Meeting Abstract

15.3  Tuesday, Jan. 4  Variation in pulmonary compliance and volume in anuran amphibians is driven by lymph mobilization and not gas exchange HEDRICK, MS*; HILLMAN, SS; DREWES, RC; WITHERS, PC; California State University, East Bay; Portland State University; California Academy of Sciences; University of Western Australia michael.hedrick@csueastbay.edu

Lymph movement from ventral regions to dorsally-located lymph hearts in anurans is accomplished by the combined actions of specific skeletal muscles, lymph sac compliance and lung ventilation. We hypothesize that species with increased lung compliance and lung volume (V_lung) will be more effective at changing lymph sac compliance and lymph mobilization. Thus, terrestrial species should have greater lung compliance and V_lung compared with aquatic species. This study examined the variation in lung compliance and V_lung in 17 anuran species representing 7 families that span a large range of body mass (M) and ecomorph types. Maximal lung compliance (C_max) scaled to M^0.77 (r² = 48%) while V_lung measured at 0.4 kPa pressure scaled to M^0.66 (r² = 37%). Body shape did not explain the variation in C_max and V_lung because there was a strong correlation between M and snout-vent length (r² = 94%) for all species. Lymph flux rates (ml kg^-1 min^-1), measured in a previous study, were highest in a terrestrial bufonid (Rhinella marina) compared with a semi-aquatic ranid (Lithobates catesbeianus) and an aquatic pipid (Xenopus laevis). C_max and V_lung were significantly different between these three species with R. marina > L. catesbeianus > X. laevis; thus, there is a strong correlation between lymph flux rate and C_max and V_lung. We suggest that the considerable variation in lung compliance and V_lung is primarily explained by species’ ecomorphology and related to lymph flux requirements in different environments. Supported by NSF-IOS 0843082.