Biology Reference
In-Depth Information
cichlid coloration, Gunter et al. (2011) have compared transcription in the
bright blue skin of males to yellow skin in females of the Malawi cichlid
Pseudotropheus saulosi
. Among the cDNA microarray-identifi ed 46 clones
that displayed expression differences between the two sexes, fi ve have been
confi rmed to be differentially expressed by relative quantitative Real-Time
PCR (qRT-PCR). This gene list includes a representative from the endosomol-
to-Golgi vesicle traffi cking pathway
Coatmer protein complex
subunit zeta-1
(
Copz-1
), a critical determinant of pigmentation. Transcriptional differences
and putative functional diversifi cation of genes seem to cause the coloration
of blue males and yellow females among the cichlids. Incidentally, van der
Sluijs et al. (2010) have found that the coloration of progenies of
Pundamilia
pundamilia
in the turbid areas of Lake Victoria is determined by the dames
but not the sires.
Apart from these African examples, there are others describing how
mate choice may lead to increased isolation between strains. For instance,
Fukamachi et al. (2009) identifi ed a medaka mutant (
colur interfere: ci
)
that is distinctly unattractive to breeding partners. The
ci,
a mutation on
the
somatolatin α
(
SLα
) gene, seems to reduce orange pigment color cells
(xanthophores) in the skin. Though there are extremely strong mating
preferences, the mutant and SLα-transgenic strains of medaka prefer to
mate with partners from their strain leading to increased isolation between
these strains.
2.12 Morphotypes and differentiation
Among vertebrates, the occurrence of an array of morphotypes within a
sex is astounding, although this area of sexual differentiation is hardly
covered by molecular biologists. The intense sperm competition has driven
the males to develop an alternate strategy, in which males have been forced
'to make best use of a bad situation' (Taborsky, 2001). Some of these male
morphotypes require explanation/defi nition. Accordingly, a territorial male
constructs a nest or defends a territory and courts with the female(s) in his
territory. Sneakers are relatively small males, which dart and steal spawning
with territorial females, e.g., bluegill sunfi sh. Facing intense competition,
the spermatozoa of sneakers swim faster than those of pirates, whose
sperms are the slowest swimmers (e.g.,
Telmatochromis vittatus,
Fitzpatrick
et al., 2007). Satellites are slightly larger males and may be tolerated by
territorial males; with the same body color and behavior, they may deceive
the parental/territorials, as in some species like the bluegill sunfi sh. The
satellites are not homogenous and the term has been indiscriminately used
(e.g., Oliveria et al., 2001b,c, Table 21). For instance, among yellow morphs
of the cichlid
Pelvicachromis pulcher
, a pair-forming male, who has lost his
territory or partner, is also called a 'satellite' (Martin and Taborsky, 1997).
