Correlation between meiotic behaviour and species reproductive performance and ecological spread: a case study of eight Nigerian Solanum L. species.
The unstable genomes among the diploid Solanum species viz: Solanum macrocarpon, S. aethiopicum, S. gilo, S. anguivi and the varieties of S. melongena are indicative of progressive evolutionary changes. The high occurrence of chromosome bridges, clumps unequal anaphase chromosomes and faulty cytokinesis led to the production of poor quality pollen. However, bivalents were regular in S. torvum, S. erianthum and the tetraploid S. scabrum while their mitotic chromosomes were small-sized and symmetrical. The diploids with unstable genomes were cosmopolitan and found in the four ecological zones while the regular and normal diploids were limited in their distribution to the savanna, arid and semi arid. However, the tetraploid S. scabrum was restricted to the rainforest of Southern Nigeria. The colchicine induced tetraploid and its intermediate aneuploids suggest the likely origin of the natural polyploids. Consequently, the impact of genome changes was revealed in the evolution of different adaptive features and species ability to occupy new environment.