scholarly journals Hypotheses to explain the origin of species in Amazonia

2008 ◽  
Vol 68 (4 suppl) ◽  
pp. 917-947 ◽  
Author(s):  
J. Haffer
Keyword(s):  
Species Interactions ◽  
Environmental Gradients ◽  
Milankovitch Cycles ◽  
Barrier Effect ◽  
Climatic Fluctuations ◽  
Canopy Density ◽  
Sea Level Fluctuations ◽  
Animal Populations ◽  
Barrier Formation ◽  
Parapatric Speciation

The main hypotheses proposed to explain barrier formation separating populations and causing the differentiation of species in Amazonia during the course of geological history are based on different factors, as follow: (1) Changes in the distribution of land and sea or in the landscape due to tectonic movements or sea level fluctuations (Paleogeography hypothesis), (2) the barrier effect of Amazonian rivers (River hypothesis), (3) a combination of the barrier effect of broad rivers and vegetational changes in northern and southern Amazonia (River-refuge hypothesis), (4) the isolation of humid rainforest blocks near areas of surface relief in the periphery of Amazonia separated by dry forests, savannas and other intermediate vegetation types during dry climatic periods of the Tertiary and Quaternary (Refuge hypothesis), (5) changes in canopy-density due to climatic reversals (Canopy-density hypothesis) (6) the isolation and speciation of animal populations in small montane habitat pockets around Amazonia due to climatic fluctuations without major vegetational changes (Museum hypothesis), (7) competitive species interactions and local species isolations in peripheral regions of Amazonia due to invasion and counterinvasion during cold/warm periods of the Pleistocene (Disturbance-vicariance hypothesis) and (8) parapatric speciation across steep environmental gradients without separation of the respective populations (Gradient hypothesis). Several of these hypotheses probably are relevant to a different degree for the speciation processes in different faunal groups or during different geological periods. The basic paleogeography model refers mainly to faunal differentiation during the Tertiary and in combination with the Refuge hypothesis. Milankovitch‡ cycles leading to global main hypotheses proposed to explain barrier formation separating populations and causing the differentiation of species in Amazonia during the course of geological history are based on different factors, as follow: (1) Changes in the distribution of land and sea or in the landscape due to tectonic movements or sea level fluctuations (Paleogeography hypothesis), (2) the barrier effect of Amazonian rivers (River hypothesis), (3) a combination of the barrier effect of broad rivers and vegetational changes in northern and southern Amazonia (River-refuge hypothesis), (4) the isolation of humid rainforest blocks near areas of surface relief in the periphery of Amazonia separated by dry forests, savannas and other intermediate vegetation types during dry climatic periods of the Tertiary and Quaternary (Refuge hypothesis), (5) changes in canopy-density due to climatic reversals (Canopy-density hypothesis) (6) the isolation and speciation of animal populations in small montane habitat pockets around Amazonia due to climatic fluctuations without major vegetational changes (Museum hypothesis), (7) competitive species interactions and local species isolations in peripheral regions of Amazonia due to invasion and counterinvasion during cold/warm periods of the Pleistocene (Disturbance-vicariance hypothesis) and (8) parapatric speciation across steep environmental gradients without separation of the respective populations (Gradient hypothesis). Several of these hypotheses probably are relevant to a different degree for the speciation processes in different faunal groups or during different geological periods. The basic paleogeography model refers mainly to faunal differentiation during the Tertiary and in combination with the Refuge hypothesis. Milankovitch cycles leading to global climatic-vegetational changes affected the biomes of the world not only during the Pleistocene but also during the Tertiary and earlier geological periods. New geoscientific evidence for the effect of dry climatic periods in Amazonia supports the predictions of the Refuge hypothesis. The disturbance-vicariance hypothesis refers to the presumed effect of cold/warm climatic phases of the Pleistocene only and is of limited general relevance because most extant species originated earlier and probably through paleogeographic changes and the formation of ecological refuges during the Tertiary.

scholarly journals Evolutionary Responses to Conditionality in Species Interactions across Environmental Gradients

2018 ◽  
Vol 192 (6) ◽  
pp. 715-730 ◽  
Author(s):  
Anna M. O’Brien ◽  
Ruairidh J. H. Sawers ◽  
Jeffrey Ross-Ibarra ◽  
Sharon Y. Strauss
Keyword(s):  
Species Interactions ◽  
Environmental Gradients

scholarly journals The emergent interactions that govern biodiversity change

2020 ◽  
Vol 117 (29) ◽  
pp. 17074-17083 ◽  
Author(s):  
James S. Clark ◽  
C. Lane Scher ◽  
Margaret Swift
Keyword(s):  
Species Interactions ◽  
Environmental Gradients ◽  
Local Population ◽  
Species Abundance ◽  
Community Change ◽  
Model Specification ◽  
Data Simulation ◽  
Breeding Bird ◽  
Probabilistic Uncertainty ◽  
Nonlinear Responses

