Genetic variability in reaction norms reflects differences in the ability of individuals, populations and ultimately species to respond to environmental change. By increasing our understanding of how ...genotype × environment interactions influence evolution, studies of genetic variation in phenotypic plasticity serve to refine our capacity to predict how populations will respond to natural and anthropogenic environmental variability, including climate change. Given the extraordinary variability in morphology, behaviour and life history in salmonids, one might anticipate the research milieu on reaction norms in these fishes to be empirically rich and intellectually engaging. Here, I undertake a review of genetic variability in continuous and discontinuous (threshold) norms of reaction in salmonid fishes, as determined primarily (but not exclusively) by common-garden experiments. Although in its infancy from a numerical publication perspective, there is taxonomically broad evidence of genetic differentiation in continuous, threshold and bivariate reaction norms among individuals, families and populations (including inter-population hybrids and backcrosses) for traits as divergent as embryonic development, age and size at maturity, and gene expression. There is compelling inferential evidence that plasticity is heritable and that population differences in reaction norms can reflect adaptive responses, by natural selection, to local environments. As a stimulus for future work, a series of 20 research questions are identified that focus on reaction-norm variability, selection, costs and constraints, demographic and conservation consequences, and genetic markers and correlates of phenotypic plasticity.
Over-exploitation and subsequent collapse of marine fishes has focused
attention on the ability of affected populations to recover to former abundance
levels and on the degree to which their ...persistence is
threatened by extinction. Although potential for recovery
has been assessed indirectly, actual changes in population
size following long-term declines have not been examined empirically. Here
I show that there is very little evidence for rapid recovery from prolonged
declines, in contrast to the perception that marine fishes are highly resilient
to large population reductions. With the possible exception
of herring and related species that mature early in life and are fished with
highly selective equipment, my analysis of 90 stocks reveals that many gadids
(for example, cod, haddock) and other non-clupeids (for example, flatfishes)
have experienced little, if any, recovery as much as 15 years after 45-99%
reductions in reproductive biomass. Although the effects of overfishing on
single species may generally be reversible, the actual time
required for recovery appears to be considerable. To exempt marine fishes
from existing criteria used to assign extinction risk would
be inconsistent with precautionary approaches to fisheries management and
the conservation of marine biodiversity.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
Background
Previous studies have identified an inverse association between melanoma and smoking; however, data from population‐based studies are scarce.
Objectives
To determine the ...association between smoking and socioeconomic (SES) on the risk of development of melanoma. Furthermore, we sought to determine the implications of smoking and SES on survival.
Methods
We conducted a population‐based case–control study. Cases were identified from the Welsh Cancer Intelligence and Surveillance Unit (WCISU) during 2000–2015 and controls from the general population. Smoking and SES were obtained from data linkage with other national databases. The association of smoking status and SES on the incidence of melanoma were assessed using binary logistic regression. Multivariate survival analysis was performed on a melanoma cohort using a Cox proportional hazard model using survival as the outcome.
Results
During 2000–2015, 9636 patients developed melanoma. Smoking data were obtained for 7124 (73·9%) of these patients. There were 26 408 controls identified from the general population. Smoking was inversely associated with melanoma incidence odds ratio (OR) 0·70, 95% confidence interval (CI) 0·65–0·76. Smoking was associated with an increased overall mortality hazard ratio (HR) 1·30, 95% CI 1·09–1·55, but not associated with melanoma‐specific mortality. Patients with higher SES had an increased association with melanoma incidence (OR 1·58, 95% CI 1·44–1·73). Higher SES was associated with an increased chance of both overall (HR 0·67, 95% CI 0·56–0·81) and disease‐specific survival (HR 0·69, 95% CI 0·53–0·90).
Conclusions
Our study has demonstrated that smoking appeared to be associated with reduced incidence of melanoma. Although smoking increases overall mortality, no association was observed with melanoma‐specific mortality. Further work is required to determine if there is a biological mechanism underlying this relationship or an alternative explanation, such as survival bias.
What's already known about this topic?
Previous studies have been contradictory with both negative and positive associations between smoking and the incidence of melanoma reported.
Previous studies have either been limited by publication bias because of selective reporting or underpowered.
What does this study add?
