Reproductive biology of the Clinidae

 

Klipfishes (family Clinidae) are benthic fishes found in nearshore, usually rocky, algal-covered habitats. This group of fishes includes species that form pairs and establish nest-territories where the eggs are deposited and cared for, as well as viviparous (live-bearing) species. The evolution of viviparity involved the acquisition of internal fertilization, followed by the retention of the developing embryos inside the female’s body. The ripe eggs of the female are fertilized within the extended ovaries. The introduction of sperm into the female is done by a special intromittent muscular papilla at the apex of which is the male genital pore. Each embryo develops within its own follicular envelope until they are ready for liberation.

Two reproductive strategies have been found in klipfishes. Species of the Australian genera Heteroclinus and Cristiceps, and the South African genus Blennophis produce a high number of relatively small eggs that develop synchronously and are released an-masse. Species of the South African genus Clinus, on the other hand, produce relatively large eggs that develop asynchronously and are apparently released in small, discrete batches throughout the year. An unknown aspect of the reproductive narrative of klipfishes is the role paternity plays in their reproductive strategies and how much it contributes to the genetic diversity of this family.

Genetic studies can help resolve some of these issues. In the first instance, genetics can help determine kinship and paternity. Using techniques such as DNA fingerprinting, one can determine whether each brood results from a mating with a single male or whether there is multiple paternity with the female mating with multiple males, for each of the strategies mentioned above. Different patterns may be expected in terms of those species showing synchronous or asynchronous development of eggs.

The two strategies may also result in differing levels of genetic diversity in the respective populations, with reproductive input from a single versus multiple males contributing to successive generations. Here, DNA sequence data from mitochondrial and nuclear genes can provide some perspective as to the diversity of the population.

A number of key questions can be asked with respect to this study system and various projects, involving both field sampling and laboratory based genetic analyses, can be completed, addressing certain of these questions. These include: are the examined species multiple spawners? Do they exhibit multiple paternity? How many males contribute to a brood? Are multiple fertilizations concurrent or sequential? How does paternity whether singular or multiple relate to overall genetic diversity?

There is potential for developing any initial work further, into a MSc or PhD study in which the evolutionary implications and significance of the various strategies and reproductive biology of this group can be investigated further.

 

  

 Clinus superciliosus