Genetic structure and mode of reproduction in five species of sea stars (Echinodermata: Asteroidea) from the Alaskan coast

1992 ◽  
Vol 70 (9) ◽  
pp. 1723-1728 ◽  
Author(s):  
William B. Stickle ◽  
David W. Foltz ◽  
Masaya Katoh ◽  
Hong L. Nguyen
Keyword(s):  
Genetic Structure ◽  
Allozyme Variation ◽  
Population Variation ◽  
Population Divergence ◽  
Sea Star ◽  
Sea Stars ◽  
Mode Of Reproduction ◽  
Pisaster Ochraceus ◽  
The Family ◽  
Leptasterias Polaris

Genetic structure was studied in five sea star species with diverse patterns of reproduction. Eleven sea star samples from six locations in Alaska, representing five species and three genera in the family Asteriidae, were analyzed for allozyme variation at 16–25 loci. Levels of intra- and inter-population variation were determined for three brooding species (Leptasterias hexactis, Leptasterias epichlora, and Leptasterias polaris) and two free-spawning species with long planktonic larval periods (Evasterias troschelii and Pisaster ochraceus). Population divergence of L. epichlora (FST = 0.156) was much higher than that off. ochraceus (FST = 0.006) or E. troschelii (FST = 0.023). Earlier work in our laboratory found that L. hexactis also showed significant interpopulation differences in allele frequencies. Expected heterozygosity was 0.050 in E. troschelii, 0.083 in L. polaris, 0.092 in P. ochraceus, 0.135 in L. epichlora, and 0.151 in L. hexactis, and was unrelated to mode of reproduction.

?Tethyaster albertensis, a Late Cretaceous (Turonian) sea star from the Cardium Formation, Alberta, Canada

1990 ◽  
Vol 64 (6) ◽  
pp. 1045-1049 ◽  
Author(s):  
Russell L. Hall ◽  
Suzan Moore
Keyword(s):  
North America ◽  
Late Cretaceous ◽  
Sea Star ◽  
Sea Stars ◽  
Peace River ◽  
The North ◽  
The Family ◽  
Cardium Formation ◽  
Northern Alberta ◽  
Limited Change

Although many of the surviving lineages of sea stars appeared during an early Mesozoic radiation of the class and have undergone limited change since then, they have left a very poor fossil record, particularly in the Mesozoic of North America (Blake, 1981). This record from the Late Cretaceous of Alberta is made more significant by the fact that it is apparently only the second occurrence of a member of the family Astropectinidae in the Cretaceous of North America; Lophidiaster silentiensis was described by McLearn (1944) from the Lower Cretaceous (Albian) Hasler Formation, from a now-submerged locality on the Peace River in northern Alberta. All previously recorded fossil sea stars from the North American Cretaceous are representatives of the family Goniasteridae.

scholarly journals Genetic variation associated with lower susceptibility to sea star wasting syndrome in the keystone species, Pisaster ochraceus

2021 ◽  
Author(s):  
Andrea Burton ◽  
Sarah Gravem ◽  
Felipe Barreto
Keyword(s):  
Genetic Variation ◽  
Keystone Species ◽  
Disease Status ◽  
Sea Star ◽  
Sea Stars ◽  
Protein Coding ◽  
Functional Studies ◽  
Pisaster Ochraceus ◽  
Wasting Syndrome ◽  
Asymptomatic Individuals

