scholarly journals Genetic population structure of the monogenean parasite Gyrodactylus thymalli and its host European grayling (Thymallus thymallus) in a large Norwegian lake

Hydrobiologia ◽  
2020 ◽  
Author(s):  
Ruben Alexander Pettersen ◽  
Claudia Junge ◽  
Kjartan Østbye ◽  
Tor Atle Mo ◽  
Leif Asbjørn Vøllestad
Keyword(s):  
Genetic Structure ◽  
Evolutionary Biology ◽  
Isolation By Distance ◽  
Genetic Structuring ◽  
Thymallus Thymallus ◽  
Homing Behavior ◽  
Genetic Population ◽  
Monogenean Parasite ◽  
European Grayling ◽  
Genetic Clusters

Abstract Understanding how populations are structured in space and time is a central question in evolutionary biology. Parasites and their hosts are assumed to evolve together, however, detailed understanding of mechanisms leading to genetic structuring of parasites and their hosts are lacking. As a parasite depends on its host, studying the genetic structure of both parasite and host can reveal important insights into these mechanisms. Here, genetic structure of the monogenean parasite Gyrodactylus thymalli and its host the European grayling (Thymallus thymallus) was investigated in 10 tributaries draining into the large Lake Mjøsa in Norway. The population genetic structure of spawning grayling was studied using microsatellite genotyping, while G. thymalli was studied by sequencing a mitochondrial DNA gene (dehydrogenase subunit 5). Two main genetic clusters were revealed in grayling, one cluster comprising grayling from the largest spawning population, while the remaining tributaries formed the second cluster. For both taxa, some genetic differentiation was observed among tributaries, but there was no clear isolation-by-distance signature. The structuring was stronger for the host than for the parasite. These results imply that moderate to high levels of gene flow occur among the sub-populations of both taxa. The high parasite exchange among tributaries could result from a lack of strong homing behavior in grayling as well as interactions among individual fish outside of the spawning season, leading to frequent mixing of both host and parasite.

scholarly journals Patterns of genetic structuring at the northern limits of the Australian smelt (Retropinna semoni) cryptic species complex

2017 ◽  
Author(s):  
Md Rakeb-Ul Islam ◽  
Daniel J Schmidt ◽  
David A Crook ◽  
Jane M Hughes
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Cryptic Species ◽  
Isolation By Distance ◽  
Gene Tree ◽  
Phylogeographic Structure ◽  
Genetic Structuring ◽  
River Population ◽  
Genetic Population ◽  
Eastern Australia

Freshwater fishes often exhibit high genetic population structure due to the prevalence of dispersal barriers (e.g., waterfalls) whereas population structure in diadromous fishes tends to be weaker and driven by natal homing behaviour and/or isolation by distance. The Australian smelt (Retropinninae: Retropinna semoni) is a facultatively diadromous fish with a broad distribution spanning inland and coastal drainages of south-eastern Australia. Previous studies have demonstrated variability in population genetic structure and movement behaviour (potamodromy, facultative diadromy, estuarine residence) across the southern part of its geographic range. Some of this variability may be explained by the existence of multiple cryptic species. Here, we examined genetic structure of populations at the northern extent of the species’ distribution, using ten microsatellite loci and sequences of the mitochondrial cyt b gene. We tested the hypothesis that connectivity among rivers should be low due to a lack of dispersal via the marine environment, but high within rivers due to potamodromous behaviour. We investigated populations corresponding with two putative cryptic species, the South East Queensland (SEQ), and Central East Queensland (CEQ) lineages. In agreement with our hypothesis, highly significant overall FST values suggested that both groups exhibit very low dispersal among rivers (SEQ FST = 0.13; CEQ FST = 0.30). The two putative cryptic species, formed monophyletic clades in the mtDNA gene tree and among river phylogeographic structure was also evident within clades. Microsatellite data indicated that connectivity among sites within rivers was also limited, suggesting potamodromous behaviour does not homogenise populations at the within-river scale. Overall, northern groups in the smelt cryptic species exhibit higher among-river population structure and smaller geographic ranges than southern groups. These properties make northern Australian smelt populations potentially susceptible to future conservation threats, and we define eight genetically distinct management units to guide future conservation management.

