Search results for "LITTER"
showing 10 items of 315 documents
GENETIC BASIS OF THE TRADE-OFF BETWEEN OFFSPRING NUMBER AND QUALITY IN THE BANK VOLE
2004
One of the main tenets of modern life-history theory is the negative relationship (trade-off) between the number and quality of offspring produced. Theory predicts a negative genetic correlation between these traits since both are closely related to fitness of individuals. However, the genetic basis of the trade-off has only been tested to a limited extent in natural populations. We examined whether size and quality of offspring are negatively related to litter size in the bank vole Clethrionomys glareolus. First, we found a significant negative phenotypic correlation between the number and size of offspring at birth in both laboratory and field populations of the bank vole. Second, a large…
Optimal allocation of reproductive effort: manipulation of offspring number and size in the bank vole
2001
The number of offspring attaining reproductive age is an important measure of an individual's fitness. However, reproductive success is generally constrained by a trade-off between offspring number and quality. We conducted a factorial experiment in order to study the effects of an artificial enlargement of offspring number and size on the reproductive success of female bank voles (Clethrionomys glareolus). We also studied the effects of the manipulations on growth, survival and reproductive success of the offspring. Potentially confounding effects of varying maternal quality were avoided by cross-fostering. Our results showed that the number of offspring alive in the next breeding season w…
Analysis of the influence of the PrP genotype on the litter size in Polish sheep using classification trees and logistic regression
2014
The relation between prion protein (PrP) genotype class and litter size was analysed in Polish Merino, Black-headed, Ile de France and Berrichon du Cher sheep in Poland. Litter size was analysed with the classification tree technique and multiple logistic regression for effects of breed, age of ewe, PrP genotype, litter size of ewe at her birth, and at her rearing and year of ewe's birth. The resulting classification tree was 6-level deep and contained 21 leaves. Age, breed and year of birth were more important determinants of litter size than PrP genotype. Importance of PrP genotype in the tree development was 0.560 relative to age of ewe. While the logistic regression analysis showed that…
A trade-off between current and future sex allocation revealed by maternal energy budget in a small mammal.
2011
Sex-allocation theories generally assume differential fitness costs of raising sons and daughters. Yet, experimental confirmation of such costs is scarce and potential mechanisms are rarely addressed. While the most universal measure of physiological costs is energy expenditure, only one study has related the maternal energy budget to experimentally controlled offspring sex. Here, we experimentally test this in the bank vole (Myodes glareolus) by simultaneously manipulating the litter's size and sex ratio immediately after birth. Two weeks after manipulation, when mothers were at the peak of lactation and were pregnant with concurrent litters, we assessed their energy budget. We found that …
Reproductive costs and litter size in the bank vole.
1995
The potential reproductive costs for free-ranging bank vole (Clethrionomys glareolus) offspring and mothers were assessed by manipulating litter size and by determining the effects of nursing varied numbers of offspring. Litter enlargement did not increase the number of weanlings per mother. The mass of juveniles was significantly lower in the enlarged litters and higher in the reduced litters, compared to the control group. However, the survival of juveniles from weaning aged three months did not depend on their mass at weaning. Data from a previous study (Mappes et al. 1995) indicated that a higher mass at weaning may increase juveniles' abilities to maturate and breed during their summer…
Maternal effort and male quality in the bank vole, Clethrionomys glareolus.
1999
Parental investment in reproduction is adjusted according to potential benefits in terms of offspring survival and/or mating success. If male quality affects the reproductive success of a female, then females mating with high-quality males should invest more in reproduction. Although the subject has been of general interest, further experimental verification of the hypothesis is needed. We studied whether female bank voles (Clethrionomys glareolus) adjusted their maternal effort according to male quality, measured as mating success. To enable the measurement of maternal effort during nursing separately from male genetic effects the litters were cross-fostered. Further, the genetic backgroun…
Absence of long-term effects of reproduction on longevity in the mouse model.
2014
Background Most human demographic data, particularly those on natural fertility populations, find no relationship or even a positive association between fertility and longevity. The present study aims to ascertain whether there is a trade-off between fertility and longevity in the mouse model. Methods The study was focused on the first litter produced by 10- to 14-wk-old hybrid (C57BL/6JIco female X CBA/JIco male) mice. A single female/male per litter was individually housed with a male/female at the age of 25 and 52 wk, respectively, until the end of reproductive life in females or natural death in males under controlled housing conditions. Post-reproductive females and virgin mice were re…
LID - 10.3791/59466 [doi]
2019
The following protocol is intended to respond to the requirements set by the European Union’s Marine Strategy Framework Directives (MSFD) for the D10C3 Criteria reported in the Commission Decision (EU), related to the amount of litter ingested by marine animals. Standardized methodologies for extracting litter items ingested from dead sea turtles along with guidelines on data analysis are provided. The protocol starts with the collection of dead sea turtles and classification of samples according to the decomposition status. Turtle necropsy must be performed in authorized centers and the protocol described here explains the best procedure for gastrointestinal (GI) tract isolation. The three…
Effects of litter size and sex on meat quality traits of kid meat
2004
The influence of litter size and sex on meat quality traits was investigated using 40 Nebrodi kids slaughtered at 47 days of age. Carcass measurements (body components, carcass joints, pelvic limb tissue composition, meat fatty acid composition and M. longissimus dorsi (LD) colour), body weight at birth and at slaughter were evaluated. Nebrodi kids had a low body weight at birth, with significant differences between male and female (4.1 kg versus 3.9 kg) and between single and twin (4.2 kg versus 3.8 kg). Male kids were heavier at birth and at slaughter, however, females had a higher percentage of kidney and pelvic fat (2.1% versus 1.5% of the right side; P < 0.01). Both males and females, …
Is reproduction really costly? Energy metabolism of bank vole (Clethrionomys glareolus) females through the reproductive cycle
2007
Energetic requirements during reproduction are important determinants of the onset of reproduction and of breeding strategy (e.g., breeding post-partum) and therefore affect female reproductive output in seasonally varying environments. To balance the energetic needs of breeding with energy availability, females must optimize energy allocation between their own energy use and energy allocated to their litter. Here, we studied energetic costs and potential energetic trade-offs of reproduction in female bank voles (Clethrionomys glareolus). We measured energy consumption, i.e., metabolic rates as determined from carbon dioxide production of females either with their pups (breeding unit) to fi…