Special reading - counter intuitive behaviour -2- filial cannabilism in sand gobys Flashcards
who is the paper written by?
Nicholas D.S. Deal (2014)
background info
- looking into the effect of predator exposure on parental investment in current brood vs future broods
- examine filial cannibalism and nest characteristics In the sand goby
what was the question of the experiment?
does predator exposure increase filial cannibalism?
what was the hypothesis?
- predict that san gobys that perceive a high risk of predation will be less likely to engage in total filial cannibalism, and in cases of partial filial cannibalism, eat fewer of their eggs
- especially if filial cannibalism is performed to improve future reproductive success
what are the aims?
examine the effect of perceived predation risk on filial cannibalism in sand gobys by comparing the behaviour of egg tending males exposed to a perch (predatory fish) with that of males guarding eggs in a comparatively safer environment
secondary aim: looking at the effect of predation threat on nest construction to test whether filial cannabilism is used to acquire energy for nest building
how were the experiments set up?
took place in an aquarium separated into 2 sections, a nesting compartment and exposure compartment
the nesting compartment contained an artificial nesting site(flower pot), a male was added, built a nest, then a female goby was placed in the aquarium to reproduce and then the female was removed.
half of the males had perch placed in the exposure section of their aquarium and the other half were used as a control
throughout the experiment egg numbers were counted regularly, furthermore quality of nest construction was assessed
how was nest construction assessed?
good quality = sand covered the flowerpot and the entrance to make it smaller than it would be if it was just the flower pot
poor quality = sand covered the pot but not the entrance so it was a larger gap that the high quality ones
what parameters were measured?
1) egg numbers ( at beginning and end of experiment)
2) male weight
3) nest construction and maintenance
what were the results?
- exposure to perch tended to decrease males engaging in total filial cannibalism
- all males consumed atleast some eggs
- 18/64 males engaged in total filial cannibalism
- males with small clutches were significantly more likely to engage in total filial cannibalism
- total filial cannibals lost significantly less weight than partial filial cannibals
- filial cannibalism was shown to have no effect on nest construction and maintenance
what do the results mean?
- partial cannibalism was not influenced by the presence of a predatory perch
- for total cannibalism males tended to consume their entire brood less often in the presence of perch
- overall insufficient evidence to show that parental predation risk influences filial cannibalism