scholarly journals Patterns of genetic structuring at the northern limits of the Australian smelt (Retropinna semoni) cryptic species complex

2017 ◽  
Author(s):  
Md Rakeb-Ul Islam ◽  
Daniel J Schmidt ◽  
David A Crook ◽  
Jane M Hughes
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Cryptic Species ◽  
Isolation By Distance ◽  
Gene Tree ◽  
Phylogeographic Structure ◽  
Genetic Structuring ◽  
River Population ◽  
Genetic Population ◽  
Eastern Australia

Freshwater fishes often exhibit high genetic population structure due to the prevalence of dispersal barriers (e.g., waterfalls) whereas population structure in diadromous fishes tends to be weaker and driven by natal homing behaviour and/or isolation by distance. The Australian smelt (Retropinninae: Retropinna semoni) is a facultatively diadromous fish with a broad distribution spanning inland and coastal drainages of south-eastern Australia. Previous studies have demonstrated variability in population genetic structure and movement behaviour (potamodromy, facultative diadromy, estuarine residence) across the southern part of its geographic range. Some of this variability may be explained by the existence of multiple cryptic species. Here, we examined genetic structure of populations at the northern extent of the species’ distribution, using ten microsatellite loci and sequences of the mitochondrial cyt b gene. We tested the hypothesis that connectivity among rivers should be low due to a lack of dispersal via the marine environment, but high within rivers due to potamodromous behaviour. We investigated populations corresponding with two putative cryptic species, the South East Queensland (SEQ), and Central East Queensland (CEQ) lineages. In agreement with our hypothesis, highly significant overall FST values suggested that both groups exhibit very low dispersal among rivers (SEQ FST = 0.13; CEQ FST = 0.30). The two putative cryptic species, formed monophyletic clades in the mtDNA gene tree and among river phylogeographic structure was also evident within clades. Microsatellite data indicated that connectivity among sites within rivers was also limited, suggesting potamodromous behaviour does not homogenise populations at the within-river scale. Overall, northern groups in the smelt cryptic species exhibit higher among-river population structure and smaller geographic ranges than southern groups. These properties make northern Australian smelt populations potentially susceptible to future conservation threats, and we define eight genetically distinct management units to guide future conservation management.

Genetic structure in relation to movements in wild European grayling (Thymallus thymallus) in three Norwegian rivers

2006 ◽  
Vol 63 (6) ◽  
pp. 1309-1319 ◽  
Author(s):  
Jan Heggenes ◽  
Tore Qvenild ◽  
Michael D Stamford ◽  
Eric B Taylor
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Movement Pattern ◽  
Behavioral Strategies ◽  
Genetic Structuring ◽  
Thymallus Thymallus ◽  
European Grayling ◽  
Movement Data ◽  
Linear Distance ◽  
The Relationship

The relationship among genetic structure, movements, and barriers was studied in European grayling (Thymallus thymallus). Gene flow is closely related to movement patterns, and genetic differentiation may be negatively correlated with movement. Grayling movements in the Glomma River (8149 tagged) and the neighboring Trysilelva River (4070 tagged) were different among sampling sites. Most individuals were stationary (±0.5 km), but some individuals moved long distances (≤153 km). The movement data indicated potential for gene flow between the two upstream sampling sites in the Glomma River and between the two midstream sites in the Trysilelva River. Allele frequencies at seven microsatellite loci indicated pairwise differentiation across sampling sites. Genetic structuring was generally consistent with the observed movement pattern. Isolation-by-linear-distance or number of potential barriers (dams, lakes) was not significant among sites within streams or among sites within the two southern streams. They were significant, however, if two outlying northern populations in the Pasvik River were included. Our results suggest that although grayling may move long distances, they also exhibit genetic structuring within large continuous river systems. Fish movement, often the result of flexible and adaptive behavioral strategies, is the ecological mechanism for gene flow. Movements may be the adaptive link explaining how environmental conditions affect genetic structuring.

