Why mountains matter for biodiversity Perrigo, Allison; Hoorn, Carina; Antonelli, Alexandre
Journal of biogeography,
February 2020, Volume:
47, Issue:
2
Journal Article
Peer reviewed
Open access
Mountains are arguably Earth's most striking features. They play a major role in determining global and regional climates, are the source of most rivers, act as cradles, barriers and bridges for ...species, and are crucial for the survival and sustainability of many human societies. The complexity of mountains is tightly associated with high biodiversity, but the processes underlying this association are poorly known. Solving this puzzle requires researchers to generate more primary data, and better integrate available geological and climatic data into biological models of diversity and evolution. In this perspective, we highlight emerging insights, which stress the importance of mountain building through time as a generator and reservoir of biodiversity. We also discuss recently proposed parallels between surface uplift, habitat formation and species diversification. We exemplify these links and discuss other factors, such as Quaternary climatic variations, which may have obscured some mountain‐building evidence due to erosion and other processes. Biological evolution is complex and the build‐up of mountains is certainly not the only explanation, but biological and geological processes are probably more intertwined than many of us realize. The overall conclusion is that geology sets the stage for speciation, where ecological interactions, adaptive and non‐adaptive radiations and stochastic processes act together to increase biodiversity. Further integration of these fields may yield novel and robust insights.
ABSTRACT We review geological evidence on the origin of the modern transcontinental Amazon River, and the paleogeographic history of riverine connections among the principal sedimentary basins of ...northern South America through the Neogene. Data are reviewed from new geochronological datasets using radiogenic and stable isotopes, and from traditional geochronological methods, including sedimentology, structural mapping, sonic and seismic logging, and biostratigraphy. The modern Amazon River and the continental-scale Amazon drainage basin were assembled during the late Miocene and Pliocene, via some of the largest purported river capture events in Earth history. Andean sediments are first recorded in the Amazon Fan at about 10.1-9.4 Ma, with a large increase in sedimentation at about 4.5 Ma. The transcontinental Amazon River therefore formed over a period of about 4.9-5.6 million years, by means of several river capture events. The origins of the modern Amazon River are hypothesized to be linked with that of mega-wetland landscapes of tropical South America (e.g. várzeas, pantanals, seasonally flooded savannahs). Mega-wetlands have persisted over about 10% northern South America under different configurations for >15 million years. Although the paleogeographic reconstructions presented are simplistic and coarse-grained, they are offered to inspire the collection and analysis of new sedimentological and geochronological datasets.
RESUMO Este trabalho é uma revisão das evidências geológicas sobre a origem do moderno rio Amazonas transcontinental, e a história paleogeográfica das conexões ribeirinhas entre as principais bacias sedimentares do norte da América do Sul durante o Neógeno. São revisados novos conjuntos de dados geocronológicos usando isótopos radiogênicos e estáveis, e de métodos geocronológicos tradicionais, incluindo sedimentologia, mapeamento estrutural, exploração sísmica e bioestratigrafia. O atual rio Amazonas e sua bacia continental se formaram durante o final do Mioceno e do Plioceno, através de alguns dos maiores eventos de captura de rio na história da Terra. Os sedimentos andinos são registrados pela primeira vez no leque fluvial do Amazonas por volta de 10,1-9,4 Ma, com um grande aumento na sedimentação a cerca de 4,5 Ma. O rio Amazonas transcontinental, portanto, se formou durante um período de cerca de 4,9 a 5,6 milhões de anos, por meio de vários eventos de captura de rios. Acredita-se que as origens do moderno rio Amazonas estejam ligadas às paisagens de inundação da América do Sul tropical (por exemplo, várzeas, pantanais, savanas sazonalmente inundadas). As áreas pantanosas persistiram em cerca de 10% do norte da América do Sul sob diferentes configurações por mais de 15 milhões de anos. Embora as reconstruções paleogeográficas apresentadas sejam simplistas, elas são oferecidas para inspirar a coleta e análise de novos conjuntos de dados sedimentológicos e geocronológicos.
