Data from: Islands in the desert for cavity-nesting bees and wasps: ecology, patterns of diversity, and conservation at oases of Baja California peninsula

Aims: The oases of Baja California peninsula (BCP) have been proposed as
important hotspots of biodiversity that hold an exceptional richness in
the middle of desert conditions. We provide the effect of habitat,
climatic, biogeographic and anthropogenic disturbance on communities of
cavity nesting taxa, emphasizing on bees, wasps and their natural enemies.
Location: Baja California Peninsula, Northwest Mexico. Methods: In oases
of BCP and desert neighbor environments, trap-nesting taxa were evaluated
in response to factors affecting the nest abundance, richness, and
community structure. We used statistical models to find the variables
controlling the nest abundance and ecological analyses to determine the
habitat effect on diversity under different scenarios of disturbance and
latitude. Results: The nest abundance varied between bees and wasps, but
solar irradiation and relative humidity influenced the abundance of both
groups. In general, abundance and richness were higher in oases. Bees did
not discriminate between oasis and desert habitats to nest and mud-daubing
wasps were highly dependent of oases. However, there were exceptions in
both groups. The degree of anthropogenic disturbance affected the species
composition, richness, and natural enemies. Main conclusions: The oases of
Baja California seem to be functioning as mesic islands into the desert,
each oasis hosting a great and unique richness of cavity-nesting taxa.
About 65% of nest abundance and 50% of species occurred exclusively in the
oasis. Thus, at least 21 species could be threatened if the oases of BCP
disappear in the future. Local conditions are shaping the community
structure of species, but also large-scale factors, e.g. climate and
biogeographic patterns seem to be influencing the community structure.
Since habitat loss and fragmentation can be a major problem in most oases,
strategies to maintain the ecosystem services of pollinators and predators
should be included in the conservation programs of these fragile habitats.