A Comparison Study on Residual Yolk, Morphological Change and Locomotion Performance Between Hatchlings of the Red-eared Slider Turtle(Trachemys scripta elegans) and the Chinese Stripe-necked Turtle(Mauremys sinensis)
SHENG Cheng;HONG Mei-Ling;SHI Hai-Tao;College of Life Sciences, Hainan Normal University;Chengdu Institute of Biology, Chinese Academy of Sciences;
The Red-eared Slider Turtle(Trachemys scripta elegans) is ranked as one of the 100 world′s worst invasive species. Our previous study found out that hatchlings of Red-eared Slider Turtle was able to survive for more than 30 days without eating any food. In order to reveal the underlying mechanism of this physiological phenomenon, we compared the morphological change between the Red-eared Slider Turtle and native Chinese Stripe-necked Turtle(Mauremys sinensis). We measured their body weight, body height, length and width of carapace, plastron length, head length, head width, head height and tail length and their locomotion performance, including maximum distance of continuous movement, stop times of 60 s running, and of 1 000 mm swimming within 1 h after hatched, and the dry weight of the residual yolk at 0 h, 24 h, 48 h, 72 h, 96 h, 240 h post hatching without providing any food. We got following results:(1) the dry weight of residual yolk in the Red-eared Slider Turtle was significantly higher than that in the Chinese Stripe-necked Turtle(20.5% vs. 5.2%, t = 7.93, df = 18, P 0.001) hatched at the optimum temperature for yolk utilization(about 29℃). Without providing any food, the residual yolk in the Chinese Stripe-necked Turtles was 3.4% after 72 h, and was totally absorbed within 96 h. While the dry weight of residual yolk in the Red-eared Slider Turtle were 11.9% after 96 h hatched, and it took 31 days being totally absorbed(Table 2). That indicated the Red-eared Slider Turtle can suffered longer time of starvation with the heavier of residual yolk.(2) The initial body weight(measured within 1 h after hatched) of Red-eared Slider Turtle(9.45 ± 1.04 g, n = 42) is significantly greater than Chinese Stripe-necked Turtle(7.07 ± 1.21 g, n = 30)(t = 8.933, df = 70, P 0.001). Analysis of covariance(ANCOVA) for testing body traits difference between these two species showed that only two values, carapace length and head height, were significantly greater in the Red-eared Slider Turtle than those in native turtle(F(1, 69) = 9.899, P = 0.002; F(1, 69) = 7.102, P = 0.010) while showed a shorter tail length(F(1, 69) = 526.93, P 0.001) and bigger body size in the Red-eared Slider Turtle than native turtle(Table 1).(3) The Chinese Stripe-necked Turtle made a continually moving 80.3 ± 14.4 cm maximally by stopping 5.6 ± 0.3 times/min. In contrast, the Red-eared Slider Turtle only moved 29.8 ± 11.7 cm by stopping 4.0 ± 0.2 times/min. It took 32.8 ± 4.3 s and 61.2 ± 7.2 s to swim 1 m for the Chinese Stripe-necked Turtle and the Red-eared Slider Turtle, respectively. These findings suggested that in contrast with the Chinese Stripe-necked Turtle, the Red-eared Slider Turtle hatchling had larger body size with more residual yolk, but had lower locomotion performance. All these biological characteristics helped the slider tolerance of starved. Our results could provide basic information on the invasive mechanism in Red-eared Slider Turtle.