Seasonal changes in the histology of the gonads and dorsal skin of the fathead minnow, Pimephales promelas

1978 ◽  
Vol 56 (10) ◽  
pp. 2103-2109 ◽  
Author(s):  
R. J. F. Smith
Keyword(s):  
Seasonal Changes ◽  
Pimephales Promelas ◽  
Mucous Cell ◽  
Cell Number ◽  
Alarm Substance ◽  
Breeding Period ◽  
Dorsal Skin ◽  
Nonbreeding Season ◽  
Alarm Substance Cells ◽  
Dermal Connective Tissue

In central Saskatchewan gonad weights of male and female fathead minnows reach peak values between June 1 and July 31. The precise timing of the peak seems to be determined by local weather (temperature). Gonad histology shows a predominance of early gametogenic stages during winter with gametogene sis being completed in the spring. The histology of the dorsal skin is similar in both sexes during the nonbreeding season but males develop a dorsal pad during the breeding season. Pad development involves seasonal changes in epidermal thickness, mucous cell number, and dermal connective tissue thickness. Males also lose their alarm substance cells briefly during the peak breeding period.

Effect of hormone treatments on alarm substance cell counts in the pearl dace, Semotilus margarita

1986 ◽  
Vol 64 (2) ◽  
pp. 291-295 ◽  
Author(s):  
Jeaniene D. Smith ◽  
R. J. F. Smith
Keyword(s):  
Pimephales Promelas ◽  
Mucous Cell ◽  
Cell Loss ◽  
Alarm Substance ◽  
Androgen Treatment ◽  
Cell Counts ◽  
Sexual Characteristics ◽  
Alarm Substance Cells ◽  
The Difference ◽  
Induced Changes

The seasonal loss of alarm substance cells that normally occurs in breeding male and female pearl dace, Semotilus margarita, could not be induced by treatment with androgen, estrogen, salmon gonadotropin, or prolactin. Treatment with carp pituitary did lead to a significant reduction in alarm substance cell numbers. Androgen treatment induced changes in tuberculation and mucous cell counts. Salmon gonadotropin and carp pituitary increased breeding colouration. Prolactin treatment increased mucous cell counts. The lack of response of pearl dace alarm substance cells to androgen contrasts with the situation in fathead minnows, Pimephales promelas, where seasonal alarm substance cell loss is under androgen control. The difference may reflect differences in the annual cycle of secondary sexual characteristics.

Male fathead minnows (Pimephales promelas Rafinesque) retain their fright reaction to alarm substance during the breeding season

1976 ◽  
Vol 54 (12) ◽  
pp. 2230-2231 ◽  
Author(s):  
R. J. F. Smith
Keyword(s):  
Breeding Season ◽  
Pimephales Promelas ◽  
Field Tests ◽  
Alarm Substance ◽  
Skin Extract ◽  
Fathead Minnows ◽  
Fright Reaction ◽  
Alarm Substance Cells

In laboratory and field tests, breeding male fathead minnows respond to conspecific skin extract with a fright reaction despite their own seasonal loss of alarm substance cells. Their fright reaction is facilitated by the presence of other fatheads.

Seasonal loss of alarm substance cells in North American cyprinoid fishes and its relation to abrasive spawning behaviour

1976 ◽  
Vol 54 (7) ◽  
pp. 1172-1182 ◽  
Author(s):  
R. Jan F. Smith
Keyword(s):  
Histological Examination ◽  
North American ◽  
Seasonal Changes ◽  
Alarm Substance ◽  
Epidermal Thickness ◽  
Mucus Production ◽  
Tentative Evidence ◽  
Substance Loss ◽  
Spawning Behaviour ◽  
Alarm Substance Cells

Histological examination of skin from preserved specimens of nine species of cyprinoids and one catastomid revealed seasonal loss of alarm substance cells in the males from seven cyprinoid species and reduction in the females from two species. Six of these species have abrasive spawning behaviour, while the behaviour of the seventh species has not been extensively studied. This is taken as tentative evidence that seasonal alarm substance loss is related to abrasive spawning behaviour. Several species also show seasonal changes in mucus production and epidermal thickness.

Winter coexistence of voles in spruce forest: relevance of seasonal changes in aggression

1975 ◽  
Vol 53 (8) ◽  
pp. 1004-1011 ◽  
Author(s):  
Brian N. Turner ◽  
Michael R. Perrin ◽  
Stuart L. Iverson
Keyword(s):  
Microtus Pennsylvanicus ◽  
Meadow Vole ◽  
Breeding Period ◽  
Spruce Forest ◽  
Vole Population ◽  
Reproductive Condition ◽  
Interspecific Aggression ◽  
Meadow Voles ◽  
Nonbreeding Season ◽  
Short Period

Beginning in November 1973, numerous meadow voles (Microtus pennsylvanicus) moved onto a spruce forest grid occupied by red-backed voles (Clethrionomys gapperi). A resident meadow vole population resulted, the two species coexisting until April 1974, when most meadow voles disappeared from the grid during a relatively short period. Interspecific aggression levels, as determined from voles temporarily removed from the populations and tested in paired encounters in a laboratory arena, were low during the winter, but increased when males of both species entered reproductive condition in the spring. Microtus was generally dominant in early breeding period encounters, but this dominance declined concurrently with the meadow voles' disappearance from the forest. It is argued that meadow voles did not leave the forest to breed, or because the snow cover melted, since this species will live and reproduce in forest in the absence of Clethrionomys. The results are interpreted as support for an earlier hypothesis that competitive habitat exclusion varies seasonally with reproduction-related aggression. Thus, these species apparently may coexist in either of their preferred habitats when interspecific aggression is low (the nonbreeding season), but this relationship terminates when interspecific aggression levels increase with the resumption of breeding in the spring.

