scholarly journals Ecological Load and Balancing Selection in Circumboreal Barnacles

Author(s):  
Joaquin C B Nunez ◽  
Stephen Rong ◽  
Alejandro Damian-Serrano ◽  
John T Burley ◽  
Rebecca G Elyanow ◽  
...  

Abstract Acorn barnacle adults experience environmental heterogeneity at various spatial scales of their circumboreal habitat, raising the question of how adaptation to high environmental variability is maintained in the face of strong juvenile dispersal and mortality. Here, we show that 4% of genes in the barnacle genome experience balancing selection across the entire range of the species. Many of these genes harbor mutations maintained across 2 My of evolution between the Pacific and Atlantic oceans. These genes are involved in ion regulation, pain reception, and heat tolerance, functions which are essential in highly variable ecosystems. The data also reveal complex population structure within and between basins, driven by the trans-Arctic interchange and the last glaciation. Divergence between Atlantic and Pacific populations is high, foreshadowing the onset of allopatric speciation, and suggesting that balancing selection is strong enough to maintain functional variation for millions of years in the face of complex demography.

2020 ◽  
Author(s):  
Joaquin C. B. Nunez ◽  
Stephen Rong ◽  
Alejandro Damian-Serrano ◽  
John T. Burley ◽  
Rebecca G. Elyanow ◽  
...  

AbstractAcorn barnacle adults experience environmental heterogeneity at various spatial scales of their circumboreal habitat, raising the question of how adaptation to high environmental variability is maintained in the face of strong juvenile dispersal and mortality. Here we show that 4% of genes in the barnacle genome experience balancing selection across the entire range of the species. Many of these genes harbor mutations maintained across 2 million years of evolution between the Pacific and Atlantic oceans. These genes are involved in ion regulation, pain reception, and heat tolerance, functions which are essential in highly variable ecosystems. The data also reveal complex population structure within and between basins, driven by the trans-Arctic interchange and the last glaciation. Divergence between Atlantic and Pacific populations is high, foreshadowing the onset of allopatric speciation, and suggesting that balancing selection is strong enough to maintain functional variation for millions of years in the face of complex demography.


2016 ◽  
Vol 73 (10) ◽  
pp. 1507-1519 ◽  
Author(s):  
Ryan R.E. Stanley ◽  
Claudio DiBacco ◽  
Simon R. Thorrold ◽  
Paul V.R. Snelgrove ◽  
Corey J. Morris ◽  
...  

We examined spatial variation in otolith geochemistry as a natural tag in juvenile Atlantic cod (Gadus morhua) to resolve geographic patterns during early life history. Individuals from 54 inshore sites spanned five embayments in eastern Newfoundland. Otolith composition differed at all spatial scales and related inversely to spatial scale. Classification analysis revealed increasing discrimination at coarser spatial scales: site (26%–58%), bay (49%), and coast (76%). Assignment success declined by ∼10% per added site with increasing sampling sites per bay, demonstrating fine-scale (<100 km) variation. When we partitioned environmental variability from observed otolith chemistry using predictive models, assignment success improved by 56%, 14%, and 5% for site, bay, and coast, respectively. Our results demonstrate environmental influence on spatial structure of otolith chemistry and illustrate the importance of resolving baseline variability in otolith chemistry when conducting assignment tests. Collectively, our results describe the potential utility of juvenile otolith composition in evaluating contributions of subpopulations to the Northwest Atlantic cod stock and highlight important limitations imposed by environmental variation at scales less than 100 km.


eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Kevin Axelrod ◽  
Alvaro Sanchez ◽  
Jeff Gore

Microorganisms often exhibit a history-dependent phenotypic response after exposure to a stimulus which can be imperative for proper function. However, cells frequently experience unexpected environmental perturbations that might induce phenotypic switching. How cells maintain phenotypic states in the face of environmental fluctuations remains an open question. Here, we use environmental perturbations to characterize the resilience of phenotypic states in a synthetic gene network near a critical transition. We find that far from the critical transition an environmental perturbation may induce little to no phenotypic switching, whereas close to the critical transition the same perturbation can cause many cells to switch phenotypic states. This loss of resilience was observed for perturbations that interact directly with the gene circuit as well as for a variety of generic perturbations-such as salt, ethanol, or temperature shocks-that alter the state of the cell more broadly. We obtain qualitatively similar findings in natural gene circuits, such as the yeast GAL network. Our findings illustrate how phenotypic memory can become destabilized by environmental variability near a critical transition.


