Dispersion of adult male Peromyscus leucopus in relation to female reproductive status

1989 ◽  
Vol 67 (4) ◽  
pp. 1047-1052 ◽  
Author(s):  
Xuhua Xia ◽  
John S. Millar
Keyword(s):  
Mating System ◽  
Adult Male ◽  
Early Pregnancy ◽  
Peromyscus Leucopus ◽  
Natural Populations ◽  
Negative Relationship ◽  
Late Pregnancy ◽  
Adult Males ◽  
Adult Females ◽  
Female Reproductive Status

We studied dispersion of adult male Peromyscus leucopus in relation to the stage of pregnancy of adult females in natural populations monitored with Longworth live traps. Because postpartum mating is common in P. leucopus and days to parturition measures how far a female is from her next mating, we predicted that a female in early pregnancy (many days to parturition) would have fewer adult males in her neighbourhood than a female in late pregnancy (few days to parturition). Number of adult males caught within 30 m of each adult female was recorded and number of days to parturition for each female was obtained by bringing females back to the laboratory and allowing them to give birth. A negative relationship was found between number of adult males in a female's neighbourhood and days to parturition of the female (r = −0.419, p < 0.01), with the latter accounting for 8.8% of the variance in the former. These results support the hypothesis of a promiscuous mating system in P. leucopus.

Effects of adults on survival and recruitment of Peromyscus leucopus

1987 ◽  
Vol 65 (10) ◽  
pp. 2519-2523
Author(s):  
Gregory H. Adler ◽  
Mark L. Wilson ◽  
Michael J. DeRosa
Keyword(s):  
Adult Female ◽  
Adult Male ◽  
Peromyscus Leucopus ◽  
Survival Rates ◽  
Adult Males ◽  
Control Grid ◽  
Young Males ◽  
Young Females ◽  
Breeding Seasons ◽  
And Control

A population of Peromyscus leucopus (white-footed mouse) in northeastern Massachusetts was manipulated for 3 years to determine the effects of adults on survival and recruitment. Two experimental grids were established, from which either all adult males or all adult females were removed continually. The effects of these two manipulations were compared with demography on a control grid. Manipulations had no apparent effect on breeding intensity of young, survival rates of adults, or residency rates of adults and young. Recruitment of adult males was higher on the adult male removal grid than on the control grid. Recruitment rates of adult males and of young males and young females were lower on the adult female removal grid than on the control grid. Survival rates of young males were higher on the adult female removal grid than on the control grid; this effect may have been due to either reduced adult female residency or adult male recruitment. All differences between experimental and control grids were noted only during breeding seasons. Adult males apparently limited recruitment of adult consexuals. The effects of manipulations on other measured parameters were inconclusive because of high immigration rates of adult males onto the adult male removal grid and reduced recruitment of adult males and decreased production of young on the adult female removal grid.

scholarly journals Patterns of pair formation and mating in an ectoparasitic caligid copepod Lepeophtheirus salmonis (Krøyer 1837): implications for its sensory and mating biology

1998 ◽  
Vol 353 (1369) ◽  
pp. 753-764 ◽  
Author(s):  
M. Q. Hull ◽  
A. W. Pike ◽  
A. J. Mordue ◽  
G. H. Rae
Keyword(s):  
Adult Male ◽  
Host Finding ◽  
Pair Formation ◽  
Adult Males ◽  
Unmated Female ◽  
Female Ratio ◽  
Genital Complex ◽  
Adult Females ◽  
Mating Biology ◽  
Reproductive Events

Non–invasive observations of single cohort and manipulated populations of the sealouse on laboratory–maintained salmon established the sequence of reproductive events and mating. Protandry occurs with adult male emergence synchronized with pre–adult II female emergence, the stage at which most pair formation and pre–copular guarding takes place. Male competence for pair formation and mating was achieved within 24 h of the final moult and pairing occurred according to the preference hierarchy, virgin adult females greater than pre–adult II females much greater than pre–adult I females. This hierarchy broke down when the adult male to unmated female ratio increased rapidly. Males mated successfully not only with newly moulted adult females, but also with older virgin females in which enlargement of the genital complex and premature extrusion of egg strings had occurred. Multiple mating by adult males was demonstrated and may be widespread. Significant inter–host transfer was also demonstrated. Adult males were more mobile than adult females and showed significantly more inter–host transfer. Ablation of the distal tip of the antennules significantly reduced the success of host–finding, pair formation and males' mating.