THE FRIGHT REACTION IN NORTH AMERICAN FISH

1963 ◽  
Vol 41 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Wolfgang Pfeiffer
Keyword(s):  
North American ◽  
Alarm Substance ◽  
Fish Skin ◽  
Cyprinid Species ◽  
Fright Reaction ◽  
Skin Physiology ◽  
Alarm Substance Cells

The fright reaction was found in five species of North American Cyprinidae including the predaceous northern squawfish, and in two species of Catostomidae. The threshold for Cyprinidae is 1/1000 N ("normal") extract or lower, that for Catostomidae at least a 1/100 N extract. The cyprinid species reacted very strongly to extract from other Cyprinidae but less strongly to catostomid extract; catostomid species reacted strongly to extract from other Catostomidae but less strongly to cyprinid extract. Salmon extract did not produce any reaction in Cyprinidae or Catostomidae. The epidermis of all species studied contained alarm substance cells; the epidermis of the Catostomidæ was very similar to that of the Cyprinidae. There was a relationship between number and size of the alarm substance cells (histology) and the quantity of alarm substance in the fish skin (physiology). The ability to respond to the alarm substance first appeared in young redside shiners at an age of 42 days, in young zebrafish at an age of 32 days, when the fish were kept at 26 °C.

scholarly journals Biometrics of Razorbills Alca torda staying during the nonbreeding season in the Polish Baltic zone

Ornis Svecica ◽  
2013 ◽  
Vol 23 (3–4) ◽  
pp. 159-163
Author(s):  
Włodzimierz Meissner ◽  
Joanna Drozdowska ◽  
Szymon Bzoma
Keyword(s):  
Baltic Sea ◽  
Wing Length ◽  
Breeding Population ◽  
Breeding Period ◽  
Clinal Variation ◽  
The Baltic Sea ◽  
Final Size ◽  
Alca Torda ◽  
Nonbreeding Season ◽  
The Baltic

Biometrical analysis of Razorbills Alca torda captured or drowned in fishing nets in the Polish economic zone of the Baltic Sea is based on measurements of 98 individuals collected in the non-breeding period (October–April) in 2006–2013. These birds are assumed to represent the breeding population of the Baltic Sea as recoveries show that very few other birds visit that area. Bill depth and wing length of juveniles were much smaller than in older birds which suggests that the final size of these measurements is not achieved during the first winter but continue to increase as the birds grow older. In older birds only total head length and bill length were significantly larger in males than in females. Mean bill depth of Razorbills from the Polish Baltic zone fits well to clinal variation from south-west to north of the European part of the breeding range. However, mean wing length was much larger than expected according to the regression, which might result from differences in measuring technique. On the other hand it cannot be excluded that the Baltic population may actually have longer wings.

Seasonal reproduction in the highveld mole-rat, Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)

2002 ◽  
Vol 80 (5) ◽  
pp. 810-820 ◽  
Author(s):  
L Janse van Rensburg ◽  
N C Bennett ◽  
M van der Merwe ◽  
A S Schoeman
Keyword(s):  
Body Mass ◽  
Reproductive Tract ◽  
Plasma Testosterone ◽  
Breeding Period ◽  
Corpora Lutea ◽  
Seasonal Breeding ◽  
Nonbreeding Season ◽  
Ovarian Histology ◽  
Mole Rat ◽  
Reproductive Females

The highveld mole-rat, Cryptomys hottentotus pretoriae, is a cooperatively breeding rodent that exhibits seasonal breeding and a reproductive division of labour. Body mass, reproductive-tract morphometrics, ovarian histology, and plasma oestrogen and progesterone concentrations were studied for both reproductive and non-reproductive females from 55 colonies, the main objective being to determine the inclination of this species towards seasonal breeding. Offspring are born from July through to November. However, qualitative analysis of ovarian histology revealed that reproductive females retain the potential for ovulation and subsequent production of corpora lutea during the late-summer nonbreeding period (December–March). Seasonal differences were found in ovarian morphometrics and hormone concentrations that are associated with enhanced follicular activation in April and May and subsequent conceptions from July through to November during the breeding period. The nonbreeding period coincides with maximal dispersal opportunities in the summer-rainfall areas inhabited by the highveld mole-rat. Body mass, reproductive-tract morphometrics, testicular histology, and plasma testosterone concentrations were determined for reproductive and non-reproductive males from 37 colonies. Available evidence suggests that there is a gradual increase in testicular mass for reproductive males as the breeding season approaches, but after September the testicular parameters fall. Seminiferous-tubule diameter was significantly greater in reproductive males but exhibited no seasonal variation. Testosterone concentrations were higher in reproductive males. Current data support a lack of gonadal regression in males during the nonbreeding season.

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