scholarly journals GENETIC VARIATION AND GEOGRAPHIC DIFFERENTIATION IN MITOCHONDRIAL DNA OF THE HORSESHOE CRAB, LIMULUS POLYPHEMUS

Genetics ◽  
1986 ◽  
Vol 112 (3) ◽  
pp. 613-627
Author(s):  
Nancy C Saunders ◽  
Louis G Kessler ◽  
John C Avise
Keyword(s):  
Mitochondrial Dna ◽  
Gene Flow ◽  
Horseshoe Crab ◽  
Gulf Coast ◽  
Sequence Divergence ◽  
Clonal Diversity ◽  
Limulus Polyphemus ◽  
Site Variation ◽  
Horseshoe Crabs ◽  
Or Gene

ABSTRACT Restriction site variation in mitochondrial DNA (mtDNA) of the horseshoe crab (Limulus polyphemus) was surveyed in populations ranging from New Hampshire to the Gulf Coast of Florida. MtDNA clonal diversity was moderately high, particularly in southern samples, and a major genetic "break" (nucleotide sequence divergence approximately 2%) distinguished all sampled individuals which were north vs. south of a region in northeastern Florida. The area of genotypic divergence in Limulus corresponds to a long-recognized zoogeographic boundary between warm-temperate and tropical marine faunas, and it suggests that selection pressures and/or gene flow barriers associated with water mass differences may also influence the evolution of species widely distributed across such transition zones. On the other hand, a comparison of the mtDNA divergence patterns in Limulus with computer models involving stochastic lineage extinction in species with limited gene flow demonstrates that deterministic explanations need not necessarily be invoked to account for the observations. Experiments to distinguish stochastic from deterministic possibilities are suggested. Overall, the pattern and magnitude of mtDNA differentiation in horseshoe crabs is very similar to that typically reported for freshwater and terrestrial species assayed over a comparable geographic range. Results demonstrate for the first time that, geographically, at least some continuously distributed marine organisms can show considerable mtDNA genetic differentiation.

scholarly journals A genetic discontinuity in a continuously distributed species: mitochondrial DNA in the American oyster, Crassostrea virginica.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 397-406 ◽  
Author(s):  
C A Reeb ◽  
J C Avise
Keyword(s):  
Mitochondrial Dna ◽  
Crassostrea Virginica ◽  
Clonal Diversity ◽  
American Oyster ◽  
Ecological History ◽  
High Dispersal ◽  
Site Variation ◽  
Dispersal Capability ◽  
History Of ◽  
Glacial Periods

Abstract Restriction site variation in mitochondrial DNA (mtDNA) of the American oyster (Crassostrea virginica) was surveyed in continuously distributed populations sampled from the Gulf of St. Lawrence, Canada, to Brownsville, Texas. mtDNA clonal diversity was high, with 82 different haplotypes revealed among 212 oysters with 13 endonucleases. The mtDNA clones grouped into two distinct genetic arrays (estimated to differ by about 2.6% in nucleotide sequence) that characterized oysters collected north vs. south of a region on the Atlantic mid-coast of Florida. The population genetic "break" in mtDNA contrasts with previous reports of near uniformity of nuclear (allozyme) allele frequencies throughout the range of the species, but agrees closely with the magnitude and pattern of mtDNA differentiation reported in other estuarine species in the southeastern United States. This concordance of mtDNA phylogenetic pattern across independently evolving species provides strong evidence for vicariant biogeographic processes in initiating intraspecific population structure. The post-Miocene ecological history of the region suggests that reduced precipitation levels in an enlarged Floridian peninsula may have created discontinuities in suitable estuarine habitat for oysters during glacial periods, and that today such population separations are maintained by the combined influence of ecological gradients and oceanic currents on larval dispersal. The results are consistent with the hypothesis that historical vicariant events, in conjunction with contemporary environmental influences on gene flow, can result in genetic discontinuities in continuously distributed species with high dispersal capability.

