The relationship between modularity and snake lifestyle
The network also presented a modular structure, in which the consumption of different resources divided the network into six different food modules (Table 1 and Supplementary material Appendix 1 Table A3). We expected that if the snake lifestyle was related to the formation of food modules, the distribution of lifestyles in the different modules would not be random. In fact, modules were associated with particular lifestyles, as indicated by significant or marginally significant probability values present in all modules but module 3 (Table 2). Module 3, was composed of species with the greatest variety in diet and lifestyle, such as boid snakes. Modules with more specific combinations of lifestyle and diet showed all significant or marginally significant probability values (Figure 4). Moreover, the formation of groupings based on diet and lifestyle occurred by species that specialise in the consumption of certain food resources, probably associated with their lifestyle. For example, the smallest module (number 5) was formed by only two arboreal species of the genus Dipsas that feed exclusively on mollusks; another module grouped species of terrestrial habits, such as Drepanoides anomalus, Drymoluber dichrous , andMastigodryas boddaerti , which feed on squamate eggs, whereas another module grouped fossorial species, such as Atractus spp. that are specialists in preying upon earthworms. On the other hand, the remaining modules grouped species with varied lifestyles and generalist diets.
As a consequence of the association between lifestyles and modular structure, modules often show dissimilar combinations of lifestyles. Dissimilarity values ranged from 0.33 to 1 (Table 2). The most dissimular module (Module 0) was composed exclusively of snakes with the fossorial lifestyle, such as the Atractus species, specialists in the consumption of earthworms. The most similar modules were modules 1 and 3, which as well as module 2 have the largest variety of lifestyles and food resources consumed by the snakes (Supplementary material Appendix 1 Table A3).