Observational studies have not yet shown that environmental variables can explain pervasive nonlinear patterns of species abundance, because those patterns could result from (indirect) interactions with other species (e.g., competition), and models only estimate direct responses. The experiments that could extract these indirect effects at regional to continental scales are not feasible. Here, a biophysical approach quantifies environment– species interactions (ESI) that govern community change from field data. Just as species interactions depend on population abundances, so too do the effects of environment, as when drought is amplified by competition. By embedding dynamic ESI within framework that admits data gathered on different scales, we quantify responses that are induced indirectly through other species, including probabilistic uncertainty in parameters, model specification, and data. Simulation demonstrates that ESI are needed for accurate interpretation. Analysis demonstrates how nonlinear responses arise even when their direct responses to environment are linear. Applications to experimental lakes and the Breeding Bird Survey (BBS) yield contrasting estimates of ESI. In closed lakes, interactions involving phytoplankton and their zooplankton grazers play a large role. By contrast, ESI are weak in BBS, as expected where year-to-year movement degrades the link between local population growth and species interactions. In both cases, nonlinear responses to environmental gradients are induced by interactions between species. Stability analysis indicates stability in the closed-system lakes and instability in BBS. The probabilistic framework has direct application to conservation planning that must weigh risk assessments for entire habitats and communities against competing interests.

scholarly journals Evolutionary responses to conditionality in species interactions across environmental gradients

2015 ◽  
Author(s):  
Anna M. O’Brien ◽  
Ruairidh J.H. Sawers ◽  
Jeffrey Ross-Ibarra ◽  
Sharon Y. Strauss
Keyword(s):  
Statistical Models ◽  
Species Interactions ◽  
Environmental Gradients ◽  
Niche Partitioning ◽  
Character Displacement ◽  
Arms Race ◽  
Positive Interactions ◽  
Common Pattern ◽  
Interacting Species ◽  
Stressful Environments

AbstractThe outcomes of many species interactions are conditional on the environments in which they occur. A common pattern is that outcomes grade from being more positive under stressful conditions to more antagonistic or neutral under benign conditions. The evolutionary implications of conditionality in interactions have received much less attention than the documentation of conditionality itself, with a few notable exceptions. Here, we predict patterns of adaptation and co-adaptation between partners along abiotic gradients, positing that when interactions become more positive in stressful environments, fitness outcomes for mutations affecting interactions align across partners and selection should favor greater mutualistic adap-tation and co-adaptation between interacting species. As a corollary, in benign environments, if interactions are strongly antagonistic, we predict antagonistic co-adaptation resulting in Red Queen or arms-race dynamics, or reduction of antagonism through character displacement and niche partitioning. We predict no adaptation if interactions are more neutral. We call this the CoCoA hypothesis: (Co)-adaptation and Conditionality across Abiotic gradients. We describe experimental designs and statistical models that allow testing predictions of CoCoA, with a focus on positive interactions. While only one study has included all the elements to test CoCoA, we briefly review the literature and summarize study findings relevant to CoCoA and highlight opportunities to test CoCoA further.

scholarly journals Changes in Crimea’s climate over the recent decades

2020 ◽  
pp. 1-6
Author(s):  
Andrey Kharitonovich Degterev
Keyword(s):  
Global Warming ◽  
North Atlantic ◽  
Heat Waves ◽  
The Black Sea ◽  
Milankovitch Cycles ◽  
Modern Theory ◽  
Climatic Fluctuations ◽  
Temperature Changes ◽  
Average Temperature ◽  
The Republic

This article is dedicated to assessment of the climate changes of the Republic of Crimea over the last few decades. Throughout the analysis, the research utilized data on air temperature changes in the temperate latitudes of Europe by paleoclimatic data, as well as by changes in average temperature of surface waters in the Black Sea according coastal measurements. It is demonstrated that on the background of global warming there are natural manifestations of climatic fluctuations with periods of up to 20 years that relate to warm episodes such as El Niño and North-Atlantic fluctuation. The research methodology is based on the modern theory of global warming, which replaced the Milankovitch cycles concept used until the 1980’s. One of the main consequences of global warming for Russia lies in the significant increase in the frequency of reoccurrence of dangerous hydrometeorological phenomena. Examples of such phenomena include strong floods and heat waves. In a number of regions, the increase in temperature is also accompanied by spread of agents of dangerous diseases – ticks and marsh mosquitoes. However, the most notable damage caused by the climate change in Russia comes from drought.  

