If variation in a species was only due to meiosis, how would that limit the evolution of that species?

But the ultimate source of NEW genes or forms of genes (alleles) is genetic mutation. Without mutation, you are bound to run out of various combinations of existing genes eventually, which puts that species in a bit of an evolutionary pickle. Continual genetic diversity (fed by mutations) is necessary for the survival of the species. Less genetic variation means fewer possible adaptations that could result in higher reproductive success, which means the species is more likely to be wiped out by disease or competition for resources or mates.

phaneritic textures in which phaner means visible so phaneritic textures are standard of impertinent volcanic rocks. these rocks crystallized gradually under the surface of earth. when the magma cools deliberately then the ores have chance to develop and produce long crystals.