scholarly journals Harvesting of males delays female breeding in a socially monogamous mammal; the beaver

2006 ◽  
Vol 3 (1) ◽  
pp. 107-109 ◽  
Author(s):  
Howard Parker ◽  
Frank Rosell ◽  
Atle Mysterud
Keyword(s):  
Mating System ◽  
Reproductive Cycle ◽  
Negative Impact ◽  
Sex Ratios ◽  
Castor Fiber ◽  
Adult Males ◽  
Timing Of Reproduction ◽  
Pregnant Females ◽  
Socially Monogamous

Human exploitation may skew adult sex ratios in vertebrate populations to the extent that males become limiting for normal reproduction. In polygynous ungulates, females delay breeding in heavily harvested populations, but effects are often fairly small. We would expect a stronger effect of male harvesting in species with a monogamous mating system, but no such study has been performed. We analysed the effect of harvesting males on the timing of reproduction in the obligate monogamous beaver ( Castor fiber ). We found a negative impact of harvesting of adult males on the timing of parturition in female beavers. The proportion of normal breeders sank from over 80%, when no males had been shot in the territories of pregnant females, to under 20%, when three males had been shot. Harvesting of males in monogamous mammals can apparently affect their normal reproductive cycle.

scholarly journals Thyroid hormone concentrations associated with age, sex, reproductive status and apparent reproductive failure in the Amazon river dolphin (Inia geoffrensis)

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
T R Robeck ◽  
R S Amaral ◽  
V M F da Silva ◽  
A R Martin ◽  
G A Montano ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Reference Intervals ◽  
Amazon River ◽  
Adult Males ◽  
Serum Samples ◽  
Pregnant Females ◽  
Pregnancy And Lactation ◽  
Inia Geoffrensis ◽  
Males And Females ◽  
Group Sex

AbstractThis study was conducted to characterize immunoreactive thyroid hormone concentrations in wild Amazon river dolphins, also called boto (Inia geoffrensis) by age group, sex, pregnancy and lactation status, and to determine if thyroid hormone concentration differences could be detected between pregnant females with and without successful parturition outcomes. Radioimmunoassays were used to analyse total T3 and total T4 in 182 serum samples collected from 172 botos living in the Mamirauá Sustainable Development Reserve, in the Brazilian Amazon from 2003 through 2015. Age significantly affected tT3 and tT4 concentrations in males, with values in immature males and females being significantly lower than those in adult males, whereas no age effects were noted between immature females and adult non-pregnant, non-lactating females. Significant sex differences were noted in tT3 concentrations between immature males and females and in tT4 concentrations between adult males and females. These resulted in significant differences in the tT3:tT4 ratio between males and females within the immature and adult groups. Lactating and non-pregnant adult females had significantly higher tT3 concentrations than pregnant females, and this difference was primarily driven by a 12% drop in tT3 concentrations during the last two-thirds of pregnancy. No differences in thyroid hormone concentrations were detected between females diagnosed as pregnant and later found to have or not have a live calf. These results are the first to define thyroid hormone reference intervals and normal physiological variations in a wild population of river dolphins.

Reproduction affects flight activity in female and male Daubenton’s bats, Myotis daubentoni

2007 ◽  
Vol 85 (5) ◽  
pp. 653-664 ◽  
Author(s):  
M. Dietz ◽  
E.K.V. Kalko
Keyword(s):  
Energy Demand ◽  
Late Summer ◽  
Climatic Conditions ◽  
Flight Activity ◽  
Adult Males ◽  
Reproductive Condition ◽  
Small Individual ◽  
Pregnant Females ◽  
Pregnancy And Lactation ◽  
Lactating Females

Nearly all mammals in the temperate zone breed in spring and summer when climatic conditions are favourable and food is abundant. Similar to other mammals, food requirements of female bats are particularly high during pregnancy and lactation and of males during spermatogenesis. Seasonal changes in energy demand and reproductive condition should therefore result in different foraging activity within and between sexes. This assumption was tested on 16 adult females and 13 adult males of the Palaearctic Daubenton’s bat, Myotis daubentoni (Kuhl, 1817), that were radio-tracked during pregnancy, lactation, and post-lactation periods. Pregnant females, as hypothesized, flew significantly longer (mean: 358.9 min; 70% of the night length) than males (mean: 228.5 min; 42.4% of the night length) during spring. In contrast, nightly flight time of lactating females decreased and was significantly less than that of pregnant females, but was similar to that of males during the same period. The longest flight times of males were registered during late summer when spermatogenetic activity is high. However, there were distinct differences in the use of foraging areas between female and male Daubenton’s bats. Female bats used small, individual foraging areas during pregnancy and lactation. The pattern was reversed in females after the young had been weaned and in males after they entered spermatogenesis. Overall, the results confirmed our proposition that flight activity reflects the higher energy demand and nutrition requirements in the different reproductive periods.