Demography of a population of Peromyscus leucopus

1979 ◽  
Vol 57 (2) ◽  
pp. 323-328 ◽  
Author(s):  
Richard M. Harland ◽  
Peter J. Blancher ◽  
John S. Millar
Keyword(s):  
Peromyscus Leucopus ◽  
Adult Males ◽  
Adult Mice ◽  
Adult Females ◽  
Young Of The Year ◽  
Juvenile Males ◽  
Initial Capture

Livetrapping and removal trapping were used to monitor a population of Peromyscus leucopus. Breeding adult arid young of the year females averaged 2.0 and 1.1 litters per year, respectively. Nest mortality was 12–31%, while 58% of the juveniles disappeared within 2 weeks after weaning. The rate of disappearance of juvenile males (77%) was higher than that of juvenile females (44%); the greater loss of males was attributed to mortality. Loss of subadult and adult mice within 2 weeks after initial capture averaged 45 and 51%, respectively, and did not differ between the sexes. However, more males than females were recorded as entering the trapping grids, indicating that males tend to explore new areas more than females. Among resident mice, adult males had the highest rate of disappearance (0.31/week) while adult females had the lowest (0.05/week).

Wounding in Hawaiian monk seals (Monachus schauinslandi)

1993 ◽  
Vol 71 (3) ◽  
pp. 458-468 ◽  
Author(s):  
Lisa M. Hiruki ◽  
William G. Gilmartin ◽  
Brenda L. Becker ◽  
Ian Stirling
Keyword(s):  
Coral Reef ◽  
Adult Male ◽  
Marine Debris ◽  
Adult Males ◽  
Monachus Schauinslandi ◽  
Aggressive Interactions ◽  
Size Classes ◽  
Adult Females ◽  
Northwestern Hawaiian Islands ◽  
Monk Seals

Injuries observed on endangered Hawaiian monk seals (Monachus schauinslandi) at Laysan Island and French Frigate Shoals in the northwestern Hawaiian Islands in 1988 and 1989 were classified into six major types, based on the source of the wounds: mating attempts by adult male monk seals; nonmating aggressive interactions with other seals; attacks by large sharks; attacks by cookiecutter sharks (Isistius brasiliensis); contact with coral reef or debris; and entanglement in netting or marine debris. At both locations, injuries inflicted by adult male seals during mobbing incidents, in which many males attempt to mate with one seal, were seen more frequently than other types of injuries in 1988 and 1989. Injury data from 1982 – 1987 at Laysan Island and from 1985 – 1989 at French Frigate Shoals were used to compare the distribution of mating injuries inflicted by adult males and injuries inflicted by large sharks over size and sex classes of seals. Mating injuries caused by adult male seals were seen primarily on adult females but were also seen on seals in other size classes. Mating injuries inflicted by adult males occurred earlier in the year and with greater frequency at Laysan Island than at French Frigate Shoals. Injuries inflicted by large sharks were observed more often on adult male seals than on seals in other size classes at Laysan Island; however, no such difference was seen among size classes at French Frigate Shoals.

On the mating system of polar bears

1986 ◽  
Vol 64 (10) ◽  
pp. 2142-2151 ◽  
Author(s):  
Malcolm A. Ramsay ◽  
Ian Stirling
Keyword(s):  
Sex Ratio ◽  
Sea Ice ◽  
Mating System ◽  
Breeding Season ◽  
Large Body ◽  
Arctic Sea Ice ◽  
Polar Bears ◽  
Adult Males ◽  
Terrestrial Mammals ◽  
Adult Females

Polar bears are intimately associated with arctic sea ice and their distribution is approximated by its winter extent. They are the only terrestrial mammals, other than humans, to have adapted so completely to sea ice, a quite different habitat, spatially and temporally, from that occupied by other terrestrial mammals. We propose that the dynamics of sea ice and the associated variability in access to food have played a major role in the evolution of the social structure and mating system of polar bears. Adult females and males move to areas of the sea ice where the greatest success in hunting is realized. Such regions are unpredictable in location, however, both seasonally and annually. Because female distributions are unpredictable, adult males are unable to defend stable territories that will encompass the home ranges of one or more females and may instead distribute themselves among different sea-ice habitats at the same relative densities as solitary adult females. Females keep nursing cubs with them for more than 1 year; hence the mean interbirth interval is 2 or more years. This results in a functionally skewed sex ratio, with fewer females available to breed in any one year than males, and in intrasexual competition among males for access to breeding females. Consequently, established dominance hierarchies among males are unstable, and wounding, scarring, and breakage of canine teeth are common; these are evidence of direct physical confrontations during the breeding season. Large body size is advantageous in these fights and this has resulted in one of the highest degrees of sexual dimorphism among terrestrial mammals. Because of the funtionally skewed sex ratio and the shifting distribution of both females and males, however, even the largest male probably cannot be certain of locating a larger than average number of receptive females in any one breeding season.

