scholarly journals Phylogeography of an Amazonian Cichlid supports strong structuration by water current and past evolution by vicariance associated to the Amazon's formation.

2021 ◽  
Author(s):  
Nicolas Leroux ◽  
François-Étienne Sylvain ◽  
Eric Normandeau ◽  
Aleicia Holland ◽  
Adalberto Luis Val ◽  
...  
Keyword(s):  
Fish Species ◽  
Salt Water ◽  
Site Effect ◽  
Ecological Speciation ◽  
Water Current ◽  
Water Types ◽  
Black And White ◽  
Evolutionary Forces ◽  
Strong Structuration ◽  
White Water

Amazonia is characterized by very heterogeneous riverscapes dominated by two drastically divergent water types: black (ion-poor, dissolved organic carbonate rich and acidic) and white (nutrient rich and turbid) waters. Recent phylogeographic and genomic studies have associated the ecotone formed by these environments to ecologically driven speciation in fish species. With the objective of better understanding the evolutionary forces behind the Amazonian Teleostean diversification, we sampled 240 Mesonauta festivus from 12 sites on a wide area of the Amazonian basin. These sites included three confluences of black and white water environments to seek for repeated evidences of ecological speciation at these ecotones. Our genetic dataset of 41,268 SNPs is contrasting with previous results and supports a low structuring power of water types. Conversely, we detected a strong pattern of isolation by unidirectional downstream water current and evidence of past events of vicariance potentially linked to the Amazon River formation and salt-water incursions that occurred 2.5 Mya. Using a combination of population genetic, phylogeographic analysis and environmental association models, we decomposed the spatial variance from the environmental genetic variance specifically to assess which evolutive forces have shaped inter-population differences in M. festivus’ genome. Our sampling design comprising four major Amazonian rivers and three confluences of black and white water rivers supports the possibility that past studies potentially confounded ecological speciation with a site effect unrepresentative of the full Amazonian watershed. While ecological speciation admittedly played a role in Amazonian fish species diversification, we argue that neutral evolutionary processes explain most of the divergence between M. festivus populations.

scholarly journals Patterns, Mechanisms and Genetics of Speciation in Reptiles and Amphibians

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 646 ◽  
Author(s):  
Wollenberg Valero ◽  
Marshall ◽  
Bastiaans ◽  
Caccone ◽  
Camargo ◽  
...  
Keyword(s):  
Ecological Speciation ◽  
Integrative Taxonomy ◽  
Future Research ◽  
Phenotypic Traits ◽  
South American ◽  
Evolutionary Forces ◽  
Speciation Rates ◽  
Genetic Mechanisms ◽  
Genetics Of Speciation ◽  
Patterns And Processes

In this contribution, the aspects of reptile and amphibian speciation that emerged from research performed over the past decade are reviewed. First, this study assesses how patterns and processes of speciation depend on knowing the taxonomy of the group in question, and discuss how integrative taxonomy has contributed to speciation research in these groups. This study then reviews the research on different aspects of speciation in reptiles and amphibians, including biogeography and climatic niches, ecological speciation, the relationship between speciation rates and phenotypic traits, and genetics and genomics. Further, several case studies of speciation in reptiles and amphibians that exemplify many of these themes are discussed. These include studies of integrative taxonomy and biogeography in South American lizards, ecological speciation in European salamanders, speciation and phenotypic evolution in frogs and lizards. The final case study combines genomics and biogeography in tortoises. The field of amphibian and reptile speciation research has steadily moved forward from the assessment of geographic and ecological aspects, to incorporating other dimensions of speciation, such as genetic mechanisms and evolutionary forces. A higher degree of integration among all these dimensions emerges as a goal for future research.

scholarly journals The density and biomass of mesozooplankton and ichthyoplankton in the Negro and the Amazon Rivers during the rainy season: the ecological importance of the confluence boundary

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3308 ◽  
Author(s):  
Ryota Nakajima ◽  
Elvis V. Rimachi ◽  
Edinaldo N. Santos-Silva ◽  
Laura S.F. Calixto ◽  
Rosseval G. Leite ◽  
...  
Keyword(s):  
Rainy Season ◽  
Fish Larvae ◽  
Amazon River ◽  
Black And White ◽  
Black Water ◽  
Negro River ◽  
Feeding Habitat ◽  
White Water ◽  
Ecological Importance ◽  
Density And Biomass

The boundary zone between two different hydrological regimes is often a biologically enriched environment with distinct planktonic communities. In the center of the Amazon River basin, muddy white water of the Amazon River meets with black water of the Negro River, creating a conspicuous visible boundary spanning over 10 km along the Amazon River. Here, we tested the hypothesis that the confluence boundary between the white and black water rivers concentrates prey and is used as a feeding habitat for consumers by investigating the density, biomass and distribution of mesozooplankton and ichthyoplankton communities across the two rivers during the rainy season. Our results show that mean mesozooplankton density (2,730 inds. m−3) and biomass (4.8 mg m−3) were higher in the black-water river compared to the white-water river (959 inds. m−3; 2.4 mg m−3); however an exceptionally high mesozooplankton density was not observed in the confluence boundary. Nonetheless we found the highest density of ichthyoplankton in the confluence boundary (9.7 inds. m−3), being up to 9-fold higher than in adjacent rivers. The confluence between white and black waters is sandwiched by both environments with low (white water) and high (black water) zooplankton concentrations and by both environments with low (white water) and high (black water) predation pressures for fish larvae, and may function as a boundary layer that offers benefits of both high prey concentrations and low predation risk. This forms a plausible explanation for the high density of ichthyoplankton in the confluence zone of black and white water rivers.