The keystone species, Pisaster ochraceus, suffered mass mortalities along the northeast Pacific Ocean from Sea Star Wasting Syndrome (SSWS) outbreaks in 2013-2016. Causation of SSWS is still debated, leading to concerns as to whether outbreaks will continue to impact this species. Considering the apparent link between ocean temperature and SSWS, the future of this species and intertidal communities remains uncertain. We surveyed populations of sea stars along the Oregon coast in 2016, two years after the epidemic began. Cohabitation of asymptomatic and symptomatic individuals allowed us to ask whether lower susceptibility in asymptomatic individuals differed genetically. We performed restriction site-associated DNA sequencing (2bRAD-seq) to genotype thousands of single nucleotide polymorphism (SNP) loci. By comparing allele frequencies between symptomatic and asymptomatic individuals, we detected three loci that may be under selection. A multivariate analysis showed a clear separation between groups based on disease status in two of the three geographic regions, along with several regions across the genome having small statistical contributions to this separation. A draft annotation of protein-coding regions allowed us to identify 120 predicted genes that are linked to these markers and are putatively associated with lower susceptibility. Our results suggest that some variation in disease severity can be attributed to genetic variation. However, differences in phenotype have a highly polygenic nature with no single or few genomic regions having strong predictive effects. The genes associated with these regions may form the basis for functional studies aiming to understand disease progression in infected individuals.

scholarly journals Reciprocal abundance shifts of the intertidal sea stars, Evasterias troschelii and Pisaster ochraceus , following sea star wasting disease

2019 ◽  
Vol 286 (1901) ◽  
pp. 20182766 ◽  
Author(s):  
Sharon W. C. Kay ◽  
Alyssa-Lois M. Gehman ◽  
Christopher D. G. Harley
Keyword(s):  
Indirect Effects ◽  
Interference Competition ◽  
Disease Outbreaks ◽  
Ecological Communities ◽  
Population Declines ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Field Surveys ◽  
Pisaster Ochraceus

Disease emergence occurs within the context of ecological communities, and disease driven declines in host populations can lead to complex direct and indirect ecological effects. Varying effects of a single disease among multiple susceptible hosts could benefit relatively resistant species. Beginning in 2013, an outbreak of sea star wasting disease (SSWD) led to population declines of many sea star species along the west coast of North America. Through field surveys and laboratory experiments, we investigated how and why the relative abundances of two co-occurring sea star species, Evasterias troschelii and Pisaster ochraceus , shifted during the ongoing wasting epidemic in Burrard Inlet, British Columbia, Canada. We hypothesized that Evasterias is competitively inferior to Pisaster but more resistant to SSWD. Thus, we predicted that SSWD-induced declines of Pisaster could mitigate the negative effects of SSWD on Evasterias , as the latter would experience competitive release. We document shifts in sea star abundance from 2008–2017: Pisaster abundance and mean size declined during the outbreak, while Evasterias abundance increased from relatively rare to numerically dominant within the intertidal. When exposed to symptomatic sea stars, Pisaster and Evasterias both showed signs of SSWD, but transmission and susceptibility was lower in Evasterias. Despite diet overlap documented in our field surveys, Evasterias was not outcompeted by Pisaster in laboratory trails conducted with the relatively small Pisaster available after the outbreak. Interference competition with larger Pisaster , or prey exploitation by Pisaster during the summer when Evasterias is primarily subtidal, may explain the rarity of Evasterias prior to Pisaster declines. Our results suggest that indirect effects mediated by competition can mask some of the direct effects of disease outbreaks, and the combination of direct and indirect effects will determine the restructuring of a community after disturbance.

Crinitostella laguardai, new genus and species of wood-dwelling deep-sea sea-star (Asteroidea: Caymanostellidae) from the Gulf of Mexico

2021 ◽  
pp. 1-7
Author(s):  
Carolina Martin-Cao-Romero ◽  
Francisco Alonso Solís-Marín ◽  
Guadalupe Bribiesca-Contreras
Keyword(s):  
Gulf Of Mexico ◽  
Deep Sea ◽  
New Genus ◽  
Phylogenetic Position ◽  
Published Data ◽  
Sea Star ◽  
New Genus And Species ◽  
Sea Stars ◽  
The Family ◽  
Phylogenetic Hypotheses

Abstract The Caymanostellidae is a family of rarely encountered wood-dwelling deep-sea sea-stars, with only six species, in two genera, described to date. During the COBERPES 5 expedition on board the RV ‘Justo Sierra’, off Tabasco, Gulf of Mexico in 2013, 12 specimens were recovered from a single piece of sunken wood. Herein we describe a new genus and species of caymanostellid, Crinitostella laguardai gen. nov., sp. nov. This species represents the shallowest known caymanostellid (418–427 m depth), and the first known occurrence of the Caymanostellidae from the Gulf of Mexico. The family Caymanostellidae displays affinities with several groups, such as Asterinidae and Korethrasteridae, making it difficult to infer its phylogenetic position evidenced by the myriad of contrasting phylogenetic hypotheses proposed. In an attempt to shed some light on the phylogenetic relationships of the family, sequences of nuclear and mitochondrial DNA of the new species were generated and combined with published data. As previously suggested, caymanostellids seem to be part of valvatacean polytomy rather than velatids.

