Statistical phylogeographic tests of competing 'Lake Carpentaria hypotheses' in the mouth-brooding freshwater fish, Glossamia aprion (Apogonidae)

2012 ◽  
Vol 63 (5) ◽  
pp. 450 ◽  
Author(s):  
Benjamin D. Cook ◽  
Mark Adams ◽  
Peter B. Mather ◽  
Jane M. Hughes

Glacial cycles during the Pleistocene reduced sea levels and created new land connections in northern Australia, where many currently isolated rivers also became connected via an extensive paleo-lake system, ‘Lake Carpentaria’. However, the most recent period during which populations of freshwater species were connected by gene flow across Lake Carpentaria is debated: various ‘Lake Carpentaria hypotheses’ have been proposed. Here, we used a statistical phylogeographic approach to assess the timing of past population connectivity across the Carpentaria region in the obligate freshwater fish, Glossamia aprion. Results for this species indicate that the most recent period of genetic exchange across the Carpentaria region coincided with the mid- to late Pleistocene, a result shown previously for other freshwater and diadromous species. Based on these findings and published studies for various freshwater, diadromous and marine species, we propose a set of ‘Lake Carpentaria’ hypotheses to explain past population connectivity in aquatic species: (1) strictly freshwater species had widespread gene flow in the mid- to late Pleistocene before the last glacial maximum; (2) marine species were subdivided into eastern and western populations by land during Pleistocene glacial phases; and (3) past connectivity in diadromous species reflects the relative strength of their marine affinity.

1997 ◽  
Vol 54 (6) ◽  
pp. 1400-1407 ◽  
Author(s):  
R A Myers ◽  
G Mertz ◽  
J Bridson

We examine the spatial scale of variability in recruitment for 11 marine, three anadromous, and five freshwater species. Generally the spatial scale of recruitment correlations for marine species is approximately 500 km, compared with less than 50 km for freshwater; anadromous species fall between these two scales. The scale for marine species is comparable with (but less than) that of the largest-scale environmental variables (and is compatible with the idea that large-scale environmental agents influence recruitment). Our results are consistent with the hypothesis that predation is a more important factor in determining recruitment in freshwater than it is in the marine environment.


2003 ◽  
Vol 75 (11-12) ◽  
pp. 2249-2261 ◽  
Author(s):  
P. Matthiessen

This topic reviews the whole field of endocrine disruption (ED) in marine fish and compares this with our knowledge of the situation in freshwater species. In broad terms, similar types of ED have been observed in the two groups, although effects in the marine environment tend to be less marked, presumably due to dispersion and dilution. There are, however, some data which suggest that marine fish that are top-predators can experience ED due to biomagnification of organochlorines. Processes such as smoltification, metamorphosis, and hermaphroditism, which are common in some marine species, may be particularly susceptible to ED, but have as yet been scarcely studied. As with freshwater fish, firm links to population-level effects have not yet been demonstrated, although it is not unreasonable to suppose that they are occurring in some locations. The topic concludes with some recommendations for future research.


2019 ◽  
Author(s):  
Sofia L. Mendes ◽  
Maria M. Coelho ◽  
Vitor C. Sousa

AbstractIn freshwater fish, processes of population divergence and speciation are often linked to the geomorphology of rivers and lakes that isolate populations. However, current geographical isolation does not necessarily imply total absence of gene flow during the divergence process. Here, we focused on four species of the genus Squalius in Portuguese rivers: S. carolitertii, S. pyrenaicus, S. aradensis and S. torgalensis. Previous studies based on eight nuclear and mitochondrial markers revealed incongruent patterns, with nuclear loci suggesting that S. pyrenaicus was a paraphyletic group since its northern populations were genetically closer to S. carolitertii than to its southern populations. For the first time, we successfully applied a genomic approach to the study of the relationship between these species, using a Genotyping by Sequencing (GBS) approach. Our results revealed a species tree with two main lineages: (i) S. carolitertii and S. pyrenaicus; (ii) S. torgalensis and S. aradensis. Regarding S. carolitertii and S. pyrenaicus, we found evidence for past introgression between the two in the northern part of S. pyrenaicus distribution. This introgression reconciles previous mitochondrial and nuclear incongruent results and explains the apparent paraphyly of S. pyrenaicus. Our demographic modelling estimates are consistent across models, suggesting that the northern populations of S. pyrenaicus received a contribution of approximately 90% from S. carolitertii and 10% from southern S. pyrenaicus. This illustrates that even in freshwater species currently allopatric, we are able to detect past gene flow events in present-day genomes, suggesting speciation is more complex than simply allopatric.


