Limited gene flow in Uca minax (LeConte 1855) along a tidally influenced river system

Staton, Joseph L.; Borgianini, Stephen A.; Gibson, Ian B.; Brodie, Renae J.; Greig, Thomas W.

doi:10.2478/s11535-013-0200-7

Cited by 7 publications

(3 citation statements)

References 53 publications

(62 reference statements)

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“…In both of the fabrics discussed above, the bioturbated lithosome is interpreted to have been deposited during low river discharge, because bioturbation must be associated with brackish‐water colonization windows and tidally facilitated larvae recruitment (Lettley et al ., ; Staton et al ., ; Gingras et al ., ). During low river discharge: (i) smaller volumes of mud are delivered to the system; (ii) the salinity limit extends landward; and (iii) the turbidity maximum zone contracts and shifts landward.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Using ichnological relationships to interpret heterolithic fabrics in fluvio‐tidal settings

Melnyk¹,

Gingras

2019

Sedimentology

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In fluvio-tidal settings, the sediment is dominantly derived from the river systems. However, the importance of landward tidal transport of sediment in tidally influenced sedimentary environments is difficult to assess, particularly in the rock record. This problem is addressed using two intervals within the Lower Cretaceous McMurray Formation, each representing a distinct inclined heterolithic stratification motif. The ichnological variation between the heterolithic intervals is analyzed to determine which lithosomes are associated with brackish-water (tidally influenced) colonization windows. From this, the relative fluvial influence responsible for the deposition of the fine and coarse members can be determined. Both of the inclined heterolithic stratification fabrics studied record the deposition of fluvio-tidal point bars wherein the heterolithic bedding represents variations in river discharge. The first fabric comprises inclined heterolithic stratification in which bioturbation only occurs in mudstone beds. This fabric indicates that deposition occurred in more proximal positions within a fluvio-tidal system (i.e. the outermost inner to middle estuary or distributary channels). In this example sand deposition is interpreted to represent high-energy, freshwater dune migration within a fluvial-dominated setting, whereas mud beds reflect brackish-water suspension deposition during times of low river discharge. The second fabric, which is interpreted to have developed in more distal depositional positions (i.e. the middle estuary or seaward of the turbidity maximum in deltas), consists of inclined heterolithic stratification with laminated mudstone and bioturbated sandstone. In these inclined heterolithic stratification successions the mudstone beds were deposited under the influence of freshwater and heightened sedimentation rates, whereas bioturbated sandstone was colonized under brackish-water conditions and in the presence of tidally facilitated sediment transport. In both examples, the bioturbated lithosomes are related to colonization windows that indicate the predominance at that time of marine or tidally influenced processes over fluvial processes.

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Section: Interpretation and Discussionmentioning

confidence: 99%

Using ichnological relationships to interpret heterolithic fabrics in fluvio‐tidal settings

Melnyk¹,

Gingras

2019

Sedimentology

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“…The microhabitat, and local selective pressure, in which each species occurs, allied with estuarine and coastline geomorphology, could also explain the different genetic structuring between the two species or within groups (close populations). Furthermore, a set of abiotic variables, such as local currents, tide regimes, wind effects, and coast morphology may also influence the degree of gene flow (Aoki et al., 2008; Robins et al., 2013; Staton et al., 2014). Even if it remains unclear, if estuarine retention is a passive or active process, larval behavior resulting in local recruitment seems to be the most plausible explanation for the here observed levels of moderate to high genetic structure of M. mordax .…”

Section: Discussionmentioning

confidence: 99%

Comparing the effect of larval dispersal strategies on morphological versus genetic differentiation in two neotropical fiddler crabs