scholarly journals Sexual dimorphism in thyroid function and type 1 iodothyronine deiodinase activity in pre-pubertal and adult rats

2007 ◽  
Vol 192 (1) ◽  
pp. 121-130 ◽  
Author(s):  
Michelle P Marassi ◽  
Rodrigo S Fortunato ◽  
Alba C Matos da Silva ◽  
Valmara S Pereira ◽  
Denise P Carvalho ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Adult Male ◽  
Gonadal Hormones ◽  
Adult Males ◽  
Adult Rats ◽  
Iodothyronine Deiodinase ◽  
Adult Females ◽  
Serum T3 ◽  
Serum Tsh

Iodothyronine deiodinase activities are regulated by sex steroids; however, the mechanisms underlying the reported sexual dimorphism are poorly defined. In the present report, we aimed to investigate whether type 1 deiodinase (D1) sexual dimorphism exists early in sexual development by studying pre-pubertal male (Pm) and female (Pf) rats, as well as adult controls (C) and gonadectomized male and females rats. Adult male Wistar rats were studied 21 days after orchiectomy (Tex), and adult females were studied 21 days after ovariectomy (Ovx), and after estradiol benzoate (Eb) replacement. Serum total triiodothyronine (T3) was higher in pre-pubertal (P) rats than in the matching adults, with no difference between genders, although in adult males T3 was significantly lower than in females. There were no sex or age differences in serum total T4. Serum TSH in pre-pubertal (P) rats was within the adult female range, and both were significantly lower than in adult males. D1 activity in liver was greater in Pm than in Pf. In adult females, liver D1 activity was lower, while in adult males it was higher than in P rats. The same pattern of D1 activity was found in kidney. In thyroid and pituitary, D1 activity was similar in Pm, Pf, and adult females, which were all significantly lower than in the adult male. There were no differences in serum T3 and T4 between C and Tex males, but serum TSH was significantly decreased in Tex rats. Hepatic and renal D1 activities were lower in Tex than in C, but no changes were detected in thyroid and pituitary. In Ovx females, T3 was significantly lower than in the C group. Serum T4 was significantly decreased by estradiol replacement therapy in Ovx rats, in both doses used, whereas TSH was unchanged. Eb replacement increased liver and thyroid D1 activity, but in the kidney, only the highest estradiol dose promoted a significant D1 increase. In conclusion, in males, hepatic and renal D1 activity appears to be significantly influenced by gonadal hormones, in contrast to females, in which only exogenous Eb treatment stimulated D1 activity. The comparison between pre-pubertal and adult rats suggests that serum T3 is not the main regulator of D1 activity, and other factors, besides T3 and gonadal hormones, can modulate D1 activity during murine maturation.

scholarly journals Adult male coatis play with a band of juveniles

2013 ◽  
Vol 73 (2) ◽  
pp. 353-355 ◽  
Author(s):  
CJ Logan ◽  
JT Longino
Keyword(s):  
Costa Rica ◽  
Breeding Season ◽  
Adult Male ◽  
Model System ◽  
Adult Males ◽  
La Selva ◽  
Biological Station ◽  
Nasua Narica ◽  
Adult Females ◽  
Post Hoc

This study examined the play behaviour in one group of coatis (Nasua narica) at La Selva Biological Station in Costa Rica. We incidentally found adult males playing with juvenile coatis, and conducted post-hoc analyses to investigate this interaction. Coati groups consist of adult females and juveniles of both sexes until male juveniles reach two years of age and leave the band to become solitary. Adult males only tolerate juveniles for a brief period during breeding season when the males court females to mate. Outside of the breeding season, adult males are known to prey on juveniles. In this study, when adult males were present with the band, play occurred more than was expected by chance, and adult males engaged in many of these play bouts. Because the mechanisms driving infanticidal behaviour are not well understood, and adult male coatis show a range of behaviours from infanticide to highly affiliative interactions with juveniles, using coatis as a model system may elucidate mechanisms underlying infanticide.

scholarly journals Impact of botfly parasitism on Microtus townsendii populations

1980 ◽  
Vol 58 (9) ◽  
pp. 1683-1692 ◽  
Author(s):  
Rudy Boonstra ◽  
Charles J. Krebs ◽  
Terry D. Beacham
Keyword(s):  
Negative Relationship ◽  
Adult Males ◽  
Adult Females ◽  
Significant Negative Relationship ◽  
Breeding Condition ◽  
Survival Differences ◽  
The Impact ◽  
Large Adult ◽  
Microtus Townsendii ◽  
Better Than

