  Formation of diverse patterns in spatially extended reaction-diffusion
systems is an important aspect of study which is pertinent to many chemical and
biological processes. Of special interest is the peculiar phenomenon of chimera
state having spatial coexistence of coherent and incoherent dynamics in a
system of identically interacting individuals. In the present article, we
report the emergence of various collective dynamical patterns while considering
a system of prey-predator dynamics in presence of a two-dimensional diffusive
environment. Particularly, we explore the observance of four distinct
categories of spatial arrangements among the species, namely spiral wave,
spiral chimera, completely synchronized oscillations, and oscillation death
states in a broad region of the diffusion-driven parameter space. Emergence of
amplitude mediated spiral chimera states displaying drifted amplitudes and
phases in the incoherent subpopulation is detected for parameter values beyond
both Turing and Hopf bifurcations. Transition scenarios among all these
distinguishable patterns are numerically demonstrated for a wide range of the
diffusion coefficients which reveal that the chimera states arise during the
transition from oscillatory to steady state dynamics. Furthermore, we
characterize the occurrence of each of the recognizable patterns by estimating
the strength of incoherent subpopulations in the two-dimensional space.
