i.e. Geraniaceae, Francoaceae + Melianthaceae, Hypseocharitaceae, Vivianiaceae) all originated within a narrow time frame during the Eocene (36.9–49.9 Mya) based on the five fossil calibration points. The divergence of most of the extant genera occurred much later, from the Miocene onwards. The South American–South African disjunction in Francoaceae apparently goes back to long distance dispersal with an estimated divergence time of the lineages in the Middle Miocene [11.2 (5.9–17.7) Mya]. Diversification in Melianthus appears to be much more recent than previously assumed [starting approximately 3.4 (1.9–5.2) Mya rather than approximately 8–20 Mya]. However, divergence of the Andean Hypseocharis lineage [36.9 (31.9–42.8) Mya] significantly predates the main Andean uplift: Current distributions likely go back to northward migrations and subsequent extinctions in Patagonia. Similarly, Rhynchotheca, Balbisia, and Viviania have a current southern distribution limit > 10°N of the fossil finds, indicating a massive northward displacement. The present evidence suggests that niche conservatism likely played a major role in the historical biogeography of Geraniales.

A dated phylogeny of the papaya family (Caricaceae) reveals the crop’s closest relatives and the family’s biogeographic history

Papaya (Carica papaya) is a crop of great economic importance, and the species was among the first plants to have its genome sequenced. However, there has never been a complete species-level phylogeny for the Caricaceae, and the crop’s closest relatives are therefore unknown. We investigated the evolution of the Caricaceae based on sequences from all species and genera, the monospecific Carica, African Cylicomorpha with two species, South American Jacaratia and Vasconcellea with together c. 28 species, and Mexican/Guatemalan Jarilla and Horovitzia with four species. Most Caricaceae are trees or shrubs; the species of Jarilla, however, are herbaceous. We generated a matrix of 4711 nuclear and plastid DNA characters and used maximum likelihood (ML) and Bayesian analysis to infer species relationships, rooting trees on the Moringaceae. Divergence times were estimated under relaxed and strict molecular clocks, using different subsets of the data. Ancestral area reconstruction relied on a ML approach. The deepest split in the Caricaceae occurred during the Late Eocene, when the ancestor of the Neotropical clade arrived from Africa. In South America, major diversification events coincide with the Miocene northern Andean uplift and the initial phase of the tectonic collision between South America and Panama resulting in the Panamanian land bridge. Carica papaya is sister to Jarilla/Horovitzia, and all three diverged from South American Caricaceae in the Oligocene, 27 (22–33) Ma ago, coincident with the early stages of the formation of the Panamanian Isthmus. The discovery that C. papaya is closest to a clade of herbaceous or thin-stemmed species has implications for plant breeders who have so far tried to cross papaya only with woody highland papayas (Vasconcellea).

Genus paracoccidioides: Species recognition and biogeographic aspects.

BackgroundParacoccidioidomycosis is a systemic mycosis caused by Paracoccidioides brasiliensis (species S1, PS2, PS3), and Paracoccidioides lutzii. This work aimed to differentiate species within the genus Paracoccidioides, without applying multilocus sequencing, as well as to obtain knowledge of the possible speciation processes.Methodology/Principal FindingsSingle nucleotide polymorphism analysis on GP43, ARF and PRP8 intein genes successfully distinguished isolates into four different species. Morphological evaluation indicated that elongated conidia were observed exclusively in P. lutzii isolates, while all other species (S1, PS2 and PS3) were indistinguishable.To evaluate the biogeographic events that led to the current geographic distribution of Paracoccidioides species and their sister species, Nested Clade and Likelihood Analysis of Geographic Range Evolution (LAGRANGE) analyses were applied. The radiation of Paracoccidioides started in northwest South America, around 11–32 million years ago, as calculated on the basis of ARF substitution rate, in the BEAST program. Vicariance was responsible for the divergence among S1, PS2 and P. lutzii and a recent dispersal generated the PS3 species, restricted to Colombia. Taking into account the ancestral areas revealed by the LAGRANGE analysis and the major geographic distribution of L. loboi in the Amazon basin, a region strongly affected by the Andes uplift and marine incursions in the Cenozoic era, we also speculate about the effect of these geological events on the vicariance between Paracoccidioides and L. loboi.Conclusions/SignificanceThe use of at least 3 SNPs, but not morphological criteria, as markers allows us to distinguish among the four cryptic species of the genus Paracoccidioides. The work also presents a biogeographic study speculating on how these species might have diverged in South America, thus contributing to elucidating evolutionary aspects of the genus Paracoccidioides.

