Behavioural complementarity among frugivorous birds and lizards can promote plant diversity in island ecosystems

The behavioural complementarity of fruit-eating animals is thought to exert a key role in plant community assembly. However, a mechanistic understanding of the causal links between the two processes is still lacking.
This study assesses if complementarity between dispersers in feeding and microhabitat-use behaviour enhances community-scale dispersal services, resulting in a more diverse community of seedlings.
We used a Bayesian approach to connect a comprehensive database of seed dispersal effectiveness at a community scale with a transition probability model that accounts for behavioural complementarity. Our model system was the thermosclerophyllous shrubland of the Canary Islands. There, fleshy-fruited plants rely on two types of frugivores: lizards and birds.
Lizards consumed all plant species and preferentially used open areas; whereas birds foraged for small single-seeded fruits and dispersed their seeds beneath plants. Through feeding on different sets of plants, they generated a rich seed-rain community. By diversifying the microhabitat of deposition, more species could find suitable recruitment sites.
Distinct foraging and microhabitat-use choices led to complementary dispersal services. Lizards ensured that all plant species were present in the seedling community, while birds promoted a more even distribution of them. As a result, diversity in the community of seedlings was enhanced.
Overall, our work underscores that behavioural complementarity promotes diversity in the early-regenerating plant communities. These enhanced dispersal services rely on the presence of all functional groups. Thus, in communities where frugivores display unique behaviours, preserving a diverse community of dispersers should be a conservation target.

Methods
The excel document contains data used for model parameterization (field studies and green house experiments)

##Data to estimate abundance of dispersers 

Abundance_disperser. On monthly basis, individuals per ha of each frugivore type.

##Data related to diet choice

seed_traps (per month) Composition of the seed rain from birds and lizards on monthly basis. Numbers correspond to seed counts (in 1 m2).

fruit_production Counts of number of fruits found in fruit traps of 5 m2 established every 25 m along a 500 m transect running across the study area. 

Fruit traits from the study species. Number of seeeds per fruit, radial diameter (mm), carbohydrate content (percentage)

Fruits per_Bout Estimates of fruits consumed per foraging bout for each p-th plant and f-th frugivore type

##Data to estimate microhabitat preferences

Microhabitat. Number of faeces found in each tray on montly basis. Trays are classified according to microhabitat type (open vs covered).

fruit_production (see above)

Climate 

##Data for post-dispersal emergence and survival

gut_damage Number of seeds dispersed that were damaged after dispersal (on plant species and frugivore-type basis).

emergence Contains information about the seed sowing experiment (Total_sowed, Emerged, Percentage_emerged (sowing experiment)). In addition it contains the ratios between number of ingested vs control seeds that emerged in the greehouse experiment. The percentage of seedlings emerged * ratios results in the emergence rates of the different species according to the frugivore-type and microhabitat of deposition (Percentage_Lizard, Percentage_bird).

One_year_survival. Data from plots of 2 m2, where we marked newly emerged seedlings and followed their survival one year later. Data correspond to counts.