2021 ◽  
Vol 8 ◽  
Author(s):  
Lauric Reynes ◽  
Didier Aurelle ◽  
Cristele Chevalier ◽  
Christel Pinazo ◽  
Myriam Valero ◽  
...  

Dispersal is a central process that affects population growth, gene flow, and ultimately species persistence. Here we investigate the extent to which gene flow occurs between fragmented populations of the deep-water brown algae Ericaria zosteroides (Turner) Greville (Sargassaceae, Fucales). These investigations were performed at different spatial scales from the bay of Marseille (western Provence) to Corsica. As dispersal of zygotes is shown to be limited over distances beyond a few meters, we used a multidisciplinary approach, based on Lagrangian modeling and population genomics to test the hypothesis that drifting of fertile parts of thallus (eggs on fertile branches), mediated by ocean currents, enable occasional gene flow between populations. Therefore we assessed the respective contribution of oceanographic connectivity, geographical isolation, and seawater temperatures to the genetic structure of this species. The genetic structure was assessed using 10,755 neutral SNPs and 12 outlier SNPs genotyped by dd-RAD sequencing in 261 individuals of E. zosteroides. We find that oceanographic connectivity is the best predictor of genetic structure, while differentiation in outlier SNPs can be explained by the depth of populations, as emphasized by the minimum seawater temperature predictor. However, further investigations will be necessary for clarifying how depth drives adaptive genetic differentiation in E. zosteroides. Our analyses revealed that local hydrodynamic conditions are correlated with the very high divergence of one population in the Bay of Marseille. Overall, the levels of gene flow mediated by drifting were certainly not sufficient to counteract differentiation by local genetic drift, but enough to allow colonization several kilometers away. This study stresses the need to consider secondary dispersal mechanisms of presumed low dispersal marine species to improve inference of population connectivity.


2016 ◽  
Vol 73 (9) ◽  
pp. 2333-2341 ◽  
Author(s):  
Jennifer R. Ovenden ◽  
Bree J. Tillett ◽  
Michael Macbeth ◽  
Damien Broderick ◽  
Fiona Filardo ◽  
...  

Abstract We report population genetic structure and fine-scale recruitment processes for the scallop beds (Pecten fumatus) in Bass Strait and the eastern coastline of Tasmania in southern Australia. Conventional population pairwise FST analyses are compared with novel discriminant analysis of principal components (DAPC) to assess population genetic structure using allelic variation in 11 microsatellite loci. Fine-scale population connectivity was compared with oceanic features of the sampled area. Disjunct scallop beds were genetically distinct, but there was little population genetic structure between beds connected by tides and oceanic currents. To identify recruitment patterns among and within beds, pedigree analyses determined the distribution of parent–offspring and sibling relationships in the sampled populations. Beds in northeastern Bass Strait were genetically distinct to adjacent beds (FST 0.003–0.005) and may not contribute to wider recruitment based on biophysical models of larval movement. Unfortunately, pedigree analyses lacked power to further dissect fine-scale recruitment processes including self-recruitment. Our results support the management of disjunct populations as separate stocks and the protection of source populations among open water beds. The application of DAPC and parentage analyses in the current study provided valuable insight into their potential power to determine population connectivity in marine species with larval dispersal.