Influence of temperature, water current, illumination, and time on activity and substrate selection in juvenile smallmouth bass (Micropterus dolomieui)

1981 ◽  
Vol 59 (12) ◽  
pp. 2322-2330 ◽  
Author(s):  
Hugh R. MacCrimmon ◽  
William H. Robbins
Keyword(s):  
Water Temperature ◽  
Smallmouth Bass ◽  
Water Current ◽  
Activity Levels ◽  
Substrate Selection ◽  
Black And White ◽  
Micropterus Dolomieui ◽  
Highly Correlated ◽  
Fish Activity ◽  
Selection Of

Behaviour of wild juvenile smallmouth bass, Micropterus dolomieui, in the laboratory was significantly influenced by water temperature, current, and illumination. Activity increased with increasing water temperature and (or) water current. When exposed to black and white substrate, selection of black was inversely dependent on temperature and current, and highly correlated with fish activity (r = 0.995, P < 0.001, inverse cubic relation). Substrate pattern influenced fish activity, aggregation, and social interaction. Activity levels increased with increasing incident illumination whereas selection of black substrate declined, particularly at higher water temperatures. Older juveniles became less active with age and preferred black substrate when available, thereby indicating a developing behavioural pattern which favours survival and energy conservation under natural nursery conditions by the discrete use of available cover.

scholarly journals The abundance and biomass of mesozooplankton and ichthyoplankton in the confluence boundary of the Negro and the Amazon Rivers

2017 ◽  
Author(s):  
Ryota Nakajima ◽  
Elvis V Rimachi ◽  
Edinaldo N Santos-Silva ◽  
Adi Khen ◽  
Tetsuo Yamane ◽  
...  
Keyword(s):  
Juvenile Fish ◽  
Boundary Spanning ◽  
Amazon River ◽  
Black And White ◽  
Black Water ◽  
Negro River ◽  
Feeding Habitat ◽  
White Water ◽  
Black Water River ◽  
Planktonic Communities

The boundary zone between two different hydrological regimes is often a biologically enriched environment with distinct planktonic communities. In the center of the Amazon River basin, muddy white water of the Amazon River meets with black water of the Negro River, creating a conspicuous visible boundary spanning over 10 km along the Amazon River. Here, we tested the hypothesis that the confluence boundary between the white and black water rivers concentrates prey and is used as a feeding habitat for juvenile fish by investigating the abundance, biomass and distribution of mesozooplankton and ichthyoplankton communities across the two rivers. Our results show that mesozooplankton abundance and biomass were higher in the black-water river compared to the white-water river; however an exceptionally high mesozooplankton abundance was not observed in the confluence boundary. Nonetheless we found the highest abundance of ichthyoplankton in the confluence boundary, being up to 9-fold higher than in adjacent rivers. The confluence boundary between black and white water rivers may function as a boundary layer that offers benefits of both high zooplankton prey concentrations (black-water) and low predation risk (white-water). This forms a plausible explanation for the high abundance of ichthyoplankton in the confluence zone of black and white water rivers.

scholarly journals The abundance and biomass of mesozooplankton and ichthyoplankton in the confluence boundary of the Negro and the Amazon Rivers

2017 ◽  
Author(s):  
Ryota Nakajima ◽  
Elvis V Rimachi ◽  
Edinaldo N Santos-Silva ◽  
Adi Khen ◽  
Tetsuo Yamane ◽  
...  
Keyword(s):  
Juvenile Fish ◽  
Boundary Spanning ◽  
Amazon River ◽  
Black And White ◽  
Black Water ◽  
Negro River ◽  
Feeding Habitat ◽  
White Water ◽  
Black Water River ◽  
Planktonic Communities

The boundary zone between two different hydrological regimes is often a biologically enriched environment with distinct planktonic communities. In the center of the Amazon River basin, muddy white water of the Amazon River meets with black water of the Negro River, creating a conspicuous visible boundary spanning over 10 km along the Amazon River. Here, we tested the hypothesis that the confluence boundary between the white and black water rivers concentrates prey and is used as a feeding habitat for juvenile fish by investigating the abundance, biomass and distribution of mesozooplankton and ichthyoplankton communities across the two rivers. Our results show that mesozooplankton abundance and biomass were higher in the black-water river compared to the white-water river; however an exceptionally high mesozooplankton abundance was not observed in the confluence boundary. Nonetheless we found the highest abundance of ichthyoplankton in the confluence boundary, being up to 9-fold higher than in adjacent rivers. The confluence boundary between black and white water rivers may function as a boundary layer that offers benefits of both high zooplankton prey concentrations (black-water) and low predation risk (white-water). This forms a plausible explanation for the high abundance of ichthyoplankton in the confluence zone of black and white water rivers.