scholarly journals Costly mate preferences can promote reproductive isolation along ecological gradients

2020 ◽  
Author(s):  
Thomas G. Aubier ◽  
Mathieu Joron
Keyword(s):  
Reproductive Isolation ◽  
Environmental Gradients ◽  
Mate Preferences ◽  
Spatially Explicit ◽  
Ecological Gradients ◽  
Ecological Gradient ◽  
Rule Based ◽  
Viability Selection ◽  
Parapatric Speciation ◽  
Female Choosiness

AbstractSpecies often replace each-other spatially along ecological or environmental gradients. In models of parapatric speciation driven by assortative mating, delayed mating when females are too choosy about mates has so far been ignored. Yet, this generates a cost of choosiness, which should cause direct sexual selection against female choosiness. In our spatially-explicit individual-based model, disruptive viability selection leads to divergence of an ecological trait in a population distributed along an ecological gradient. Additionally, female choosiness (following a ‘matching mating rule’ based on the same ecological trait) can evolve at the risk of delaying mating, and can limit gene flow between diverging populations. We show that, along ecological gradients, a cost of choosiness associated with delayed mating modifies the genotypic frequencies on which viability selection acts. This cost can even remove much of the viability selection acting indirectly against choosiness at the ends of the gradient, thereby favouring the evolution of strong choosiness. A cost of choosiness can therefore promote reproductive isolation in parapatry, depending on the characteristics of the ecological gradient.

Facilitation and the Organization of Communities

Ecology ◽  
2012 ◽  
Author(s):  
Christopher J. Lortie
Keyword(s):  
Species Interactions ◽  
Environmental Gradients ◽  
Plant Competition ◽  
Historical Background ◽  
Positive Interactions ◽  
Plant Interactions ◽  
Reciprocal Effect ◽  
Early 21St Century ◽  
Analytical Approaches ◽  
Plant Plant

Species interactions are a cornerstone of ecological research wherein the effects of an individual of one species on another individual, frequently a different species, are studied. Within versus between species interactions are also commonly contrasted as a means to infer relative importance, but the majority of theory advances, at least at the community level, are associated with interactions between individuals of different species. Interactions can range from positive to negative, and effects are measured at all levels of development, or life history stages, of an organism. Positive interactions have been extensively studied in both population and community ecology. Facilitation, however, is a relatively specific term that has evolved primarily to describe positive plant–plant interactions (see Defining Facilitation). Facilitation, or positive interactions, is a relatively recent subset of these species interactions in general, including related processes, such as competition, mutualism, and parasitism. Facilitation is best viewed as the antithesis of the plant competition literature, as it shares many of the main attributes, both in terms of scope and approach, and arose as a comparator to this research. Facilitation studies mainly refer to positive plant–plant interactions, as the term was proposed in the plant literature and extensively used to describe interactions that include a positive effect of one species on another. Mutualism and parasitism research is often plant–insect based and formally identifies the reciprocal effect in the interaction, that is, (+, +) in mutualism and (+,−) in parasitism, whereas facilitation studies are generally (+,0) or (+,?), with the second effect often unreported. Interactions that include at least one negative interaction are usually described as competition in the plant literature and do not apply the term facilitation (although the frequency of both being discussed concomitantly is increasing). Hence, the term facilitation, owing to historical use, describes the subset of interactions that are (+,0) and is mostly specific to within plants, although its usage is expanding. The research on facilitation has most likely peaked, similar to plant competition studies, in that facilitation has been clearly established as an important process in the formation of plant communities. Additional studies simply demonstrating facilitation are increasing unlikely to be present in the literature. That said, the implications to theory and other, more nuanced aspects of interaction, such as context dependence, shifting balances, and importance of the environment, as they relate to facilitation, are still largely unexplored. In the early 21st century the most contentious debates, with respect to facilitation, center on either disagreement concerning what a community is and whether research should be conducted at this scale or on how to use environmental gradients (i.e., stress) most effectively. Both of these topics are described herein, with readings also included on Historical Background, Experimental and Analytical Approaches, Evolution, other taxa, and Applications.

