scholarly journals Metapopulation dynamics of the migratory fish Prochilodus lineatus (Characiformes: Prochilodontidae) in a lotic remnant of the Grande River, Southeastern Brazil

2021 ◽  
Vol 19 (4) ◽  
Author(s):  
Violeta R. Perini ◽  
Alessandro L. Paschoalini ◽  
Nilo Bazzoli ◽  
Elizete Rizzo ◽  
Daniel C. Carvalho
Keyword(s):  
Population Dynamics ◽  
Genetic Structure ◽  
Environmental Changes ◽  
River System ◽  
Southeastern Brazil ◽  
Metapopulation Dynamics ◽  
Migratory Fish ◽  
Prochilodus Lineatus ◽  
Allele Number ◽  
Significant Genetic Structure

ABSTRACT River impoundments for electricity generation lead to environmental changes which severely affect fish migration and species richness. However, little is known about their effect on the genetic structure and population dynamics downstream from the reservoir. Here, we analyzed a set of ten microsatellite loci of Prochilodus lineatus, an important South American migratory fish. Specimens (n = 150) were sampled from five sites in a remnant lotic system that includes sections of the Grande, Pardo and Mogi Guaçu rivers, southeastern Brazil. The data showed that all microsatellites were polymorphic with the allele number per locus ranging from 5 to 32, and genetic diversity (H e ) varied from 0.74 to 0.80. Indices of genetic differentiation and Bayesian analysis showed a significant genetic structure and three genetic clusters inhabiting this river system. An asymmetric gene flow suggests source-sink metapopulation dynamics from tributaries (genetic source) to the main river (genetic sink). A genetic cluster that was not detected in the upper Mogi and Pardo rivers tributaries may indicate there is a “trapped gene pool” downstream from the Porto Colômbia dam. Thus, here we provide new insights into the genetic structure and population dynamics of a migratory fish species in a highly dammed river basin.

Change of channel pattern and construction of fluvial terraces driven by SAMS since the LGM in southeastern South America: records from Tietê River, Brazil

2021 ◽  
Author(s):  
Caio Breda ◽  
Fabiano Nascimento Pupim
Keyword(s):  
Environmental Conditions ◽  
Environmental Changes ◽  
Late Quaternary ◽  
River System ◽  
Luminescence Dating ◽  
Southeastern Brazil ◽  
Stream Power ◽  
Climatic Fluctuations ◽  
Tropical Regions ◽  
Fluvial Terraces

<p>The last 30 ka is a period marked by well-documented abrupt environmental changes on Earth. Despite the growing efforts to investigate the effects of past environmental changes in the fluvial dynamics, there is a lack of studies in intraplate tropical regions. Here, we applied geomorphological, sedimentological, and optically stimulated luminescence dating (OSL) technics to investigate the effects of environmental factors on the evolution of the Upper and Middle Tietê River during the Late Quaternary. Tietê River is one of the most important rivers of the southeast of Brazil, flowing from steepest to low-relief intraplate terrains, and under tropical climate. In order to understand the responses of the Tietê River system to environmental changes during the Late Quaternary, two main questions were tentatively answered: (i) what are the most important allogeneic factors for the evolution of this system?; (ii) how did climatic fluctuations affect river dynamics over time? We recognized a sequence of seven terraces, from 2 to 105 m above the channel, in the Middle Tietê valley. These terraces are formed by thin deposits (< 10 m), composed of sandy and conglomeratic sediments. The high and intermediate terrace levels of the Middle Tietê River are strath, while the low terraces of the middle reach are cut-and-fill. The formation of seven terrace levels in the Middle Tietê River was controlled by the combination of low erosion resistance of the lithological substrate and high stream power and coarse bedload that increase the erosion efficiency of the channels. OSL dating of sedimentary deposits in different terrace levels indicate 5 periods of aggradation in the Middle Tietê valley since the Last Glacial Maximum: 18.5 ± 2.0 ka; 9.8 ± 1.0 to 8.6 ± 0.8 ka; 7.1 ± 0.7 to 5.8 ± 0.5 ka; 4.2 ± 0.4 to 3.1 ± 0.3 ka; and 0.6 ± 0.06 ka. The results indicate that the activity of the South American Monsoon System induced the occurrence of climatic fluctuations and changes in vegetation cover in the river valleys of southeastern Brazil over the past 20 ka. The aggradation periods are correlated with more arid environmental conditions and sparser vegetation, while the incision events in the valley developed under transitions to humid environmental conditions and stimulated by vegetation recovery.</p><p><strong>Key-words: </strong>Tietê River, fluvial evolution, fluvial terraces, Quaternary geochronology.</p>

