We investigate statistical properties of multispecies competition ecosystems subjected to both symmetric and asymmetric dichotomous noises. The expression of the stationary probability distribution function （SPDF） i...We investigate statistical properties of multispecies competition ecosystems subjected to both symmetric and asymmetric dichotomous noises. The expression of the stationary probability distribution function （SPDF） is analytically derived by means of mean-field approximation, and verified by stochastic simulations. The results indicate that： （i） A noise amplitude （a0）, a noise autocorrelation time （τ0） and a noise symmetry parameter （k） all can affect the SPDF; （ii） There is an optimal τ0, which makes the mean value of population density be maximal, near which a transition takes place, i.e., the stationary mean value of species density （（x）st） suddenly falls to a lower constant, （iii） As k decreases, the maximum of （x）xt and the optimal 70 increase. The parameter planes of TO -- a20 and τ0- k for the transition are plotted.展开更多
Although it has become clear that sexual selection may shape mating systems and drive speciation, the potential constraints of environmental factors on processes and outcomes of sexual selection are largely unexplored...Although it has become clear that sexual selection may shape mating systems and drive speciation, the potential constraints of environmental factors on processes and outcomes of sexual selection are largely unexplored. Here, we investigate the geographic variation of such environmental factors, more precisely the quality and quantity of nest resources （bivalve shells） along a salinity gradient in the Baltic Sea Area （Baltic Sea, Sounds and Belts, and Kattegat）. We further test whether we find any salinity-associated morphological differences in body size between populations of common gobies Pomatoschistus microps, a small marine fish with a resource-based mat- ing system. In a geographically expansive field study, we sampled 5 populations of P. microps occurring along the salinity gradient （decreasing from West to East） in the Baltic Sea Area over 3 consecutive years. Nest resource quantity and quality decreased from West to East, and a correla- tion between mussel size and male body size was detected. Population density, sex ratios, mating- and reproductive success as well as brood characteristics also differed between populations but with a less clear relation to salinity. With this field study we shed light on geographic variation of distinct environmental parameters possibly acting on population differentiation. We provide insights on relevant ecological variation, and draw attention to its importance in the framework of context-dependent plasticity of sexual selection.展开更多
基金Supported by the Yunnan Provincial Foundation of China under Grant Nos.2009CD036 and 08Z0015the National Natural Science Foundations of China under Grant Nos.50734009 and 10865006
文摘We investigate statistical properties of multispecies competition ecosystems subjected to both symmetric and asymmetric dichotomous noises. The expression of the stationary probability distribution function （SPDF） is analytically derived by means of mean-field approximation, and verified by stochastic simulations. The results indicate that： （i） A noise amplitude （a0）, a noise autocorrelation time （τ0） and a noise symmetry parameter （k） all can affect the SPDF; （ii） There is an optimal τ0, which makes the mean value of population density be maximal, near which a transition takes place, i.e., the stationary mean value of species density （（x）st） suddenly falls to a lower constant, （iii） As k decreases, the maximum of （x）xt and the optimal 70 increase. The parameter planes of TO -- a20 and τ0- k for the transition are plotted.
文摘Although it has become clear that sexual selection may shape mating systems and drive speciation, the potential constraints of environmental factors on processes and outcomes of sexual selection are largely unexplored. Here, we investigate the geographic variation of such environmental factors, more precisely the quality and quantity of nest resources （bivalve shells） along a salinity gradient in the Baltic Sea Area （Baltic Sea, Sounds and Belts, and Kattegat）. We further test whether we find any salinity-associated morphological differences in body size between populations of common gobies Pomatoschistus microps, a small marine fish with a resource-based mat- ing system. In a geographically expansive field study, we sampled 5 populations of P. microps occurring along the salinity gradient （decreasing from West to East） in the Baltic Sea Area over 3 consecutive years. Nest resource quantity and quality decreased from West to East, and a correla- tion between mussel size and male body size was detected. Population density, sex ratios, mating- and reproductive success as well as brood characteristics also differed between populations but with a less clear relation to salinity. With this field study we shed light on geographic variation of distinct environmental parameters possibly acting on population differentiation. We provide insights on relevant ecological variation, and draw attention to its importance in the framework of context-dependent plasticity of sexual selection.