Sex Ratios and Lengths of Adult Sea Lampreys (Petromyzon marinus) from a Lake Ontario Tributary

1974 ◽  
Vol 31 (1) ◽  
pp. 122-124 ◽  
Author(s):  
I. C. Potter ◽  
F. W. H. Beamish ◽  
B. G. H. Johnson
Keyword(s):  
Narrow Range ◽  
Sex Ratios ◽  
Petromyzon Marinus ◽  
Lake Ontario ◽  
Sea Lamprey ◽  
Adult Males ◽  
Sea Lampreys ◽  
Males And Females ◽  
The Mean ◽  
Humber River

The mean lengths of adult males and females of the sea lamprey (Petromyzon marinus) migrating into the Humber River from Lake Ontario in each of the years 1968–1972 varied little, and were similar to those found by other workers in recently established populations in the upper lakes. In contrast, the ratio of males to females, which lay within the narrow range of 1:1 to 1.26:1, was similar to those reported for long-established populations.

PATERNAL GENETIC EFFECTS ON OFFSPRING FITNESS ARE CONTEXT DEPENDENT WITHIN THE EXTRAPAIR MATING SYSTEM OF A SOCIALLY MONOGAMOUS PASSERINE

Evolution ◽  
2005 ◽  
Vol 59 (3) ◽  
pp. 645 ◽  
Author(s):  
Tim Schmoll ◽  
Verena Dietrich ◽  
Wolfgang Winkel ◽  
Jörg T. Epplen ◽  
Frank Schurr ◽  
...  
Keyword(s):  
Mating System ◽  
Genetic Effects ◽  
Offspring Fitness ◽  
Extrapair Mating ◽  
Socially Monogamous ◽  
Context Dependent

Reproductive strategies of a warm temperate vespertilionid, the large-footed myotis, Myotis moluccarum (Microchiroptera:Vespertilionidae)

1999 ◽  
Vol 47 (3) ◽  
pp. 261 ◽  
Author(s):  
S. Lloyd ◽  
L. S. Hall ◽  
A. J. Bradley
Keyword(s):  
Light Microscopy ◽  
Reproductive Cycle ◽  
Reproductive Strategies ◽  
Post Partum ◽  
Sperm Storage ◽  
Adult Males ◽  
Short Period ◽  
Myotis Myotis ◽  
Monthly Changes ◽  
Warm Temperate

A population of M. moluccarum, which is known to be polyoestrous and monotocous, giving birth to two consecutive offspring annually, was investigated to determine the female reproductive cycle. The population was visited, and observations recorded, at approximately 5-week intervals from July 1994 to February 1995. At each visit, 2–4 females were collected and their reproductive tracts were removed, fixed and processed for light microscopy. During visits conducted after parturition periods, the age of the offspring was estimated in order to determine the duration of parturition. The two gestation periods of the breeding season were of approximately equal duration (11.5–12 weeks) despite the initial pregnancy occurring over much cooler months. While some copulations take place prior to ovulation, sperm storage is not a necessity, and copulation can occur until the time of ovulation. First ovulations of the season take place in early August and although several follicles may mature only one is ovulated. Analysis of climatic variables indicates that females undergo the first ovulation and pregnancy of the season during the cooler part of the year whereas lactation occurs during the warmer, wetter months. A post-partum oestrus occurs soon after parturition and adult males leave the population before the birth of the second offspring. Individual variation in the time before the post-partum oestrus may account for the reduced synchrony noted in the second parturition period. Monthly changes in the corpus luteum and ovaries are documented. The reproductive cycle of M. moluccarum resembles most closely that of tropical and sub-tropical vespertilionids; however, pre-ovulatory copulation, a short period of sperm storage and the development of typical over-wintering follicles (aspects of reproduction seen in species from cooler climates) remain inherent in the large-footed myotis.