An Assessment of Environmental Changes in Three Lakes from King's County (Nova Scotia, Canada) Using Diatom-Based Paleolimnological Techniques

2008 ◽  
Vol 43 (2-3) ◽  
pp. 85-98 ◽  
Author(s):  
Joshua R. Thienpont ◽  
Brian K. Ginn ◽  
Brian F. Cumming ◽  
John P. Smol
Keyword(s):  
Nova Scotia ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Lake Management ◽  
River System ◽  
210Pb Dating ◽  
Hydroelectric Power ◽  
Diatom Assemblages ◽  
Shoreline Development ◽  
Before And After

Abstract Paleolimnological approaches using sedimentary diatom assemblages were used to assess water quality changes over the last approximately 200 years in three lakes from King's County, Nova Scotia. In particular, the role of recent shoreline development in accelerating eutrophication in these systems was assessed. Sediment cores collected from each lake were analyzed for their diatom assemblages at approximately 5-year intervals, as determined by 210Pb dating. Analyses showed that each system has changed, but tracked different ecosystem changes. Tupper and George lakes recorded shifts, which are likely primarily related to climatic warming, with diatom assemblages changing from a preindustrial dominance by Aulacoseira spp. to present-day dominance by Cyclotella stelligera. In addition to the recent climatic-related changes, further diatom changes in the Tupper Lake core between approximately 1820 and 1970 were coincident with watershed disturbances (farming, forestry, and construction of hydroelectric power infrastructure). Black River Lake has recorded an increase in diatom-inferred total phosphorus since about 1950, likely due to impoundment of the Black River system for hydroelectric generation and subsequent changes in land runoff. Before-and-after (i.e., top-bottom) sediment analyses of six other lakes from King's County provided further evidence that the region is being influenced by climatic change (decreases in Aulacoseira spp., increases in planktonic diatom taxa), as well as showing other environmental stressors (e.g., acidification). However, we recorded no marked increase in diatom-inferred nutrient levels coincident with shoreline cottage development in any of the nine study lakes. Paleolimnological studies such as these allow lake managers to place the current limnological conditions into a long-term context, and thereby provide important background data for effective lake management.

New Zealand translocations: theory and practice

1995 ◽  
Vol 2 (1) ◽  
pp. 39 ◽  
Author(s):  
Doug P. Armstong ◽  
Ian G. McLean
Keyword(s):  
Population Dynamics ◽  
New Zealand ◽  
Experimental Tests ◽  
Theory And Practice ◽  
Habitat Requirements ◽  
Metapopulation Dynamics ◽  
Behavioural Adaptation ◽  
New Locations ◽  
History Of ◽  
Tests Of Hypotheses

One of the most common tools in New Zealand conservation is to translocate species to new locations. There have now been over 400 translocations done for conservation reasons, mainly involving terrestrial birds. Most translocations have been done strictly as management exercises, with little or no reference to theory. Nevertheless, translocations always involve some underlying theory, given that people must inevitably choose among a range of potential translocation strategies. We review theory relevant to translocations in the following areas: habitat requirements, susceptibility to predation, behavioural adaptation, population dynamics, genetics, metapopulation dynamics, and community ecology. For each area we review and evaluate the models that seem to underpin translocation strategies used in New Zealand. We report experiments testing some of these models, but note that theory underlying translocation strategies is largely untested despite a long history of translocations. We conclude by suggesting key areas for research, both theoretical and empirical. We particularly recommend that translocations be designed as experimental tests of hypotheses whenever possible.

