Body size and female reproduction in the water adult females larger than 500 mm SVL and 32 adult males Ledong, Hainan under permit to our laboratory in Hainan monitor lizard （Varanus salvator） were studied. Forty-tw...Body size and female reproduction in the water adult females larger than 500 mm SVL and 32 adult males Ledong, Hainan under permit to our laboratory in Hainan monitor lizard （Varanus salvator） were studied. Forty-two larger than 400 mm SVL were donated by local people in in 2013 and 2014. The largest male and female measured 745 and 755 mm SVL, respectively. The mean SVL was greater in adult females than in adult males. Males had larger heads （head width） than females of the same SVL. The smallest reproductive female in our sample was 565 mm SVL. Females produced a single clutch of 17.1 （10-23） pliable-shelled eggs per breeding season stretching from mid-June and mid-September. Clutch size and clutch mass were all positively related to female SVL. However, there was no significant linear relationship between egg mass and female SVL. Larger females generally produced more eggs, and thus heavier clutches than did smaller ones. There was no significant linear relationship between relative clutch mass and female SVL. Phylogenetic generalized least squares （PGLS） analysis, accounting for phylogenetic relationships, showed that clutch size was positively correlated with mean maternal SVL in varanid lizards. PGLS analysis showed that phylogenetic relationships did not affect clutch （or/and egg） mass and the SVL although there were significant linear relationship between clutch （or/and egg） mass and mean maternal SVL. Therefore, we could draw some general conclusions about the body size and reproductive tactics in varanid lizards that larger females generally produced more eggs, larger eggs and thus heavier clutches than did smaller ones.展开更多
Monitor lizards(Varanidae)inhabit both the mainland and islands of all geological types and have diversified into an exceptionally wide range of body sizes,thus providing an ideal model for examining the role of mainl...Monitor lizards(Varanidae)inhabit both the mainland and islands of all geological types and have diversified into an exceptionally wide range of body sizes,thus providing an ideal model for examining the role of mainland versus island in driving species evolution.Here we use phylogenetic comparative methods to examine whether a link exists between body size driven diversification and body size-frequency distributions in varanid lizards and to test the hypothesis that island lizards differ from mainland species in evolutionary processes,body size,and life-history traits(offspring number and size).We predict that:1)since body size drives rapid diversification in groups,a link exists between body size-driven diversification and body size-frequency distributions;2)because of various environments on island,island species will have higher speciation,extinction,and dispersal rates,compared with mainland species;3)as a response to stronger intraspecific competition,island species will maximize individual ability associated with body size to outcompete closely-related species,and island species will produce smaller clutches of larger eggs to increase offspring quality.Our results confirm that the joint effect of differential macroevolutionary rates shapes the species richness pattern of varanid lizards.There is a link between body size-driven diversification and body sizefrequency distributions,and the speciation rate is maximized at medium body sizes.Island species will have higher speciation,equal extinction,and higher dispersal rates compared with mainland species.Smaller clutch size and larger hatchling in the island than in mainland species indicate that offspring quality is more valuable than offspring quantity for island varanids.展开更多
Blood cell morphology and count are not uniform across species.Recently,between-species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa,and this finding was inter...Blood cell morphology and count are not uniform across species.Recently,between-species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa,and this finding was interpreted in the context of the metabolic theory.In the present study,we examined the numbers and the size of blood cells in 2 species of monitor lizards,the mangrove-dwelling monitor(Varanus indicus)and the savannah monitor(V.exanthematicus),and we compared these traits in individuals of different body size.The results revealed that during the course of ontogeny,the size of red blood cells increases with body mass.Because the mass-specific metabolic rate decreases with body size and the cell volume-to-surface ratio decreases with the cell size,changes in the erythrocyte size might be the result of oxygen transport adjustment.展开更多
基金Financial supports were provided by grants from Natural Science Foundation of China (31270571)Hainan Key Program of Science and Technology (ZDXM20110008)131 Talent Project of Hangzhou City
文摘Body size and female reproduction in the water adult females larger than 500 mm SVL and 32 adult males Ledong, Hainan under permit to our laboratory in Hainan monitor lizard （Varanus salvator） were studied. Forty-two larger than 400 mm SVL were donated by local people in in 2013 and 2014. The largest male and female measured 745 and 755 mm SVL, respectively. The mean SVL was greater in adult females than in adult males. Males had larger heads （head width） than females of the same SVL. The smallest reproductive female in our sample was 565 mm SVL. Females produced a single clutch of 17.1 （10-23） pliable-shelled eggs per breeding season stretching from mid-June and mid-September. Clutch size and clutch mass were all positively related to female SVL. However, there was no significant linear relationship between egg mass and female SVL. Larger females generally produced more eggs, and thus heavier clutches than did smaller ones. There was no significant linear relationship between relative clutch mass and female SVL. Phylogenetic generalized least squares （PGLS） analysis, accounting for phylogenetic relationships, showed that clutch size was positively correlated with mean maternal SVL in varanid lizards. PGLS analysis showed that phylogenetic relationships did not affect clutch （or/and egg） mass and the SVL although there were significant linear relationship between clutch （or/and egg） mass and mean maternal SVL. Therefore, we could draw some general conclusions about the body size and reproductive tactics in varanid lizards that larger females generally produced more eggs, larger eggs and thus heavier clutches than did smaller ones.
基金This work was supported by grants from the Narural Science Foundation of Zhejiang Province to L-H.L.(LY17C030003)National Natural Science Foundation of China to L.-H,L.(31971414)and XJ(31470471)Finance Science and Technology Project of Hainan Province to Y.D.(ZDYF2018219).
文摘Monitor lizards(Varanidae)inhabit both the mainland and islands of all geological types and have diversified into an exceptionally wide range of body sizes,thus providing an ideal model for examining the role of mainland versus island in driving species evolution.Here we use phylogenetic comparative methods to examine whether a link exists between body size driven diversification and body size-frequency distributions in varanid lizards and to test the hypothesis that island lizards differ from mainland species in evolutionary processes,body size,and life-history traits(offspring number and size).We predict that:1)since body size drives rapid diversification in groups,a link exists between body size-driven diversification and body size-frequency distributions;2)because of various environments on island,island species will have higher speciation,extinction,and dispersal rates,compared with mainland species;3)as a response to stronger intraspecific competition,island species will maximize individual ability associated with body size to outcompete closely-related species,and island species will produce smaller clutches of larger eggs to increase offspring quality.Our results confirm that the joint effect of differential macroevolutionary rates shapes the species richness pattern of varanid lizards.There is a link between body size-driven diversification and body sizefrequency distributions,and the speciation rate is maximized at medium body sizes.Island species will have higher speciation,equal extinction,and higher dispersal rates compared with mainland species.Smaller clutch size and larger hatchling in the island than in mainland species indicate that offspring quality is more valuable than offspring quantity for island varanids.
基金supported by grant SVV-2012-265206by the Grant Agency of Charles University(No.62910/2010).
文摘Blood cell morphology and count are not uniform across species.Recently,between-species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa,and this finding was interpreted in the context of the metabolic theory.In the present study,we examined the numbers and the size of blood cells in 2 species of monitor lizards,the mangrove-dwelling monitor(Varanus indicus)and the savannah monitor(V.exanthematicus),and we compared these traits in individuals of different body size.The results revealed that during the course of ontogeny,the size of red blood cells increases with body mass.Because the mass-specific metabolic rate decreases with body size and the cell volume-to-surface ratio decreases with the cell size,changes in the erythrocyte size might be the result of oxygen transport adjustment.
