Plate morphs in freshwater samples of Gasterosteus aculeatus from Arctic and Atlantic Canada: Complementary comments on a recent contribution

1983 ◽  
Vol 61 (5) ◽  
pp. 1174-1177 ◽  
Author(s):  
Brian W. Coad

Additional analyses of museum samples for plate morphs in the freshwater threespine stickleback from Arctic and Atlantic Canada confirm the scarcity of the low morph in mainland Atlantic Canada as shown by Hagen and Moodie (D. W. Hagen and G. E. E. Moodie. 1982. Can. J. Zool. 60: 1032–1042). Insular Newfoundland samples show evidence that populations containing the low morph are not uncommon and this agrees well with Hagen and Moodie's climatic explanation for plate morph distribution. This climatic explanation does not, however, account for the high frequencies of low morph populations shown here to occur in Arctic Canada. Two populations are identified which may be monomorphic for the low morph, and a monomorphic partial population is reported from an inland stream. Both these types of populations are rare in eastern North America.

2017 ◽  
Vol 13 (11) ◽  
pp. 20170392 ◽  
Author(s):  
Matthew D. Regan ◽  
Ivan S. Gill ◽  
Jeffrey G. Richards

Anthropogenic increases in global temperature and agricultural runoff are increasing the prevalence of aquatic hypoxia throughout the world. We investigated the potential for a relatively rapid evolution of hypoxia tolerance using two isolated (for less than 11 000 years) populations of threespine stickleback: one from a lake that experiences long-term hypoxia (Alta Lake, British Columbia) and one from a lake that does not (Trout Lake, British Columbia). Loss-of-equilibrium (LOE) experiments revealed that the Alta Lake stickleback were significantly more tolerant of hypoxia than the Trout Lake stickleback, and calorimetry experiments revealed that the enhanced tolerance of Alta Lake stickleback may be associated with their ability to depress metabolic rate (as indicated by metabolic heat production) by 33% in hypoxia. The two populations showed little variation in their capacities for O 2 extraction and anaerobic metabolism. These results reveal that intraspecific variation in hypoxia tolerance can develop over relatively short geological timescales, as can metabolic rate depression, a complex biochemical response that may be favoured in long-term hypoxic environments.


1982 ◽  
Vol 60 (5) ◽  
pp. 1032-1042 ◽  
Author(s):  
D. W. Hagen ◽  
G. E. E. Moodie

In the threespine stickleback (Gasterosteus aculeatus) three plate morphs, controlled by major genes, are easily distinguished: the low-plated, partially plated, and completely plated morphs. We give the results of a geographic survey for these morphs, with 177 samples from New Brunswick, Prince Edward Island, and adjacent regions. The low-plated morph is virtually absent. Most sites are either monomorphic for the completely plated morph or polymorphic with high frequencies of that morph. Polymorphic sites are most frequent in fresh water where the frequency of partials is much higher. Polymorphic sites are also more than twice as frequent on Prince Edward Island than on the mainland. But sites with high frequencies of the partial morph, with one exception, occur only on the mainland. Populations with high frequencies of partials predominate in lakes and their tributaries near the sea. Hybridization between the low-plated leiurus and completely plated trachurus cannot account for most of the polymorphism in North America. The global distribution of plate morphs shows an association with climate, and the virtual absence of the low-plated morph in this survey can be accounted for by the action of climatic selection or an associated variable.