Palaeobiodiversity and taxonomic resolution: linking past trends with present patterns

Palaeobiodiversity and taxonomic resolution: linking past trends with present patterns

Update: Updated DIVA program

ISSN 1948-6596 news and update update Updated DIVA program Botanists have long been stuck on the flora agenda, collecting and cataloging plants, and eventually producing narrative explanations of distributions. With increased data access and new analytic tools, the approach is now rapidly chang- ing towards synthesis of more general character. A recent paper in PNAS, by Alexandre An- tonelli and colleagues improves the standard set of tools for biogeographic reconstruction. The core of this paper is a molecular phylogeny of the coffee family (Rubiaceae), with broad taxon sam- pling but main focus on the Neotropics. The in- credible biodiversity of this region is often ex- plained from the extent and geological age of its rainforests, and from niche conservatism, whereby the once-widespread tropical biomes became restricted to low latitudes after the global cooling at the Eocene-Oligocene transition. The Andes is often assumed to have played a big role in South America, although it is poorly under- stood, first of all because the orogeny was often considered as a single, time-limited event. Little attention has been given to the fact that discrete geological structures were uplifted at different times, and to how the mountains affected the cli- mate of adjacent lowlands and constrained disper- sal within the lowlands. Montane biotas are often assumed to be young, recruited from adjacent lowlands, but mountains also seem to play a role as crates of biodiversity and dispersal centers. The study presents standard parsimony and Bayesian phylogenetic analysis and a likelihood estimation of evolutionary time. Building on Ron- quist’s DIVA program, Johan Nylander developed a new tool for biogeographic reconstruction, which uses a Bayesian sample of highly probable trees, thereby generating credibility support val- ues for alternative relationships. Thus, even with partially resolved trees and incomplete taxon sampling, the method provides very stable recon- structions of ancestral areas for the different phy- logenetic nodes. The combined chronogram and bio- geographic analysis demonstrates: (1) an old world origin of the Rubiaceae with dispersal to North America, before the opening of the North Atlantic in the Eocene, and (2) then to South America (which rejects the former view of Gond- wanic origin). (3) During late Oligocene to early Miocene, when the Amazon drained west through a Western Andean Portal, radiation took place in what is now the northern Andes and Amazonia, while the southern Andean region was out of reach. (4) From the mid-Miocene the Andes was connected as a continuous dispersal avenue, but at the same time it was isolated from the eastern Amazonian lowlands by marine incursions from the north and enormous wetlands. (5) Finally, when the present Amazonian drainage pattern to the Atlantic was established in the upper Mio- cene, there was a strong flora exchange through- out the tropical South American lowlands. Alto- gether, the study reveals a clear sequence of events of dispersal and diversification in distinct areas. The analytic approach has been used also in two recent studies of transoceanic dispersal in birds, and we must expect many further examples to follow. Antonelli, A., Nylander, J.A.A., Persson, C. & Sanmartin, I. (2009) Tracing the impact of the Andean uplift on Neotropical plant evolution. Proceedings of the National Academy of Sciences USA, 106, Jon Fjeldsa Natural History Museum of Denmark, Univer- sity of Copenhagen, Denmark e-mail: jfjeldsaa@snm.ku.dk http://snm.ku.dk/english/staffsnm/staff/profile/? id=75192 Edited by Camilla Flojgaard © 2009 the authors; journal compilation © 2009 The International Biogeography Society — frontiers of biogeography 1.1, 2009

Distribution Models and a Dated Phylogeny for Chilean Oxalis Species Reveal Occupation of New Habitats by Different Lineages, not Rapid Adaptive Radiation

