Sexual differences in interyear survival and life-span of Richardson's ground squirrels

1989 ◽  
Vol 67 (7) ◽  
pp. 1827-1831 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Sex Ratio ◽  
Life Span ◽  
Older Adult ◽  
Litter Size ◽  
Ground Squirrels ◽  
Sexual Differences ◽  
Maximum Life Span ◽  
Southern Alberta ◽  
Males And Females ◽  
Size At Birth

Although equal numbers of males and females were weaned in a population of Richardson's ground squirrels studied in southern Alberta, interyear survival was lower for males than for females in each year of life. Consequently, the sex ratio was biased toward females in both the yearling and older adult cohorts (overall ≤ 23 males per 100 females), and maximum life-span of males was 4 years, whereas that of females was 6 years. Compared with several other species of Spermophilus, Richardson's ground squirrels have a larger litter size at birth and a shorter life-span.

Variation in Weight, Size, and Sex Ratio of Coccinellid Adults (Coleoptera: Coccinellidae)

1966 ◽  
Vol 98 (6) ◽  
pp. 639-644 ◽  
Author(s):  
B. C. Smith
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Water Content ◽  
Food Supply ◽  
Sexual Differences ◽  
Intraspecies Variation ◽  
Food Scarcity ◽  
Food Requirement ◽  
Males And Females

AbstractThe weight and size of coccinellid adults varied with species, sex, and feeding. Intraspecies variation in weight was generally similar in the eight species studied. Females were more variable than males in body size. Females of some species were heavier and larger than males, and species can be classified on a basis of difference in the weight and size of the sexes.An increase in the food supply after a period of food scarcity affected the sex ratio, as the minimum food requirement of females was greater than males. Females increased in weight more rapidly than males after feeding. The availability of food in the field affected the weight and size of some species. Adult water content was influenced by feeding but not by sex or the quantity of food given to the larva.Males were more abundant in species with small sexual differences in weight and size. The degree of difference in weight and size between males and females may be used as a criterion to select species that are best adapted to survive when food is scarce.

Reproductive strategy of the Australian Sharpnose Shark, Rhizoprionodon taylori (Elasmobranchii: Carcharhinidae), from Cleveland Bay, Northern Queensland

1992 ◽  
Vol 43 (1) ◽  
pp. 67 ◽  
Author(s):  
CA Simpfendorfer
Keyword(s):  
Litter Size ◽  
Reproductive Strategy ◽  
Life Histories ◽  
Early Embryo ◽  
Northern Territory ◽  
Embryonic Diapause ◽  
Early Embryo Development ◽  
Males And Females ◽  
Developmental Traits ◽  
Size At Birth

Reproduction and early embryo development of Rhizoprionodon taylori from Cleveland Bay, Queensland, was studied on the basis of 455 specimens caught between May 1987 and February 1990. Males and females mature at sizes larger than those reported from northern Western Australia, the Northern Territory and far northern Queensland. Mating occurs annually in summer, and the gestation period is approximately 11.5 months. After development to a small blastodermic disc, the embryos enter a state of diapause that lasts approximately 7 months. R. taylori is the only species of shark that is known to have a period of embryonic diapause. The litter size ranges from 1 to 10 (mean 4.9, being markedly larger than that for other carcharhinid species of a similar size. The size at birth is 220- 260 mm. The reproductive and developmental traits are discussed in relation to the life histories of this species and other carcharhinids.

The effect of inbreeding on reproduction in mice

1982 ◽  
Vol 34 (1) ◽  
pp. 49-54 ◽  
Author(s):  
R. G. Beilharz
Keyword(s):  
Sex Ratio ◽  
Litter Size ◽  
Average Rate ◽  
Inbreeding Coefficient ◽  
Conception Rate ◽  
Common Ancestry ◽  
Effective Number ◽  
Laboratory Mice ◽  
The Family ◽  
Males And Females

ABSTRACTAn unselected, non-inbred population of laboratory mice has been propagated for 25 generations by 20 pairs (families) of mice, each leaving one son and one daughter selected at random from the litter. The daughter was given the family number of her dam, while her mate came from another family varying systematically in different generations. The breeding plan precluded any possibility of common ancestry for five generations. In later generations the inbreeding coefficient rose at an average rate expected from a population with an effective number of approximately 80, to approximately 0·13 in generation 25. The rise occurred in cycles, repeating every five generations. Data are presented to demonstrate that overall reproduction (total weight of young produced at 9 weeks of age, per female mated) and the components of survival from birth to 9 weeks, survival from sexing (3 weeks) to 9 weeks separately for males and females, and 9-week weight of males and females, were each sensitive to changes in inbreeding coefficient. In contrast, conception rate, litter size (live young born) and sex ratio did not reflect changes in the inbreeding coefficient. The magnitude of the depression in overall reproduction was substantially greater than that in any of the affected components.

scholarly journals Crossbreeding and consanguinity management in pig farms in the departments of Ouémé and Plateau in Benin

