Placental Scars and Estimation of Litter Size: An Experimental Test in the Arctic Fox

1995 ◽  
Vol 76 (4) ◽  
pp. 1220-1225 ◽  
Author(s):  
O. Strand ◽  
T. Skogland ◽  
T. Kvam
2011 ◽  
Vol 49 (No. 11) ◽  
pp. 474-482 ◽  
Author(s):  
H. Wierzbicki

The study presents estimates of heritability for fur coat and reproduction traits in arctic and silver foxes kept on Polish farms. The estimates of variance components were calculated using the DFREML and single-trait animal models. Due to a discrete character of fur coat traits, they were analysed twice: (1) without normalisation of their scores distribution, (2) after the normal probability scale transformation of their scores. Linear models included random additive genetic and common litter environment effects, and fixed effects of farm × year × birth season in the silver fox or year × birth season in the arctic fox as well as the fixed effect of female age when the reproduction traits were analysed. Moreover, the estimation of variance components for fur coat traits was done by a linear model with (Model 2) or without (Model 1) inbreeding coefficients included as linear covariable. In the arctic fox accounting for inbreeding and the data transformation did not markedly influence the estimates of heritability and the portion of litter variation calculated for the fur coat traits. An inbreeding effect was negligible (except for body size – BS) likely due to the low inbred level of the arctic fox population. In the silver fox the comparison of estimates derived using 2 different linear models and 2 data sets revealed more differences than it was found in the arctic fox. Accounting for inbreeding usually led to lower estimates of heritability, mainly when heritabilities were derived from the normal probability scale-transformed data. Most of the estimates of heritability of reproduction traits were found within the range reported by other authors. However, somewhat higher heritabilities were found for litter size at birth – LSB (0.205) and litter size at weaning – LSW (0.250).    


Oikos ◽  
1998 ◽  
Vol 83 (3) ◽  
pp. 545 ◽  
Author(s):  
Magnus Tannerfeldt ◽  
Anders Angerbjörn ◽  
Anders Angerbjorn

1989 ◽  
Vol 49 (1) ◽  
pp. 67-81 ◽  
Author(s):  
Páll Hersteinsson ◽  
Anders Angerbjörn ◽  
Karl Frafjord ◽  
Asko Kaikusalo

2015 ◽  
Vol 502 ◽  
pp. 510-516 ◽  
Author(s):  
Kathrine Eggers Pedersen ◽  
Bjarne Styrishave ◽  
Christian Sonne ◽  
Rune Dietz ◽  
Bjørn Munro Jenssen

Polar Biology ◽  
2021 ◽  
Author(s):  
Peter S. Ungar ◽  
Blaire Van Valkenburgh ◽  
Alexandria S. Peterson ◽  
Aleksandr A. Sokolov ◽  
Natalia A. Sokolova ◽  
...  

2011 ◽  
Vol 49 (No. 1) ◽  
pp. 16-27 ◽  
Author(s):  
H. Wierzbicki ◽  
A. Filistowicz ◽  
W. Jagusiak

Three data sets were available: records on conformation and coat traits for the arctic fox from one farm (5 540 observations, collected between 1983 and 1997), and the same traits for the silver fox from three farms (8 199 observations, collected between 1984 and 1999). The third set comprised 5 829 observations on reproductive performance of the arctic fox from one farm, collected between 1984 and 1999. The GLM procedure was used to test the significance of fixed effects on the analysed reproduction traits as well as differences between groups. Phenotypic trends as well as relationship and inbreeding across the studied years were computed. Most of the phenotypic trends were positive. Low relationship and inbreeding coefficients in the arctic and silver fox populations under study were estimated. The average relationship coefficients for the silver and arctic fox populations were 0.015 and 0.010, respectively, whereas the average inbreeding coefficients for the same species were 0.0039 and 0.0016, respectively. No inbreeding was found in the arctic fox breeding females.  


2003 ◽  
Vol 117 (3) ◽  
pp. 430 ◽  
Author(s):  
Eva Fuglei ◽  
Nils A. Øritsland

This work was conducted to determine effect of season and starvation on metabolic rate during running in the Arctic Fox (Alopex lagopus) on Svalbard (78°55’N, 11°56’E), Norway. Indirect calorimetry was used to measure metabolic rate of foxes running on a treadmill and heart rate was monitored using implanted radio transmitters. The relationship between heart rate and metabolic rate was also examined. Metabolic rate increased with running speed. In July the metabolic rate during running almost fitted general equations predicted for mammals, while it was up to 20% lower in January, indicating seasonal variation in metabolic rate. There was a significant positive linear relationship between heart rate and weight specific metabolic rate, suggesting that heart rate can be used as an indicator of metabolic rate. Starvation for 11 days decreased the net cost of running by 13% in January and 17% in July, suggesting that a starved fox runs more energetically efficient than when fed. Heart rate measured in July decreased by 27% during starvation. Re-feeding reversed the starvation-induced reduction in metabolic rate and heart rate during running almost up to post-absorptive levels. The present results are from one fox, and must be considered as preliminary data until further studies are conducted.


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