Introduction of the rabbit flea, Spilopsyllus cuniculi (Dale), to a subantarctic island (Kerguelen Archipelago) and its assessment as a vector of myxomatosis

2000 ◽  
Vol 27 (1) ◽  
pp. 91 ◽  
Author(s):  
T. Chekchak ◽  
J.-L. Chapuis ◽  
B. Pisanu ◽  
P. Boussès
Keyword(s):  
Myxoma Virus ◽  
Adult Males ◽  
Main Island ◽  
Subantarctic Island ◽  
Pregnant Females ◽  
Founding Population ◽  
Rate Of Spread ◽  
On This Island ◽  
Males And Females ◽  
Kerguelen Archipelago

Introductions of the rabbit flea, Spilopsyllus cuniculi (Dale), were made on an island (3.1 km2) of the Kerguelen subantarctic archipelago in January and December 1987. Despite a small founding population, the species succeeded in establishing itself. Three years after introduction, the rate of spread was 614 ± 133 m (between 1990 and 1993). Despite the subantarctic climate of Kerguelen, the burdens were similar to those noted in habitats favourable to this ectoparasite. The flea burden of adult rabbits after colonisation of the whole island was higher for pregnant females (182 ± 21, n = 98) than for non-pregnant ones (85 ± 16, n = 68) or males (20 ± 3, n = 116). The circulation of myxoma virus, present on this island for several decades, has been favoured by the flea. As a result, the proportion of rabbits with antibodies rose from 34% before introduction of the flea to 85% in 1998. Moreover, the introduction of fleas has changed the relative proportions of both adult males and females with antibodies. Those proportions were not different before the introduction but more males than females showed antibodies when the flea colonised the whole island. Finally, the prospects of the introduction of Spilopsyllus cuniculi on the main island of the archipelago are discussed.

Biased sex ratios and parasite mating probabilities

Parasitology ◽  
1993 ◽  
Vol 107 (3) ◽  
pp. 287-295 ◽  
Author(s):  
R. M. May ◽  
M. E. J. Woolhouse
Keyword(s):  
Population Dynamics ◽  
Sex Ratio ◽  
Mating System ◽  
Sex Ratios ◽  
Theoretical Framework ◽  
Main Body ◽  
Female Mating ◽  
The Mean ◽  
Mated Female

SummaryAn earlier paper (May, 1977) developed a theoretical framework for exploring the consequences of dioecy for the population dynamics of schistosomes, assuming an unbiased sex ratio. This paper extends the analysis to biased sex ratios, as have been reported in practice. We consider the relationships of the mean number and distribution of worms among hosts, the sex ratio, and the mating system (monogamous or polygamous) to: (i) the female mating probability, Φ the prevalence of mated female worms. Ω: and (iii) the mean number of mated female worms per host, ξ. Among other results, we show how high values of Φ are associated with male-biased sex ratios and polygamous mating; that Ω is independent of the mating system and is relatively unaffected by the sex ratio; and that ξ is maximal for unbiased sex ratios given monogamous mating, and for female-biased sex ratios if mating is polygamous. These results, together with the confounding effects of the mean number and distribution of worms, are described in detail in the main body of the paper.

scholarly journals The Male Reproductive Cycle of the Spotted Toad-Headed Agama,Phrynocephalus maculatus, in Iran

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Soheila Rahmani ◽  
Vida Hojati
Keyword(s):  
Reproductive Cycle ◽  
Arid Regions ◽  
Tunica Albuginea ◽  
Reproductive Activity ◽  
Seminal Vesicles ◽  
Adult Males ◽  
Germinal Layer ◽  
Histological Studies ◽  
The Right ◽  
Semnan Province

The spotted toad-headed agama,Phrynocephalus maculatus, distributed in the central and southeastern arid regions of Iran, belongs to the Agamidae family. In this research, the male reproductive cycle of this species was studied from 5 April to 5 August, 2013. Totally, 40 adult males were collected at midday from southern deserts of Damghan County, located in Semnan Province of Iran. Testes were removed and processed for morphometric and histological studies. The spermatogenic cycle begins from early April, mating occurs in mid-May, and it ends in August. Maximum reproductive activity occurs in early June and reduces from early July and ends in August. The numbers of seminal vesicles were 33–127 and their diameter varied between 69.0 and 258.3 microns. The diameter of tunica albuginea varied between 3.0 and 8.1 microns. The diameter of germinal layer varied between 10.0 and 110.0 microns. There were significant differences in macroscopic and microscopic testicular characters between months. Also, there were no significant differences in the testicular and hemipenal characters between the left side and the right side of body. Since spermatogenesis occurs from April through August,P. maculatusfollows an associated reproductive cycle typical for temperate species.

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