2019 ◽  
Vol 12 (11) ◽  
pp. 1816-1825
Author(s):  
Ignace Ogoudanan Dotché ◽  
Simon Idohou ◽  
Mahamadou Dahouda ◽  
Pascal Kiki ◽  
Benoit Govoeyi ◽  
...  
Keyword(s):  
Litter Size ◽  
Slow Growth ◽  
Education Level ◽  
Male And Female ◽  
Genetic Types ◽  
Married Men ◽  
Pig Farms ◽  
Males And Females ◽  
Weaning Piglets ◽  
Size At Birth

Background: The improvement in pig zootechnical performances is a common practice in Benin. This improvement of the performances is made by the choice of the best reproducers in farms and the crossbreeding between the different breeds. Aim: This study aims to characterize practices related to consanguinity management in pigs reared in Ouémé and Plateau. Materials and Methods: Crossbreeding and consanguinity data were collected from 60 farms in these two departments. Frequencies and averages were calculated and compared between departments, genetic types, and origin of progenitors. Results: The majority of the investigated pig farmers in both departments were married men of primary or secondary education level. Most of them cross animals without a specific crossbreeding scheme. These crossings were performed to a greater extent (p<0.05) in Ouémé (94.28%) than in Plateau (52%). In general, farmers cross improved animals of high breeding values with the crossbred ones. These crossings were mainly performed to improve zootechnical performances. Renewing animals were commonly chosen from the farm or were provided from nearby farms. The majority of pig breeders in Ouémé (100%) and Plateau (86.67%) obtained reproductive animals from nearby farms. Males and females were sometimes bought from the same farm or from farms that pig breeders have sold reproductive animals in the previous years. In the case of selection within their own farm, male and female progenitors are separated at puberty by the majority of the breeders of Plateau (42.11%) and Ouémé (50%). Inbred mating was reported by breeders. More than half of breeders mate animals having a parental link in both departments. The mating was performed between animals of the same mother in 37.93% of farms in Ouémé and in 45.46% in Plateau. The main consanguinity consequences mentioned by the breeders were the high mortality at birth and weaning, piglets' weakness at the birth, the slow growth, and the decrease in litter size. Sows with at least one parent from external farm had a litter size at birth and weaning and a live-born piglets' number significantly higher than sows with both parents from the same farm. Conclusion: Rigorous monitoring of crossing and the filial links are necessary for pig farms for ensuring the improvement of zootechnical performances.

scholarly journals Life extension in Drosophila melanogasteras a result of development in conditions of high larval density

2018 ◽  
Vol 15 (2) ◽  
pp. 167-173
Author(s):  
A. S. Karaman ◽  
A. M. Vaiserman ◽  
A. K. Koliada ◽  
O. G. Zabuga ◽  
A. V. Pisaruk ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Life Expectancy ◽  
Life Span ◽  
Larval Density ◽  
Reproductive Activity ◽  
Life Extension ◽  
Maximum Life Span ◽  
Males And Females ◽  
The Mean ◽  
Density Methods

Aim. To investigate the life expectancy and reproductive activity of Drosophila melanogaster that developed in conditions of increased larval density. Methods. Mean and maximum life span were determined in males and females in the different experimental groups. The reproductive activity was evaluated by counting the total number of eggs laid by one female per day. Results. A significant increase of the mean life span compared to control was observed in adults that hatched from pupae during the first and second days after the beginning of the emergence: males — 24 % and 23.5 %, females — 23.8 % and 29.3 % respectively. The level of reproductive activity (fecundity) is statistically lower in two groups which hatched last. Conclusions. Based on the results obtained, we suggest that development in conditions of increased larval density can lead to increase in the life span of D. melanogaster.Keywords: life span, Drosophila melanogaster, reproductive activity, development.

Reproduction of Richardson's ground squirrel (Spermophilus richardsonii) in southern Saskatchewan

1972 ◽  
Vol 50 (12) ◽  
pp. 1577-1581 ◽  
Author(s):  
D. H. Sheppard
Keyword(s):  
Sex Ratio ◽  
Litter Size ◽  
Ground Squirrel ◽  
Ground Squirrels ◽  
Spermophilus Richardsonii ◽  
Live Trapping ◽  
Native Grassland ◽  
Adult Sex Ratio ◽  
The Mean ◽  
Sexually Mature

Adult Richardson's ground squirrels (n = 238) were collected near Regina, Saskatchewan in April and May of 1969 and 1970. The adult sex ratio (males: females) of collected animals was 1:3.3 compared with a juvenile sex ratio of 1:1 obtained by live trapping in 1967and 1968. The breeding season extended from 3 to 28 April but 77.8% of all conceptions occurred between 7 and 16 April. All yearlings seemed to be sexually mature and the mean litter size for all females baaed on living embryos was 6.93 ± 0.18. Mortality of embryos was 6.83%. Yearlings were smaller than adults but mean litter sizes of yearlings and adults did not differ. Ground squirrels collected from cropland had a significantly larger mean litter size, were somewhat heavier, and had significantly longer humeri than those from native grassland.