Color Polymorphism and Genetic Structure in the Sea Star Pisaster ochraceus

2006 ◽  
Vol 211 (3) ◽  
pp. 248-262 ◽  
Author(s):  
C. D. G. Harley ◽  
M. S. Pankey ◽  
J. P. Wares ◽  
R. K. Grosberg ◽  
M. J. Wonham
Keyword(s):  
Genetic Structure ◽  
Color Polymorphism ◽  
Sea Star ◽  
Pisaster Ochraceus

scholarly journals What doesn’t kill them makes them stronger: an association between elongation factor 1-αoverdominance in the sea starPisaster ochraceusand “sea star wasting disease”

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1876 ◽  
Author(s):  
John P. Wares ◽  
Lauren M. Schiebelhut
Keyword(s):  
Pacific Coast ◽  
Functional Relationship ◽  
Elongation Factor ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Pisaster Ochraceus ◽  
The Pacific ◽  
The Relationship ◽  
Elongation Factor 1

In recent years, a massive mortality event has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease event, known as ‘sea star wasting disease’ (SSWD), is linked to viral infection. In one affected sea star (Pisaster ochraceus), previous work had identified that the elongation factor 1-αlocus (EF1A) harbored an intronic insertion allele that is lethal when homozygous yet appears to be maintained at moderate frequency in populations through increased fitness for heterozygotes. The environmental conditions supporting this increased fitness are unknown, but overdominance is often associated with disease. Here, we evaluate populations ofP. ochraceusto identify the relationship between SSWD and EF1A genotype. Our data suggest that there may be significantly decreased occurrence of SSWD in individuals that are heterozygous at this locus. These results suggest further studies are warranted to understand the functional relationship between diversity at EF1A and survival inP. ochraceus.

H3 histone RNA in eggs and embryos of the sea star Pisaster ochraceus

1988 ◽  
Vol 66 (10) ◽  
pp. 1040-1044
Author(s):  
D. K. Banfield ◽  
J. D. G. Boom ◽  
B. M. Honda ◽  
M. J. Smith
Keyword(s):  
Sea Urchins ◽  
Transcript Abundance ◽  
Single Copy ◽  
Sea Star ◽  
Sea Stars ◽  
Pisaster Ochraceus ◽  
Homologous Sequences ◽  
Order Of Magnitude ◽  
Transcript Concentration ◽  
Rna Concentration

Unlike sea urchins, sea stars have little stored histone RNA in their eggs. In an effort to quantify this difference, we have measured H3 RNA concentration in eggs and embryos of the sea star Pisaster ochraceus. The amount of H3 transcript in P. ochraceus 12-h embryos has been measured by RNA excess hybridization kinetics, using a single-strand 32P-labelled coding sequence probe. There are 1 × 105 H3 transcripts in each 12-h embryo. Putative egg H3 transcript concentration was estimated by reciprocal plots. The number of egg H3 homologous sequences (150/egg) is at least an order of magnitude less than rare complex-class, single-copy nuclear DN A transcripts. Slot blots and Northern blots indicate that sea star embryos do not reach the level of H3 transcript abundance seen in sea urchins until at least 16 h of development.

scholarly journals What doesn’t kill them makes them stronger: An association between elongation factor 1-α overdominance in the sea star Pisaster ochraceus and "sea star wasting disease”

