Data from: Niche packing, but not niche expansion, explains the co-occurrence of hummingbirds-visited plants

Tropical mountains often harbour high species richness. Yet the mechanisms
behind such high richness remain poorly understood. One prominent
hypothesis for high species richness is niche partitioning, which reduces
competition and promotes coexistence. Here, we evaluate niche structure
and specialisation of plant species based on the floral traits related to
pollination interactions across an elevational gradient in the northern
Andes. Niche structure can vary among sites, either expanding or
contracting, or becoming more or less packed. We sampled eleven
communities of hummingbird-visited plants along an elevation gradient in
the Ecuadorian Andes and measured a series of functional traits associated
with hummingbird pollination. We used the traits of all co-occurring
species to calculate community weighted means, functional richness, and
mean nearest neighbour distances and evaluated how they varied across
elevation. Additionally, we measured specialisation based on
plant-hummingbird interaction records to assess if packing is associated
with narrower resource use or greater niche overlap. Species and
functional richness were constant along the elevation gradient; however,
niche packing was stronger at mid-elevation. We found changes in network
specialisation, where the least specialised communities were those with
higher niche packing. These results suggest that traits related to
pollination and plant reproduction help to explain species co-occurrence
and specialisation.