The relative influence of nature vs. nurture on the expression of circatidal rhythms in the American horseshoe crab Limulus polyphemus

2020 ◽  
Vol 649 ◽  
pp. 83-96
Author(s):  
TN Thomas ◽  
WH Watson ◽  
CC Chabot
Keyword(s):  
Horseshoe Crab ◽  
Marine Organism ◽  
Locomotor Behavior ◽  
Video Tracking ◽  
Limulus Polyphemus ◽  
Behavioral Differences ◽  
Early Environment ◽  
Tidal Cycles ◽  
Horseshoe Crabs ◽  
Nature Vs Nurture

The horseshoe crab Limulus polyphemus exhibits rhythmic locomotor behavior that is controlled by both internal clocks and external tidal cycles. Recent findings demonstrate that adult horseshoe crabs from a 2 tides d-1 environment usually express 2 bouts of activity d-1, while adults from areas with 1 dominant tide d-1, or with negligible tides (atidal), generally express 1 bout of activity d-1. Horseshoe crabs from these different environments are genetically distinct, so it is not known if these behavioral differences are driven by genetics or by the tides they experience early in life. To address this question, freshly spawned horseshoe crab eggs from populations that experience these 3 distinct environmental tidal regimes were reared in the laboratory under 1 of the above 3 artificial tidal conditions. Then the activity of individual larval and 2nd instar juveniles was recorded over 3 wk using video tracking software. Endogenous circatidal rhythms were present in most (88/108) of the freshly molted juveniles from all 3 populations, even when they were raised in atidal conditions, indicating a strong genetic influence. To our knowledge, this is the first demonstration of the presence of genetically driven endogenous circatidal rhythms in an individual juvenile marine organism. Nevertheless, the early environment was also capable of having an impact, because it significantly affected rhythm expression in crabs in the 1 tide d-1 population. Thus, overall, the tidal environment to which horseshoe crab eggs are exposed during development appears to have less of an influence than genetics on their expression of tidal rhythms of locomotion.

scholarly journals Seasonal movement of the American horseshoe crab Limulus polyphemus in a semi-enclosed bay on Cape Cod, Massachusetts (USA) as determined by acoustic telemetry

2010 ◽  
Vol 56 (5) ◽  
pp. 575-586 ◽  
Author(s):  
Mary-Jane James-Pirri
Keyword(s):  
Acoustic Telemetry ◽  
Horseshoe Crab ◽  
Limulus Polyphemus ◽  
Cape Cod ◽  
Telemetry Data ◽  
Seasonal Movement ◽  
Continuous Record ◽  
Horseshoe Crabs ◽  
Enclosed Bay ◽  
Males And Females

Abstract American horseshoe crabs Limulus polyphemus were tracked using acoustic telemetry and traditional tagging in a semi-enclosed bay on Cape Cod (Pleasant Bay), Massachusetts, USA, to determine seasonal movement patterns. Fifty-five actively spawning females were fitted with transmitters in 2008 and 2009 and were tracked using acoustic telemetry from May 2008 through July 2010. Fifteen crabs with transmitters also had archive depth-temperature tags attached. In addition, over 2000 spawning crabs (males and females) were tagged with US Fish and Wildlife (USFWS) button tags over the same period. Ninety-one percent of the crabs with transmitters were detected during this study. In the spring, crabs were primarily located in the northern section of the bay near spawning beaches, whereas in the fall crabs moved towards the deeper portions of the bay, and some may have overwintered in the bay. There was evidence that a majority (58%–71%) of the females with transmitters spawned in two sequential seasons. One archive tag was recovered resulting in a year-long continuous record of depth and temperature data that, when integrated with telemetry data, indicated that the crab overwintered in the bay. The live recapture rate of crabs with USFWS button tags was 11%, with all re-sighted crabs except one observed inside Pleasant Bay. Eighty-three percent of recaptures were found within 2.5km of the tagging location, and 51% were observed at the same beach where they were tagged. This study provides further evidence that horseshoe crabs in Pleasant Bay may be philopatric to this embayment.

