Studies on the European hare. XXVII. Methods for determination of Age in the European hare

Caboń-Raczyńska, Krystyna; Raczyński, J.

doi:10.4098/at.arch.72-7

Cited by 11 publications

(7 citation statements)

References 3 publications

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“…In scientific research, the age of animals is often assessed based on dry lens weight. Laboratory weighing of lenses can help to discriminate between juvenile (up to 1 year old) and adult (more than 1 year old) individuals [ 22 , 29 , 30 , 31 , 32 , 33 ]. Since the lens weight gain in the first year of life is more intense, the weight data indicate the time of birth [ 36 ].…”

Section: Discussionmentioning

confidence: 99%

“…After drying, the lenses were weighed on an analytical balance (Pioneer OHAUS, Nänikon, Switzerland) with an accuracy of 0.001 g. This method is based on the observation that the eye-lens weight increases relatively intensively during the first year of life, whereas a lower increase is recorded in the following years. In accordance with this principle and based on the data obtained in the study, the animals were categorized as juveniles or adults, with an eye-lens-weight cutoff value of 290 mg [ 29 , 30 , 31 , 32 , 33 ].…”

Section: Methodsmentioning

confidence: 99%

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Logistic Regression Model for Determination of the Age of Brown Hare (Lepus europaeus Pall.) Based on Body Weight

Flis

Czyżowski

Beeger

et al. 2022

Animals

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We developed an algorithm to classify brown hares into two age classes, juveniles (up to 1 year old) and adults (over 1 year old), based on body weight, which can be determined by both the examination of live animals and postmortem analysis. Considering the strong correlation between lens weight and carcass weight, we assumed that hares could be classified into one of the two age groups based only on carcass weight, using a logistic regression model. Using logistic regression, a model was constructed to assess the age of hares based on their body weight. For comparison with the current age-assessment method based on the dry lens weight, a logistic regression classifying the hares based on the dry lens weight was performed as well. The results of the study facilitated the development of a method to classify hares into age groups based on body weight. The proposed approach is innovative, as it allows for the determination of the age of not only culled (postmortem) but also live hares. The method is easy and does not require laboratory tests; hence, the results can be used immediately following evaluation. This method allows hares to be categorized into two age groups (juveniles and adults). With an accuracy of 97.52% and 95.45% in the case of juvenile and adult hares, respectively, the proposed approach can be widely used both in population management and scientific research.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Logistic Regression Model for Determination of the Age of Brown Hare (Lepus europaeus Pall.) Based on Body Weight

Flis

Czyżowski

Beeger

et al. 2022

Animals

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show abstract

“…Determination of the animal age based on the lens weight is possible, because the growth of lens lasts to grow up to the death (Lord 1959 ; Augusteyn 2008 ) and, hence, the dry mass of the eye lens has commonly been used to estimate the age of mammalian species (Lord 1959 ; Friend 1967 ; Dapson 1980 ; Augusteyn 2014 ). The individuals with a dry weight of the lenses less than 275 mg were classified as juveniles (Andersen and Jensen 1972 ; Cabon-Raczynska and Raczynski 1972 ; Suchentrunk et al 1991 ). The liver samples were perfused with a cold solute on containing 0.13 M NaCl, 0.5 mM KCl, and 0.8 mM MgCl 2 supplemented with 0.1 mM phenylmethylsulfonyl fluoride (PMSF) and stored at − 20 °C until H1 histones were isolated.…”

Section: Methodsmentioning

confidence: 99%

Brown Hare’s (Lepus europaeus) Histone H1 Variant H1.2 as an Indicator of Anthropogenic Stress