2020 ◽  
pp. 16-17
Author(s):  
Zac Waipara

We have not yet emerged into a post-COVID world. The future is fluid and unknown. As the Academy morphs under pressure, as design practitioners and educators attempt to respond to the shifting world – in the M?ori language, Te Ao Hurihuri – how might we manage such changes? There is an indigenous precedent of drawing upon the past to assist with present and future states – as the proverb ka mua ka muri indicates, ‘travelling backwards into the future,’ viewing the past spread out behind us, as we move into the unknown. Indigenous academics often draw inspiration from extant traditional viewpoints, reframing them as methodologies, and drawing on metaphor to shape solutions. Some of these frameworks, such as Te Whare Tapa Wh?, developed as a health-based model, have been adapted for educational purposes. Many examples of metaphor drawn from indigenous ways of thinking have also been adapted as design or designrelated methodologies. What is it about the power of metaphor, particularly indigenous ways of seeing, that might offer solutions for both student and teacher? One developing propositional model uses the Pacific voyager as exemplar for the student. Hohl cites Polynesian navigation an inspirational metaphor, where “navigating the vast Pacific Ocean without instruments, only using the sun, moon, stars, swells, clouds and birds as orienting cues to travel vast distances between Polynesian islands.”1 However, in these uncertain times, it becomes just as relevant for the academic staff member. As Reilly notes, using this analogy to situate two cultures working as one: “like two canoes, lashed together to achieve greater stability in the open seas … we must work together to ensure our ship keeps pointing towards calmer waters and to a future that benefits subsequent generations.”2 The goal in formulating this framework has been to extract guiding principles and construct a useful, applicable structure by drawing from research on twoexisting models based in Samoan and Hawaiian worldviews, synthesised via related M?ori concepts. Just as we expect our students to stretch their imaginations and challenge themselves, we the educators might also find courage in the face of the unknown,drawing strength from indigenous storytelling. Hohl describes the advantages of examining this approach: “People living on islands are highly aware of the limitedness of their resources, the precarious balance of their natural environment and the long wearing negative effects of unsustainable actions … from experience and observing the consequences of actions in a limited and confined environment necessarily lead to a sustainable culture in order for such a society to survive.”3 Calculated risks must be undertaken to navigate this space, as shown in this waka-navigator framework, adapted for potential use in a collaborative, studio-style classroom model. 1 Michael Hohl, “Living in Cybernetics: Polynesian Voyaging and Ecological Literacy as Models fordesign education, Kybernetes 44, 8/9 (October 2015). https://doi.org/ 10.1108/K-11-2014-0236.2 Michael P.J Reilly, “A Stranger to the Islands: Voice, Place and the Self in Indigenous Studies”(Inaugural Professorial Lecture, University of Otago, Dunedin, New Zealand, 2009).http://hdl.handle.net/10523/51833 Hohl, “Living in Cybernetics”.


<em>Abstract</em>.—Stream fishes carry out their life histories across broad spatial and temporal scales, leading to spatially structured populations. Therefore, incorporating metapopulation dynamics into models of stream fish populations may improve our ability to understand mechanisms regulating them. First, we reviewed empirical research on metapopulation dynamics in the stream fish ecology literature and found 31 papers that used the metapopulation framework. The majority of papers applied no specific metapopulation model, or included space only implicitly. Although parameterization of spatially realistic models is challenging, we suggest that stream fish ecologists should incorporate space into models and recognize that metapopulation types may change across scales. Second, we considered metacommunity theory, which addresses how trade-offs among dispersal, environmental heterogeneity, and biotic interactions structure communities across spatial scales. There are no explicit tests of metacommunity theory using stream fishes to date, so we used data from our research in a Great Plains stream to test the utility of these paradigms. We found that this plains fish metacommunity was structured mainly by spatial factors related to dispersal opportunity and, to a lesser extent, by environmental heterogeneity. Currently, metacommunity models are more heuristic than predictive. Therefore, we propose that future stream fish metacommunity research should focus on developing testable hypotheses that incorporate stream fish life history attributes, and seasonal environmental variability, across spatial scales. This emerging body of research is likely to be valuable not only for basic stream fish ecological research, but also multispecies conservation and management.