2016 ◽  
Author(s):  
John P. Wares ◽  
Lauren M Schiebelhut
Keyword(s):  
Pacific Coast ◽  
Functional Relationship ◽  
Elongation Factor ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Pisaster Ochraceus ◽  
The Pacific ◽  
The Relationship ◽  
Elongation Factor 1

In recent years, a massive plague has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease, known as 'sea star wasting disease' (SSWD), is thought to be caused by viral infection. In the affected sea star Pisaster ochraceus, previous work had identified that the elongation factor 1-α (EF1A) locus harbored an intronic insertion allele that is lethal when homozygous yet appears to be maintained at moderate frequency in populations through increased fitness for heterozygotes. The environmental conditions supporting this increased fitness are unknown, but overdominance is often associated with disease. Here, we evaluate populations of P. ochraceus to identify the relationship between SSWD and EF1A genotype. Our data suggest that there may be significantly decreased infection or mortality rates in individuals that are heterozygous at this locus. These results suggest further studies to understand the functional relationship between diversity at EF1A and survival in P. ochraceus.

scholarly journals What doesn’t kill them makes them stronger: An association between elongation factor 1-α overdominance in the sea star Pisaster ochraceus and "sea star wasting disease”

2016 ◽  
Author(s):  
John P. Wares ◽  
Lauren M Schiebelhut
Keyword(s):  
Pacific Coast ◽  
Functional Relationship ◽  
Elongation Factor ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Pisaster Ochraceus ◽  
The Pacific ◽  
The Relationship ◽  
Elongation Factor 1

In recent years, a massive plague has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease, known as 'sea star wasting disease' (SSWD), is thought to be caused by viral infection. In the affected sea star Pisaster ochraceus, previous work had identified that the elongation factor 1-α (EF1A) locus harbored an intronic insertion allele that is lethal when homozygous yet appears to be maintained at moderate frequency in populations through increased fitness for heterozygotes. The environmental conditions supporting this increased fitness are unknown, but overdominance is often associated with disease. Here, we evaluate populations of P. ochraceus to identify the relationship between SSWD and EF1A genotype. Our data suggest that there may be significantly decreased infection or mortality rates in individuals that are heterozygous at this locus. These results suggest further studies to understand the functional relationship between diversity at EF1A and survival in P. ochraceus.

Testing ecological release as a compensating mechanism for mass mortality in a keystone predator

2020 ◽  
Vol 637 ◽  
pp. 59-69 ◽  
Author(s):  
J Sullivan-Stack ◽  
BA Menge
Keyword(s):  
Community Dynamics ◽  
Limiting Factor ◽  
Sea Star ◽  
Top Predator ◽  
Oregon Coast ◽  
Ecological Release ◽  
Keystone Predator ◽  
Pisaster Ochraceus ◽  
Wasting Syndrome

Top predator decline has been ubiquitous across systems over the past decades and centuries, and predicting changes in resultant community dynamics is a major challenge for ecologists and managers. Ecological release predicts that loss of a limiting factor, such as a dominant competitor or predator, can release a species from control, thus allowing increases in its size, density, and/or distribution. The 2014 sea star wasting syndrome (SSWS) outbreak decimated populations of the keystone predator Pisaster ochraceus along the Oregon coast, USA. This event provided an opportunity to test the predictions of ecological release across a broad spatial scale and determine the role of competitive dynamics in top predator recovery. We hypothesized that after P. ochraceus loss, populations of the subordinate sea star Leptasterias sp. would grow larger, more abundant, and move downshore. We based these predictions on prior research in Washington State showing that Leptasterias sp. competed with P. ochraceus for food. Further, we predicted that ecological release of Leptasterias sp. could provide a bottleneck to P. ochraceus recovery. Using field surveys, we found no clear change in density or distribution in Leptasterias sp. populations post-SSWS, and decreases in body size. In a field experiment, we found no evidence of competition between similar-sized Leptasterias sp. and P. ochraceus. Thus, the mechanisms underlying our predictions were not in effect along the Oregon coast, which we attribute to differences in habitat overlap and food availability between the 2 regions. Our results suggest that response to the loss of a dominant competitor can be unpredictable even when based in theory and previous research.

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