Our large study identified an inverse association between smoking status and melanoma incidence.
Although smoking status was negatively associated with overall disease survival, no significant association was noted in melanoma‐specific survival.
Socioeconomic status remains closely associated with melanoma. Although higher socioeconomic populations are more likely to develop the disease, patients with lower socioeconomic status continue to have a worse prognosis.
Linked Comment: Thompson and Friedman. Br J Dermatol 2020; 182:1080.
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Chromosomal rearrangements such as inversions can play a crucial role in maintaining polymorphism underlying complex traits and contribute to the process of speciation. In Atlantic cod (Gadus ...morhua), inversions of several megabases have been identified that dominate genomic differentiation between migratory and nonmigratory ecotypes in the Northeast Atlantic. Here, we show that the same genomic regions display elevated divergence and contribute to ecotype divergence in the Northwest Atlantic as well. The occurrence of these inversions on both sides of the Atlantic Ocean reveals a common evolutionary origin, predating the >100 000-year-old trans-Atlantic separation of Atlantic cod. The long-term persistence of these inversions indicates that they are maintained by selection, possibly facilitated by coevolution of genes underlying complex traits. Our data suggest that migratory behaviour is derived from more stationary, ancestral ecotypes. Overall, we identify several large genomic regions-each containing hundreds of genes-likely involved in the maintenance of genomic divergence in Atlantic cod on both sides of the Atlantic Ocean.
Natural environmental change has produced countless opportunities for species to disperse into and persist in habitats where they previously did not exist. Introduction and stocking programmes have ...facilitated similar sorts of colonization opportunities across considerably greater geographical scales and often in much shorter periods of time. Even though the mechanism of colonization differs, the result can be the same: evolutionary change in the colonizing population in response to novel selection pressures. As a consequence, some human‐mediated fish transfers have unintentionally yielded novel research opportunities to study how phenotypes and genes interact with their environment and affect ecological and evolutionary change. The primary purpose here is to explore how work, directly or indirectly involved with human‐mediated transfers, has unintentionally yielded novel research and research opportunities in fish ecology and evolution. Insights have produced new knowledge or altered previously held perceptions on topics such as local adaptation, rate of evolutionary change, phenotypic plasticity, alternative reproductive strategies, population structure and colonization probability. Well‐documented stocking programmes, especially in terms of history, numbers and original population sources, can provide highly fertile ground for generating further insights on the ecology and evolution of fishes and of the factors likely to influence the success of conservation‐based, restoration programmes.
The recovery of depleted species depends on their population dynamics at low abundance. Classical population growth models, applied widely in fisheries science, assume that per capita offspring ...production increases as abundance declines (compensation). However, slow or absent recovery by many depleted fishes might reflect unexpectedly weak compensation or the presence of Allee effects (depensation). Using meta-analytical techniques to describe reproductive dynamics, we find considerable variability among 207 exploited marine fish stocks (104 species) in how standardized per capita population growth changes with abundance. Although many species exhibit strong compensatory dynamics (negative density dependence), others show much weaker compensation than expected, and some exhibit evidence of an Allee effect, such as Atlantic cod (
Gadus morhua
) and Alaskan walleye pollock (
Theragra chalcogramma
). As data at low levels of abundance become increasingly available, it appears that compensation, while strong in some species, is comparatively weak or nonexistent in others, thus providing an explanation for why the recovery of some depleted stocks, despite reductions in exploitation, has been considerably less than what classic models of population growth would otherwise suggest.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We investigate mitochondrial (COI, 16S rDNA) and nuclear (ITS2, 28S rDNA) genetic structure of North East Atlantic lineages of Terebellides, a genus of sedentary annelids mainly inhabiting ...continental shelf and slope sediments. We demonstrate the presence of more than 25 species of which only seven are formally described. Species boundaries are determined with molecular data using a broad range of analytical methods. Many of the new species are common and wide spread, and the majority of the species are found in sympatry with several other species in the complex. Being one of the most regularly encountered annelid taxa in the North East Atlantic, it is more likely to find an undescribed species of Terebellides than a described one.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•A framework to assess animal health impact on greenhouse gas (GHG) intensity is proposed.•We assessed impact of parasitism on performance and GHG emissions (CH4, N2O) in ...ewes.•Parasitism reduced intake, lamb weight gain and increased ewe body weight loss.•Daily GHG production reduced but GHG intensity for lamb weight gain increased.•Parasitism contributes to global warming largely from reduced feed efficiency.