Mitochondrial DNA diversity among populations of striped bass in the southeastern United States

1989 ◽  
Vol 67 (4) ◽  
pp. 891-907 ◽  
Author(s):  
Isaac I. Wirgin ◽  
Rui Proenca ◽  
Joseph Grossfield
Keyword(s):  
Mitochondrial Dna ◽  
South Carolina ◽  
Striped Bass ◽  
Gulf Coast ◽  
Sequence Divergence ◽  
River System ◽  
Restriction Enzymes ◽  
Mtdna Sequence ◽  
Apalachicola River ◽  
Atlantic Coastal

Mitochondrial DNA (mtDNA) genotypes were determined for Atlantic striped bass from the St. Johns River in northeastern Florida and several hatchery reared individuals from Monck's Corner, South Carolina. Adults and hatchery-reared descendants of striped bass with high lateral line scale counts were sampled from several sites in the Apalachicola River system along the Gulf coast of Florida. In addition, naturally reproduced 1985 year class juveniles from the Apalachicola system were sampled. All mtDNA genotypes were compared with those observed in our sample of approximately 200 fish from the Atlantic coastal migratory stock. Ten different restriction endonucleases were used, generating 169 mtDNA fragments in most individuals. Heteroplasmy was observed in striped bass from both the St. Johns River and the Apalachicola system. Base sequence divergence among the populations surveyed was extremely low (maximum p = 0.0004), among the lowest reported for any animal species to date. However, the restriction enzymes RsaI and XbaI both revealed base substitutions unique to populations of Gulf Coast striped bass. Approximately 57% of striped bass from the Apalachicola system displayed an XbaI genotype not seen in any of our Atlantic collections. Four discrete mtDNA size classes were detected, differing by approximately 200, 300, and 400 base pairs from the smallest mtDNA molecule observed. The largest genotype was only seen in the Apalachicola system. The smallest genotype, while restricted to Gulf Coast striped bass sampled for this study, has been frequently observed in the Atlantic coastal migratory stock. The presence of mtDNA genotypes unique to the Apalachicola systems suggests the continued existence of a maternal lineage of striped bass of Gulf ancestry and points to the use of mtDNA as a valuable tag in the management of these populations. The lack of mtDNA sequence divergence in striped bass suggests a very recent origin for these populations.

scholarly journals The Draft Genome and Transcriptome of the Atlantic Horseshoe Crab,Limulus polyphemus

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Stephen D. Simpson ◽  
Jordan S. Ramsdell ◽  
Winsor H. Watson III ◽  
Christopher C. Chabot
Keyword(s):  
Horseshoe Crab ◽  
Molecular Mechanisms ◽  
Transcriptome Assembly ◽  
Draft Genome ◽  
Limulus Polyphemus ◽  
Rna Seq ◽  
Accessory Gene ◽  
Large Dataset ◽  
Horseshoe Crabs ◽  
Atlantic Horseshoe Crab

The horseshoe crab,Limulus polyphemus, exhibits robust circadian and circatidal rhythms, but little is known about the molecular mechanisms underlying those rhythms. In this study, horseshoe crabs were collected during the day and night as well as high and low tides, and their muscle and central nervous system tissues were processed for genome and transcriptome sequencing, respectively. The genome assembly resulted in7.4×105contigs with N50 of 4,736, while the transcriptome assembly resulted in9.3×104contigs and N50 of 3,497. Analysis of functional completeness by the identification of putative universal orthologs suggests that the transcriptome has three times more total expected orthologs than the genome. Interestingly, RNA-Seq analysis indicated no statistically significant changes in expression level for any circadian core or accessory gene, but there was significant cycling of several noncircadian transcripts. Overall, these assemblies provide a resource to investigate theLimulusclock systems and provide a large dataset for further exploration into the taxonomy and biology of the Atlantic horseshoe crab.

scholarly journals The American Horseshoe Crab (Limulus polyphemus)

EDIS ◽  
2020 ◽  
Vol 2020 (5) ◽  
pp. 3
Author(s):  
Savanna Barry ◽  
Holly Abeels ◽  
Shelly Krueger
Keyword(s):  
Horseshoe Crab ◽  
Forest Resources ◽  
Limulus Polyphemus ◽  
Human Medicine ◽  
Fact Sheet ◽  
Living Fossils ◽  
Horseshoe Crabs ◽  
Aquatic Sciences

