January 30, 2017 by Domino Joyce,
The Conversation
The males of some species go to
extraordinary lengths to attract females – but some simply cheat. Take African
cichlid fish. Many males build underwater "sandcastle" structures
that the females use to judge the quality of their potential mates. But, as my
colleagues and I found out during a recent study, some
males don't bother with this show of construction prowess, and instead are able
to father offspring by engaging in "sneaky mating".
There are hundreds of species of
colourful cichlid fish in Lake Malawi, Africa, and about two hundred of these
build pit- or volcano-shaped structures known as "bowers" out of
sand. Each species builds a slightly different type of sand bower, and they
function as a signal of male quality, both to other
males, and to
females.
The females are what are known as mouthbrooders. After
courtship with their male partners, which takes place on top of the bower, the
females lay eggs and pick them up in their mouths. The males then fertilise the eggs while
they are still in the females' mouths.
The females then carry the eggs
for about three weeks until they hatch into baby fish known as "fry".
The male contributes no parental care, nothing but his genetic material. So the
females need to ensure they choose high quality males, and they use the shape
of his bower to do this.
The males even help the females
to do this by congregating in breeding arenas called
"leks". The females can then visit a lek and judge a
large number of males at once, usually laying only a handful of eggs with each
chosen male. The ability to build and defend a bower in this hotbed of male
activity is thought to demonstrate the quality of the male to the females. It
takes two to three weeks for each male to build his bower and he has to work
hard to maintain it over a breeding season of several weeks
Posts