Climate models suggest that Asian paleoenvironments, monsoons and continental aridification were primarily governed by tectonic uplift and sea retreat since the Eocene with potential contribution of ...global climate changes. However, the cause and timing of these paleoenvironmental changes remain poorly constrained. The recently well-dated continental mudflat to ephemeral saline lake sedimentary succession, situated in the Xining Basin at the northeastern margin of the Tibetan Plateau (NW China), provides a unique opportunity to develop additional proxy successions in this area that are placed accurately in time. Here, a palynological record from this succession is reported. High abundances of desert and steppe–desert taxa such as Ephedripites and Nitrariadites/Nitraripollis are found, which can be differentiated by the presence of broad leaved deciduous forest taxa in the lower part of the section (particularly up to 36.4Ma; magnetochron C16r), and a sudden increase of Pinaceae (Pinuspollenites, Piceaepollenites and Abiespollenites) which is dated at 36.1Ma (C16n.2n). Coexistence Approach (CoA) indicates that from 39.9 to 36.4Ma (C17n.1n) regional climate was warm and wet, while from 36.4 to 33.5Ma (C16n.2n–C13r) climate tends to be cooler and drier. The data indicate that paleoenvironmental and palynological changes on the NE part of the Tibetan Plateau resulted from a combination of long-term tectonic uplift forcing and long- and short-term climate changes. The increase of taxa such as Piceaepollenites and Abiespollenites indicates not only a cooling and drying trend prior to the Eocene/Oligocene (E/O) boundary, but also the existence of high altitude mountain habitats in the periphery of the Xining Basin. The sudden Pinaceae event correlates closely in time with a marked aridification step as viewed from the lithology of the Xining Basin that was linked to the sea retreat out of the Tarim Basin.
► New pollen record from an Eocene/Oligocene continental succession (NE Tibet, China). ► Broad leaved forest and steppe–desert taxa on mountain slopes until c. 36Ma. ► Cold tolerant conifer taxa arise in mountain forest from c. 36Ma onwards. ► Pollen suggest a high topography in NE Tibet prior to the E/O boundary. ► Stepwise aridification noted in Xining Basin relates to sea retreat in Tarim Basin.
The Shillong Plateau is a unique basement‐cored uplift in the foreland of the eastern Himalaya that accommodates part of the India‐Eurasia convergence since the late Miocene. It was uplifted in the ...late Pliocene to 1600 m, potentially inducing regional climatic perturbations by orographically condensing part of the Indian Summer Monsoon (ISM) precipitations along its southern flank. As such, the eastern Himalaya‐Shillong Plateau‐ISM is suited to investigate effects of tectonics, climate, and erosion in a mountain range‐broken foreland system. This study focuses on a 2200 m thick sedimentary section of the Siwalik Group strategically located in the lee of the Shillong Plateau along the Dungsam Chu at the front of the eastern Bhutan Himalaya. We have performed magnetostratigraphy constrained by vitrinite reflectance and detrital apatite fission track dating, combined with sedimentological and palynological analyses. We show that (1) the section was deposited between ~7 and 1 Ma in a marginal marine deltaic transitioning into continental environment after 5 Ma, (2) depositional environments and paleoclimate were humid with no major change during the depositional period indicating that the orographic effect of the Shillong Plateau had an unexpected limited impact on the paleoclimate of the Bhutanese foothills, and (3) the diminution of the flexural subsidence in the basin and/or of the detrital input from the range is attributable to a slowdown of the displacement rates along the Main Boundary Thrust in eastern Bhutan during the latest Miocene‐Pleistocene, in response to increasing partitioning of the India‐Eurasia convergence into the active faults bounding the Shillong Plateau.