Among the World's most challenging environments for plant life is the Atacama Desert, an arid zone extending over 1300 km and from sea level to 2000/3000 m altitude along the southwestern Andean foothills. Plants there and in the adjacent Mediterranean zone exhibit striking adaptations, and we here address the question whether in a species-rich clade such adaptations arose in parallel, at different times, or simultaneously. Answering this type of question has been a major concern of evolutionary biology over the past few years, with a growing consensus that lineages tend to be conservative in their vegetative traits and niche requirements. Combined nuclear and chloroplast DNA sequences for 112 species of Oxalidales (4900 aligned nucleotides) were used for a fossil-calibrated phylogeny that includes 43 of the 54 species of Chilean Oxalis, and species distribution models (SDMs) incorporating precipitation, temperature, and fog, and the phylogeny were used to reconstruct ancestral habitat preferences, relying on likelihood and Bayesian techniques. Since uneven collecting can reduce the power of SDMs, we compared 3 strategies to correct for collecting effort. Unexpectedly, the Oxalis flora of Chile consists of 7 distant lineages that originated at different times prior to the last Andean uplift pulse; some had features preadapting them to seasonally arid or xeric conditions. Models that incorporated fog and a "collecting activity surface" performed best and identified the Mediterranean zone as a hotspot of Oxalis species as well as lineage diversity because it harbors a mix of ancient and young groups, including insufficiently arid-adapted species. There is no evidence of rapid adaptive radiation.

Plate motions, Andean orogeny, and volcanism above the South Atlantic convection cell

The geometric and kinematic evolution of the Andes provides insight onto the nature of the force balance beneath the South American plate. While the Andean load is opposed on its western edge by the force induced by subduction of the Nazca plate, its more elusive eastern counterpart, which we explore herein, requires some contribution from the mantle beneath the South Atlantic. Using a mantle flow model, we show that the Andes owe their existence to basal drag beneath South America caused by a cylindrical convection cell under the South Atlantic. We find that the observed Andean uplift requires both westward push from active upwelling beneath Africa and westward drag toward the downgoing Nazca slab. These mutually-reinforcing downwellings and upwellings amount to 38% and 23% of the total driving force, respectively. Further decomposition reveals that the South Atlantic cell is most vigorous near its center, rendering the net drag force higher where the Andes also reach their highest elevation. Kinematic reconstructions suggest that the South Atlantic cell could have grown owing to the migration of the Nazca slab until ~50Ma. We propose that from 50Ma onwards, the cell may have ceased growing westward because (i) it had reached an optimal aspect ratio and (ii) the Nazca slab became anchored into the lower mantle. Continued westward motion of the plates, however, moved the surface expressions of spreading and convergence away from the upwelling and downwelling arms of this cell. Evidence for this scenario comes from the coeval tectonic, morphologic, and magmatic events in Africa and South America during the Tertiary.

Evolutionary islands in the Andes: persistence and isolation explain high endemism in Andean dry tropical forests

AbstractAim The tropical Andes are a world biodiversity hotspot. With diverse biomes and dramatic, geologically recent mountain uplift, they offer a system to study the relative contributions of geological and biome history to species richness. There are preliminary indications that historical species assembly in the Andes has been influenced by physiographical heterogeneity and that distinct biomes have evolved in relative isolation despite physical proximity. Here we test this ‘Andean biotic separation hypothesis’ by focusing on the low‐elevation, seasonally dry tropical forest (SDTF) biome to determine whether patterns of plant diversification within the SDTF differ from those in mid‐ and high‐elevation biomes.Location Tropical Andes, South America.Methods Densely sampled time‐calibrated phylogenies for five legume genera (Amicia, Coursetia, Cyathostegia, Mimosa and Poissonia) containing species endemic to the Andean SDTF biome were used to investigate divergence times and levels of geographical structure. Geographical structure was measured using isolation‐by‐distance methods. Meta‐analysis of time‐calibrated phylogenies of Andean plant groups was used to compare the pattern and tempo of endemic species diversification between the major Andean biomes.Results Long‐term persistence of SDTF in the Andes is suggested by old stem ages (5–27 Ma) of endemic genera/clades within genera, and deep divergences coupled with strong geographical structure among and within species. Comparison of species diversification patterns among different biomes shows that the relatively old, geographically confined pattern of species diversification in SDTF contrasts with the high‐elevation grasslands that show rapid and recent radiations driven by ecological opportunities.Main conclusions The SDTF biome has a long history in the Andes. We suggest that the diverse SDTF flora has been assembled gradually over the past c. 19 Ma from lineages exhibiting strong phylogenetic niche conservatism. These patterns suggest that Andean SDTFs have formed stable and strongly isolated ‘islands’ despite the upheavals of Andean uplift. Indeed, the Andean SDTFs may represent some of the most isolated and evolutionarily persistent continental plant communities, similar in many respects to floras of remote oceanic islands.

