Breeding and Development of the Tscherskia triton in Jeju Island

The greater long-tail hamster, Tscherskia triton, is widely distributed in Northern China, Korea and adjacent areas of Russia. Except for its distribution, biological characteristics related to life history, behavior, and ecological influences for this species are rarely studied in Korea. This study was conducted to obtain biological information on breeding, growth and development that are basic to species-specific studies. The study adopted laboratory management of a breeding programme for T. triton collected in Jeju Island from March, 2015 to December, 2016. According to the study results, the conception rate was 31.67% and the mice in the large cages had a higher rate of conception than those in the small cages (56.7 vs. 6.7%). The gestation period was $22{\pm}1.6days$ (ranges from 21 to27 days), and litter size ranged from 2 to 7, with a mean of $4.26{\pm}1.37$ in the species. The minimum age for weaning was between $19.2{\pm}1.4days$ (range of 18-21 days). There were no significant differences by sex between mean body weight and external body measurements at birth. However, a significant sexual difference was found from the period of weaning (21 days old) in head and body length, as well as tail length (HBL-weaning, $106.50{\pm}6.02$ vs. $113.34{\pm}4.72mm$, p<0.05; HBL-4 months, $163.93{\pm}5.42$ vs. $182.83{\pm}4.32mm$, p<0.05; TL-4 months, $107.23{\pm}3.25$ vs. $93.95{\pm}2.15mm$, p<0.05). Gompertz and Logistic growth curves were fitted to data for body weight and lengths of head and body, tail, ear, and hind foot. In two types of growth curves, males exhibited greater asymptotic values ($164.840{\pm}7.453$ vs. $182.830{\pm}4.319mm$, p<0.0001; $163.936{\pm}5.415$ vs. $182.840{\pm}4.333mm$, p<0.0001), faster maximum growth rates ($1.351{\pm}0.065$ vs. $1.435{\pm}0.085$, p<0.05; $2.870{\pm}0.253$ vs. $3.211{\pm}0.635$, p<0.05), and a later age of maximum growth than females in head and body length ($5.121{\pm}0.318$ vs. $5.520{\pm}0.333$, p<0.05; $6.884{\pm}0.336$ vs. $7.503{\pm}0.453$, p<0.05). However, females exhibited greater asymptotic values ($105.695{\pm}5.938$ vs. $94.150{\pm}2.507mm$, p<0.001; $111.609{\pm}14.881$ vs. $93.960{\pm}2.150mm$, p<0.05) and longer length of inflection ($60.306{\pm}1.992$ vs. $67.859{\pm}1.330mm$, p<0.0001; $55.714{\pm}7.458$ vs. $46.975{\pm}1.074mm$, p<0.05) than males in tail length. These growth rate constants, viz. the morphological characters and weights of the males and females, were similar to each other in two types of growth curves. These results will be used as necessary data to study species specificity of T. triton with biological foundations.

제주도 서식 비단털쥐(Tscherskia triton)의 번식과 발달

중국 북부와 한국, 러시아 지역에 서식하는 비단털쥐(Tscherskia triton)의 분포를 제외한 생활사, 행동, 생태와 관련된 생물학적 특징에 대해서는 거의 연구된 바 없다. 이에 본 연구는 제주도에서 포획된 개체(n=9)를 대상으로 종 단위 연구의 기본이 되는 번식과 성장 및 발달에 대한 생물학적 정보를 밝히기 위하여 2015년 3월부터 2016년 12월까지 사육실에서 진행되었다. 연구결과, 임신률은 31.7%였고 좁은 케이지에서 보다 넓은 케이지에서 더 높게 나타났다(56.7 vs. 6.7%). 임신기간은 $22{\pm}1.6$일(범위 21-27일), 한배의 산자수(litter size)는 $4.26{\pm}1.37$마리(범위 2-7 마리)였다. 최소이유시기는 $19.2{\pm}1.4$일(범위 18-21일)이었다. 출생 직후 새끼의 체중과 외부형태의 크기는 성별로 차이가 없었으나, 이유시기부터 암수의 머리와 몸통길이(HBL)와 꼬리길이(TL)는 차이가 있는 것으로 나타났다(HBL-weaning, $106.50{\pm}6.02$ vs. $113.34{\pm}4.72mm$, p<0.05; HBL-4 months, $163.93{\pm}5.42$ vs. $182.83{\pm}4.32mm$, p<0.05; TL-4 months, $107.23{\pm}3.25$ vs. $93.95{\pm}2.15mm$, p<0.05). Gompertz 모형과 logistic 모형을 적용하였을 때, 머리-몸통길이에서는 수컷이 암컷보다 최대 성숙 길이가 길었고($164.840{\pm}7.453$ vs. $182.830{\pm}4.319mm$, p<0.0001; $163.936{\pm}5.415$ vs. $182.840{\pm}4.333mm$, p<0.0001), 성장률도 빨랐으나($1.351{\pm}0.065$ vs. $1.435{\pm}0.085$, p<0.05; $2.870{\pm}0.253$ vs. $3.211{\pm}0.635$, p<0.05), 성장곡선의 기울기가 최대가 되는 일령은 암컷보다 조금 늦었다($5.121{\pm}0.318$ vs. $5.520{\pm}0.333$, p<0.05; $6.884{\pm}0.336$ vs. $7.503{\pm}0.453$, p<0.05). 한편 꼬리의 최대길이($105.695{\pm}5.938$ vs. $94.150{\pm}2.507mm$, p<0.001; $111.609{\pm}14.881$ vs. $93.960{\pm}2.150mm$, p<0.05)와 변곡점에서의 길이($60.306{\pm}1.992$ vs. $67.859{\pm}1.330mm$, p<0.0001; $55.714{\pm}7.458$ vs. $46.975{\pm}1.074mm$, p<0.05)는 암컷이 수컷보다 긴 것으로 나타났다. 두 성장모형에서 암수의 체중과 외부형태형질에 대한 성장률은 비교 결과 유사하였다. 이러한 결과는 비단털쥐의 종적 특징을 밝히는데 필요한 자료로 이용될 것이다.