Martins,

Marochi,

Masunari

et al. 2023

Marine Ecology

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The dispersal mode of estuarine invertebrates has a strong effect on genetic variability and phenotypic expression, potentially maintaining gene flow among widely separated populations or limiting connectivity among close ones. Understanding the dispersal strategies effects can support adequate strategies for environment management and understand the evolutionary history of the studied species. A comparative study on the effect of larval dispersal strategies (export vs retention) along the overall geographic distribution ranges of adult populations of two co‐distributed fiddler crab species was performed. Geometric morphometric techniques were used to evaluate morphological differentiation in the shape of the carapace and major cheliped propodus in 10 populations of Minuca mordax and five populations of Leptuca leptodactyla. Potential genetic differentiation was assessed using DNA sequence data from up to 170 fiddler crab specimens, corresponding to the mitochondrial gene cytochrome c oxidase subunit 1 (COX1). Patterns of genetic and morphological characteristics diverged among populations of both species. In terms of morphology, populations of both species showed intraspecific variation in the shape of the carapace and, to a lesser extent, in the major cheliped propodus. This observed intraspecific variation followed a clear geographic pattern of morphometric differentiation, in which the geographic origin is associated with a phenotypic response to the environmental diversity along the extended Brazilian coast. In contrast, there are shared haplotypes in populations separated by more than 4000 km, but with significant ΦST values among most populations of L. leptodactyla and M. mordax, suggesting a moderate to high level of gene flow. Therefore, it can be concluded that the split of the Central South Equatorial Current has not acted as an efficient long‐term barrier to the dispersal of larvae in both species. In M. mordax, a slight limitation of genetic exchange can be observed between the southernmost populations and the remaining ones. This first evidence of genetic structuring within this widely distributed species is consistent with its documented strategy to retain larvae in the estuarine environments. However, occasional transport of larvae to more open coastal waters seems to maintain stepwise gene flow between neighboring populations. Overall, our results still provide evidence of more pronounced genetic homogeneity in a species with a larval export strategy (L. leptodactyla) compared to a species with a larval retention strategy (M. mordax). This suggests that larval dispersal strategies, coupled with the microhabitat in which the respective species occur, have a noticeable effect on the degree of gene flow. Most likely, these biological aspects are further influenced by the estuarine and coastline geomorphology.

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“…Calculating evolvabilities requires an estimation of the ancestral mean shape and the ancestral P-matrix (Hansen & Houle, 2008;Berner et al, 2010;Hansen & Voje, 2011). Population genetics studies on fiddler crab species have documented little phylogenetic structure among spatially separated populations, even across potential geographic barriers (Warwick, 2009;Warwick et al, 2009;Silva et al, 2010;Laurenzano et al, 2012;Staton et al, 2013;Wieman et al, 2014). In most cases, one haplotype dominated the samples, and was present across a wide geographic range, whereas other haplotypes were rare and usually limited to one population.…”

Section: Methodsmentioning

confidence: 99%

Constraints on geographic variation in fiddler crabs (Ocypodidae: Uca) from the western Atlantic

Hopkins

Haber

Thurman

2016

J of Evolutionary Biology

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A key question in evolutionary biology is how intraspecific variation biases the evolution of a population and its divergence from other populations. Such constraints potentially limit the extent to which populations respond to selection, but may endure long enough to have macroevolutionary consequences. Previous studies have focused on the association between covariation patterns and divergence among isolated populations. Few have focused on geographic variation among semi-connected populations, however, even though this may be indicative of early selective pressures that could lead to long-term divergence and speciation. Here, we test whether covariation in the shape of the carapace of fiddler crabs (genus Uca Leach, 1814) is important for structuring geographic variation. We find that morphological divergence among populations is associated with evolvability in the direction of divergence in only a few species. The shape of the ancestral covariation matrix in these species differs from other species in having notably more variation concentrated along fewer directions (i.e. higher eccentricity). For most species, there is some evidence that covariation has constrained the range of directions into which populations have diverged but not the degree of divergence. These results suggest that even though fiddler crab populations have diverged morphologically in directions predicted by covariation, constraints on the extent to which divergence has occurred may only be manifested in species where variation patterns are eccentric enough to limit populations' ability to respond effectively in many directions.

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Limited gene flow in Uca minax (LeConte 1855) along a tidally influenced river system

Cited by 7 publications

References 53 publications

Using ichnological relationships to interpret heterolithic fabrics in fluvio‐tidal settings

Using ichnological relationships to interpret heterolithic fabrics in fluvio‐tidal settings

Comparing the effect of larval dispersal strategies on morphological versus genetic differentiation in two neotropical fiddler crabs

Constraints on geographic variation in fiddler crabs (Ocypodidae: Uca) from the western Atlantic

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