Impacts of Cenozoic global cooling, surface uplift, and an inland seaway on South American paleoclimate and precipitation 18O

Research Article| March 01, 2012 Impacts of Cenozoic global cooling, surface uplift, and an inland seaway on South American paleoclimate and precipitation δ18O M. Louise Jeffery; M. Louise Jeffery † 1Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA †E-mail: louisej@umich.edu Search for other works by this author on: GSW Google Scholar Christopher J. Poulsen; Christopher J. Poulsen 1Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Todd A. Ehlers Todd A. Ehlers 1Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA2Department of Geosciences, Universität Tübingen, 72074 Tübingen, Germany Search for other works by this author on: GSW Google Scholar GSA Bulletin (2012) 124 (3-4): 335–351. https://doi.org/10.1130/B30480.1 Article history received: 06 Jan 2011 rev-recd: 06 Jun 2011 accepted: 14 Jun 2011 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation M. Louise Jeffery, Christopher J. Poulsen, Todd A. Ehlers; Impacts of Cenozoic global cooling, surface uplift, and an inland seaway on South American paleoclimate and precipitation δ18O. GSA Bulletin 2012;; 124 (3-4): 335–351. doi: https://doi.org/10.1130/B30480.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Stable isotope records of precipitation δ18O (δ18Oprec) have been used as paleoclimate and paleoelevation archives of orogens. However, interpretation of these records is limited by knowledge of how δ18Oprec responds to changes in global and regional climate during mountain-building events. In this study the influence of atmospheric CO2 levels, the extent of the Antarctic ice sheet, changes in Andean surface elevation, and the presence of the South American inland seaway on climate and δ18Oprec in South America are quantified using the GENESIS v3 atmospheric general circulation model with isotope-tracking capabilities. Results are presented in the context of Cenozoic South American climate and δ18Oprec changes. More specifically, we find: (1) Precipitation rates in the Andes are sensitive to Andean surface elevation, the seaway and, to a lesser extent, CO2 levels. Increasing Andean elevations and the presence of a seaway both cause large increases in precipitation, but in different parts of the Andes. The growth of the Antarctic ice sheet is found to have a small influence on South American precipitation. (2) The stable isotopic composition of precipitation is sensitive to all of the parameters investigated. An increase in δ18Oprec of up to 8‰ is found in simulations with higher atmospheric CO2. In agreement with previous studies, δ18Oprec decreases with increasing Andean elevation by an amount greater than that predicted by the modern adiabatic lapse rate. Furthermore, the presence of an inland seaway causes a decrease in δ18Oprec of 1–8‰ in the northern and central Andes. The amount of depletion is dependent on the isotopic composition of the seaway. Simulations without the Antarctic ice sheet result in δ18Oprec that is 0–3‰ lower than the modern. Finally, time-specific simulations for the Miocene and Eocene show that δ18Oprec has decreased during the Cenozoic and that local geographical gradients of δ18Oprec have increased, particularly in regions of high modern elevation. We demonstrate that in addition to Andean uplift and associated climate change, CO2 levels and an inland seaway are likely to have influenced δ18Ocarb records from South America. Consideration of these global and paleogeographic changes is necessary when interpreting paleoclimate or paleoelevation from stable isotope records of δ18Oprec. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Fracturing of the Panamanian Isthmus during initial collision with South America

Tectonic collision between South America and Panama began at 23–25 Ma. The collision is significant because it ultimately led to development of the Panamanian Isthmus, which in turn had wide-ranging oceanic, climatic, biologic, and tectonic implications. Within the Panama Canal Zone, volcanic activity transitioned from hydrous mantle-wedge−derived arc magmatism to localized extensional arc magmatism at 24 Ma, and overall marks a permanent change in arc evolution. We interpret the arc geochemical change to result from fracturing of the Panama block during initial collision with South America. Fracturing of the Panama block led to localized crustal extension, normal faulting, sedimentary basin formation, and extensional magmatism in the Canal Basin and Bocas del Toro. Synchronous with this change, both Panama and inboard South America experienced a broad episode of exhumation indicated by (U-Th)/He and fission-track thermochronology coupled with changing geographic patterns of sedimentary deposition in the Colombian Eastern Cordillera and Llanos Basin. Such observations allow for construction of a new tectonic model of the South America–Panama collision, northern Andes uplift and Panama orocline formation. Finally, synchroneity of Panama arc chemical changes and linked uplift indicates that onset of collision and Isthmus formation began earlier than commonly assumed.

