A salt bath will keep you going? Euryhalinity tests and genetic structure of caridean shrimps from Iberian rivers (original) (raw)
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Freshwater Biology, 2007
1. We determined whether two sympatric mitochondrial DNA (mtDNA) lineages of freshwater shrimp (Decapoda: Atyidae: Paratya australiensis) represent biological species and if they had concerted or independent population responses to hydrographic factors in small streams (the Granite Creeks) in southeastern Australia. 2. Allozyme data indicated the presence of two gene pools at sites where the P. australiensis lineages were co-occurring and the gene pools were statistically assigned with high probability to each respective lineage. This indicated that these mtDNA lineages in P. australiensis were reproductively isolated and thus biological species. 3. Populations of both lineages were genetically homogeneous among lowland sites within streams, but were isolated by steep stream gradients among upland sites and for lowlandupland site comparisons. However, the magnitude of differentiation was markedly different between the two lineages. Allozyme diversity also differed between the two lineages, suggesting that they have different effective population sizes. Thus, differences in the magnitude of genetic divergence among populations were probably because of different life-history characteristics, including dispersal ability and population size. 4. Genetic population structure was mostly temporally stable, despite the extreme effects of drought during the first year and substantial stream-flow during the second. However, stable isotope analyses revealed greater local movement in both lineages during the second year, as greater hydrological connectivity provided more opportunities for dispersal. Thus, although lowland populations within streams were genetically homogeneous, stable isotope data indicated that connections may be sporadic and result from accumulated small-scale movements among refugial pools. 5. Both lineages were therefore found to have similar small-scale population responses to the unstable habitats of the Granite Creeks. Results highlight the importance of refugia for the capacity of biota to recover from drought and the need for multiple restored patches to reinstate natural population processes (e.g. resilience, recolonization) in degraded systems.
Scientia Marina, 2010
The red and blue shrimp, Aristeus antennatus, inhabits deep shelf waters in the Mediterranean Sea, where the shallower portion of its distribution supports a large commercial fishery. Recent prospecting surveys in the western Mediterranean have detected virgin stocks dwelling at more than 1000 m, but the extent of gene flow between the exploited shallowdwelling stock and the deep-dwelling stock is unknown. To investigate the genetic structure of the population and estimate the depth component of gene flow, a portion of the mitochondrial DNA 16S gene (547 pb) was sequenced for 321 individuals from four different depths (350, 700, 1100 and 1500 m) at a location in the Catalan Sea. Haplotype and nucleotide diversity values were low and did not significantly differ across depths. Analysis of molecular variance showed no significant genetic differences between depths. Mismatch distribution and neutrality tests indicated that A. antennatus has undergone recent demographic expansion in the two shallowest layers. Our results suggest that the species is genetically structured as a sort of metapopulation in which gene flow that occurs during the larval and juvenile stages, when larvae are carried downstream and juveniles are carried upstream by cascading, plays an important role in the resilience of the exploited layers.
Ecosphere, 2018
Knowledge of cryptic species distributions and their relationships with environmental factors may be extremely valuable for biodiversity conservation. In freshwater ecosystems, morphologically cryptic species often have different geographic distributions that can overlap to varying extents. The importance of differential species responses to environmental conditions in determining their spatial distributions is, however, unclear. Here, we evaluated the importance of species responses to environmental drivers, in particular the physicochemical factors, in the spatial distributions and environmental relationships of two shrimp species complexes Caridina indistincta Calman, 1926 and Paratya australiensis Kemp, 1917. We analyzed shrimp specimens from 89 sites in 17 catchments across SouthEast Queensland by sequencing a fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) to identify individuals. Furthermore, although there is evidence that morphologically the cryptic species of these shrimps differ very little, we made detailed morphological assessments to combine with molecular data, hoping to be able to distinguish among the species more easily and cheaply for future studies. There were significant morphological differences among the three cryptic species of the C. indistincta species complex, specifically in carapace length (cl), number of dorsal teeth (nDt), number of ventral teeth (nVt), teeth posterior to orbital margin (TPOM), and the calculated ratios A/rl, and rl/cl, while the two lineages of the P. australiensis species complex differed in the number of dorsal teeth (nDt) and the calculated ratios of A/rl, rl/cl, and rh/ch. To determine the importance of species responses in explaining the spatial distribution of cryptic species based on the species-variables relationships, a redundancy analysis (RDA) was used to summarize these relationships. This ordination analysis showed distinct differences among cryptic species in their correlation with water quality variables and elevation. C. indistincta sp. B and C. indistincta sp. D were significantly associated with elevation and dissolved oxygen range, respectively. As well, P. australiensis lineages 4 and 6 were significantly correlated with elevation and conductivity, respectively. Overall, our results demonstrated the advantage of using analyses of biotic and abiotic variables as a valid approach for defining species responses to abiotic factors in cryptic species of atyid freshwater shrimps.
