Cryptic hybridization in marine fishes: significance of narrow hybrid zones in identifying stable hybrid populations

Abstract

The distributional features of 11 case studies of triads of putative clades of marine fishes and one of multimorphs were analysed to provide the philosophical basis on which a hybridization hypothesis is framed. In the triads, one intermediate population restricted to a Narrow Hybrid Zone is predictably of hybrid origin though passing as a valid species. The holistic nature of the Narrow Hybrid Zone model holds together the seemingly discordant wealth of information about hamlets (Serranidae) under the hybridization hypothesis. Numerical imbalance between hybridizing species, environmental disturbances and intergradation of parental habitats are highly potent factors conducive to species crossing in marine waters. Scarcely distinguishable inter-specific multiformity of tropical marine fishes with the accompanying identification problems gives cause to suspect that many hybrid taxa among marine fishes had gained species status. The popular notion that frequency of hybridization is least among tropical marine fishes becomes untenable in the light of possible false recognition of hybrid derivatives as distinct species.

Keywords:

• Hybridization
• Marine Fishes
• Narrow Hybrid Zone
• Species Triad
• Numerical Imbalance
• Intergradation Of Habitats