Diversification in Adelomyia hummingbirds follows Andean uplift

The Andes are known to have influenced speciation patterns in many taxa, yet whether species diversification occurred simultaneously with their uplift or only after uplift was complete remains unknown. We examined both the phylogenetic pattern and dates of branching in Adelomyia hummingbirds in relation to Andean uplift to determine whether diversification coincides with the chronological phases of the uplift or with recent climatic fluctuations after Andean formation. Results suggest that the genus Adelomyia originated in the central Andes in the Miocene and was found to be comprised of six deeply divergent phylogroups dating between 3.5 and 6 Ma. The most basal splits in the tree, corresponding to the most southerly distributed of the six phylogroups, diverged in the late Miocene, whereas the northern phylogroups originated during the early-to-mid-Pliocene, when the northern Andes reached heights sufficient to support Adelomyia populations. Although we provide evidence for a southern origin for the group, the subsequent diversification of the northern phylogroups did not strictly follow the hypothesized south-to-north orogeny of the Andes. Further genetic structure within phylogroups may have resulted from Pleistocene climate fluctuations after the onset of the six lineages during the Mio-Pliocene. We explore the processes that promoted diversification in the Andes and suggest that in at least some groups, divergence was coupled to Andean orogeny.

Andean uplift promotes lowland speciation through vicariance and dispersal in Dendrocincla woodcreepers

Andean uplift contributed importantly to the build-up of high Neotropical diversity. Final uplift of the Eastern Cordillera of Colombia separated once-contiguous lowland faunas east and west of the Andes between 5 and 3.5 million years ago (Ma hereafter). We used DNA sequences from several moderate- to fast-evolving mitochondrial and two slow-evolving nuclear genes to generate a well-supported phylogeny of Dendrocincla woodcreepers, a genus with multiple species endemic to lowland regions both east and west of the Andes. A time-calibrated phylogeny and dispersal-vicariance analysis indicated that uplift of the Eastern Cordillera of Colombia resulted in the initial vicariant separation of a widespread lowland form east and west of the Andes at c. 3.6 Ma. This was followed by two separate east-to-west dispersal events over or around the completed Andes, each producing a genetically distinct lineage. Our analysis suggests that Andean uplift promoted the build-up of biodiversity in lowland Neotropical faunas both through vicariance-based speciation during uplift and through dispersal-based speciation following uplift. In contrast to the multiple colonizations of the trans-Andean region by Dendrocincla, the Atlantic Forest was colonized from the Amazon only once, followed by in situ diversification.

Diversification in the Andes: Age and origins of South American Heliotropium lineages (Heliotropiaceae, Boraginales)

The uplift of the Andes was a major factor for plant diversification in South America and had significant effects on the climatic patterns at the continental scale. It was crucial for the formation of the arid environments in south-eastern and western South America. However, both the timing of the major stages of the Andean uplift and the onset of aridity in western South America remain controversial. In this paper we examine the hypothesis that the Andean South American groups of Heliotropium originated and diversified in response to Andean orogeny during the late Miocene and a the subsequent development of aridity. To this end, we estimate divergence times and likely biogeographical origins of the major clades in the phylogeny of Heliotropium, using both Bayesian and likelihood methods. Divergence times of all Andean clades in Heliotropium are estimated to be of late Miocene or Pliocene ages. At least three independent Andean diversification events can be recognized within Heliotropium. Timing of the diversification in the Andean lineages Heliotropium sects.Heliothamnus, Cochranea, Heliotrophytum, Hypsogenia, Plagiomeris, Platygyne clearly correspond to a rapid, late Miocene uplift of the Andes and a Pliocene development of arid environments in South America.