Key Points
The Himalayan foreland basin sediments of the Siwalik Group exposed at Dungsam Chu (eastern Bhutan) were deposited between 7 and 1 Ma
The orographic effect of the Shillong Plateau had a limited impact on the wet paleoclimate of the Bhutanese foothills in the Pliocene
Plio‐Pleistocene slowdown of deformation on the MBT results from partitioning of the India‐Eurasia convergence into the Shillong Plateau
The unparalleled biodiversity found in the American tropics (the Neotropics) has attracted the attention of naturalists for centuries. Despite major advances in recent years in our understanding of ...the origin and diversification of many Neotropical taxa and biotic regions, many questions remain to be answered. Additional biological and geological data are still needed, as well as methodological advances that are capable of bridging these research fields. In this review, aimed primarily at advanced students and early-career scientists, we introduce the concept of "trans-disciplinary biogeography," which refers to the integration of data from multiple areas of research in biology (e.g., community ecology, phylogeography, systematics, historical biogeography) and Earth and the physical sciences (e.g., geology, climatology, palaeontology), as a means to reconstruct the giant puzzle of Neotropical biodiversity and evolution in space and time. We caution against extrapolating results derived from the study of one or a few taxa to convey general scenarios of Neotropical evolution and landscape formation. We urge more coordination and integration of data and ideas among disciplines, transcending their traditional boundaries, as a basis for advancing tomorrow's ground-breaking research. Our review highlights the great opportunities for studying the Neotropical biota to understand the evolution of life.
The Amazon drainage basin is extremely biodiverse, yet the origins of this diversification remain much debated. One of the possible drivers of plant diversity are the marine incursions that reached ...Amazonia during the Miocene and connected western Amazonia with the Caribbean. In the Miocene, large parts of western Amazonia were covered by extensive wetlands that, during high eustatic episodes, were episodically colonised by coastal taxa such as mangroves. In this paper, we hypothesise that some of these mangrove community taxa could adapt to freshwater conditions enriching the modern plant composition of the Amazon drainage basin. To assess the past plant composition in the basin, we statistically analyse the palynological composition of two Miocene sections from western Amazonia that were especially rich in presumed mangrove pollen (
Zonocostites ramonae
). We identify the pollen taxa that coexisted with this community using clustering methods supported by Kendall’s W coefficient concordance analysis. Our results suggest that at least fourteen taxa are closely associated with
Zonocostites ramonae
(
Cricotriporites guianensis
,
Deltoidospora adriennis
,
Psilabrevitricolporites devriesii
,
Psiladiporites redundantis
,
Psilamonocolpites amazonicus
,
P. rinconii
,
Psilatricolporites crassoexinatus
,
P. labiatus
,
P. operculatus
,
Psilatriporites corstanjei
,
Retitricolporites kaarsii
,
Rhoipites guianensis
,
Rhoipites hispidus
, and
Tetracolporopollenites transversalis
). We also illustrate the pollen of this fossil mangrove, and some of its associated fossil taxa, using light microscopy (LM) and scanning electron microscopy (SEM), and we compare them with potential nearest living relatives (NLR). We found that pollen of the modern mangrove
Rhizophora mangle
is the NLR of
Zonocostites ramonae.
Of the three associated taxa, the best analogy is between
Psilabrevitricolporites devriesii
and
Humiria balsamifera
, the latter a taxon best known from the coastal
restinga
vegetation in Brazil and Surinam. Tentatively, we assign
Forsteronia
spp. as NLR for
Cricotriporites guianensis,
and we propose
Euterpe
sp. for
Psilamonocolpites rinconii
(but also
Oenocarpus
,
Hyospathe
,
Prestoea
, and
Sabinaria
are affine). Based on this study we propose that, at least for some fossil taxa of the Miocene mangrove environment, there are still NLR or relict species that occur in inland Amazonia and along the South American coastline. We thus conclude that the Amazonian flora, like riverine fauna such as the pink river dolphin (
Inia
) and selected fish taxa, carry an imprint of the Miocene coastal communities.
