Plant speciation and polyploidy: in habitat divergence and environmental perspective

Abstract

Habitat divergence plays a driving role in speciation. Severe environmental fluactuations and/or stress may bring about unreduced gamete formation in germline or mitotic errors in somatic tissues, enabling the establishment of new genomic states. However, fixation of any such variation should involve merchanisms that produce reproductively isolated lineages. This could be realized either through polyploidy enabling alteration in genomic constitution involving chromosome duplication and/or numerical/structural chromome alterations or by hybridization/homoploidy. Whereas polyploidy may lead to stable genomic states owing to their tolerance to post-polyploid genetic modification; the interspecies hybridization is often maladaptive but can also promote speciation through generation of homoploid hybrids (i.e. hybridization without polyploidy) enabling reproductive isolation of evolving hybrids. However, homoploidy as a speciation mechanism is considered only as a minor contributor in evolution, but polyploidy, more particularly autopolyploidy stands apart as a major evolutionary force owing to its wide occurrence and short generation time, and shall continue to be as an effective speciation mechanism to sustain habitat disturbance emanating from rigors of climate change.