Foraging ants on the extrafloral nectaries repel nectar thieves but not the effective pollinator of Vigna luteola (Fabaceae) in a Mexican coastal sand dune

While some studies have shown that ants that visit extrafloral nectaries may defend their host plants against potential herbivores, recent researches have shown that such ant-plant mutualism may be broken in some cases. For example, the presence of ants on plants could also drive away pollinators and seed dispersers. However, it is not yet known what mechanisms could favor that ant presence on plants does not affect other mutualistic interactions involving plants. In this work, we performed a series of field experiments to test the hypothesis that the presence of ants on EFNs located at the base of the inflorescences of Vigna luteola (Fabaceae) may have a negative effect on floral visitors but not on potential pollinators in a Mexican coastal sand dune. In general, we found that the presence of ants on the plants decreased the rate of flower visitation. However, we observed that the time of visitation of the effective pollinators the bee (Pseudocentron) sp. on the flowers was less compared to that of other floral visitors. This strategy may allow that ants cannot aggressively scare away the effective pollinators. In summary, we show that the effective pollinators of V. luteola present strategies that allow them to visit the flowers without being aggressively attacked by the ants that visit the extrafloral nectaries (EFNs). Therefore, the presence of ants on plants could have a dual function: protecting plants against potential herbivores as well as, filtering flowers against nectar thieves

Averting biodiversity collapse in tropical forest protected areas

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon¹⁻³. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses⁴⁻⁹. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.Keywords: Ecology, Environmental scienc

Readme

File where there is information about the methods used for each experiment and the column names of each data set

Expe3Abundance

Experiment 3-Abundance. Data on cumulative number of seedlings established over time from the natural seed bank in sites of single vs. recurrent defecation

Expe3Richness

Experiment 3-Richness. Data on cumulative number of species established over time from the natural seed bank in sites of single vs. recurrent defecation