2021 ◽  
Author(s):  
◽  
Jennifer Vander Veur

<p>Determining the magnitude of dispersal and connectivity between populations has important implications for marine conservation. Species with limited dispersal capabilities exhibit restricted gene flow leading to isolation and, ultimately, differentiated populations. In this ecological study I investigated the gastropods Austrolittorina antipodum (Philippi, 1847) and Austrolittorina cincta (Quoy and Gaimard, 1833) to determine how ecology and behaviour influence the dispersal and connectivity of these species. The aim of this study was to determine population size and structure, settlement, fecundity, and adult movement rates. Methodologies included: population surveys, deployment of settlement pads and adult density manipulations, dissections, and a tagging study. These elements of a species ecology and behaviour can enhance or restrict population connectivity by: cohort partitioning resulting from habitat requirements, fluctuating settlement due to variable larval mortality or adult densities impacting dispersal, skewed sex ratios and effective populations sizes altering larval production, and adult movement leading to behavioural isolation or facilitating gene flow, along with other possible effects. Population surveys revealed both species had a Vermeij (1972) "type 1 distribution" (shell size increasing from the low to high shore), with the highest density of individuals on the low shore and the majority of mature adults on the high shore. Overall, A. antipodum was 16 times more abundant than A. cincta. Shifts to a smaller mean size of both species, along all shore heights following periods of peak settlement indicates settlers are potentially triggering competitive interactions or ontogenetic migrations in other cohorts.Settlement surveys revealed that peak settlement for Austrolittorina spp. was from February to April, declining at the beginning of March. Multiple peaks in settlement may act as a buffer limiting the potential of stochastic events to hinder dispersal during reproductive seasons. Settlement rates were not affected by adult density in control treatments; however, settlement was higher on pads deployed within adult populations compared to pads deployed adjacent to adult populations, suggesting the presences of adults has some effect on settlement. Fecundity results revealed A. antipodum to have more mature females than A. cincta, with males of both species reaching sexual maturity before females. Sex ratios of both species were skewed towards more females, with effective population sizes that included approximately 88% of each species population. A. antipodum’s larger population may be due to variation between the species' demographics, such as the distribution of mature females and juveniles leading to greater spawning success and juvenile survivorship. Tagging transplant/translocation experiments used to examine movement revealed that both species traveled similar distances. On average A. antipodum traveled 24.1m (±23.5m) and A. cincta traveled 18.7m (±16m) in eight months. There was no evidence of behavioural isolation occurring between low and high shore individuals. The wide ranging movements of adults indicated adults have the potential to maintain population connectivity on small scales. The findings of this study suggest both species facilitate dispersal with multiple peaks in settlement, large effective populations, and high adult mobility. Behavioural variation between the species appears to affect population connectivity, with the distribution of A. antipodum demographics potentially enhancing connectivity.</p>


Toxins ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 470 ◽  
Author(s):  
Wei Gao ◽  
Yoko Kanahara ◽  
Misako Yamada ◽  
Ryohei Tatsuno ◽  
Hiroyuki Yoshikawa ◽  
...  

To clarify the differences in toxin selectivity between marine and freshwater pufferfish, we conducted experiments in artificially reared nontoxic specimens of Takifugu pardalis (marine) and Pao suvattii (freshwater) using tetrodotoxin (TTX) and paralytic shellfish poison (PSP; decarbamoylsaxitoxin (dcSTX) or saxitoxin (STX)). T. pardalis specimens were administered feed homogenate containing TTX or dcSTX (dose of toxin, 55.2 nmol/fish) and P. suvattii specimens were administered feed homogenate containing TTX + STX (dose of each toxin, 19.2 nmol/fish) by oral gavage. The toxin content in the intestine, muscle, skin, liver, and gonads was quantified after 24 and 48 or 72 h. In T. pardalis, TTX administered into the intestine was absorbed into the body and transferred and retained mainly in the skin and liver, while dcSTX was hardly retained in the body, although it partly remained in the intestine. In strong contrast, in P. suvattii, little TTX remained in the body, whereas STX was absorbed into the body and was transferred and retained in the ovary and skin. The findings revealed that TTX/PSP selectivity differs between the marine species T. pardalis and the freshwater species P. suvattii. T. pardalis, which naturally harbors TTX, selectively accumulates TTX, and P. suvattii, which naturally harbors PSP, selectively accumulates PSP.


1983 ◽  
Vol 53 (1) ◽  
pp. 82-92 ◽  
Author(s):  
F. Hovenkamp ◽  
W. Hovenkamp ◽  
J.J. van der Heide

Two new amphipod species of the family Bogidiellidae were found in the hyporheal of two small rivers on Corsica. Both new species, Bogidiella (Bogidiella) cyrnensis n. sp. and B. paolii n. sp. (provisionally placed in the subgenus Medigidiella, but a definitive classification will have to wait till males are found), encountered at altitudes of 135 m and 750 m, respectively, show more affinities with certain freshwater species of Sardinia than with marine species of the Mediterranean.


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