Pliocene diversification within the South American Forest falcons (Falconidae: Micrastur)

The Neotropics are one of the most species rich regions on Earth, with over 3150 species of birds. This unrivaled biodiversity has been attributed to higher proportions of mountain ranges, tropical rain forest or rain fall in the forest than in any other major biogeographic regions. Five primary hypotheses aim to explain processes of diversification within the Neotropics; (1) the Pleistocene refuge hypothesis, (2) the riverine barrier hypothesis, (3) the Miocene marine incursions hypothesis, (4) the ecological gradient hypothesis, and (5) the impact of the last Andean uplift serving as a barrier between eastern and western population Andean populations. We assessed these hypotheses to see which best explained the species richness of the forest-falcons (Micrastur), a poorly known lineage of birds that inhabit lowland and mid-elevation humid forest. Our analyses suggest all speciation events within the genus Micrastur probably occurred in the last 2.5–3.6myrs, at or before the Pliocene/Pleistocene boundary, with the basal split within the genus being 7myrs old. Hence our data allow us to formerly reject the classical Pleistocene refuge for Micrastur, Our divergence time estimates are younger that dates for the Miocene marine incursions, the riverine barrier and the Andean uplift hypotheses.

Repeated eastward shifts of arc magmatism in the Southern Andes: A revision to the long-term pattern of Andean uplift and magmatism

Abstract The Southern Andes have been built through the stacking of crustal sheets in discrete periods during the last 100 My. The first important shortening took place in Late Cretaceous at the time of eastward arc expansions potentially linked to two areas of subducted slab shallowings of 200 and 800 km wide respectively. These shallowings have progressed to two smaller flat slabs in Eocene times, where rather anhydrous subducted slabs generated a discontinuous arc emplaced in the foreland area at the time of mountain building. Discrete segments of the former Late Cretaceous slab shallowings would have fallen down at this time producing early slab steepening settings where within-plate products and extensional basins developed such as in the southern Chubut Province. Then Late Oligocene times coincide with the final steepening of the broad Late Cretaceous to Eocene shallow subduction zone with the emplacement of voluminous volcanic plateaux in central Patagonia and extensional basins in the hinterland zone. Lately a long quiescence period was interrupted by the development of three Miocene shallow subduction settings more than 400 km long each, evidenced by arc expansions and associated with Andean construction. Most of these areas were extensionally reactivated in the last 5 My at the time of retraction and steepening of formerly shallow subduction zones, being associated with voluminous mantle derived materials and shallow asthenospheric injection. While some of these shallow subduction configurations could be explained by subduction of highly buoyant oceanic lithosphere related to seismic ridges, in particular those of the Aluk/Farallones and Chilean ridges, other mechanisms remain more speculative. The alternation of shallow subduction zones and their steepening in the last 100 My in the Southern Andes explain location and timing of main magmatic fluxes in the arc and retroarc areas, as well as the presence of coeval foreland mountain systems east of the Main Andes.

Temporal patterns of diversification in Andean Eois, a species-rich clade of moths (Lepidoptera, Geometridae)

The timing of the origin of present day Neotropical animal diversity is still a matter of debate. For a long time, a preponderance of glacial (i.e. Pleistocene) radiations has been proposed. However, recent data from molecular clock studies indicate a preglacial origin for most of the examined taxa. We performed a fossil-calibrated molecular dating analysis of the genus Eois, which is a major component of one of the world's most diverse assemblages of herbivorous insects. We found that diversification of Eois took place in the Miocene following a pattern best explained by density-dependent diversification. A strong slowdown of diversification towards the present was detected. Diversification of Eois does overlap with increased Andean uplift and diversification of the most commonly used host plant genus Piper. These findings match the patterns found for the majority of Neotropical tetrapods and for three other unrelated, ecologically different lepidopteran genera.

Exhumation and uplift of the Sierras Pampeanas: preliminary implications from K–Ar fault gouge dating and low-T thermochronology in the Sierra de Comechingones (Argentina)

The Sierras Pampeanas in central and north-western Argentina constitute a distinct morphotectonic feature between 27°S and 33°S. The last stage of uplift and deformation in this area are interpreted to be closely related to the Andean flat-slab subduction of the Nazca plate beneath the South American plate. K–Ar fault gouge dating and low-temperature thermochronology along two transects within the Sierra de Comechingones reveal a minimum age for the onset of brittle deformation about 340 Ma, very low exhumation rates since Late Paleozoic time, as well as a total exhumation of about 2.3 km since the Late Cretaceous. New Ar–Ar ages (7.54–1.91 Ma) of volcanic rocks from the San Luis volcanic belt support the eastward propagation of the flat-slab magmatic front, confirming the onset of flat-slab related deformation in this region at 11.2 Ma. Although low-temperature thermochronology does not clearly constrain the signal of the Andean uplift, it is understood that the current structural relief related to the Comechingones range has been achieved after the exhumation of both fault walls (circa 80–70 Ma).