ABSTRACT Amazonia (defined herein as the Amazon basin) is home to the greatest concentration of biodiversity on Earth, providing unique genetic resources and ecological functions that contribute to ...ecosystem services globally. The lengthy and complex evolutionary history of this region has produced heterogeneous landscapes and riverscapes at multiple scales, altered the geographic and genetic connections among populations, and impacted rates of adaptation, speciation, and extinction. In turn, ecologically diverse Amazonian biotas promoted further diversification, species coexistence, and coevolution, with biodiversity accumulating over tens of millions of years. Important events in Amazonian history included: (i) late Cretaceous and early Paleogene origin of major rainforest plant and animal groups; (ii) Eocene-Oligocene global cooling with rainforests contracting to tropical latitudes separating Atlantic coastal and Amazonian rainforests; (iii) Miocene uplift of central and northern Andes that separated Pacific coastal and Amazonian rainforests, spurred formation of mega-wetlands in the western Amazon, and contributed to the origin of the modern transcontinental Amazon River; (iv) late Neogene formation of the Panamanian Isthmus that facilitated the Great American Biotic Interchange; (v) Pleistocene climate oscillations followed by late Pleistocene-Holocene human colonization and megafaunal extinctions; and (vi) modern era of widespread anthropogenic deforestation, defaunation, and ecological transformations of regional landscapes and global climates. Amazonian conservation requires decade-scale investments into biodiversity documentation and monitoring to leverage existing scientific capacity, and strategic habitat planning to allow continuity of evolutionary and ecological processes now and into the future.
RESUMEN La Amazonía (definida como la cuenca amazónica) concentra la mayor biodiversidad de la Tierra, proporcionando recursos genéticos y funciones ecológicas únicas que contribuyen a los servicios ecosistémicos a nivel mundial. La compleja historia evolutiva de esta región produjo paisajes heterogéneos a múltiples escalas geográficas, alteró las conexiones geográficas y genéticas entre las poblaciones e influyó en las tasas de adaptación, especiación y extinción. Las biotas amazónicas, ecológicamente diversas, promovieron una mayor diversificación, coexistencia de especies y coevolución, acumulando biodiversidad a lo largo de decenas de millones de años. Acontecimientos importantes en la historia de la Amazonía incluyeron: (i) orígenes durante el Cretácico tardío y el Paleógeno temprano de los principales grupos de plantas y animales; (ii) enfriamiento global del Eoceno-Oligoceno, contrayendo los bosques a latitudes tropicales y separando los de la costa Atlántica de los amazónicos; (iii) levantamiento de los Andes centrales y del norte en el Mioceno, separando las selvas tropicales de la costa del Pacífico y de la Amazonía, estimulando la formación de megahumedales en la Amazonía occidental y contribuyendo al origen del moderno Río Amazonas transcontinental; (iv) formación del istmo de Panamá durante el Neógeno tardío, facilitando el Gran Intercambio Biótico Americano; (v) oscilaciones climáticas del Pleistoceno seguidas por la colonización humana y las extinciones de megafauna; (vi) era moderna de deforestación antropogénica generalizada, defaunación y transformaciones ecológicas de paisajes regionales y climas globales. La conservación de la Amazonía requiere inversiones por décadas en la documentación y el seguimiento de la biodiversidad para impulsar la capacidad científica existente, así como la planificación estratégica del hábitat para permitir la continuidad de los actuales y futuros procesos evolutivos y ecológicos.
Recent studies suggest increasing sensitivity to orbital variations across the Eocene-Oligocene greenhouse to icehouse climate transition. However, climate simulations and paleoenvironmental studies ...mostly provide snapshots of the past climate, therefore overlooking the role of this short-term variability in driving major environmental changes and possibly biasing model-data comparisons. We address this problem by performing numerical simulations describing the end-members of eccentricity, obliquity, and precession. The orbitally induced biome variability obtained in our simulations allows to reconcile previous apparent mismatch between models and paleobotanical compilations. We show that precession-driven intermittent monsoon-like climate may have taken place during the Eocene, resulting in biomes shifting from shrubland to tropical forest in the intertropical convergence zone migration region. Our Oligocene simulations suggest that, along with decreased
CO
, orbital variations crucially modulated major faunal dispersal events around the EOT such as the Grande Coupure by creating and fragmenting the biome corridors along several key land bridges.
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