Molecular Ecology, 2008
There has been a recent appreciation of the ecological impacts of zooplanktonic species invasions. The North American brine shrimp Artemia franciscana is one such alien invader in hyper-saline water ecosystems at a global scale. It has been shown to outcompete native Artemia species, leading to their local extinction. We used partial sequences of the mitochondrial Cytochrome c Oxidase Subunit 1 (COI or cox1) gene to investigate the genetic diversity and phylogeography of A. salina, an extreme halophilic sexual brine shrimp, over its known distribution range (Mediterranean Basin and South Africa) and to assess the extent of local endemism, the degree of population structure and the potential impact of traditional human saltpan management on this species. We also examined the phylogenetic relationships in the genus Artemia using COI sequences. Our results show extensive regional endemism and indicate an early Pleistocene expansion of A. salina in the Mediterranean Basin. Subsequent population isolation in a mosaic of Pleistocene refugia is suggested, with two or three refugia located in the Iberian Peninsula. Two instances of longdistance colonization were also observed. Surprisingly, given its strong phylogeographical structure, A. salina showed a signature of correlation between geographical and genetic distance. Owing to strong 'priority effects', extensive population differentiation is retained, despite dispersal via migrant birds and human management of saltpans. The foreseeable expansion of A. franciscana is likely to be followed by substantial loss of genetic diversity in Mediterranean A. salina. Large genetic divergences between Mediterranean and South African A. salina suggest that the latter deserves species status. Fig. 3 Statistical parsimony network showing the nested design used in NCPA. Only second (continuous thin line), third (continuous thick line) and statistically informative 1stlevel clades (discontinuous thin line) are shown. Sizes of ellipses are proportional to the number of individuals included (ellipses with numbers bottom left). The populations where each haplotype was found are shown next to the haplotype code. Lines linking haplotypes indicate single substitutions. Small black circles indicate missing haplotypes.
Estuaries, 2003
The brown shrimp, Farfantepenaeus aztecus, is the major component of the Gulf of Mexico shrimp fishery, and it is critical that we understand its environmental requirements. Brown shrimp spend a large portion of their postlarval (PL) and juvenile life within estuaries distributed along salinity gradients and yet our understanding of the salinity tolerance of various age groups is limited. A series of 48-hr bioassays were conducted in which various ages of F. aztecus (PL-10, PL-13, PL-15, PL-17, PL-20, and PL-23) were acclimated from a salinity of 26‰ to 1‰, 2‰, 4‰, 8‰, 12‰, and 26‰ in order to determine their tolerance to these salinities. Finally, PL-80 F. aztecus were transferred directly from 25‰ to 2‰, 4‰, and 8‰ waters to study the effects of rapid salinity reductions on juvenile survival. Survival of 10and 13-day-old PLs was significantly different from the control (26‰) for all salinities tested. Survival of PL-15 shrimp and older was significantly lower than survival of the controls at 1‰ and 2‰ but similar to the control at all other salinities tested. A 4-wk growth trial was conducted with juvenile shrimp at 2‰, 4‰, 8‰, and 12‰. There was no significant difference in survival among treatments, although shrimp maintained at 8‰ and 12‰ grew significantly more than shrimp maintained at 2‰ and 4‰. There was no growth difference between shrimp at the two low salinities or between shrimp at the two high salinities. Survival of juveniles transferred directly from 25‰ to various salinities were 100% at 25‰, 94.2% at 8‰, 67.3% at 4‰, and 63.5% at 2‰. These results suggest that PL-13 and younger brown shrimp would have a better chance of survival by delaying entry into estuaries susceptible to rapid salinity declines. The brown shrimp juveniles would be more densely distributed in areas with salinities greater than 4‰ than in salinities less than 4‰. Although food availability and bottom type also affect shrimp distribution survival and growth, salinity may also greatly affect the shrimp and its fishery.
