Fig. 2
From: Small-scale phenotypic differentiation along complex stream gradients in a non-native amphipod
Overview of morphological characteristics assessed in this study. a Males were identified by the presence of genital papillae (g.p.). b Intersexual individuals show female (oostegites; oo.) and male (genital papillae; g.p.) sexual characteristics. The following parameters we measured as distances or areas (marked by red lines) and used to assess population variation in c body length, d gill area (circumference of the six gills on the right body site; considered herein as a ‘physiological trait’), e lengths of the 1st antennae (a.I) and the smaller 2nd antennae (a.II), from the first pedunculus to the tip of the flagellum, and f size of the 1st gnathopod on the right body size of males (length from the tip of the dactylus to the base of the propodus). g Females carry their developing broods in an external brood pouch that is formed by (h) four pairs of oostegites (oo.)