Seasonal changes in the prolactin cell of the pituitary gland of the freshwater stickleback, Gasterosteus aculeatus, form leiurus

1974 ◽  
Vol 152 (1) ◽  
Author(s):  
Michael Benjamin
Keyword(s):  
Pituitary Gland ◽  
Seasonal Changes ◽  
Gasterosteus Aculeatus ◽  
Prolactin Cell ◽  
Freshwater Stickleback

Seasonal changes in carotenoid and lipid storage by threespine stickleback, Gasterosteus aculeatus

2013 ◽  
Vol 97 (2) ◽  
pp. 209-214 ◽  
Author(s):  
C. A. Black ◽  
R. J. Scott ◽  
M. A. Bernards
Keyword(s):  
Seasonal Changes ◽  
Gasterosteus Aculeatus ◽  
Threespine Stickleback ◽  
Lipid Storage

Postglacial evolution in lateral plate morphs in Norwegian freshwater populations of the threespine stickleback (Gasterosteus aculeatus)

1995 ◽  
Vol 73 (5) ◽  
pp. 898-906 ◽  
Author(s):  
Tom Klepaker
Keyword(s):  
Gasterosteus Aculeatus ◽  
Alternative Hypothesis ◽  
Morphological Variability ◽  
Threespine Stickleback ◽  
Evolutionary Stage ◽  
Lateral Plate ◽  
Land Uplift ◽  
Founding Population ◽  
Freshwater Stickleback ◽  
Age Range

Norwegian freshwater stickleback populations were founded after the last glacial period, and the progressive uplift of the land has produced an age range (1000 – 13 000 years) of the stickleback habitats. Most of the freshwater populations of today have probably been formed by isolation of marine sticklebacks in the process of land uplift. The freshwater threespine stickleback is known for its great morphological variability. Three distinct morphs ("low," "partial," and "complete") are recognized on the basis of variation in the lateral row of plates. Among the Norwegian populations, all three morphs were found, but the low morph was by far the most common and occurred mostly in monomorphic populations. The presence of the complete and partial morphs was mostly restricted to young lakes near the sea. It is likely that the plate polymorphism in this region is a transitionary evolutionary stage from a founding population dominated by complete to a monomorphic low population. The hypothesis of a polytypic origin of the low morph is discussed, and an alternative hypothesis is proposed. Within each plate morph, the number of plates also varied, and populations with exceptionally low plate numbers were mostly confined to three different areas. Within these areas, populations with plateless specimens also occurred. These plateless specimens tended to inhabit old lakes. The low plate number and plateless populations were found in parts of Norway that were deglaciated early. The advanced plate reduction can therefore be a result of a longer period of isolation and freshwater evolution. Other populations may be on their way towards extreme plate reduction, but have not yet reached the level of platelessness.

Seasonal changes in the basophilic cells of the pituitary gland of the ground squirrel (Citellus tridecemlineatus)

1958 ◽  
Vol 131 (4) ◽  
pp. 727-735 ◽  
Author(s):  
R. A. Hoffman ◽  
M. X. Zarrow
Keyword(s):  
Pituitary Gland ◽  
Seasonal Changes ◽  
Ground Squirrel

scholarly journals All day-long: Sticklebacks effectively forage on whitefish eggs during all light conditions

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255497
Author(s):  
Jan Baer ◽  
Sarah Maria Gugele ◽  
Joachim Bretzel ◽  
J. Tyrell DeWeber ◽  
Alexander Brinker
Keyword(s):  
Egg Production ◽  
Gasterosteus Aculeatus ◽  
Energy Content ◽  
Stomach Content Analysis ◽  
Pelagic Zone ◽  
Light Conditions ◽  
Egg Predation ◽  
Large Numbers ◽  
Potential Benefits ◽  
Freshwater Stickleback