Genetic variability and demographic history of Heliothis virescens (Lepidoptera: Noctuidae) populations from Brazil inferred by mtDNA sequences

2011 ◽  
Vol 102 (3) ◽  
pp. 333-343 ◽  
Author(s):  
K.C. Albernaz ◽  
K.L. Silva-Brandão ◽  
P. Fresia ◽  
F.L. Cônsoli ◽  
C. Omoto
Keyword(s):  
Genetic Structure ◽  
Genetic Variability ◽  
Heliothis Virescens ◽  
Demographic History ◽  
Haplotype Diversity ◽  
Low Frequency ◽  
Haplotype Network ◽  
Demographic Expansion ◽  
Significant Genetic Structure ◽  
History Of

AbstractIntra- and inter-population genetic variability and the demographic history of Heliothis virescens (F.) populations were evaluated by using mtDNA markers (coxI, coxII and nad6) with samples from the major cotton- and soybean-producing regions in Brazil in the growing seasons 2007/08, 2008/09 and 2009/10. AMOVA indicated low and non-significant genetic structure, regardless of geographical scale, growing season or crop, with most of genetic variation occurring within populations. Clustering analyzes also indicated low genetic differentiation. The haplotype network obtained with combined datasets resulted in 35 haplotypes, with 28 exclusive occurrences, four of them sampled only from soybean fields. The minimum spanning network showed star-shaped structures typical of populations that underwent a recent demographic expansion. The recent expansion was supported by other demographic analyzes, such as the Bayesian skyline plot, the unimodal distribution of paired differences among mitochondrial sequences, and negative and significant values of neutrality tests for the Tajima's D and Fu's FS parameters. In addition, high values of haplotype diversity (Ĥ) and low values of nucleotide diversity (π), combined with a high number of low frequency haplotypes and values of θπ<θW, suggested a recent demographic expansion of H. virescens populations in Brazil. This demographic event could be responsible for the low genetic structure currently found; however, haplotypes present uniquely at the same geographic regions and from one specific host plant suggest an initial differentiation among H. virescens populations within Brazil.

scholarly journals Comparing on site human and video counts at Igarapava fish ladder, south eastern Brazil

2006 ◽  
Vol 4 (2) ◽  
pp. 291-294 ◽  
Author(s):  
Mark D. Bowen ◽  
Simone Marques ◽  
Luiz G. M. Silva ◽  
Volney Vono ◽  
Hugo P. Godinho
Keyword(s):  
Fish Species ◽  
Accurate Method ◽  
Fish Passage ◽  
Southeastern Brazil ◽  
Human Observer ◽  
Full Spectrum ◽  
Prochilodus Lineatus ◽  
Number Of Species ◽  
Fish Ladder ◽  
Number Of Individuals

On site human observations and video images were collected and compared at the window of the Igarapava Dam fish ladder (IDFL), rio Grande , Southeastern Brazil, between March 1st and June 30th, 2004. We conducted four experiments with two humans (Observer 1 and Observer 2) observing fish passage in the IDFL window while a Sony 3CCD video camera (Observer 3) recorded fish passage at the same time. Experiments, each one hour in length, were distributed throughout the diel cycle using full spectrum lights. We identified fish species, the number of individuals for each species, and the real time that they passed. Counts from each human observer were compared to the video counts. The fish species most commonly observed in the window were - curimba (Prochilodus lineatus), mandi-amarelo (Pimelodus maculatus), piau-três-pintas (Leporinus friderici) and ferreirinha (Leporinus octofasciatus). The number of species and individuals were indistinguishable for the three observers. But, the number of species and individuals were significantly different among experiments. Thus, the three observers register the same number of species and count the same number of individuals even when these two response variables differ significantly among experiments. Based on these results, we concluded that the video count was an accurate method to assess fish passage at the IDFL.

