The word "hybrid" derives from the
Greek, meaning "son of outrageous conduct". The word "hybrid"
in the world of cichlids has been become nothing short of controversial,
if not an emotional topic for many.
Hybrid cichlids are any cross of two previously
unmixed groups or bloodlines of fish. In the most common usage,
hybrid refers to the crossing of any two or more species, Genus
or Family of animal. Less common usage, but of importance to any
breeder of cichlids, is intra-specific hybridization. This is
the crossing of two distinct bloodlines, variants, or locations
within a species. Some of these intra-specific crosses may be
the crossing of two differently named variants, two differently
colored variants, or could simply be the crossing of the same
species collected from separate geographical populations.
DNA fingerprinting on the cichlids of the Rift
Lakes shows that geographically separated, but similar morphs
are less closely related than different morphs living side by
side.(1) It is easy to understand
that one can get a blending of different characteristics when
you cross blue and orange fish, but it is less obvious when the
fish look similar, but have hidden differences. The result is
the same. The hybrid either expresses one or the other allele,
or some combination of the two. We can simplify things by saying
that each parent contributes one copy of each gene and they work
as a pair to shape the new hybrid cichlid and its behavior.
How these two copies may work together, or not
work well together, is impossible to predict. First generation
hybrids of Metriaclima zebra and Labeotropheus fuelleborni show
interesting results.(2) M. zebra
eat particles floating in the water and therefore, their mouths
and teeth are designed for this type of feeding. L. fuelleborni
scrape algae off rocks with teeth uniquely designed for such a
purpose. The 1st generation hybrids of M.zebra and L. fuelleborni
had jaws and teeth were a melding of the two traits, but had more
in common with the less specialized open water styled feeding
of the M. zebra. It is not an uncommon result for specialized
features or abilities to be diminished or lost after hybridization
events. If this occurred naturally in the original habitat, then
environmental pressures shape what happens next. If the mouth
and teeth offer a competitive advantage over the specialized teeth,
then the specialization can be modified or lost. If the environmental
pressure that resulted in the specialization is still there, then
that pressure drives a re-specialization or the hybrids may be
reabsorbed by one or both of the parent species.
Is this at all unnatural? Evidence suggests
not. Studies on the cichlid Pungu maclareni from the Cameroon
point to this species of cichlid being the result of very recent
hybridization between two species.(3)
The other cichlid species in the crater lakes show a comparatively
high degree of hybridization compared to average fish. In a rapidly
changing environment, recent evidence suggests that hybridization,
or extreme outcrossing is a way for individuals to get an evolutionary
jump start on the competition. The term hybrid vigor has often
been used to describe the extreme phenotypes commonly found after
a hybridization event. Certain characteristics may be masked by
being in a heterozygous (having an unalike pair of alleles) and
these features may offer an advantage that other individuals do
not offer. The healthiest fish get the mates, and there new genotypes
are carried into the population.
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