The ecology of hybrids between the peamouth, Mylocheilus caurinus, and the redside shiner, Richardsonius balteatus, at Stave Lake, British Columbia, Canada

1993 ◽  
Vol 71 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Nevin Aspinwall ◽  
Douglas Carpenter ◽  
Judy Bramble

Extensive hybridization between the peamouth, Mylocheilus caurinus, and the redside shiner, Richardsonius balteatus, at Stave Lake, British Columbia, provided an opportunity to examine the ecology of hybrid fishes over a 26-year period. Spatial distribution and feeding ecology of the hybrids were compared with those of the parental species. At Stave Lake, M. caurinus was primarily oriented to the limnetic zone at all depths, while R. balteatus was oriented to surface waters in the littoral zone. The hybrids (F1 hybrids and hybrid backcrosses to M. caurinus combined) mimicked the M. caurinus pattern, being significantly more abundant in the limnetic zone. Adult M. caurinus consumed primarily zooplankton with occasional adult insects, while R. balteatus consumed primarily adult insects. The diet of hybrids was not significantly different from that of M. caurinus; they consumed large quantities of zooplankton and some insects.

1993 ◽  
Vol 71 (3) ◽  
pp. 550-560 ◽  
Author(s):  
Nevin Aspinwall ◽  
John D. McPhail ◽  
Allan Larson

Hybridizing populations of the peamouth, Mylocheilus caurinus, and the redside shiner, Richardsonius balteatus, from Stave Lake, British Columbia, were examined three times over a 26-year interval to determine (i) whether swamping or introgression was occurring, (ii) whether the hybrids were being continually produced, and (iii) whether the composition of the hybrid population was constant. The hybrids were present at all three sampling periods with a rate of hybridization of 5.7% in 1966–1967, 14.1% in 1982, and 6.7% in 1991. F1 hybrids comprised no less than 80% of the hybrids at each sampling period. The remaining hybrids were mostly hybrid backcrosses to M. caurinus. Analysis of mitochondrial DNA (mtDNA) revealed that F1 hybrids were produced by females of both species, although not in equal proportions each year. Hybrid backcrosses to M. caurinus were more abundant as fingerlings than as adults, suggesting that selection is operating against them. After a 26-year interval, no evidence of swamping was detected when diagnostic morphological characters were employed. An analysis of allozyme data suggests that introgression is not occurring. The continued production of the hybrids over the three sampling periods suggests continuity in the environmental factors responsible for hybridization. Likewise, the greater proportion of F1 hybrids than backcrosses over the three sampling periods suggests a continued selective disadvantage of the backcrosses.


1995 ◽  
Vol 73 (2) ◽  
pp. 330-338 ◽  
Author(s):  
Nevin Aspinwall ◽  
John D. McPhail

Since at least 1952, the peamouth, Mylocheilus caurinus and the redside shiner, Richardsonius balteatus, have engaged in extensive hybridization (5.7–14.1% of the combined gene pools) in Stave Lake, British Columbia. A research project initiated in 1966 and continued to 1991 demonstrated that genetic swamping of the two species has not occurred. A study was conducted to determine the strength of premating and postmating isolating mechanisms between these two species. Temporal isolation is weak because both species had spawning periods in Devils Creek that overlapped by approximately 1.5 months. Also, both species spawned at night, and only on nights preceded by a sunny day. Both species were group spawners and both spawned on the first riffle of Devils Creek. Hybrid sterility is not well developed. While male F1 hybrids have low fertility, female F1 hybrids are as fertile as females of either species and would allow swamping if other postmating mechanisms were not operating. Hybrid inferiority was examined by laboratory experiments in which we measured survival of fingerling hybrids. While F1 hybrids displayed survival equal to that of M. caurinus, hybrid backcrosses to M. caurinus showed a 20% lower survival rate than M. caurinus. Also, hybrid backcrosses to M. caurinus included a significant proportion (8.4%) of deformed individuals.