The three-spined stickleback Gasterosteus aculeatus invaded Lake Contance in the 1940s and expanded in large numbers from an exclusively shoreline habitat into the pelagic zone in 2012. Stickleback abundance is very high in the pelagic zone in winter near the spawning time of pelagic whitefish Coregonus wartmanni, and it is hypothesized that this is triggered by the opportunity to consume whitefish eggs. Field sampling has qualitatively confirmed predation of whitefish eggs by stickleback, but quantification has proven difficult due to stormy conditions that limit sampling. One fundamental unknown is if freshwater stickleback, known as visual feeders, can successfully find and eat whitefish eggs during twilight and night when whitefish spawn. It is also unknown how long eggs can be identified in stomachs following ingestion, which could limit efforts to quantify egg predation through stomach content analysis. To answer these questions, 144 individuals were given the opportunity to feed on whitefish roe under daylight, twilight, and darkness in controlled conditions. The results showed that stickleback can ingest as many as 100 whitefish eggs under any light conditions, and some individuals even consumed maximum numbers in complete darkness. Furthermore, eggs could be unambiguously identified in the stomach 24 hours after consumption. Whitefish eggs have 28% more energy content than the main diet of sticklebacks (zooplankton) based on bomb-calorimetric measurements, underlining the potential benefits of consuming eggs. Based on experimental results and estimates of stickleback abundance and total egg production, stickleback could potentially consume substantial proportions of the total eggs produced even if relatively few sticklebacks consume eggs. Given the evidence that stickleback can feed on eggs during nighttime spawning and may thereby hamper recruitment, future studies aimed at quantifying actual egg predation and resulting effects on the whitefish population are urgently needed.

Statistical Studies of the Seasonal Changes in the Pituitary Gland of Rasbora daniconius (Pisces: Cyprinidae)

Copeia ◽  
1973 ◽  
Vol 1973 (2) ◽  
pp. 348 ◽  
Author(s):  
H. N. Bhargava ◽  
A. K. Raizada
Keyword(s):  
Pituitary Gland ◽  
Seasonal Changes ◽  
Statistical Studies

Genetic variability in freshwater and anadromous sticklebacks (Gasterosteus aculeatus) of southern British Columbia

1985 ◽  
Vol 63 (3) ◽  
pp. 528-533 ◽  
Author(s):  
R. E. Withler ◽  
J. D. McPhail
Keyword(s):  
British Columbia ◽  
Gasterosteus Aculeatus ◽  
Electrophoretic Variation ◽  
Average Heterozygosity ◽  
Polymorphic Loci ◽  
Allelic Frequencies ◽  
Marine Habitats ◽  
Freshwater Habitats ◽  
Threespine Sticklebacks ◽  
Freshwater Stickleback

Electrophoretic variation at eight loci was compared between anadromous and freshwater populations of threespine sticklebacks (Gasterosteus aculeatus) collected from 56 sites in southwestern British Columbia and northwestern Washington. Allelic frequencies at five polymorphic loci were heterogeneous among populations and the average allelic frequencies at four loci differed between anadromous and freshwater sticklebacks. The average number of polymorphic loci was greater in anadromous (4.6) than in freshwater (3.2) populations. The average heterozygosity was 0.113 ± 0.001 in anadromous and 0.117 ± 0.003 in freshwater stickleback populations. Anadromous populations were more polymorphic but less heterogeneous than freshwater populations. The standardized genetic variance indicated only moderate differentiation among anadromous populations from marine habitats, but considerable differentiation among populations from freshwater habitats. Our data are consistent with the hypothesis of postglacial polyphyletic origins for freshwater populations of Gasterosteus, but also indicate that selection favours different alleles in marine and freshwater environments, at least at the Mdh-1 locus.

scholarly journals Seasonal Changes in the Pituitary Gland of the Eel

BMJ ◽  
1940 ◽  
Vol 1 (4135) ◽  
pp. 565-567 ◽  
Author(s):  
H. M. Evans
Keyword(s):  
Pituitary Gland ◽  
Seasonal Changes
Sign in / Sign up

Export Citation Format

Share Document