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Ossification and behaviour, do they interact?

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With calcein vital stains and using UV light, it is possible to see the skeleton of young fish very well, while they don't need to be anesthesised or x-rayed.

 

calcein.jpg(Photo Craig Albertson)

We have two systems in the lab where such observations can be very useful to help us answer research questions on interactions between morphology and behaviour:

- Annual killifish sometimes show cannibalism as fry. Very often the cannibals grow to much larger sizes than their non-cannibalising kin. Is cannibalism inducing morphological allometric changes in the head, such that cannibals start looking more like related piscivorous species?

 

- Scale-eating cichlids often have asymmetric beaks, pointing either to the left or to the right. That is supposed to make them more efficient when attacking prey to rip some scales off their flanks. Is this asymmetry present from early ossification? Or is it determined by behavioural preferences, such that young scale-eaters are still rather symmetric?

 

This is a project for a Bsc. or Msc. student. In collaboration with the technical workshop, the student will build a setup where behaviour of fry can be observed and photographs of the skeleton made. This setup will be tested and improved using fry of annual killifish, of which we have a steady weekly supply. Then an experiment using fry of scale-eating cichlids will be carried out.

Supervision is by Tom JM Van Dooren (t.j.m.van.dooren@biology.leidenuniv.nl)

 

Braconid parasitoids of Drosophila lay their eggs in the larvae of Drosophila. They are represented on all continents. As Drosophila melanogaster has now a cosmopolitan distribution this species has become an important host for many Asobara species. Currently we keep 5 species in our laboratory: Asobara tabida, a palearctic species, A. citri, an African species, A. japonicus from Japan, A. pleuralis from Indonesia and A. persimilis from Australia.  Although D. melanogaster has the same developmental period from egg to adult in worldwide, the 5 Asobara species differ markedly in developmental time, from 21 days in A.tabida to 12 days in A. pleuralis, measured at 25 C, with the other species having intermediate developmental times. This poses the question which selective pressures act on developmental time, and which constraints prevent species to have shorter developemental times. Our hypothesis is that a shorter developmental time has costs, because it is traded off against other life-history characters, like fecundity or longevity.
The practical work involves measuring of size, weight, egg load, fecundity and lipoprotein contents of Asobara wasps reared under standard laboratory conditions.

This project can be done as BSc stage (4 months), or be extended to a MSc research project.

 

Supervision: Majeed Askari Seyahooei & Jacques van Alphen

Contact: m.a.seyahooei@biology.leidenuniv.nl      

 

Leptopilina boulardi is a Drosophila parasitic wasp originating from Africa, which can now be found in many subtropical and Mediterranean regions as a parasitoid of Drosophila melanogaster. We collect 10 populations of this parasitoid from five different climatic zone in Iran. We culture these lines in our lab since their collection in the summer of 2006. We have measured a number of life history traits of these lines, which show significant variation between lines from different climatic zones. We want to investigate the hypothesis that the observed differences in longevity and metabolic rate for these lines are adaptations to the local climate. Several lines originated from the Caspian coast with a very wet and mild climate, while others originate from the hot and dry desert and Mediterranean climates found in the interior of Iran. Coastal and interior collection sites differ enormously in rainfall and seasonal temperatures.
To study if metabolic rate is an adaptation to local climateto and to study how metabolic rate affects the trade-off between longevity and fecundity we will measure longevity of different lines at a constant temperature and measuring the metabolic rate of individuals in a group of 20 wasps with a sensitive respirometer at different ages of the wasps, at time of emerging, 5, 10, 15 and 20 days after emerging. The egg loads of the wasps will be measured at the time of dead.
Longevity of the wasp will be measured in the presence of food and without food and egg load of the wasps will be measured at the time of death when the body is still fresh by dissection of the ovarioles and by counting the eggs on photographs of dissected ovarioles.

Supervision: Majeed Askari Seyahooei & Jacques van Alphen

Contact: m.a.seyahooei@biology.leidenuniv.nl      

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