Seasonal Changes in Thyroid Activity in Male and Female Frog, Rana perezi

1995 ◽  
Vol 97 (1) ◽  
pp. 66-75 ◽  
Author(s):  
B. Gancedo ◽  
A.L. Alonso-Gómez ◽  
N. de Pedro ◽  
I. Corpas ◽  
M.J. Delgado ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Thyroid Activity ◽  
Male And Female ◽  
Rana Perezi

The reproductive cycle of the viviparous seaperch, Cymatogaster aggregata Gibbons

1968 ◽  
Vol 46 (6) ◽  
pp. 1221-1234 ◽  
Author(s):  
John P. Wiebe
Keyword(s):  
Oocyte Maturation ◽  
Reproductive Cycle ◽  
Sertoli Cells ◽  
Reproductive Behavior ◽  
Seasonal Changes ◽  
Environmental Temperature ◽  
Interstitial Cells ◽  
Early Spring ◽  
Seminiferous Tubules ◽  
Male And Female

The natural reproductive cycle of male and female Cymatogaster aggregata is described with reference to gametogenesis, development of secondary sex structures, reproductive behavior, and gestation. Spermatocytogenesis starts in early spring and by June or July clusters of spermatozoa fill the seminiferous tubules. Concurrently the Sertoli cells and interstitial cells of Leydig increase in size and secondary sex structures develop on the male anal fin. When the sexes mingle in summer, the males perform very elaborate reproductive behavior. Fertilization occurs about mid-December—5 months after mating—and the ovary is then modified to maintain the young embryos until parturition in mid-summer. Oocyte formation is highest in July and August, just after parturition, while vitellogenesis and oocyte maturation occur mainiy from October to December. These seasonal changes are discussed in relation to changes in environmental temperature and photoperiod.

scholarly journals Seasonal changes in group size and composition of Arabian sand gazelle Gazella subgutturosa marica Thomas, 1897 during a period of drought in central western Saudi Arabia

2011 ◽  
Vol 57 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Peter Low Cunningham ◽  
Torsten Wronski
Keyword(s):  
Saudi Arabia ◽  
Group Size ◽  
Protected Area ◽  
Seasonal Changes ◽  
Continuous Monitoring ◽  
Group Structure ◽  
Male And Female ◽  
Adult Sex Ratio ◽  
Gazella Subgutturosa ◽  
Mixed Groups

Abstract Group size variations of the Arabian sand gazelle Gazella subgutturosa marica were studied during a period of drought at the Mahazat as-Sayd Protected Area in central western Saudi Arabia. Significant differences in median group sizes were observed between all seasons except summer. Single animals were observed mainly during summer while group sizes exceeding 10 individuals were observed mainly during winter. Solitary male and female groups were typically observed during winter and mixed groups mainly during the autumn rutting period. Most mixed groups were two to four times larger during winter than summer. The adult sex ratio (male: female) for all seasons combined was in parity and highest during autumn (1:1.23), probably as a result of prolonged drought conditions. The variability in group structure related to environmental conditions may be one factor permitting G. s. marica to adapt to hyper-arid habitats and climatic regimes in central western Saudi Arabia. The value of continuous monitoring of the gazelle population is emphasised for this drought prone region.

Seasonal changes of brain GnRH-I, -II, and -III during the final reproductive period in adult male and female sea lamprey

2011 ◽  
Vol 170 (2) ◽  
pp. 276-282 ◽  
Author(s):  
Stacia A. Sower ◽  
Eileen Balz ◽  
Allisan Aquilina-Beck ◽  
Scott I. Kavanaugh
Keyword(s):  
Adult Male ◽  
Seasonal Changes ◽  
Sea Lamprey ◽  
Reproductive Period ◽  
Male And Female

Effects of gonadectomy on seasonal changes in plasma LH and prolactin concentrations in male and female starlings (Sturnus vulgaris)

1984 ◽  
Vol 100 (2) ◽  
pp. 213-218 ◽  
Author(s):  
A. Dawson ◽  
A. R. Goldsmith
Keyword(s):  
Seasonal Changes ◽  
Seasonal Pattern ◽  
Maximum Size ◽  
Sturnus Vulgaris ◽  
Prolactin Secretion ◽  
Testis Size ◽  
Gonadal Steroid ◽  
Male And Female ◽  
Males And Females

ABSTRACT Intact and gonadectomized male and female starlings (Sturnus vulgaris) were held in outdoor aviaries for 1 year. Blood samples were taken frequently and assayed for LH and prolactin, and intact males were laparotomized to determine testis size. Changes in testis size in intact males were similar to those in wild starlings with maximum size during April. Hormone levels in intact males and females also followed a similar pattern to those in wild birds although absolute levels were somewhat lower. Levels of LH increased during spring, were highest in early May and then declined rapidly as birds became photorefractory. Prolactin levels did not begin to increase until April, reached a peak in late May and then declined. In gonadectomized males and females, high levels of LH were maintained throughout the early part of the year when birds were photosensitive, but declined rapidly as they became photorefractory. This occurred at the same time as in intact birds. During photorefractoriness, LH levels in gonadectomized birds were similar to those in intact birds. Prolactin showed the same seasonal pattern in gonadectomized birds as that in intact birds. These results demonstrate that gonadal steroid feedback is unimportant in initiating and maintaining photorefractoriness and confirm that increased prolactin secretion coincides with the onset of photorefractoriness. J. Endocr. (1984) 100, 213–218

Host demographic predicts ectoparasite dynamics for a colonial host during pre-hibernation mating

Parasitology ◽  
2015 ◽  
Vol 142 (10) ◽  
pp. 1260-1269 ◽  
Author(s):  
QUINN M. R. WEBBER ◽  
ZENON J. CZENZE ◽  
CRAIG K. R. WILLIS
Keyword(s):  
Seasonal Changes ◽  
Myotis Lucifugus ◽  
Adult Males ◽  
Male And Female ◽  
Adult Females ◽  
Future Reproduction ◽  
Energetic Constraints ◽  
Young Of The Year ◽  
Parasite Exposure ◽  
Parasite Dynamics

SUMMARYParasite dynamics can be mediated by host behaviours such as sociality, and seasonal changes in aggregation may influence risk of parasite exposure. We used little brown bats (Myotis lucifugus) captured during the autumn mating/swarming period to test the hypothesis that seasonal and demographic-based variation in sociality affect ectoparasitism. We predicted that ectoparasitism would: (1) be higher for adult females and young of the year (YOY) than adult males because of female coloniality; (2) increase for adult males throughout swarming because of increasing contact with females; (3) decrease for adult females and YOY throughout swarming because of reduced coloniality and transmission of individual ectoparasites to males; (4) be similar for male and female YOY because vertical transmission from adult females should be similar. Ectoparasitism was lowest for adult males and increased for males during swarming, but some effects of demographic were unexpected. Contrary to our prediction, ectoparasitism increased for adult females throughout swarming and YOY males also hosted fewer ectoparasites compared with adult and YOY females. Interestingly, females in the best body condition had the highest parasite loads. Our results suggest that host energetic constraints associated with future reproduction affect pre-hibernation parasite dynamics in bats.

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