Molecular Population Genetics of the Atlantic Sand Fiddler Crab, Uca Pugilator, Along the Atlantic Coast PDF Download
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Author: David Andrew Weese Publisher: ISBN: Category : Fiddler crabs Languages : en Pages : 63
Book Description
Author's abstract: The Atlantic sand fiddler crab, Uca pugilator, is an extremely abundant fiddler crab found along the eastern and Gulf coast of the United States. Fiddler crabs have a life cycle with an obligatory planktonic larval phase of 30-90 days, which might be expected to lead to widespread larval dispersal and consequent genetic homogeneity over considerable distances. However a large amount of morphological and behavioral variation is found between northern and southern populations along the eastern coast. This study was undertaken to determine the population genetic structure of U. pugilator and to determine whether these differences may have a genetic basis. The population structure of the fiddler crab was analyzed using 576 individuals collected from 12 sites along the eastern coast. PCR-base single stand conformation polymorphism (SSCP) was used to analyze segments of the mitochondrial 16S rRNA and the nuclear internal transcribed spacer 1 (ITS1) genes of these individuals. The ITS1 marker did not prove to be informative when screened by SSCP for this study. The 16S marker revealed a moderate amount of population structure (FST = 0.292) between populations. The results of this study reveal frequent gene flow between nearby localities, but reduced levels between populations separated by large distances. Despite the potential for high dispersal by planktonic larvae, population differentiation and isolation by distance was found between populations U. pugilator. Northern and southern regions are separated by a genetic distance of 0.3866 suggesting the potential for morphological and behavioral differentiation across the species range. INDEX WORDS: Uca pugilator, Fiddler crab, Population structure, Gene flow, Larval dispersal, Single-stand conformational polymorphism, 16S rDNA, ITS-1.
Author: David Andrew Weese Publisher: ISBN: Category : Fiddler crabs Languages : en Pages : 63
Book Description
Author's abstract: The Atlantic sand fiddler crab, Uca pugilator, is an extremely abundant fiddler crab found along the eastern and Gulf coast of the United States. Fiddler crabs have a life cycle with an obligatory planktonic larval phase of 30-90 days, which might be expected to lead to widespread larval dispersal and consequent genetic homogeneity over considerable distances. However a large amount of morphological and behavioral variation is found between northern and southern populations along the eastern coast. This study was undertaken to determine the population genetic structure of U. pugilator and to determine whether these differences may have a genetic basis. The population structure of the fiddler crab was analyzed using 576 individuals collected from 12 sites along the eastern coast. PCR-base single stand conformation polymorphism (SSCP) was used to analyze segments of the mitochondrial 16S rRNA and the nuclear internal transcribed spacer 1 (ITS1) genes of these individuals. The ITS1 marker did not prove to be informative when screened by SSCP for this study. The 16S marker revealed a moderate amount of population structure (FST = 0.292) between populations. The results of this study reveal frequent gene flow between nearby localities, but reduced levels between populations separated by large distances. Despite the potential for high dispersal by planktonic larvae, population differentiation and isolation by distance was found between populations U. pugilator. Northern and southern regions are separated by a genetic distance of 0.3866 suggesting the potential for morphological and behavioral differentiation across the species range. INDEX WORDS: Uca pugilator, Fiddler crab, Population structure, Gene flow, Larval dispersal, Single-stand conformational polymorphism, 16S rDNA, ITS-1.
