Fig. 1From: Is sperm morphology functionally related to sperm swimming ability? A case study in a wild passerine bird with male hierarchiesRelation between the decay in sperm velocity (VCL) through time and sperm design across social ranks (a-d) before manipulating the social environment. The surfaces were obtained from predicted values extracted from linear mixed models. Larger PC1 values indicate larger flagella and mid-pieces relative to head size, and they are centered by social rankBack to article page