Revealing the Circadian Rhythm of Taliang Crocodile Newt(Liangshantriton taliangensis) During Breeding Migration Using a Novel Monitoring Technique

Many animals migrate during the breeding season.It is important to study the patterns of breeding migration of wild animals,especially rare and endangered species.However,current data acquisition methods are too coarse and imprecise for investigating the circadian rhythms of migrations in amphibians.Based on the frustrated total reflection image(FTRI),we developed a new device and recorded the precise migration time of an endangered salamander,Liangshantriton taliangensis.During the breeding period,a total of 33 individuals were effectively recorded.Analysis of the data indicated that the circadian rhythm of breeding migration in L.taliangensis was bimodal,and migration mainly occurred from 05:00 to 13:00(81.82%of the total migration records).The average relative activity intensity index(RAI)of breeding migration peaked in the temperature range of 14.0–16.0°C.With increased average relative air humidity,the activity intensity first increased and then decreased,reaching a peak in the humidity range of 91.0%–97.0%.These results demonstrate that our new device is a viable and accurate method for recording the migration time of target species.It is important to reveal the breeding migration pattern of L.taliangensis,which is important for the conservation of this species.Meanwhile,this new device can be used for field monitoring and conservation studies of amphibians,reptiles and other animals.

Endocast Morphological Variation and Its Driving Forces in Scutiger boulengeri

Cranialendocasts canbeusedasareliable proxy for brain size,reflecting the evolutionary and environmental selection pressure of species.Although studies on endocasts in amphibians have increased in recent years,those performed on endocasts of Anura are comparatively rare,especially at the intraspecific level.Here,using a high-altitude endemic toad-Scutiger boulengeri-as a model,through the application of integrative methods(morphology,anatomy,phylogeny,and ecology),we studied intraspecific variations in endocast morphology and explored its driving forces.Three-dimensional reconstruction and the brain-to-endocranial cavity(BEC)index suggested that the endocast of S.boulengeri can reflect brain morphology to a large extent.Elliptic Fourier analysis andprincipal componentanalysis revealedgreat variability in the cranial endocast morphology among individuals,as well as the variation concentrated in the regions of telencephalon and optic tectum.In the species,individuals with large bodies are accompanied by a larger endocast size;the relative endocast sizes have significant cladedifferences but no sexual dimorphism.Additionally,the relative endocast sizes of S.boulengeri were not associated with phylogenetic history and aquatic preference but were positively correlated with altitude and negatively correlated with oxygen content,temperature,and precipitation factors(annual mean temperature,temperature seasonality,annual precipitation,and precipitation seasonality).Thesefindings suggested that high-altitude and extreme environmental conditions acted as important selectiveforces in morphological variation of the cranial endocastof S.boulengeri.