Formation and Maintenance of Spatial Polymorphism Induced by Niche Construction

Abstract

Niche construction, a term referring to the modification of their environments by any organism, can profoundly influence the genetic structure and evolutionary dynamics of population. In the paper, we established a 2D individualbased lattice model of niche construction with probabilistic transition rule to explore the typical spatial distribution and evolutional dynamics of polymorphism, environmental resource and genotype frequency. The effect of extinction on polymorphism was also discussed. In simulation, the model presents random, aggregative and uniform distribution patterns of different genotypes. Compared with the results in the present/absent of niche construction, it is an active force for polymorphism if without heterozygote superiority. The positive feedback between genotype and environmental resource contributes population to fit the environment better by the self-regulation of different genotypes and when the external force changes the environment, even altering the direction of niche construction. Niche construction results in the spatial heterogeneity of environmental resource, which is an ecological imprint of organism on environment and a foundation of polymorphic formation. With habitat deterioration, niche construction accelerates the formation of steady polymorphism and impedes the harmful influence of environment on the population, which embody a life-history strategy of organism under unfavorable environment. These results suggest that niche construction can lead to the coexistence with alterative polymorphism through genotype-environment feedback.

Niche Construction on Environmental Gradients: The Formation of Fitness Valley and Stratified Genotypic Distributions

“…The effects of niche construction can, arguably, persist over geological time, modulating macro-evolutionary patterns and species diversity [4] , forming the momentum of evolution towards specific directions [12] , [16] . Niche construction can accelerate the formation of steady polymorphism especially under deteriorating habitats and thus impede the negative impact of harmful environments [15] . For instance, the adaptive feedback between plants and their soil environment could account for why plants partially regulate soil nutrient content and thus possess evolutionary advantage during ecological succession and species packing [41] – [42] .…”

“…This fitness valley will further restrict potential gene flows between separated populations and thus promote allopatric speciation and diversification. The spatially local process of niche construction along a linear environmental gradient is capable of forming a reproduction barrier which facilitates speciation through genotype-environment feedback [15] , [17] . Putting evolutionary processes into a spatially heterogeneous context with the organism and its environment co-affecting and co-adapting to each other could finally help to understand how future species will survive and adapt in the era of Anthropocene [64] .…”

“…The process of niche construction can form a positive or amplified feedback between the demand and supply of limiting resources and can, thus, potentially affect the evolutionary trajectory by modifying the selective pressure of certain traits, especially those that are responsible for the niche construction [7] – [8] . Indeed, the concept of niche construction emphasizes the importance of organism-environment coupling during adaptive evolution and has been suggested to be capable of promoting stable polymorphism [9] , altering competition outcomes [10] – [11] , fixing deleterious alleles [12] – [15] , and posing evolutionary momentum of directional selection [16] – [17] . However, studies on the effect of niche construction on the spatial distribution of species and their genetic structures are lacking, especially regarding how the process of niche construction can affect the distribution of different genotypes and how it can potentially promote the formation of range boundaries which further promote diversification and polymorphism.…”

“…To examine the spatial distributions of different genotypes that differentially affect local nutrient content via the process of niche construction along a linear environmental gradient, we built a spatially-explicit individual-based cellular automaton (CA) on 200×200 lattices, where each cell contains a random-mating diploid individual with two dialelic loci E and A [15] . We assume that the frequency of allele E at generation t ( ) affects the individual's capacity of niche construction [13] and that the niche construction can affect the within-cell environmental resource positively or negatively by either producing or consuming the resource.…”