scholarly journals Birds are islands for parasites

2014 ◽  
Vol 10 (8) ◽  
pp. 20140255 ◽  
Author(s):  
Jennifer A. H. Koop ◽  
Karen E. DeMatteo ◽  
Patricia G. Parker ◽  
Noah K. Whiteman
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Evolutionary Biology ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Island Populations ◽  
Louse Species ◽  
Parasite Populations

Understanding the mechanisms driving the extraordinary diversification of parasites is a major challenge in evolutionary biology. Co-speciation, one proposed mechanism that could contribute to this diversity is hypothesized to result from allopatric co-divergence of host–parasite populations. We found that island populations of the Galápagos hawk ( Buteo galapagoensis ) and a parasitic feather louse species ( Degeeriella regalis ) exhibit patterns of co-divergence across variable temporal and spatial scales. Hawks and lice showed nearly identical population genetic structure across the Galápagos Islands. Hawk population genetic structure is explained by isolation by distance among islands. Louse population structure is best explained by hawk population structure, rather than isolation by distance per se , suggesting that lice tightly track the recent population histories of their hosts. Among hawk individuals, louse populations were also highly structured, suggesting that hosts serve as islands for parasites from an evolutionary perspective. Altogether, we found that host and parasite populations may have responded in the same manner to geographical isolation across spatial scales. Allopatric co-divergence is likely one important mechanism driving the diversification of parasites.

Population structure in two geographically sympatric and congeneric ectoparasites (Cimex adjunctus and Cimex lectularius) in the North American Great Lakes region

2017 ◽  
Vol 95 (12) ◽  
pp. 901-907 ◽  
Author(s):  
Benoit Talbot ◽  
Maarten J. Vonhof ◽  
Hugh G. Broders ◽  
M. Brock Fenton ◽  
Nusha Keyghobadi
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Isolation By Distance ◽  
Spatial Genetic Structure ◽  
Geographic Area ◽  
Abundant Species ◽  
Cimex Lectularius ◽  
Genetic Structuring ◽  
The North ◽  
Genetic Clusters

Subdivided populations can be described by different models of population structure that reflect population organization, dynamics, and connectivity. We used genetic data to investigate population structure in two geographically sympatric, congeneric species of generalist ectoparasites of warm-blooded animals. We characterized the spatial genetic structure of the eastern bat bug (Cimex adjunctus Barber, 1939), an understudied and fairly abundant species, using microsatellite markers at a spatial scale representing contemporary dispersal of the species. We found seven genetic clusters, global [Formula: see text] of 0.2, 33% of genetic variation among sites, and nonsignificant isolation-by-distance. We compared these results with the common bed bug (Cimex lectularius L., 1758), a closely related but conversely well-known species, in the same geographic area. We found stronger genetic structuring in C. lectularius than in C. adjunctus, with 11 genetic clusters, [Formula: see text] of 0.7, 57% of genetic variation among sites, and significant but weak isolation-by-distance (R2 = 0.09). These results suggest that while both species can be described as having classic metapopulation structure, C. adjunctus leans more towards a patchy population and C. lectularius leans more towards a nonequilibrium metapopulation. The difference in population structure between these species may be attributable to differences in movement potential and extinction–colonization dynamics.

