Recurrence analysis of ant activity oscillations in different densities
Felipe Marcel Neves, Felipe Marcel Neves , Ricardo Luiz Viana , Marcio Roberto Pie
Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Brazil; Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Brazil ; Departamento de Física, Universidade Federal do Paraná, Curitiba, Brazil ; Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Brazil
The phenomenon of periodic oscillations in activity has been observed in ants of the genera Leptothorax and Temnothorax, which exhibit periodic pulses of short-term activity at the colony level. Although isolated individuals and small groups of workers of these species do not show periodic oscillations, when their density increases, the predictability of dynamic activity becomes increasingly apparent. Although these results are intriguing, they have never been observed in other ant genera, nor has the transition to periodicity been well studied. Here we used recurrence quantification analysis (RQA) and recurrence plots (RPs) to compare and analyze the activity dynamics of ant species with different levels of social complexity and at different densities (1, 4 and 16 individuals). RQA and RPs are powerful nonlinear data analysis methods that quantify the number and duration of the phase space trajectory of the dynamical system, resulting in a detailed description of its behavior, including the quantification of dynamic patterns ranging from stochastic to deterministic. Three species of ants were used in our study: Gnamptogenys striatula (Ectatomminae), Linepithema micans (Dolichoderinae), Pheidole rudigenis (Myrmicinae), as well as adults of a gregarious beetle species (Tenebrio molitor) for comparison. Our data resulted in 150 time series of two hours each (300 hours). Our results show that the activity dynamics of ant groups are more predictable in comparison with isolated individuals. The differences of activity dynamics between the species are more pronounced at higher densities compared to those of isolated individuals. Some ant species and also beetles exhibit characteristic short-term periodic activity pulses in small groups of individuals, suggesting evidence that such phenomena could be a by-product of the contact rate between individuals rather than an innate phenomenon of ant societies, not only present at the colony level.