Zoomorphology ◽  
2020 ◽  
Author(s):  
Harald Ahnelt ◽  
David Ramler ◽  
Maria Ø. Madsen ◽  
Lasse F. Jensen ◽  
Sonja Windhager

AbstractThe mechanosensory lateral line of fishes is a flow sensing system and supports a number of behaviors, e.g. prey detection, schooling or position holding in water currents. Differences in the neuromast pattern of this sensory system reflect adaptation to divergent ecological constraints. The threespine stickleback, Gasterosteus aculeatus, is known for its ecological plasticity resulting in three major ecotypes, a marine type, a migrating anadromous type and a resident freshwater type. We provide the first comparative study of the pattern of the head lateral line system of North Sea populations representing these three ecotypes including a brackish spawning population. We found no distinct difference in the pattern of the head lateral line system between the three ecotypes but significant differences in neuromast numbers. The anadromous and the brackish populations had distinctly less neuromasts than their freshwater and marine conspecifics. This difference in neuromast number between marine and anadromous threespine stickleback points to differences in swimming behavior. We also found sexual dimorphism in neuromast number with males having more neuromasts than females in the anadromous, brackish and the freshwater populations. But no such dimorphism occurred in the marine population. Our results suggest that the head lateral line of the three ecotypes is under divergent hydrodynamic constraints. Additionally, sexual dimorphism points to divergent niche partitioning of males and females in the anadromous and freshwater but not in the marine populations. Our findings imply careful sampling as an important prerequisite to discern especially between anadromous and marine threespine sticklebacks.


Author(s):  
L. Leveelahti ◽  
P. Leskinen ◽  
E.H. Leder ◽  
W. Waser ◽  
M. Nikinmaa

Genetics ◽  
2021 ◽  
Vol 217 (1) ◽  
Author(s):  
Juntao Hu ◽  
Sara J S Wuitchik ◽  
Tegan N Barry ◽  
Heather A Jamniczky ◽  
Sean M Rogers ◽  
...  

Abstract Epigenetic mechanisms underlying phenotypic change are hypothesized to contribute to population persistence and adaptation in the face of environmental change. To date, few studies have explored the heritability of intergenerationally stable methylation levels in natural populations, and little is known about the relative contribution of cis- and trans-regulatory changes to methylation variation. Here, we explore the heritability of DNA methylation, and conduct methylation quantitative trait loci (meQTLs) analysis to investigate the genetic architecture underlying methylation variation between marine and freshwater ecotypes of threespine stickleback (Gasterosteus aculeatus). We quantitatively measured genome-wide DNA methylation in fin tissue using reduced representation bisulfite sequencing of F1 and F2 crosses, and their marine and freshwater source populations. We identified cytosines (CpG sites) that exhibited stable methylation levels across generations. We found that additive genetic variance explained an average of 24–35% of the methylation variance, with a number of CpG sites possibly autonomous from genetic control. We also detected both cis- and trans-meQTLs, with only trans-meQTLs overlapping with previously identified genomic regions of high differentiation between marine and freshwater ecotypes. Finally, we identified the genetic architecture underlying two key CpG sites that were differentially methylated between ecotypes. These findings demonstrate a potential role for DNA methylation in facilitating adaptation to divergent environments and improve our understanding of the heritable basis of population epigenomic variation.


Parasitology ◽  
2010 ◽  
Vol 137 (11) ◽  
pp. 1681-1686 ◽  
Author(s):  
D. C. HEINS ◽  
E. L. BIRDEN ◽  
J. A. BAKER

SUMMARYAn analysis of the metrics of Schistocephalus solidus infection of the threespine stickleback, Gasterosteus aculeatus, in Walby Lake, Alaska, showed that an epizootic ended between 1996 and 1998 and another occurred between 1998 and 2003. The end of the first epizootic was associated with a crash in population size of the stickleback, which serves as the second intermediate host. The likely cause of the end of that epizootic is mass mortality of host fish over winter in 1996–1997. The deleterious impact of the parasite on host reproduction and increased host predation associated with parasitic manipulation of host behaviour and morphology to facilitate transmission might also have played a role, along with unknown environmental factors acting on heavily infected fish or fish in poor condition. The second epizootic was linked to relatively high levels of prevalence and mean intensity of infection, but parasite:host mass ratios were quite low at the peak and there were no apparent mass deaths of the host. A number of abiotic and biotic factors are likely to interact to contribute to the occurrence of epizootics in S. solidus, which appear to be unstable and variable. Epizootics appear to depend on particular and, at times, rare sets of circumstances.


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