1953 ◽  
Vol 31 (3) ◽  
pp. 211-225 ◽  
Author(s):  
C. C. Lindsey

Anal fin rays were counted on 4766 specimens of Richardsonius balteatus from 61 localities in British Columbia. Individual counts varied from 10 to 21, and mean counts of different populations varied from 12.06 to 17.51. Significant differences in counts occurred between different bodies of water, between recently introduced populations and their parent stock, between different parts of the same lake, and between different year classes. Ray counts tended to be higher amongst females in populations with high over-all means, and higher amongst males in populations with low over-all means. A positive correlation was demonstrated between water temperatures recorded in the vicinity of developing fry and the mean numbers of anal rays produced. Within each latitudinal zone a similar correlation occurred between mean ray count and average air temperature during the spawning season, but data on 109 means of populations in U.S.A. and Canada indicated a tendency, probably genetic, towards production, at equivalent temperature, of higher ray count towards the northern end of the range. Loose correlations between anal ray count and certain other morphological characteristics suggest that these may be dependent on more or less common environmental factors but are not linked by direct causality.


2004 ◽  
Vol 55 (8) ◽  
pp. 809 ◽  
Author(s):  
Simon R. Bryars ◽  
Jon. N. Havenhand

A plankton-sampling programme for blue swimmer crab (Portunus pelagicus) larvae was conducted in the temperate waters of Gulf St Vincent, South Australia, to investigate: (1) if larval hatching is seasonal; (2) if larvae are restricted to surface waters; (3) if larvae are hatched offshore; and (4) if larval development occurs offshore. The temporal and spatial distribution and abundance of larvae indicated that hatching and zoeal development occur mainly in deeper offshore waters during the warmer months of November to March, and that zoeal development occurs in a range of depths from the neuston to at least 14 m. Although peaks in abundance usually occurred in the upper 3 m, zoeae were distributed throughout the water column, with the majority occurring in sub-surface waters below 1 m depth. There was no evidence for a daylight ontogenetic or tidal vertical migration in the four zoeal stages. Limited sampling revealed no evidence for a diurnal vertical migration in stage-1 zoea. Although the seasonal and inshore-offshore patterns of hatching observed in the study were typical for a portunid species, the broad vertical distribution differed from that observed for P. pelagicus in previous studies.


2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Marshal S. Hoy ◽  
Carl O. Ostberg

Abstract Objective A quantitative PCR (qPCR) assay for the detection of redside shiner (Richardsonius balteatus) environmental DNA (eDNA) was designed as a side product of a larger project aimed at using eDNA to determine the presence and geographic extent of native and non-native fishes in the reservoirs and associated tributaries above the three mainstem dams (Ross, Diablo, Gorge) on the Skagit River, Washington, USA. The eDNA survey results can be used to help guide additional sampling efforts that include traditional sampling methods, such as electrofishing and netting. Results The redside shiner qPCR assay (RSSCOI_540-601) was validated by testing for sensitivity using redside shiner genomic DNA from three different populations and by testing for specificity against 30 potentially sympatric species. No non-target amplification was observed in our validation tests. We then evaluated the assay on field-collected water samples where there are known populations of redside shiner and a negative control site where the target species is known to be absent. The field-collected water samples tested positive at the redside shiner sites and tested negative at the negative control site. The assay could provide resource managers with an effective means for surveying and monitoring redside shiner populations.


1981 ◽  
Vol 38 (1) ◽  
pp. 10-15 ◽  
Author(s):  
Jean-Guy J. Godin

Stomach analyses showed that pink salmon fry fed mainly during daylight hours in the littoral zone of Departure Bay and Hammond Bay, British Columbia, in May. Although the diurnal feeding patterns of the fish differed slightly between the two bays, maximum mean prey biomass in the fishes' stomachs occurred near or at dusk in both bays. Daily rations consumed by Departure Bay and Hammond Bay fish were estimated to be 13.1 and 6.6% of their dry body weight, respectively. The fry consumed similar prey items in both bays, but in differing proportions. Harpacticoid copepods, copepod nauplii, and barnacle larvae comprised numerically 93.1 and 86.2% of the diets of Departure Bay and Hammond Bay fish, respectively. About 38% of the diet of Departure Bay fish and 51% of the diet of Hammond Bay fish comprised epibenthic prey, mainly harpacticoid copepods. The data provide additional support for the importance of the detritus-microbe-consumer type food chain supporting the production of pink salmon during their early period of marine residency.Key words: pink salmon, feeding behavior, daily rhythm, diet, ration, British Columbia


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