Here we provide the first known direct measurements of pathogen challenge impacts on greenhouse gas production, yield and intensity. Twin-rearing ewes were ad libitum fed pelleted lucerne from day −32 to 36 (day 0 is parturition), and repeatedly infected with 10,000 Teladorsagia circumcincta infective larvae (n=16), or sham-dosed with water (n=16). A third group of 16 ewes were fed at 80% of uninfected ewes’ feed intake during lactation. Methane emissions were measured in respiration chambers (day 30–36) whilst total tract apparent nutrient digestibility around day 28 informed calculated manure methane and nitrous oxide emissions estimates. Periparturient parasitism reduced feed intake (−9%) and litter weight gain (−7%) and doubled maternal body weight loss. Parasitism reduced daily enteric methane production by 10%, did not affect the methane yield per unit of dry matter intake but increased the yield per unit of digestible organic matter intake by 14%. Parasitism did not affect the daily calculated manure methane and nitrous oxide production, but increased the manure methane and nitrous oxide yields per unit of dry matter intake by 16% and 4%, respectively, and per unit of digestible organic matter intake by 46% and 31%, respectively. Accounting for increased lucerne input for delayed weaning and maternal body weight loss compensation, parasitism increased the calculated greenhouse gas intensity per kg of lamb weight gain for enteric methane (+11%), manure methane (+32%) and nitrous oxide (+30%). Supplemented with the global warming potential associated with production of pelleted lucerne, we demonstrated that parasitism increased calculated global warming potential per kg of lamb weight gain by 16%, which was similar to the measured impact of parasitism on the feed conversion ratio. Thus, arising from a pathogen-induced feed efficiency reduction and modified greenhouse gas emissions, we demonstrated that ovine periparturient parasitism increases greenhouse gas intensity. This implies that ewe worm control can not only improve production efficiency but also reduce the environmental footprint of sheep production systems.
Changes to life history traits are often concomitant with prolonged periods of exploitation. In the Northwest Atlantic, 30- to 40-year declines of more than 90% of Atlantic cod (Gadus morhua) have ...been associated with significant reductions in age and length at maturity, changes most parsimoniously explained as genetic responses to fishing. Increased survival costs of reproduction associated with earlier maturity, resulting in higher natural mortality and shorter life span, negatively affect population growth rate and rate of recovery. Coupled with lower hatching rate among first-time spawners and smaller size at maturity, a modest reduction in age from 6 to 4 years can reduce annual population growth in Atlantic cod by 25%30%, based on the output of a stochastic, age-structured life history model. Earlier maturity more than doubles the probability of negative population growth every generation. These results underscore the potential for fishing-induced changes to life history traits alone to generate slow or negligible recovery in marine fishes, exacerbating negative impacts on population growth resulting from ecosystem-level alterations to interspecific competition and predation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nonanadromous Atlantic salmon (Salmo salar) exhibit a combination of variation in life history, habitat, and species co-existence matched by few vertebrates. Distributed in eastern North America and ...northern Europe, habitat ranges from hundreds of metres of river to Europe's largest lakes. As juveniles, those with access to a lake usually migrate to feed and grow prior to reproduction. Prey such as smelt (Osmerus mordax, Osmerus eperlanus) and vendace (Coregonus albula) facilitate large body size (50-85 cm at maturity) and persistence in high-diversity (>20 fish species) environments; small-bodied salmon (10-30 cm at maturity), relying on insects as prey, coexist with few (fewer than five) other fishes. At maturity, weight varies more than 400-fold (17 to 7200 g) among populations, fecundity more than 150-fold (33 to 5600), and longevity almost fivefold (3 to 14 years). Landlocked salmon are managed to support sustainable fishing, achieve conservation and restoration targets, and mitigate threats; successes are evident but multiple challenges persist. Extraordinary variability in life history coupled with extensive breadth of habitat and species co-existence render landlocked Atlantic salmon singularly impressive from a biodiversity perspective.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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