Single-male paternity in coelacanths.

Latimeria chalumnae, a 'living fossil,' is of great scientific interest, as it is closely related to the aquatic ancestors of land-living tetrapods. Latimeria show internal fertilization and bear live young, but their reproductive behaviour is poorly known. Here we present for the first time a paternity analysis of the only available material from gravid females and their offspring. We genotype two L. chalumnae females and their unborn brood for 14 microsatellite loci. We find that the embryos are closely related to each other and never show more than three different alleles per locus, providing evidence for a single father siring all of the offspring. We reconstruct the father's genotype but cannot identify it in the population. These data suggest that coelacanths have a monogamous mating system and that individual relatedness is not important for mate choice.

Population divergence in East African coelacanths.

The coelacanth, Latimeria chalumnae, occurs at the Eastern coast of Africa from South Africa up to Kenya. It is often referred to as a living fossil mainly because of its nearly unchanged morphology since the Middle Devonian. As it is a close relative to the last common ancestor of fish and tetrapods, molecular studies mostly focussed on their phylogenetic relationships. We now present a population genetic study based on 71 adults from the whole known range of the species. Despite an overall low genetic diversity, there is evidence for divergence of local populations. We assume that originally the coelacanths at the East African Coast derived from the Comoros population, but have since then diversified into additional independent populations: one in South Africa and another in Tanzania. Unexpectedly, we find a split of the Comoran coelacanths into two sympatric subpopulations. Despite its undeniably slow evolutionary rate, the coelacanth still diversifies and is therefore able to adapt to new environmental conditions.

Genetics: relatedness among east African coelacanths.

Coelacanths were discovered in the Comoros archipelago to the northwest of Madagascar in 1952. Since then, these rare, ancient fish have been found to the south off Mozambique, Madagascar and South Africa, and to the north off Kenya and Tanzania -- but it was unclear whether these are separate populations or even subspecies. Here we show that the genetic variation between individuals from these different locations is unexpectedly low. Combined with earlier results from submersible and oceanographic observations, our findings indicate that a separate African metapopulation is unlikely to have existed and that locations distant from the Comoros were probably inhabited relatively recently by either dead-end drifters or founders that originated in the Comoros.