Figure 5

Role of climate and competition in driving morphological variation. Relationships between morphology (left: body size; right: body shape, i.e. relative bill width) and environmental aridity for 17 Galerida species or populations; legend: c = crested lark; t = Thekla lark; 0 = allopatry; 1 = sympatry (e.g. t1 are populations of the Thekla lark complex that live entirely or mainly in sympatry with a crested lark representative; see Fig. 4 for naming of all populations). Multiple regression analyses suggest that variations in body size (but not in body shape) are influenced by both competition and aridity (see Table 8).