American horseshoe crabs (<em>Limulus polyphemus</em>) look prehistoric and in fact really have not changed very much in the 200 million years they have been around. This 3-page fact sheet written by Savanna Barry, Holly Abeels, and Shelly Krueger and published by the UF/IFAS Program in Fisheries and Aquatic Sciences, School of Forest Resources and Conservation tells the story of these interesting and valuable "living fossils," including their importance both to ecology and human medicine. It provides tips on how to find horseshoe crabs and a few ways you can help them.

scholarly journals Histological evaluation of five suture materials in the telson ligament of the American horseshoe crab (Limulus polyphemus)

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7061
Author(s):  
Ami E. Krasner ◽  
Amy Hancock-Ronemus ◽  
Larry S. Christian ◽  
Emily H. Griffith ◽  
Gregory A. Lewbart ◽  
...  
Keyword(s):  
Horseshoe Crab ◽  
Suture Material ◽  
Secondary Infection ◽  
Polyglycolic Acid ◽  
Tissue Reaction ◽  
Limulus Polyphemus ◽  
Histological Evaluation ◽  
Suture Materials ◽  
Soft Membrane ◽  
Horseshoe Crabs

An ideal suture material supports healing, minimizes inflammation, and decreases the likelihood of secondary infection. While there are published recommendations for suture materials in some invertebrates, there are no published recommendations for Limulus polyphemus or any chelicerate. This study evaluates the histological reaction of horseshoe crabs to five commonly used suture materials: monofilament nylon, silk, poliglecaprone, polydioxanone, and polyglycolic acid. None of the materials were superior with regards to holding nor was there any dehiscence. Nylon evoked the least amount of tissue reaction. This work also provides a histopathological description of the soft membrane at the hinge area between the opisthosoma and telson (telson ligament) and comments on euthanasia with intracardiac eugenol.

High levels of mitochondrial DNA divergence within short-eared rock-wallaby (Petrogale brachyotis) populations in northern Australia

2010 ◽  
Vol 58 (2) ◽  
pp. 104 ◽  
Author(s):  
Wendy R. Telfer ◽  
Mark D. B. Eldridge
Keyword(s):  
Mitochondrial Dna ◽  
Gene Flow ◽  
Control Region ◽  
National Park ◽  
Sequence Divergence ◽  
Mtdna Control Region ◽  
Secondary Contact ◽  
Interspecific Hybridisation ◽  
Secondary Contact Zone

Most population genetics studies of rock-wallabies conducted to date have examined remnant colonies of threatened species inhabiting southern Australia. In this study we examined the natural pattern of contemporary and long-term gene flow among colonies of the widespread and abundant short-eared rock-wallaby, Petrogale brachyotis, in the relatively unmodified landscapes of Australia’s tropical north. We sampled 105 wallabies from seven colonies 1.2 km to 250 km apart. Mitochondrial DNA (mtDNA) control region sequence analysis was conducted on samples from all colonies and microsatellite analysis (10 loci) on samples from the three largest colonies. The microsatellite data revealed no evidence of inbreeding within colonies, but higher levels of genetic diversity were found in the Kakadu National Park population compared with the smaller, more isolated colonies at Litchfield National Park. Both the mtDNA and microsatellite results showed that populations of P. brachyotis are naturally highly structured even within this relatively intact landscape, with only limited contemporary and long-term gene flow between colonies more than 1.2 km apart. Nine mtDNA control region haplotypes were identified within the seven colonies. There were unusually high levels of sequence divergence (up to 6.9%) within colonies at Litchfield NP. This divergence suggests that multiple taxa may exist within what is currently recognised as P. brachyotis. Alternatively, if current taxonomy is correct, the high levels of divergence raise the possibility of ancestral isolation and divergence of populations in allopatry with subsequent admixture at a secondary contact zone. The possibility that these unusually divergent haplotypes result from introgressive interspecific hybridisation with the sympatric P. concinna appears unlikely.

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