The impact of stocking on the genetic structure of European grayling Thymallus thymallus, Salmonidae) in two alpine rivers

Hydrobiologia ◽  
2005 ◽  
Vol 542 (1) ◽  
pp. 121-129 ◽  
Author(s):  
Nina Duftner ◽  
Stephan Koblmüller ◽  
Steven Weiss ◽  
Nikolaus Medgyesy ◽  
Christian Sturmbauer
Keyword(s):  
Genetic Structure ◽  
Thymallus Thymallus ◽  
European Grayling ◽  
Alpine Rivers ◽  
The Impact

scholarly journals Structural genomic variation leads to unexpected genetic differentiation in Lake Tanganyika’s sardines

2019 ◽  
Author(s):  
Julian Junker ◽  
Jessica A. Rick ◽  
Peter B. McIntyre ◽  
Ismael Kimirei ◽  
Emmanuel A. Sweke ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Genetic Differentiation ◽  
Evolutionary Biology ◽  
Lake Tanganyika ◽  
Isolation By Distance ◽  
Genomic Variation ◽  
Population Declines ◽  
Structural Genomic ◽  
Important Species ◽  
Lake Kivu

AbstractIdentifying patterns in genetic structure and the genetic basis of ecological adaptation is a core goal of evolutionary biology and can inform the management and conservation of species that are vulnerable to population declines exacerbated by climate change. We used reduced representation genomic sequencing methods to gain a better understanding of genetic structure among and within populations of Lake Tanganyika’s two sardine species, Limnothrissa miodon and Stolothrissa tanganicae. Samples of these ecologically and economically important species were collected across the length of Lake Tanganyika, as well as from nearby Lake Kivu, where L. miodon was introduced in 1959. Our results reveal unexpected differentiation within both S. tanganicae and L. miodon that is not explained by geography. Instead, this genetic differentiation is due to the presence of large sex-specific regions in the genomes of both species, but involving different polymorphic sites in each species. Our results therefore indicate rapidly evolving XY sex determination in the two species. Additionally, we found evidence of a large segregating inversion in L. miodon. We found all inversion karyotypes throughout Lake Tanganyika, but the frequencies vary along a north-south gradient, and differ substantially in the introduced Lake Kivu population. We do not find evidence for significant isolation-by-distance, even over the hundreds of kilometers covered by our sampling, but we do find shallow population structure.

Genetic structure, diversity, and inbreeding of eastern white pine under different management conditions

2007 ◽  
Vol 37 (12) ◽  
pp. 2652-2662 ◽  
Author(s):  
Paula E. Marquardt ◽  
Craig S. Echt ◽  
Bryan K. Epperson ◽  
Dan M. Pubanz
Keyword(s):  
Genetic Structure ◽  
Isolation By Distance ◽  
Spatial Genetic Structure ◽  
White Pine ◽  
Eastern White Pine ◽  
Mature Trees ◽  
Genetic Structuring ◽  
Old Growth ◽  
Mean Values ◽  
Growth Site

Resource sustainability requires a thorough understanding of the influence of forest management programs on the conservation of genetic diversity in tree populations. To observe how differences in forest structure affect the genetic structure of eastern white pine ( Pinus strobus L.), we evaluated six eastern white pine sites across the 234 000 acre (1 acre = 0.4046856 ha) Menominee Indian Reservation in northeastern Wisconsin (45°00′N, 88°45′W). The six sites sampled for nuclear and chloroplast DNA microsatellite markers were of contrasting densities and managed by different management systems: shelterwood, pine release, plantation, and old growth. Three of the sites had natural regeneration, which was also sampled. Mean values of spatial genetic autocorrelation were positive in all mature populations and variable; the strongest spatial structuring of genes occurred in the least disturbed old-growth site (I – E(I) = 0.031). Genetic structuring at the historical old-growth site fit the isolation-by-distance model for a neighborhood size of 130 individuals. Significant inbreeding occurred in five populations, but the seedling or sapling populations as a group (f = 0.088) are significantly less inbred than the local mature populations (f = 0.197). The increase in heterozygosity between generations was attributed to harvesting having reduced the spatial genetic structure of the mature trees.

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