4/5/2023 0 Comments Hummingbird power suite![]() Thus, 41 ( n Ϫ 1) phylogenetically independent contrasts were available for comparative analyses. Of the 43 species, 42 were included in the phylo- genetic estimate, which contained no polytomies (Fig. ![]() Flight trials were conducted on most of these individuals, but accurate kinematic data during maximal load lifts were available for only 347 individuals, but with all taxa represented. Morphological measurements were made for 484 captured individual hummingbirds from 43 species. Morphology, Kinematics, and Aerodynamic Power. Of the 75 nodes on the tree, 62 received posterior probability values Ͼ 95%, and 53 of 75 received posterior probability values of 100. Our analysis of two nuclear and one mitochondrial gene for the 75 ingroup taxa resulted in a well supported estimate of hummingbird phyloge- netic relationships. The data corresponding to the final 13 million generations of each of the five independent analyses were ultimately pooled, allowing a consensus topology with mean branch lengths and posterior probability values to be calculated on the basis of 65,000 sample points (see Fig. Recovered topologies and posterior probability values were highly correlated across the five independent analyses, again indicating that the chains had converged. Nevertheless, to be conservative, we discarded the first 2 million generations of each analysis as burn-in. Each of the five independent Bayesian analyses conducted here appeared to have converged within Ϸ 500,000 generations. In these cases, regressions were constrained to go through the origin (25). In addition to analyses of raw species data, phylogenetic similarity among these data were corrected for by calculating standardized independent contrasts (24). All comparative data were analyzed by using least squares regression. The species mean is the average of the values for the two genders. Morphological, kinematic, and power data were averaged for each gender of each species. The maximum power available to hummingbirds was calculated as the power margin: the ratio of the maximum power produced during load-lifting to the minimum power required for steady hovering. We used an empirically derived profile drag coefficient measured from a revolving hummingbird wing, and bracketed our aerodynamic power estimates by assuming either high (0.469) or low (0.139) profile drag coefficients ( C D,pro ) corresponding to high (45°) and low (15°) angles of attack of the wing (23). Physical properties of air at each site and the morphological and kinematic variables of hummingbirds were used to calculate the aerodynamic power output for flight (5). The kinematic values for each of the maximum lifts for individual hummingbirds were then averaged. ![]() Stroke amplitude was determined from angular wing positions at the maximum forward and backward positions of a wingbeat. Wingbeat frequency was determined by using the interaction frequency between the wingbeat frequency and the filming rate (60 frames per sec) of the video film (8, 9). Wingbeat kinematics during both maximal load-lifting and free flight were determined by using frame-by-frame analysis of films. The maximum weight lifted by each hummingbird was identified, and up to three lifting flight sequences were analyzed if available. beads, and thus by subtrac- tion, the total weight sustained vertically by the bird.
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