Role of Heterochronies in the Formation of the Morphological Features of Amphibians in Urban Areas

Morphogenesis evolves through evolutionary modifications in ontogeny under environmental factors. The same genotype can serve as a basis for different phenotypes, depending on environmental conditions. Changes in the rate and direction of cell proliferation can lead to phenotype modifications following Thompson's transformation theory. When acceleration and hypermorphosis are superimposed, the resulting vector can lead to recapitulations or the formation of some variants that can seriously differ from the phenotypic norm. Gene expression and other forms of morphogenetic signals are influenced by environmental factors, which have a multidirectional effect on the rate and vectorization of morphogenetic processes. Amphibian ontogenesis depends on the temperature regime, geochemical background, diet, and density of larval populations, which influence the rate and duration of separate developmental stages. The high heterogeneity of the urban environment and the presence of gradients of a number of conditions lead to heterochronic changes in the resulting vectors of amphibian morphogenesis under urban conditions towards the dominance of hypomorphoses. On the whole, the proportion of variants of morphological deviations based on heterochronies is similar (22.2-35.3%) for different amphibians, while their frequencies are more taxon-specific. The variants of deviations of ontogenesis under urbanization conditions can be considered as a model of the main directions of its destabilization during evolutionary transformations.

Automated summary

Morphogenesis is influenced by environmental factors, leading to variations in phenotype. Changes in cell proliferation rate and direction can affect phenotype modifications, while environmental conditions have a multidirectional effect on gene expression and morphogenetic signals.