Author: Katherine T. Johnson Publisher: ISBN: Category : Languages : en Pages :
Book Description
Atlantic horseshoe crabs (Limulus polyphemus) have endured decades of intense harvest pressure. Genetics studies have shown evidence of distinct sub-groups spanning the coast, although few fine-scale studies have been done to delineate these groups on a local level. Massachusetts lies directly between two of these sub-groups. With documented differences in prosomal widths of horseshoe crabs from either side of Cape Cod, it is possible that Cape Cod is a barrier to gene flow and that there are two distinct genetic groups within Massachusetts. Regulations currently consider all horseshoe crabs to be of one stock. I examined 6 microsatellite loci from 193 horseshoe crabs collected from 7 locations across Massachusetts between 5 May and 24 June 2010. I also analyzed the prosomal widths of 324 horseshoe crabs from 8 locations across Massachusetts. Data analysis revealed low divergence with a G'ST of 0.005 (95% CI -0.004 - 0.013) and a G''ST of 0.015 (95% CI -0.014 - 0.045). Wellfleet Bay showed evidence of divergence from all other sites except Buzzards Bay. Isolation by distance is apparent via the Atlantic Ocean. Phenotypic variation in the prosomal widths of horseshoe crabs shows greater divergence among sites than neutral markers and indicates the presence of additive genetic effects. Low divergence and high heterozygosity indicate that although documented population declines have occurred, effective population size (Ne) is still large enough to maintain allele frequencies. With isolation by distance, divergence is likely to increase over time if populations remain low. Phenotypic divergence shows the possibility of local adaptation and that the implementation of management units (MUs) to the north and south of Cape Cod would be recommended as a conservative measure.
Author: Gwendolyn A. Murphy Publisher: ISBN: Category : Animal burrowing Languages : en Pages : 198
Book Description
Positive rather than negative species interactions dominate in stressful environments like tidal marshes. Fiddler crabs have been shown to ameliorate environmental stress and increase primary productivity through their burrowing behavior. Most notably, bioturbation may facilitate growth of tidal marsh plants by altering soil oxygen concentration, decomposition rates, and soil drainage. In turn, plants provide protection from the elements, refuge from predators and roots provide structural support for burrows in soft substrate. However, dense vegetation may limit the fiddler crab's ability to maneuver on the surface and burrow. Similarly, there may be a threshold where fiddler crab activity becomes destructive to plant growth instead of facilitative. Relatively few fiddler crab and plant interaction studies have been conducted on the Gulf Coast compared to Atlantic Coast. Gulf Coast tidal marshes have distinct climate, dominant vegetation zones and dominant fiddler crab species, and consequently it is likely that community dynamics will differ from Atlantic Coast tidal marshes. To explore interactions between Gulf Coast fiddler crabs and tidal marsh plants, I conducted a seasonal fiddler crab habitat survey and a fiddler crab enclosure study. Both studies were conducted at Grand Bay National Estuarine Research Reserve in Mississippi, across four dominant tidal marsh vegetation zones (salt marsh, brackish marsh, fresh marsh and salt panne). Fiddler crab burrows and associated vegetation were randomly surveyed across the vegetation zones to determine fiddler crab burrow density and habitat preferences. Fiddler crab enclosures were established across the four vegetation zones. Enclosures provided a method to test impacts of fiddler crab burrowing on soil and plant parameters as well as to survey fiddler crab populations. Results of the habitat survey indicated that fiddler crabs utilized all four vegetation zones, but burrow density was statistically higher in the fresh marsh during winter compared to other zones. These results suggest that the fresh marsh may be important habitat for overwintering Gulf Coast fiddler crabs. Additionally, the fresh marsh was found to host higher fiddler crab species diversity and a more balanced sex ratio compared to other zones. The enclosure study established that fiddler crab activity had negligible impacts on plant growth in the salt and fresh marsh yet influenced plant growth in the brackish marsh (positively) and salt panne (negatively). The brackish marsh and salt panne are habitats of intermediate environmental stress for plants and fiddler crabs. Brackish marsh is more frequently inundated than the salt panne and hence bioturbation is likely to be more beneficial in the brackish marsh. Furthermore, brackish marsh below-ground structure is substantial and fiddler crab burrow density was low relative to the salt panne. My work indicates that vegetation abundance and fiddler crab burrow density may balance environmental stresses in tidal marshes and influence nature of fiddler crab and plant interactions.
Author: David Andrew Weese
Author: David Andrew Weese
Author: Katherine T. Johnson
Author: Lauren L. Bergey
Author: John Harold Christy
Author: Maria Berenice Duran
Author: Kenneth Ashton Callicott
Author: Michelle Anne Duval
Author: Gwendolyn A. Murphy
Author: Donald Yeming Young
Author: William F. Herrnkind