Amazonian paleoecological histories: one hill, three watersheds

Bush, Mark B.; De-Oliveira, P. Eduardo; Colinvaux, Paul A.; Miller, Michael C.; Moreno, Joëlle Anne

doi:10.1016/s0031-0182(04)00401-8

Cited by 134 publications

(106 citation statements)

References 83 publications

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“…On one hand, the mixture of contraction, stability, and expansion signals shown by both methods agrees with the hypothesis of a continuous and permanent forest cover since the last glacial maximum in the north-western Amazon Basin (Colinvaux et al (1996), Bush et al (2002 and Mayle et al (2004)), with different species reacting differently to climatic oscillations. On the other hand, the overall higher confidence in expansion signals, as well as the complete lack of support for contractions shown by the ML approach, agrees with refugial hypotheses (Haffer 1969;Prance 1982) and floristic transition assumptions (Colinvaux et al 2000;Bush et al 2004), possibly with fastgrowing, light-demanding and pioneer species having responded more intensely than shade-tolerant ones to climatic change. Thus, Guiana Shield forests appear to have had a more complicated history than temperate and boreal forests (Taberlet et al 1998;Hewitt 2000Hewitt , 2004Petit et al 2002;Hu et al 2009): a mixture of gradual compositional changes and expansion from refugia.…”

Section: Discussionsupporting

confidence: 60%

“…The dry-climate-with-refugia hypothesis has nevertheless been challenged (Bush & De Oliveira 2006). One alternative hypothesis, suggested by Amazonian pollen records (Colinvaux et al 1996), is that a 6°C cooling during the LGM may have caused a floristic transition, rather than rainforest fragmentation and replacement of rainforest by open, drier tropical forests (Colinvaux et al 2000;Bush et al 2004;Freycon et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Tropical rainforests that persisted: inferences from the Quaternary demographic history of eight tree species in the Guiana shield

et al. 2017

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How Quaternary climatic and geological disturbances influenced the composition of Neotropical forests is hotly debated. Rainfall and temperature changes during and/or immediately after the last glacial maximum (LGM) are thought to have strongly affected the geographical distribution and local abundance of tree species. The paucity of the fossil records in Neotropical forests prevents a direct reconstruction of such processes. To describe community-level historical trends in forest composition, we turned therefore to inferential methods based on the reconstruction of past demographic changes. In particular, we modelled the history of rainforests in the eastern Guiana Shield over a timescale of several thousand generations, through the application of approximate Bayesian computation and maximum-likelihood methods to diversity data at nuclear and chloroplast loci in eight species or subspecies of rainforest trees. Depending on the species and on the method applied, we detected population contraction, expansion or stability, with a general trend in favour of stability or expansion, with changes presumably having occurred during or after the LGM. These findings suggest that Guiana Shield rainforests have globally persisted, while expanding, through the Quaternary, but that different species have experienced different demographic events, with a trend towards the increase in frequency of light-demanding, disturbance-associated species.

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Section: Discussionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Tropical rainforests that persisted: inferences from the Quaternary demographic history of eight tree species in the Guiana shield

et al. 2017

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“…Adapted from Figure 5 in Jackson and Overpeck (2000 Cannariato et al 1999;Mix et al 1999). No-analog assemblages occur in terrestrial and marine settings and from high latitudes (Edwards et al 2005) to low (Bush et al 2004). The assemblages appear to represent truly anomalous communities and are not due to after-death mixing of fossils from temporally or spatially distinct communities (Jackson and .…”