Spatial genetic structure, population dynamics, and spatial patterns in the distribution of Ocotea catharinensis from southern Brazil: implications for conservation

2018 ◽  
Vol 48 (5) ◽  
pp. 506-516 ◽  
Author(s):  
Tiago Montagna ◽  
Miguel Busarello Lauterjung ◽  
Rafael Candido-Ribeiro ◽  
Juliano Zago da Silva ◽  
Marcia Patricia Hoeltgebaum ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Genetic Structure ◽  
Spatial Patterns ◽  
Spatial Genetic Structure ◽  
Southern Brazil ◽  
Structure Population

scholarly journals Variations in genetic structure and male genitalia suggest recent lineage diversification in the Neotropical dung beetle complex Canthon cyanellus (Scarabaeidae: Scarabaeinae)

2020 ◽  
Vol 131 (3) ◽  
pp. 505-520
Author(s):  
Janet Nolasco-Soto ◽  
Mario E Favila ◽  
Alejandro Espinosa De Los Monteros ◽  
Jorge González-Astorga ◽  
Gonzalo Halffter ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Morphological Variation ◽  
Male Genitalia ◽  
Morphological Variability ◽  
Dung Beetle ◽  
Morphological Characters ◽  
Taxonomic Assignment ◽  
Morphometric Variation ◽  
Evolutionary Forces ◽  
Significant Genetic Structure

Abstract We analysed the genetic divergence and morphology of the aedeagus (i.e. phallobase and parameres) in Canthon cyanellus at different geographical levels. The results from both approaches were compared with the current taxonomic assignment of the C. cyanellus complex, which includes three subspecies. We found a high variation in all the morphological characters of the aedeagus in the populations analysed; the morphometric variation was not geographically structured, either by population or by region. The genealogical analysis indicates a significant genetic structure that does not match either the morphological variation in the male genitalia or the previous subspecific taxonomic classification. Our results suggest that the morphological variation of the aedeagus is seemingly not an isolating reproductive barrier and that the intra- and interpopulation morphological variability of the aedeagus in the C. cyanellus complex does not permit the division into several species. We suggest that other evolutionary forces, such as genetic drift and sexual selection, have influenced the evolution of the male genitalia and the incipient differentiation of this species complex.

scholarly journals Genetic evidence of population structuring in the neotropical freshwater fish Brycon hilarii (Valenciennes, 1850)

2007 ◽  
Vol 67 (4 suppl) ◽  
pp. 889-895 ◽  
Author(s):  
A Sanches ◽  
PM. Galetti Jr
Keyword(s):  
Genetic Structure ◽  
River Basin ◽  
Migratory Fish ◽  
Mato Grosso ◽  
Paraguay River ◽  
Lack Of Information ◽  
Population Structuring ◽  
Different Seasons ◽  
Initial Idea ◽  
Management And Conservation

Brycon hilarii is a migratory fish widely distributed throughout the Paraguay River Basin. It is appreciated in sport fishing and for its superior meat quality. It is also the main species for tourist attraction in the Bonito region (State of Mato Grosso do Sul, Brazil). Considering the lack of information on the genetic structure of the fish of this species, the aim of the present study was to detect the genetic variability of Brycon hilarii through RAPD markers. A total of eighty specimens collected in different seasons at four sites of the Miranda River sub-basin (Paraguay River Basin, Brazil) were used for analysis. The results of genetic similarity, Shannon diversity, and AMOVA revealed differences between the sampling sites. Through AMOVA, differences between populations were more evident among the animals collected during the non-reproductive season, corresponding to a time of less movement of these fish. A population structuring model in which B. hilarii appears organized into genetically differentiated reproductive units that coexist and co-migrate through the studied system was suggested, contrasting the currently accepted idea that freshwater migratory fish form large panmictic populations in a determined hydrographic system. Despite the lack of a complete picture regarding the distribution of B. hilarii in the studied region, this initial idea on its population genetic structure could be an important contribution to providing aid for management and conservation programs of these fish.

Sign in / Sign up

Export Citation Format

Share Document