Pelagic species diversity, biogeography, and evolution

Paleobiology ◽  
2000 ◽  
Vol 26 (S4) ◽  
pp. 236-258 ◽  
Author(s):  
Richard D. Norris
Keyword(s):  
Species Diversity ◽  
Environmental Gradients ◽  
Water Masses ◽  
Morphological Data ◽  
Airborne Spores ◽  
Long Distance ◽  
Population Exchange ◽  
High Dispersal ◽  
Population Sizes ◽  
Parapatric Speciation

Pelagic (open-ocean) species have enormous population sizes and broad, even global, distributions. These characteristics should damp rates of speciation in allopatric and vicariant evolutionary models since dispersal should swamp diverging populations and prevent divergence. Yet the fossil record suggests that rates of evolutionary turnover in pelagic organisms are often quite rapid, comparable to rates observed in much more highly fragmented terrestrial and shallow-marine environments. Furthermore, genetic and ecological studies increasingly suggest that species diversity is considerably higher in the pelagic realm than inferred from many morphological taxonomies.Zoogeographic evidence suggests that ranges of many pelagic groups are much more limited by their ability to maintain viable populations than by any inability to disperse past tectonic and hydrographic barriers to population exchange. Freely dispersing pelagic taxa resemble airborne spores or wind-dispersed seeds that can drift almost anywhere but complete the entire life cycle only in favorable habitats. It seems likely that vicariant and allopatric models for speciation are far less important in pelagic evolution than sympatric or parapatric speciation in which dispersal is not limiting. Nevertheless, speciation can be quite rapid and involve cladogenesis even in cases where morphological data suggest gradual species transitions. Indeed, recent paleoecological and molecular studies increasingly suggest that classic examples of “phyletic gradualism” involve multiple, cryptic speciation events.Paleoceanographic and climatic change seem to influence rates of turnover by modifying surface water masses and environmental gradients between them to create new habitats rather than by preventing dispersal. Changes in the vertical structure and seasonality of water masses may be particularly important since these can lead to changes in the depth and timing of reproduction. Long-distance dispersal may actually promote evolution by regularly carrying variants of a species across major oceanic fronts and exposing them to very different selection pressures than occur in their home range. High dispersal in pelagic taxa also implies that extinction should be difficult to achieve except though global perturbations that prevent populations from reestablishing themselves following local extinction. High rates of extinction in some pelagic groups suggests either that global perturbations are common, or that the species are much more narrowly adapted than we would infer from current taxonomies.

scholarly journals Impact of Pleistocene Eustatic Fluctuations on Evolutionary Dynamics in Southeast Asian Biodiversity Hotspots

2021 ◽  
Author(s):  
Arni Sholihah ◽  
Erwan Delrieu-Trottin ◽  
Fabien L Condamine ◽  
Daisy Wowor ◽  
Lukas Rüber ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Sea Level ◽  
Evolutionary Dynamics ◽  
Biodiversity Hotspots ◽  
Freshwater Biodiversity ◽  
Climatic Fluctuations ◽  
Ample Evidence ◽  
Sea Level Fluctuations ◽  
The Impact ◽  
Eustatic Fluctuations

Abstract Pleistocene Climatic Fluctuations (PCF) are frequently highlighted as important evolutionary engines that triggered cycles of biome expansion and contraction. While there is ample evidence of the impact of PCF on biodiversity of continental biomes, the consequences in insular systems depend on the geology of the islands and the ecology of the taxa inhabiting them. The idiosyncratic aspects of insular systems are exemplified by the islands of the Sunda Shelf in Southeast Asia (Sundaland), where PCF-induced eustatic fluctuations had complex interactions with the geology of the region, resulting in high species diversity and endemism. Emergent land in Southeast Asia varied drastically with sea level fluctuations during the Pleistocene. Climate-induced fluctuations in sea level caused temporary connections between insular and continental biodiversity hotspots in Southeast Asia. These exposed lands likely had freshwater drainage systems that extended between modern islands: the Paleoriver Hypothesis. Built upon the assumption that aquatic organisms are among the most suitable models to trace ancient river boundaries and fluctuations of landmass coverage, the present study aims to examine the evolutionary consequences of PCF on the dispersal of freshwater biodiversity in Southeast Asia. Time-calibrated phylogenies of DNA-delimited species were inferred for six species-rich freshwater fish genera in Southeast Asia (Clarias, Channa, Glyptothorax, Hemirhamphodon, Dermogenys, Nomorhamphus). The results highlight rampant cryptic diversity and the temporal localization of most speciation events during the Pleistocene, with 88% of speciation events occurring during this period. Diversification analyses indicate that sea level-dependent diversification models poorly account for species proliferation patterns for all clades excepting Channa. Ancestral area estimations point to Borneo as the most likely origin for most lineages, with two waves of dispersal to Sumatra and Java during the last 5 Myr. Speciation events are more frequently associated with boundaries of the paleoriver watersheds, with 60%, than islands boundaries, with 40%. In total, one-third of speciation events are inferred to have occured within paleorivers on a single island, suggesting that habitat heterogeneity and factors other than allopatry between islands substantially affected diversification of Sundaland fishes. Our results suggest that species proliferation in Sundaland is not wholly reliant on Pleistocene sea-level fluctuations isolating populations on different islands.

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