Morphological Divergence and the Organization of Trophic Characters Among Lacustrine Populations of the Threespine Stickleback (Gasterosteus aculeatus)

1987 ◽  
Vol 44 (11) ◽  
pp. 1820-1829 ◽  
Author(s):  
Patrick A. Lavin ◽  
J. D. McPhail

A multivariate solution for dealing with patterns of character covariance, when character genotypic covariances are known, has been applied to the organization of trophic morphology among lacustrine populations of the threespine stickleback (Gasterosteus aculeatus). The quantitative genetics governing eight trophic characters were investigated using representative populations from each of three known trophic ecotypes (open-water, littoral, and intermediate) which occur in the same drainage. Character heritabilities (0.19–0.84) were all significant. Estimates of character genetic correlations (−0.65 < rG < 0.85) were obtained and their standard errors were calculated by bootstrapping. Cluster analyses of the genetic correlation matrices defined two character suites, head shape and gill raker structure. Selection gradients between trophic ecotypes indicated that directional selection had operated most strongly on characters related to food size (upper jaw length and gill raker number). These results support the hypothesis that interpopulation variability in trophic morphology is organized as an adaptive response to local selection pressures.

1974 ◽  
Vol 31 (6) ◽  
pp. 1155-1157 ◽  
Author(s):  
Brian W. Coad ◽  
G. Power

Samples of threespine sticklebacks, Gasterosteus aculeatus, from two lakes and a river in the Matamek River system, Québec were analyzed for five meristic characters. Mean vertebral number differed for each area (range 32.00–32.85) but mean soft fin ray number showed little variation (dorsal rays 11.52–11.79, anal rays 8.68–8.76). Gill raker number was higher in the lake samples (21.25 and 21.80) than in the river sample (20.76). In Matamek Lake only semiarmatus plate morphs were found; in Bill Lake, semiarmatus and trachurus morphs in a ratio of 4:1 with about 10% intermediate; and in the lower Matamek River, semiarmatus and, at a low frequency, leiurus morphs.


1986 ◽  
Vol 43 (12) ◽  
pp. 2455-2463 ◽  
Author(s):  
P. A. Lavin ◽  
J. D. McPhail

We investigated differences in the morphological and behavioural contributions to foraging success among three morphotypes (open-water, littoral, and intermediate) of the threespine stickleback (Gasterosteus aculeatus) from a single drainage system on Vancouver Island. Stomach contents from wild samples showed diet to be dependent on morphotype. Interpopulation differences in trophic morphology were associated with differences in foraging success on given prey types. The longer jaw of the bottom-browsing littoral morphotype allowed it to ingest significantly larger prey then either the intermediate or open-water populations. In addition, the littoral type spent less time manipulating benthic prey then either the open-water or intermediate morphotype. The latter observation is independent of interpopulation differences in jaw length. Both the planktivorous open-water morphotype and intermediate morphotypes were superior foragers in experiments on water column prey. The differences in water column foraging success are associated with interpopulation differences in gill raker morphology. Our results support the conclusion that inter population divergence in trophic phenotype is an adaptive response to differences in the primary trophic resources available in lakes of different morphometry.


1985 ◽  
Vol 63 (11) ◽  
pp. 2632-2638 ◽  
Author(s):  
P. A. Lavin ◽  
J. D. Mcphail

To assess interpopulation levels of morphological variability populations of Gasterosteus aculeatus were sampled from lakes within the upper Cowichan River system (Vancouver Island, British Columbia). Phenotypic divergence between populations is assumed to be a postglacial event. Nine characters were scored; eight were related to feeding and the ninth character was lateral plate number. All populations were the low plate morph; however, populations of Gasterosteus in lakes lacking piscivorous fish had significantly fewer lateral plates than populations in lakes with predatory fish species. Two distinct trophic "morphotypes" were identified, each one associated with a specific lake environment. Populations inhabiting benthic-dominated environments were found to possess reduced gill raker number and reduced gill raker length but increased upper jaw length relative to populations from limnetic environments. We propose that the interpopulation variability in trophic morphology is a response to trophic resource differences between lakes.


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.


2010 ◽  
Vol 40 (5) ◽  
pp. 917-927 ◽  
Author(s):  
Desmond J. Stackpole ◽  
René E. Vaillancourt ◽  
Geoffrey M. Downes ◽  
Christopher E. Harwood ◽  
Brad M. Potts

Pulp yield is an important breeding objective for Eucalyptus globulus Labill., but evaluation of its genetic control and genetic correlations with other traits has been limited by its high assessment cost. We used near infrared spectroscopy to study genetic variation in pulp yield and other traits in a 16-year-old E. globulus trial. Pulp yield was predicted for 2165 trees from 467 open-pollinated families from 17 geographic subraces. Significant differences between subraces and between families within subraces were detected for all traits. The high pulp yield of southern Tasmanian subraces suggested that their economic worth was previously underestimated. The narrow-sense heritability of pulp yield was medium (0.40). The significant positive genetic correlation between pulp yield and diameter (0.52) was at odds with the generally neutral values reported. The average of the reported genetic correlations between pulp yield and basic density (0.50) was also at odds with our nonsignificant estimate. Pulp yield of the subraces increased with increasing latitude, producing a negative correlation with density (–0.58). The absence of genetic correlations within subraces between pulp yield and density suggests that the correlation may be an independent response of the two traits to the same or different selection gradients that vary with latitude.


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.


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