Three anurans (Callobatrachus sanyanensis, Liaobatrachus grabaui, Mesophryne beipiaoensis) and six urodeles (Laccotriton subsolanus, Liaoxitriton zhongjiani, Jeholotriton paradoxus, Sinerpeton fengshanensis, Chunerpet...Three anurans (Callobatrachus sanyanensis, Liaobatrachus grabaui, Mesophryne beipiaoensis) and six urodeles (Laccotriton subsolanus, Liaoxitriton zhongjiani, Jeholotriton paradoxus, Sinerpeton fengshanensis, Chunerpeton tianyiensis, Liaoxitriton daohugouensis) are reported from the late Mesozoic tuff-interbedded lacustrine deposits (mostly of the Jehol Group) in northeastern China. They document the first discovery of Chinese Mesozoic lissamphibians, and their old geological age, superb preservation condition, and large taxoncmic diversity are unique compared with other findings worldwide. The anurans occupy a higher evolutionary position than typical Jurassic taxa, supporting a post-Late Jurassic age of the fossil horizons. The urodeles all have unicapitate ribs, suggesting an evolutionary grade at the cryptobranchoid level, and are advanced in osteological features over non-urodeles from the Middle and Upper Jurassic in England and Central Asia. Some urodeles (Jeholotriton and Chunerpeton) exhibit neotenic features, representing the earliest occurrence among such findings. Six fossil horizons are rscognized for the known Chinese Mesozoic anurans and urodeles: the Daohugou fossil bed, the Dabeigou Formation, the Lujiatun Bed, Jianshangou Bed and Dawangzhangzi Bed of the Yixian Formation, and the Jiufotang Formation. As implied from the osteological and phylogenetical studies, the geological age of these anurans and urodeles is the Early Cretaceous.展开更多
Why do two sexes of the same species differ in body size holds a long-standing question of evolutionary biology. While many across-species comparisons have focused on ultimate causes behind sexual size dimorphism （SS...Why do two sexes of the same species differ in body size holds a long-standing question of evolutionary biology. While many across-species comparisons have focused on ultimate causes behind sexual size dimorphism （SSD）, only have a few been directed toward elucidating its ontogenetic basis. Urodeles are an amphibian group in which the direction and degree of SSD vary greatly among species. Using demographic data yielded by skeletochronology for 33 urodele species, the current study re- veals a positive across-species correlation between SSD and the sex difference in mean age of adult animals, and the latter in- creases with the corresponding difference in age at maturity; annual growth rate does not differ between the sexes. We conclude that extended longevities in one sex, which is mediated by delayed maturation, would allow it to grow for longer and get larger, with growth rate making a weak contribution to body size. The sex-specific divergence in ontogenetic trajectory might be ex- plained by potentially high growth costs of reproduction to females in association with stronger fecundity selection, and to males that are expected to experience stronger sexual selection [Current Zoology 59 （1）： 142-150, 2013].展开更多
Regenerative capacity of the central nervous system(CNS)is unevenly distributed among vertebrates.While most mammalian species including humans elicit limited repair following CNS injury or disease,highly regenerative...Regenerative capacity of the central nervous system(CNS)is unevenly distributed among vertebrates.While most mammalian species including humans elicit limited repair following CNS injury or disease,highly regenerative vertebrates including urodele amphibians and teleost fish spontaneously reverse CNS damage.Teletost zebrafish(danio rerio)are tropical freshwater fish that proved to be an excellent vertebrate model of successful CNS regeneration.Differential neuronal,glial,and immune injury responses underlie disparate injury outcomes between highly regenerative zebrafish and poorly regenerative mammals.This article describes complications associated with neuronal repair following spinal cord injury(SCI)in poorly regenerative mammals and highlights intersecting modes of plasticity and regeneration in highly regenerative zebrafish(Figures 1 and 2).Comparative approaches evaluating immunoglial SCI responses were recently reviewed elsewhere(Reyes and Mokalled,2024).展开更多
基金This research was supported by gran ts from the National Natural Science Foundation of China(No.40302008)the Ministry of Science and Technology of China(No.2000077700)the National Science Foundation of the US.
文摘Three anurans (Callobatrachus sanyanensis, Liaobatrachus grabaui, Mesophryne beipiaoensis) and six urodeles (Laccotriton subsolanus, Liaoxitriton zhongjiani, Jeholotriton paradoxus, Sinerpeton fengshanensis, Chunerpeton tianyiensis, Liaoxitriton daohugouensis) are reported from the late Mesozoic tuff-interbedded lacustrine deposits (mostly of the Jehol Group) in northeastern China. They document the first discovery of Chinese Mesozoic lissamphibians, and their old geological age, superb preservation condition, and large taxoncmic diversity are unique compared with other findings worldwide. The anurans occupy a higher evolutionary position than typical Jurassic taxa, supporting a post-Late Jurassic age of the fossil horizons. The urodeles all have unicapitate ribs, suggesting an evolutionary grade at the cryptobranchoid level, and are advanced in osteological features over non-urodeles from the Middle and Upper Jurassic in England and Central Asia. Some urodeles (Jeholotriton and Chunerpeton) exhibit neotenic features, representing the earliest occurrence among such findings. Six fossil horizons are rscognized for the known Chinese Mesozoic anurans and urodeles: the Daohugou fossil bed, the Dabeigou Formation, the Lujiatun Bed, Jianshangou Bed and Dawangzhangzi Bed of the Yixian Formation, and the Jiufotang Formation. As implied from the osteological and phylogenetical studies, the geological age of these anurans and urodeles is the Early Cretaceous.
文摘Why do two sexes of the same species differ in body size holds a long-standing question of evolutionary biology. While many across-species comparisons have focused on ultimate causes behind sexual size dimorphism （SSD）, only have a few been directed toward elucidating its ontogenetic basis. Urodeles are an amphibian group in which the direction and degree of SSD vary greatly among species. Using demographic data yielded by skeletochronology for 33 urodele species, the current study re- veals a positive across-species correlation between SSD and the sex difference in mean age of adult animals, and the latter in- creases with the corresponding difference in age at maturity; annual growth rate does not differ between the sexes. We conclude that extended longevities in one sex, which is mediated by delayed maturation, would allow it to grow for longer and get larger, with growth rate making a weak contribution to body size. The sex-specific divergence in ontogenetic trajectory might be ex- plained by potentially high growth costs of reproduction to females in association with stronger fecundity selection, and to males that are expected to experience stronger sexual selection [Current Zoology 59 （1）： 142-150, 2013].
文摘Regenerative capacity of the central nervous system(CNS)is unevenly distributed among vertebrates.While most mammalian species including humans elicit limited repair following CNS injury or disease,highly regenerative vertebrates including urodele amphibians and teleost fish spontaneously reverse CNS damage.Teletost zebrafish(danio rerio)are tropical freshwater fish that proved to be an excellent vertebrate model of successful CNS regeneration.Differential neuronal,glial,and immune injury responses underlie disparate injury outcomes between highly regenerative zebrafish and poorly regenerative mammals.This article describes complications associated with neuronal repair following spinal cord injury(SCI)in poorly regenerative mammals and highlights intersecting modes of plasticity and regeneration in highly regenerative zebrafish(Figures 1 and 2).Comparative approaches evaluating immunoglial SCI responses were recently reviewed elsewhere(Reyes and Mokalled,2024).
