Simulation
To reveal the parameter dependency of temporal beta-diversity patterns
under neutral dynamics, simulations were performed using the R package
“ecolottery” (Munoz et al., 2018). This study focused on four
fundamental parameters of the neutral model (Hubbell, 2001): fundamental
biodiversity number (θ), local community size (J ), mortality rate
(d ), and immigration rate (m ) (Fig. 1a and b). Fundamental
biodiversity number (θ) is a value associated with the properties of
species pool diversity (Fig. 1a); specifically, species diversity in the
species pool and their evenness increase as the fundamental biodiversity
number increases, when the number of individuals included is the same
(for the detailed derivation of fundamental biodiversity number, see
Hubbell, 2001). In two extreme cases, the species pool includes only one
species when the fundamental biodiversity number is zero (θ = 0), and
all species in the species pool have one individual when the fundamental
biodiversity number is infinite (θ = ∞). The local community size
indicates the total number of individuals in a targeted local community.
Under the zero-sum assumption, the number (J ) is the same
throughout the community dynamics for each simulation. Mortality rate
(d ) indicates the proportion of mortal individuals in the local
community at each time step; thus, J × d is the actual
number of mortal individuals (D ) (Fig. 1b). The mortality rate
(d ) is identical to the turnover rate under the zero-sum
assumption because the number of mortal individuals is identical to that
of recruited (or birthed) individuals. The immigration rate (m )
is the proportion of immigrated individuals in the number of recruited
(or birthed) individuals at each time step; thus, J × d ×m is the number of immigrated individuals (M ) and J× d × (1 – m ) is the number of locally recruited (or
birthed) individuals (D – M ) (Fig. 1b). The details of
these parameters are summarised in Table 1.