Swimming energetics of an Amazonian characin in 'black' and 'white' water

1978 ◽  
Vol 56 (4) ◽  
pp. 983-987 ◽  
Author(s):  
George F. Holeton ◽  
E. Don Stevens
Keyword(s):  
Oxygen Permeability ◽  
No Reduction ◽  
Standard Metabolic Rate ◽  
Critical Swimming Speed ◽  
Ionic Permeability ◽  
Black And White ◽  
Rio Negro ◽  
The World ◽  
White Water ◽  
Metabolic Performance

Measurements were made of the swimming and metabolic performance of the Amazonian characin Triportheus angulatus in waters from the Rio Negro and the Rio Solimoẽs. When allowances for temperature and size of fish were made there was very little difference among groups of fish tested in either type of water. The most impressive performance was by a group of fish tested in Rio Negro water at 29 °C. These fish, averaging 15.9 g, had a standard metabolic rate of 231 mg∙kg−1∙h−1, an active metabolism of 631 mg∙kg−1∙h−1, and a critical swimming speed of 4.9 body lengths∙s−1 or 52 cm∙s−1.Although these fish live in waters which are often exceedingly dilute and acidic, there appears to be no reduction in their swimming or metabolic performance compared with fish from other parts of the world. This shows that the gills of T. angulatus do not have greatly reduced oxygen permeability, a situation which might be expected to accompany an adaptive reduction in branchial osmotic and ionic permeability.

scholarly journals Varying Intensities of Introgression Obscure Incipient Venom-Associated Speciation in the Timber Rattlesnake (Crotalus horridus)

Toxins ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 782
Author(s):  
Mark J. Margres ◽  
Kenneth P. Wray ◽  
Dragana Sanader ◽  
Preston J. McDonald ◽  
Lauren M. Trumbull ◽  
...  
Keyword(s):  
Reproductive Isolation ◽  
Genetic Basis ◽  
Spatial Scales ◽  
Demographic History ◽  
Type A ◽  
Ecological Speciation ◽  
Type B ◽  
Crotalus Horridus ◽  
Timber Rattlesnake ◽  
Evolutionary Forces

Ecologically divergent selection can lead to the evolution of reproductive isolation through the process of ecological speciation, but the balance of responsible evolutionary forces is often obscured by an inadequate assessment of demographic history and the genetics of traits under selection. Snake venoms have emerged as a system for studying the genetic basis of adaptation because of their genetic tractability and contributions to fitness, and speciation in venomous snakes can be associated with ecological diversification such as dietary shifts and corresponding venom changes. Here, we explored the neurotoxic (type A)–hemotoxic (type B) venom dichotomy and the potential for ecological speciation among Timber Rattlesnake (Crotalus horridus) populations. Previous work identified the genetic basis of this phenotypic difference, enabling us to characterize the roles geography, history, ecology, selection, and chance play in determining when and why new species emerge or are absorbed. We identified significant genetic, proteomic, morphological, and ecological/environmental differences at smaller spatial scales, suggestive of incipient ecological speciation between type A and type B C. horridus. Range-wide analyses, however, rejected the reciprocal monophyly of venom type, indicative of varying intensities of introgression and a lack of reproductive isolation across the range. Given that we have now established the phenotypic distributions and ecological niche models of type A and B populations, genome-wide data are needed and capable of determining whether type A and type B C. horridus represent distinct, reproductively isolated lineages due to incipient ecological speciation or differentiated populations within a single species.

Black and white waters and their possible relationship to the podzolization process

Soil Research ◽  
1983 ◽  
Vol 21 (1) ◽  
pp. 59 ◽  
Author(s):  
R Reeve ◽  
IF Fergus
Keyword(s):  
Storage System ◽  
Residual Liquid ◽  
Chemical Analyses ◽  
Black And White ◽  
Black Water ◽  
Field Evidence ◽  
Close Proximity ◽  
Leaching Experiment ◽  
Water Field ◽  
White Water

Highly coloured, organic-stained water (black water) occurs as springs, seeps and perched lakes in the Cooloola area of south-eastern Queensland (latitude 26� S.). Springs of clear, colourless water (white water) sometimes occur in close proximity to the black water. Field evidence suggests that black waters move laterally along semipermeable B horizons of humus podzols, whereas white waters are part of a much larger storage system in which the water has been decolorized by contact with the C horizons. Thus it appears that black waters are the active eluviating agent and white waters are the residual liquid phase of the podzolization process. Chemical analyses of black and white waters, and the results of a laboratory leaching experiment, support this view. Possible mechanisms and some implications for the genesis of podzol B horizons are discussed.

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