Breeding of Philander frenata (Didelphimorphia, Didelphidae) in captivity

1998 ◽  
Vol 32 (4) ◽  
pp. 434-438 ◽  
Author(s):  
Erika Hingst ◽  
Paulo Sergio D'Andrea ◽  
Ricardo Santori ◽  
Rui Cerqueira
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Litter Size ◽  
Breeding Success ◽  
Gestation Period ◽  
Sex Ratio At Birth ◽  
Laboratory Management ◽  
Sensory Contact ◽  
In Captivity ◽  
Size At Birth

Data on the reproductive biology and laboratory management of Philander frenata are presented here. Sensory contact before pairing increased breeding success and reduced aggression between pairs. Gestation period was 13–14 days, with a post-lactation oestrous. Births occurred only between August and February. Mean litter size at birth and at weaning was 5.5 (SD=2.4) and 4.0 (SD=1.9), respectively. Sex ratio at birth was statistically biased toward males. The timing of weaning was established at between 70 and 80 days old, with the young weighing from 24 g to 49 g.

scholarly journals Sex Difference in Self-Reported Sexual Functioning Among Frail Older Adults

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 313-313
Author(s):  
Brianne Olivieri-Mui ◽  
Sandra Shi ◽  
Ellen McCarthy ◽  
Dae Kim
Keyword(s):  
Older Adults ◽  
Logistic Regression ◽  
Sex Differences ◽  
Sexual Function ◽  
Older Adult ◽  
Sexual Functioning ◽  
Social Life ◽  
Well Being ◽  
Adult Males ◽  
Males And Females

Abstract Frailty may differentially impact how older adult males and females perceive sexual functioning, an important part of well-being. We assessed the level of frailty (robust, pre-frail, frail) for anyone with data on 11 sexual functioning questions asked in wave 2 of the National Social Life, Health, and Aging Project, 2010-2011 (n=2060). Questions covered five domains: overall sexual function (OSF), sexual function anxiety (SFA), changes in sexual function (CSF), erectile/vaginal dysfunction (EVD), and masturbation. Logistic regression identified sex differences in frailty and reporting worse sexual functioning. Linear regression predicted the number of domains reported as worse. Among males (n=1057), pre-frailty meant higher odds of reporting SFA (OR 1.8 95%CI 1.2-6.6), CSF (OR 1.7 95%CI 1.1-2.7), and EVD (OR 1.5 95%CI 1.0-2.2). Among females (n=1003), there was no difference in reporting by frailty. Females were more likely to report worse OSF (Robust: OR 7.4, 95%CI 4.8-11.4; Pre-frail: OR 6.2, 95%CI 3.9-9.9; Frail: OR 3.4 95%CI 1.7-6.6), but less likely to report SFA (Robust OR .3, 95%CI .2-.5; Pre-frail OR .2, 95%CI .1-.3; Frail OR .2 95%CI .1-.3). Pre-frail and frail females reported fewer domains as worse (Pre-frail coefficient -0.21 SE 0.09, Frail -0.43 SE 0.14). As frailty worsened, males reported more domains as worse (Pre-frail 0.24 SE 0.07, Frail 0.29 SE 0.08). Self-reported sexual functioning differs by sex at all levels of frailty, and reporting by males, but not females, changes with frailty. Providers should be aware that sexual functioning is of importance to both sexes despite varying degrees of frailty.

scholarly journals Mitochondrial membrane peroxidizability index is inversely related to maximum life span in mammals

1998 ◽  
Vol 39 (10) ◽  
pp. 1989-1994 ◽  
Author(s):  
Reinald Pamplona ◽  
Manuel Portero-Otín ◽  
David Riba ◽  
Cristina Ruiz ◽  
Joan Prat ◽  
...  
Keyword(s):  
Life Span ◽  
Mitochondrial Membrane ◽  
Maximum Life Span ◽  
Peroxidizability Index

Effect of climatic conditions on the annual activity and hibernation cycle of Richardson's ground squirrels and Columbian ground squirrels

1977 ◽  
Vol 55 (4) ◽  
pp. 693-703 ◽  
Author(s):  
Gail R. Michener
Keyword(s):  
Rocky Mountains ◽  
Climatic Conditions ◽  
Ground Squirrels ◽  
Active Season ◽  
Southern Alberta ◽  
Annual Activity ◽  
The Times ◽  
Columbian Ground Squirrels ◽  
Spring Emergence ◽  
Species Ecology

In 1975 and 1976 the times of spring emergence, breeding, and entry into hibernation were compared for Spermophilus richardsonii and S. columbianus in an area of sympatry in the foothills of the southern Alberta Rocky Mountains. Both species emerged earlier in 1976, which had a warmer than normal spring, than in 1975, which had a cooler than normal spring. In both years S. richardsonii emerged earlier than S. columbianus and remained active longer. Juvenile S. richardsonii entered hibernation when 17–20 weeks old whereas juvenile S. columbianus were 10–11 weeks old. Yearling S. richardsonii bred, whereas yearling S. columbianus did not. Breeding success affected the time of entry into hibernation but not the time of emergence from hibernation in the next spring. A possible relationship between the periodic arousals during hibernation and the emergence pattern of squirrels in spring is discussed. The significance of flexibility of spring emergence, length of the active season, and age at breeding to survival and species ecology is considered.

Sign in / Sign up

Export Citation Format

Share Document