H. pyrrhocephalus - morphological change?

[Lisachromis]

H. pyrrhocephalus proved capable of considerable morphological change

http://www.practicalfishkeeping.co.uk/p ... ?news=1720

Publishing their results in a recent issue of the Biological Journal of the Linnean Society, Frans Witte and co-authors measured fishes collected by bottom trawls in 1977–1981 and 1993–2001. The authors found that the total gill area of the fishes had increased by 64% in the span of two decades. At the same time, head length, eye length, and head volume decreased in size, whereas cheek depth and the depth of the levator posterior muscle (located dorsal to the gills) increased.

What do people think of this?

[Christophe de Medeiros]

Hi
I understand that the species adapted herself to an environmental change.
as said above
The authors conclude that the increase in gill area is a direct response to the hypoxic (low oxygen) conditions created in the lake. At the same time, reductions in eye size and depth of the rostral part of the sternohyoideus muscle, and reallocation of space between the opercular and suspensorial compartments of the head may have permitted accommodation of larger gills in a smaller head. The increase in the depth of the levator posterior muscle is thought to aid the fish in processing larger and tougher prey types (this shift to larger prey is possibly caused by the increased turbidity of the water).
xris

[Greg Steeves]

That is my understanding as well Chris. The morphological changes with this species may be environmental and not due to hybridization at all. Great information, thanks!