Section: No-analog Communities Of the Past: A Late-glacial Case Studymentioning

confidence: 99%

Novel climates, no-analog communities, and ecological surprises

Williams

Jackson

2007

Frontiers in Ecology and the Environment

1,436

883

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w ww ww w. .f fr ro on nt ti ie er rs si in ne ec co ol lo og gy y. .o or rg g H ow do you study an ecosystem no ecologist has ever seen? This is a problem for both paleoecologists and global-change ecologists, who seek to understand ecological systems for time periods outside the realm of modern observations. One group looks to the past and the other to the future, but both use our understanding of extant ecosystems and processes as a common starting point for scientific inference. This is familiar to paleoecologists as the principle of uniformitarianism (ie "the present is the key to the past"), whereby understanding modern processes aids interpretation of fossil records. Similarly, global-change ecologists apply a forward-projected form of uniformitarianism, using models based on present-day ecological patterns and processes to forecast ecological responses to future change. Thus, both paleoecology and global-change ecology are inextricably rooted in the current, and research into long-term ecological dynamics, past or future, is heavily conditioned by our current observations and personal experience.The further our explorations carry us from the present, the murkier our vision becomes. This is not just because fossil archives become sparser as we look deeper into the past, nor because the chains of future contingency become increasingly long. Rather, the further we move from the present, the more it becomes an inadequate model for past and future system behavior. The current state of the Earth system, and its constituent ecosystems, is just one of many possible states, and both past and future system states may differ fundamentally from the present. The more that environments, past or future, differ from the present, the more our understanding of ecological patterns and processes will be incomplete and the less accurately will our models predict key ecological phenomena such as species distributions, community composition, species interactions, and biogeochemicalprocess rates.Here, we focus on "no-analog" plant communities (Panel 1), their relationship to climate, and the challenges they pose to predictive ecological models. We briefly summarize a niche-based, conceptual framework explaining how no-analog communities arise (Jackson and Overpeck 2000). We discuss past no-analog communities, using the well documented late-glacial communities as a detailed case study (Jackson and Williams 2004), and argue that these communities were shaped by environmental conditions also without modern counterpart (Williams et al. 2001). We then turn to the future, identifying regions of the world at risk of developing future novel climates (Williams et al. 2007). Finally, we discuss the implications for global-change ecology, including the risk of future novel ecosystems (Hobbs et al. 2006) and the challenges posed for ecological forecasting. I In n a a n nu ut ts sh he el ll l: :• Many past ecological communities were compositionally unlike modern communities • The formation and dissolution of these past "no-analog" communit...

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“…Equatorial environments of South America maintained a more stable climate throughout the LGM (Brown and Ab' Saber, 1979;Ledru et al, 1996;Bush et al, 2004). Moreover, lakes and wetlands remained available in the Amazon region at the time (Bush et al, 2004). As the great egret requires shallow water for foraging and vegetation for nest-building, favourable climate conditions at lower Brazilian latitudes during the LGM are likely to have allowed the establishment of populations.…”

Section: Genetic Diversity Demographic Expansion and Effective Populmentioning

confidence: 99%

Genetic structuring among populations of the great egret, Ardea alba egretta, in major Brazilian wetlands

Corrêa

Lama

Souza

2015

Aquatic Conservation

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ABSTRACT1. Waterbirds are increasingly affected by climate change and human disturbances to the wetlands on which they roost, forage and breed. The evolutionary response of populations to such changes is influenced by genetic variability and gene flow patterns, which enable long-term survival. Thus, genetic monitoring of waterbird populations can provide valuable information to support conservation measures and management policies for wetlands.2. This study assessed past and contemporary levels of genetic diversity, estimated effective population sizes (Ne) and investigated gene flow patterns among populations of the great egret, Ardea alba egretta, settled in major Brazilian wetlands.3. Samples (N = 200) were collected from the northern, central western, south-eastern and southern regions of Brazil. AMOVA, F-statistics, assignment tests, Bayesian clustering analyses and Ne were estimated based on mitochondrial DNA (mtDNA) and microsatellite loci.4. The populations share most mitochondrial haplotypes, suggesting a common recent past. Mismatch analyses, Fs and D statistics, and SSD and Rg indices indicated significant signs of expansion in most populations. The time since expansion suggests that egrets colonized southern latitudes more recently, probably accompanying the supposed historical environmental changes in South America, with more stable habitats toward equatorial regions.5. MtDNA Ф ST revealed significant differentiation between the northern and both the central western and southern populations. Nuclear loci demonstrated significant structuring between the central western and southern populations, which showed similar effective sizes.6. Despite the considerable dispersal potential of the great egret, there is limited gene flow among populations located in different Brazilian wetlands. Therefore, colonies from different regions should be preserved, with special attention to the northern populations, whose allelic constitution differs from the other. This approach can be used to genetically monitor similar species in other wetlands or to great egret populations in other regions of the Americas.

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Amazonian paleoecological histories: one hill, three watersheds

Cited by 134 publications

References 83 publications

Tropical rainforests that persisted: inferences from the Quaternary demographic history of eight tree species in the Guiana shield

Tropical rainforests that persisted: inferences from the Quaternary demographic history of eight tree species in the Guiana shield

Novel climates, no-analog communities, and ecological surprises

Genetic structuring among populations of the great egret, Ardea alba egretta, in major Brazilian wetlands

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