Kowalski

Markowski

2018

Arch Environ Contam Toxicol

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From the liver tissues of brown hare individuals that lived in two various habitats, i.e., the agricultural region with the predominant farms and the industrial area near a metallurgical plant, histones H1 were analyzed to compare their within and between population variability. Furthermore, because agricultural production emits mainly organic pollutants and metallurgical industry is a primarily source of inorganic contaminations, we wanted to check how the brown hare individuals are sensitive for both agents. Among brown hare H1 histones, the histone H1.2 was determined as heterogeneous due to its varied mobility in two-dimensional SDS–polyacrylamide gel. The obtained electrophoretic patterns contained differently moving single spots of histone H1.2 and also its double spots have a similar rate of electrophoretic mobility. Based on this, two homozygous phenotypes (slowly migrating 2a and faster moving 2b) and a heterozygous phenotype (2a2b) was distinguished. The relatively low variable (CV < 0.25) and comparably abundant (p > 0.05) histone H1.2 homozygous phenotypes form a heterozygous phenotype in a similar proportion, at a ratio approximating 0.5. Although the brown hare population originating from agricultural area displayed a slight excess of heterozygous individuals 2a2b (F = − 0.04), it was conformed to the Hardy–Weinberg assumption (χ2 = 0.035, p = 0.853). Compared with this population, a sevenfold reduced frequency of the phenotype 2b and above tenfold increase of a heterozygosity (F = − 0.53) was observed in the brown hare population inhabiting the vicinity of metallurgical plant. Therefore, this population did not fit to the Hardy–Weinberg law (χ2 = 5.65, p = 0.017). Despite the negligible genetic differentiation (FST = 0.026) between brown hare populations inhabiting areas with different anthropogenic pressure, a statistically significant difference in the distribution of their phenotypes (χ2 = 6.01, p = 0.049) and alleles (χ2 = 6.50, p = 0.013) was noted. The collected data confirm that the brown hare species is sensitive for environmental quality and may serve as a good indicator of habitat conditions related to both organic pollution emitted by agricultural activities (PIC = 0.48) and inorganic contamination originating from metallurgical processes (PIC = 0.49). These difference in the environmental quality might be assessed by estimation of genetic variability among the brown hare populations, based on the phenotypes distribution of histone H1 variant H1.2, the protein that was not so far employed as a molecular marker of anthropogenic stress.

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“…Upon capture, hares were sexed and aged (Stroh ) whenever possible. However, the method of age determination is unreliable during winter (Caboń‐Raczyńska & Raczyński ), so we considered all hares caught in Nov.–Feb. as adults (Ernest ).…”

Section: Methodsmentioning

confidence: 99%

Predation Risk Drives Habitat‐Specific Sex Ratio in a Monomorphic Species, the Brown Hare (Lepus europaeus)

Hušek¹,

Panek²,

Tryjanowski³

2015

Ethology

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In dimorphic species, sexual habitat segregation is generally explained by the differences in nutritional needs or by a trade‐off between fulfilling food requirements and avoiding predation. However, it remains unclear whether predation risk is strong enough to drive the differences in habitat use between sexes as predicted by the predation sensitivity hypothesis. Here we test in a monomorphic species, the brown hare (Lepus europaeus), the prediction that abundance of the gender more sensitive to predation is higher in safer habitat. We used data on 1645 individually marked hares in western Poland during autumn–winter seasons of 1966/1967–1978/1979 to estimate sex‐specific annual survival rates. We analyzed the stomach contents of 134 foxes shot in 1965/1966–1994/1995 to evaluate fox predation on hares. Finally, we employed data on 26 790 hares live‐trapped in 1965/1966–1994/1995 to analyze hare sex ratio across habitats. We found that male annual survival rate was lower than that of females and that the predation risk by foxes on hares was lower in agricultural than forest habitat. Our finding, that males were more often trapped by nets in agricultural than the forest habitat, provides indirect evidence for the predation sensitivity hypothesis. We conclude that predation risk can be a driving force for habitat‐specific sex ratio in a monomorphic species such as the brown hare.

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Studies on the European hare. XXVII. Methods for determination of Age in the European hare

Cited by 11 publications

References 3 publications

Logistic Regression Model for Determination of the Age of Brown Hare (Lepus europaeus Pall.) Based on Body Weight

Logistic Regression Model for Determination of the Age of Brown Hare (Lepus europaeus Pall.) Based on Body Weight

Brown Hare’s (Lepus europaeus) Histone H1 Variant H1.2 as an Indicator of Anthropogenic Stress

Predation Risk Drives Habitat‐Specific Sex Ratio in a Monomorphic Species, the Brown Hare (Lepus europaeus)

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