[Phylogenesis of reproductive strategies in labyrinth fishes (Anabantoidei) and their sisterly groups].

Abstract

Clado- and semogenetic approaches, when used in concert, make it possible to resolve questions concerning phylogenetic relationships between a group representatives as well as phylogenesis of those representatives' traits. Parental care patterns and other forms of reproductive behavior, along with a reproductive strategy as a whole, can be subjects for semogenetic analysis to no lesser extent than morphological structures sensu stricto. One of the highly specialized forms of parental care in fishes, including suborder of labyrinth fishes and their sisterly groups, appears to be parental food provisioning. In my view, evolutionary origin of post-embryonic brood provisioning in bony fishes is related with three distinctive features, namely: 1) In fishes, different forms of post-embryonic food provisioning are convergent in their origin. 2) Any kind of brood provisioning is realized through exploiting the trait already existent and maintained by selection due to offspring fitness enhancement. 3) The main evolutionary path of this phenomenon emergence and development consists in the function expansion and replacement. This hypothesis does have the heuristic power, since it allows predicting the presence of the reproductive strategy component in question through identification of adequate basic adaptations. Despite the fact that parental care occurs in a majority of anabantoid fishes, there still are several species for which such care is not known. On cladogram, these species by no means take the basal position but are surrounded by fishes providing care for their eggs or even hatchlings. The parsimony principle leads to the suggestion that parental care is a plesiomorphic trait in the suborder Anabantoidei (or in the order Anabantiformes). It seems that the ancestors of present day non-caring species that take various positions within this phylogenetic group were fishes showing parental care. Later on, their reproductive strategy has changed as a result of r-selection. If this hypothesis is correct, the absence of parental care should be considered as a case of reproductive strategy degradation. It is quite probable that parental food provisioning was a component of the ancestral reproductive strategies. It is also possible that reproductive strategy of the present day Anabantiformes supposedly not caring for their offspring, actually includes some optional forms of parental care.