Marine …, 2009
The deep-sea habitat, from 200 to 2000 m depth, has long been thought as an ecosystem where biotic and abiotic factors vary very little and consequently species are not disturbed by processes and phenomena which could promote fast evolutionary mechanisms. Unfortunately, biological information relating to deep water is limited, especially regarding the population genetics of species inhabiting the Mediterranean Sea, and general patterns cannot be inferred. In this study we report data on the population genetic structure of Aristeus antennatus, a deep-sea decapod crustacean species which has been widely studied due to its important economic value. We surveyed and examined the variation in a 369-bp fragment of the mtDNA control region from individuals caught by Spanish and Italian trawlers in eight localities. High levels of mitochondrial control region haplotypic diversity (ranging from 0.884 to 0.989) were observed. AMOVA showed a high level of genetic variation, more within than between populations, and a low but significant FST value was recovered. Minimum spanning network did not separate any haplotype group and haplotype distribution does not mirror the geographic origin of the samples. The absence of population substructuring was also observed with a principal coordinates analysis, which uses an individual-by-individual comparison. These results revealed extensive gene flow among populations. Information on demographic history based on mismatch analysis revealed an unstable population, showing an alternate pattern of growth and decline. Our results indicated that in the western and central Mediterranean basins A. antennatus is a large panmictic population with a fluctuating abundance. The absence of deep-sea barriers and adult migration may prevent the structuring of the species into genetically differentiated populations.
Marine Ecology Progress Series, 2011
The blue and red shrimp Aristeus antenantus supports an important commercial fishery in the Western Mediterranean, adjacent Atlantic waters and Mozambique Channel (western Indian Ocean). This study investigates its genetic structure by examining a total of 506 individuals from Mediterranean, Atlantic and Indian Ocean locations. In order to identify putative genetic stocks, sequences from 16S rDNA (546 bp) and COI (514 bp) genes were used. Genetic diversity, estimated by haplotypic and nucleotidic diversity, was lower in the Western Mediterranean than in samples from other locations. The high haplotypic diversity of the Eastern Mediterranean, Atlantic and Indian Ocean samples reflects the occurrence of a number of private haplotypes, which are also responsible for significant genetic divergence between these samples and the Western Mediterranean ones. The analysis of mismatch distributions, neutrality tests, and star-like patterns present in the network of haplotypes provided consistent inference of past population expansion in the Western Mediterranean, Atlantic and Mozambique Channel regions. Our study provides the first evidence of genetic structuring in A. antennatus across its distributional range.
The pink shrimp Farfantepenaeus duorarum (Burkenroad) lives in south Florida ecosystems in different salinity regimes ranging from brackish to hypersaline. In Florida Bay, the main nursery grounds, juveniles reside in 25–50 salinity; while 20 km northwest of the Bay, juveniles inhabit more estuarine salinities between 5 and 15. In this study we investigated the hypothesis that the disparate salinity regimes in which pink shrimp juveniles reside may be due to a non-genetic resistance adaptation to different acclimation salinities in their respective nursery habitats during postlarval development when the maximum tolerance to salinity occurs. To test this hypothesis and to define salinity tolerances during ontogenetic development, salinity trials were conducted with four postlarval ages (PL 15, PL 25, PL 35 and PL 55) previously acclimated in two salinities (15 and 35) and then exposed to an abrupt salinity change for 96 h at 27.5 ± 0.5 °C. Results indicated that the degree of tolerance to salinity varies with ontogenetic development. Regardless of acclimation salinity, two clearly distinguishable salinity tolerance ages were discernable. Postlarvae of age PL 35 and PL 55 exhibited significantly higher average survival than at an age of PL 15 and PL 25. This result suggests that postlarvae between 25 and 35 d old may complete development of osmoregulatory capabilities to cope with abrupt changes in salinity, which concurs with the age at which planktonic postlarvae settle on the sea-grass banks of Florida Bay. Results regarding salinity tolerances in the two acclimation salinity groups demonstrated that postlarvae acclimated in a salinity of 15 tolerated salinities 20 units lower than those acclimated in regular 35 sea water salinity. The high survival of postlarvae recorded at salinities between 2 and 15 after a long acclimation period at a salinity of 15 suggested that non-genetic resistance adaptation (acclimation) had taken place during development, supporting our hypothesis that a preconditioning salinity during postlarval development may modify the subsequent tolerance limits of juvenile stages.► We examined the hypothesis of a non-genetic adaptation to acclimation salinities. ► We conducted salinity trials with four postlarval ages acclimated in two salinities. ► A clear shift in salinity tolerances between acclimation salinities was observed. ► Salinity tolerance ranges also vary with ontogenetic development. ► Our data support the euryplasticity hypothesis for pink shrimp early stages.