2020 ◽  
Vol 40 (6) ◽  
pp. 739-745
Author(s):  
Xenia L Rangaswami ◽  
Gordon T Ober ◽  
Sarah E Gilman

Abstract Anaerobic metabolism is an important response to stress in many organisms. Intertidal species often face heat stress during low tide. Balanus glandula (Darwin, 1854) is a high-shore intertidal barnacle common to the Pacific that experiences prolonged low-tide air exposure. It is not known whether B. glandula uses anaerobic metabolism during emersion, or if its use varies by latitude. We measured low tide D-lactate production in two US west coast populations of B. glandula separated by 14 degrees of latitude. We exposed barnacles to seven low-tide air temperatures (10, 15, 20, 25, 30, 35, and 38 °C) for which aerobic respiration has been previously measured. Our northern population of B. glandula increased D-lactate production at high air temperatures where aerobic metabolic depression is known to occur, indicating sublethal stress. In contrast, our southern population showed little increase in D-lactate over the same temperature range, coincident with high aerobic respiration across those temperatures. In a second experiment, we quantified D-lactate at 1, 2, and 6 hours post-emersion for northern B. glandula exposed to either a 10 or 38 °C low tide, to measure their potential lactate usage. While D-lactate was elevated at 38 °C compared to the 10 °C control immediately following low tide exposure, it dropped to control levels, and was likely excreted, within 1 hour of re-immersion. Our results suggest that the low latitude population of B. glandula may be more resilient to climate change than its high latitude counterpart in the absence of adaptation, which has strong implications for species distribution.


The Condor ◽  
2019 ◽  
Vol 121 (3) ◽  
Author(s):  
Iva Popovic ◽  
David P L Toews ◽  
Carson C Keever ◽  
C Toby St. Clair ◽  
Blake A Barbaree ◽  
...  

Abstract Information on how migratory populations are genetically structured during the overwintering season of the annual cycle can improve our understanding of the strength of migratory connectivity and help identify populations as units for management. Here, we use a genotype-by-sequencing approach to investigate whether population genetic structure exists among overwintering aggregations of the Pacific Dunlin subspecies (Calidris alpina pacifica) sampled at 2 spatial scales (within and among overwintering sites) in the eastern Pacific Flyway. Genome-wide analyses of 874 single nucleotide polymorphisms across 80 sampled individuals revealed no evidence for genetic differentiation among aggregations overwintering at 3 locations within the Fraser River Estuary (FRE) of British Columbia. Similarly, comparisons of aggregations in the FRE and those overwintering in southern sites in California and Mexico indicated no genetic segregation between northern and southern overwintering areas. These results suggest that Pacific Dunlin within the FRE, Sacramento Valley (California), and Guerrero Negro (Mexico) are genetically homogeneous, with no evident genetic structure between sampled sites or regions across the overwintering range. Despite no evidence for differentiation among aggregations, we identified a significant effect of geographical distance between sites on the distribution of individual genotypes in a redundancy analysis. A small proportion of the total genotypic variance (R2 =0.036, P = 0.011) was explained by the combined effect of latitude and longitude, suggesting weak genomic patterns of isolation-by-distance that are consistent with chain-like migratory connectivity between breeding and overwintering areas. Our study represents the first genome-scale investigation of population structure for a Dunlin subspecies and provides essential baseline estimates of genomic diversity and differentiation within the Pacific Dunlin.


Author(s):  
Eiichi Kobayashi ◽  
Kouhei Yurugi ◽  
Shunichi Koshimura

There is increasing concern over the possibility of the occurrence of huge Toukai, Tonankai, and Nankai earthquakes in the Nankai Trough, located in the Pacific Ocean off Japan. It is estimated that there is a 50% probability of a tsunami being generated by an earthquake in this area over the next 30 years. A tsunami attack on the coast of Japan would not only increase the sea level, but would also create strong horizontal flows in bays and ports. In particular, along the coastal area of Osaka Bay, Japan, there are numerous small ports where pleasure ships and/or fishery boats are moored. Any small ships moored in these ports would be subject to violent motion by strong lateral flows, even if they are moored to each other. As a consequence, the mooring lines would be cut, ships would move uncontrollably, and causing damage to facilities. Thus, it is very important from the viewpoint of marine-disaster prevention to gain a better understanding of the motion of small vessels originating in tsunami flows and to develop countermeasures in the face of a tsunami attack. In this paper, basic analyses of the ship motions resulting from a tsunami attack are carried out, and possible countermeasures are investigated. First, we describe mathematical models approximating the flow of tsunami and the abrupt maneuvers of relatively small vessels while being moored. Next, numerical simulations of the lateral motion of moored ships resulting from a tsunami attack on a fishery port located in the Osaka Bay are carried out. Additionally, the possibility of relatively high tension to be generated along the mooring lines is evaluated. Finally, the results of computer simulations demonstrate that such hazardous phenomena can be addressed with appropriate countermeasures.


Sign in / Sign up

Export Citation Format

Share Document