The impact of botfly (Cuterebra grisea) parasitism on populations of Microtus townsendii was studied on four areas near Vancouver, British Columbia, from 1971 to 1978. Botfly larvae were found in voles during the period from late June to late November, with a peak occurring from mid-August to mid-September. There was a significant negative relationship between vole density and the proportion of the population infested. The percentage of voles infested changed in the following manner in the three weight classes: juveniles (18.5%) > adults (16.5%) > subadults (13.0%), with the sexes showing no differences between them. Overall, noninfested voles always survived better than infested ones did in the three classes. In both adults and juveniles, survival declined as botfly larvae number increased; subadults did not show this relationship. Infested adult male voles survived more poorly at high densities (r = 0.62); adult females did not. Infested large adult males (≥ 55 g) survived better than small adults did (40–54 g), but the two size classes in females showed no survival differences. Infested adult voles had significantly lower rates of reproduction: 8% fewer males were in breeding condition, 10% fewer females were lactating, and 4% fewer females were pregnant. Parasitism significantly depressed growth rates in all weight classes above 40 g. We conclude that botflies had a significant detrimental influence on vole survival, reproduction, and growth.

scholarly journals Peak shift and epidemiology in a seasonal host–nematode system

2005 ◽  
Vol 272 (1568) ◽  
pp. 1163-1169 ◽  
Author(s):  
I.M Cattadori ◽  
B Boag ◽  
O.N Bjørnstad ◽  
S.J Cornell ◽  
P.J Hudson
Keyword(s):  
Negative Relationship ◽  
Peak Shift ◽  
Cumulative Exposure ◽  
Acquired Immunity ◽  
Host Age ◽  
Spatial Effects ◽  
Adult Males ◽  
Intensity Of Infection ◽  
Adult Females ◽  
Peak Intensity

Insight into the dynamics of parasite–host relationships of higher vertebrates requires an understanding of two important features: the nature of transmission and the development of acquired immunity in the host. A dominant hypothesis proposes that acquired immunity develops with the cumulative exposure to infection, and consequently predicts a negative relationship between peak intensity of infection and host age at this peak. Although previous studies have found evidence to support this hypothesis through between-population comparisons, these results are confounded by spatial effects. In this study, we examined the dynamics of infection of the nematode Trichostrongylus retortaeformis within a natural population of rabbits sampled monthly for 26 years. The rabbit age structure was reconstructed using body mass as a proxy for age, and the host age–parasite intensity relationship was examined for each rabbit cohort born from February to August. The age–intensity curves exhibited a typical concave shape, and a significant negative relationship was found between peak intensity of infection and host age at this peak. Adult females showed a distinct periparturient rise in T. retortaeformis infection, with higher intensities in breeding adult females than adult males and non-breeding females. These findings are consistent with the hypothesis of an acquired immune response of the host to a parasite infection, supporting the principle that acquired immunity can be modelled using the cumulative exposure to infection. These findings also show that seasonality can be an important driver of host–parasite interactions.

POPULATION ATTRIBUTES OF BLUE GROUSE IN SOUTHWESTERN ALBERTA

1966 ◽  
Vol 44 (5) ◽  
pp. 799-814 ◽  
Author(s):  
D. A. Boag
Keyword(s):  
Mortality Rate ◽  
Adult Male ◽  
Age Distribution ◽  
Older Age ◽  
Home Ranges ◽  
Adult Males ◽  
Age Classes ◽  
Adult Females ◽  
Dendragapus Obscurus ◽  
Breeding Grounds

A population of blue grouse (Dendragapus obscurus) was studied over a 10-year period in southwestern Alberta. During this time a number of population attributes were documented. Density declined from a maximum of 47 adult males in 1955 to a minimum of 6 in 1964 on the 620-acre study area. Dispersion of adult male blue grouse on the breeding grounds was accomplished by establishing territories which averaged 1.5 ac. Adult females inhabited overlapping home ranges which averaged 43 ac in size. The age distribution among marked birds on the breeding grounds in May and June indicated 75% adult (2 years and older) and 25% subadult (1 year of age). Of the adults, approximately one-half were 2-year-olds with decreasing proportions in older age classes until none remained after they were 9 years old. Juveniles formed 40% of the fall population each year. The average hatch was 5.1 chicks per breeding female. Recruitment to the population has been inadequate to maintain numbers. Excessive mortality or dispersal rates must account for this. Minimum recorded loss of chicks during their first summer averaged 27%. Mortality rate of birds more than 1 year old averaged 56% per annum. Dispersal to other breeding ranges was recorded only in juvenile grouse.

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