Andean uplift and climate evolution in the southern Atacama Desert deduced from geomorphology and supergene alunite-group minerals

Supergene alunite group minerals from the Late Eocene El Salvador porphyry Cu district, the El Hueso epithermal gold deposit and the Coya porphyry Au prospect located in the Precordillera of Northern Chile (~ 26 to 26° 30´ Lat. S) have been dated by the 40Ar/ 39Ar method and analyzed for stable isotopes. These data support published geomorphologic and sedimentologic evidence suggesting that the Precordillera in the Southern Atacama Desert had been uplifted as early as the late Eocene and, thus, significantly prior to the Altiplano which attained its high elevation only in the late Miocene. The oldest supergene alunite from the Damiana exotic deposit at El Salvador was dated at 35.8 ± 1 Ma and yielded a δD (VSMOW) value of −74‰ which indicates elevations of the Precordillera near El Salvador of at least 3000 m in the Late Eocene. In contrast, Miocene supergene alunite from El Salvador, El Hueso, and Coya have less negative δD signatures reaching values as high as −23 to −25‰ at El Hueso and El Salvador between about 8.2 and 14 Ma. Late Miocene to Holocene supergene alunite, jarosite and natroalunite ages are restricted to El Hueso and Coya located near 4000 m above sea level in the Precordillera, roughly 1000 m higher than the present elevation of El Salvador. The δD values of samples younger than ~ 5 Ma vary between −57 and −97‰. The complex evolution of the δD signatures suggests that meteoric waters recorded in supergene alunite group minerals were variably affected by evaporation and provides evidence for climate desiccation and onset of hyper arid conditions in the Central Depression of the southern Atacama Desert after 15 Ma, which agrees well with published constraints from the Atacama Desert at 23–24° Lat. S. Our data also suggest that wetter climatic conditions than at present prevailed in the latest Miocene and early Pliocene in the Precordillera. The new and previously published age constraints for El Salvador indicate that supergene mineralization at the Damiana exotic Cu deposit occurred periodically over 23 Ma in a locally exceptionally stable paleohydrologic and geomorphologic configuration.

Sedimentology-based reconstructions of paleoclimate changes in the Central Andes in response to the uplift of the Andes, Arica region between 19 and 21°S latitude, northern Chile

We focus on the sedimentological record of the Middle Miocene to modern deposits in the Andes of northern Chile between 19 and 21°S. These sediments, deposited at the Western Escarpment of the Central Depression, indicate successively more moisture on the western margin of the Altiplano and the Western Cordillera where the sources are. At the Pacific Coast, 20-Ma-old exposure ages and salic gypsisols reflect an existing and ongoing hyperarid climate. We interpret the increased divergence of climates between the Coast and the Altiplano as consequence of the Andean rise to elevations higher than approximately 2,500 m a.s.l., when the topography of the Altiplano was sufficiently high and areally extensive to attract Atlantic moisture. Accordingly, the inferred general increase in run-off was closely coupled with the uplift of the Andes if the steady rise model applies. In case that the rapid rise model for Andean uplift is correct, the inferred changes in sediment transport would have occurred independently of uplift, requiring an alternative, yet unknown driver.

Evolutionary history and taxonomy of a short-horned grasshopper subfamily: The Melanoplinae (Orthoptera: Acrididae)

The Melanoplinae is one of the largest subfamilies of the Acrididae grasshoppers, with a Holarctic–Neotropical distribution. To investigate its controversial taxonomy and evolutionary history, we studied 19 species representative of its main tribes, and 7 Acridoidea outgroup species. More than 1650 base pairs of three regions of nuclear rDNA (18S, ITS1, 28S) and one mitochondrial rDNA (12S) were combined and used to construct parsimony, maximum likelihood and Bayesian phylogenies. Our results correspond with the present geographical distribution of the taxa rather than the existing taxonomy based on morphological characters. The morphologically unclassified and atypical taxa group with the Neotropical Melanoplinae. The currently recognized Melanoplinae appear to be polyphyletic due to inclusion of the Mexican genus Netrosoma. The distribution of the American and Eurasiatic Melanoplinae fauna can be explained by climatic and geological events, such as the Andean uplift, that would have affected the diversification and migration of Neotropical taxa.