Amphibian diversity in the Amazonian floating meadows: a Hanski core-satellite species system (scripts and codes)

The Amazon catchment is the largest river basin on earth, and up to 30% of
its waters flow across floodplains. In its open waters, floating plants
known as floating meadows abound. They can act as vectors of dispersal for
their associated fauna and, therefore, can be important for the spatial
structure of communities. Here, we focus on amphibian diversity in the
Amazonian floating meadows over large spatial scales. We recorded 50
amphibian species over 57 sites, covering around 7,000 km along river
courses. Using multi-site generalised dissimilarity modelling of zeta
diversity, we tested Hanski’s core-satellite (HCS) hypothesis and
identified the existence of two functional groups of species operating
under different ecological processes in the floating meadows. ‘Core’
species are associated with floating meadows, while ‘satellite’ species
are associated with adjacent environments, being only occasional or
accidental occupants of the floating vegetation. At large scales,
amphibian diversity in floating meadows is mostly determined by stochastic
processes, whereas at regional scales, climate and deterministic processes
are central drivers. Compared with the turnover of ‘core’ species, the
turnover of ‘satellite’ species increases much faster with distances and
is also controlled by a wider range of climatic features. Distance is not
a limiting factor for ‘core’ species, suggesting that they have a stronger
dispersal ability even over large distances. This is probably related to
the existence of passive long-distance dispersal of individuals along
rivers via vegetation rafts. In this sense, Amazonian rivers can serve as
corridors, facilitating dispersal especially for species associated with
riverine habitats such as floating meadows.