Geographic Variation In Sexual Size Dimorphism And The Study Of The Breeding Behavior Of Captive PAA SPINOSA

The giant spiny frog, Paa spinosa, is known for its keratinized skin-spines on the chest and the development of hypertrophied forearms as a secondary sex organ in the males during the breeding season. Reproductive activities of the frog take place from April to October. Inhabiting rocky streams in evergreen forests and open fields on mountains 500-1,500 m above sea level, this species is highly prized in the Chinese markets for its nutritional and medicinal values. The taxonomy of frogs in this genus has been subject to controversy. Little or no information is available on female mate choice. So, the study of the behaviors of P. spinosa is very important.P. spinosa of five sites were sexually dimorphic for body size and body shape:the body size, jaw length and forelimb length of males were significantly larger than those of females. Furthermore, the degree of sexual size dimorphism (SSD) varied geographically, but the relationship between the grographic variation of sexual size dimorphism and climate was complex. Specifically, absolute sexual size dimorphism was positively correlated with the increased ambient temperature and decreased precipitation.We recorded behaviors of captive P. spinosa using an infrared video camera, and analyzed the ethogram and activity rhythm of the frog with focal and scan sampling methods. The behaviors included stillness behavior (resting, staring), social behavior (fighting, chasing), playing behavior (swimming, calling, jumping), feeding behavior (foraging), and reproductive behavior (advertisement call, aggression, dislodge, bite, wrestle, amplexus, amplexus error, reject, oviposition). The frogs mainly kept still during the day time, but were active in the evening with a peak at the time of 03:00-05:00. There were three peaks of fighting behavior in the daytime:06:00-07:00,08:00-09:00, and 11: 00-12:00, by contrast, fighting seldom appeared in the evening from 17:00 to 24:00. Calling mainly appeared at 06:00-07:00, and 13:00-14:00 in the day time, but little in the evening from 17:00 to 24:00. The reproductive behavior of Paa spinosa always took place in the evening, peaking at 17:00-01:00. The time budget of reproductive behavior was as following:amplexus (67%), wrestle (17%), and bites (15%). Based on the description of behavior, we also discussed the mechanism of behaviors. The changes of food resources, space and habitats had significant impacts on the behavior of captive P. spinosa.We analyzed the advertisement call of P. spinosa at Yuliang Mountain, Lanxi, Zhejiang province, in eastern China. Temporal and spectral call parameters were analyzed, along with call intensity. Calls comprised of three to seven notes, the last of which had the longest duration. Three formants (harmonics) were clearly distinguishable from the audio spectrogram. The dominant frequency ranged from 411-1534Hz, and was either the first or the second formant. The number of notes within a call was positively correlated to air temperature, so that calls contained more notes during the day. Also, the dominant frequency appeared to be lower at the highest temperature.