Saratoga Research Trip

[AlexJordan]

Apparently facebook will let anyone see this album without joining...we'll see:

http://www.facebook.com/album.php?aid=2040...mp;id=219002312

The asian guy in the photos is a researcher from Singapore specialising in Arowana. After having spoken with him about the reproductive habits of these fish, and their distribution in the wild, I think their threat to Saratoga is less than I initially suspected. However... I still think it's good that their inclusion on the list was rejected at this time, as decisions like this should never be made on people's opinions, rather on actual data.

I'm heading over to Singapore in March to visit him and all the farms in Singapore and do some more research over there, so I'll post photos from there as well.

[ozarowana]

Thanks for sharing Alex. Can I ask what questions you are trying to answer with this study?

[D6C1]

Elaborate a bit more on the research? ta

[robdog013]

awesome photos, I like the saratoga egg

[AlexJordan]

My research broadly examines the reproductive investment made by fishes in varying social and environmental conditions. The stuff with saratoga was to once and for all establish whether the male or female contributes most to parental care.

There is a general opinion in aquaculture and the hobby that female saratoga mouthbrood the eggs, although this is scientifically unfounded. It took some of my colleagues 3 years to establish the gender of arowana parents using techniques based on testosterone levels and inheritance patterns. Despite what many people claim, there are no consistent external sex differences in osteoglossids (although I imagine a lot of you will object to that claim ), so in order to be scientifically strong, studies need to use genetic techniques to assign sex to these fish. Note that there are studies that show genital pore differences between the sexes, during breeding, but this technique is unsuitable to determine which parent is carrying the eggs, because once they are brooding the differences may disappear.

This research trip sought to collect tissue samples to definitively answer this basic question. If the general feelings are correct, and it is the female that broods the eggs, it is an evolutionary departure from the rest of the osteoglossids (and most bony fish for that matter - cichlids are an exception to the general pattern of male brood care in fishes), and opens up many questions about why this might be the case.

I can't tell you the findings of our research due to publishing embargos, but when the study is released I'll let you know.

[ozarowana]

Thanks for that. I have always questioned the male / female brood care "supposed" differences in the Scleropages genus.

I have always wondered how they sex animals using molecular techniques. I assume the 3yrs wasn't to just determine gender as I'm sure there would be simple PCR methods for this? In regards to inheritance, do you mean population genetic diversity? As looking at inheritance from parent to offspring would have taken a while Maybe DNA marker work within the population?

[AlexJordan]

No, it didn't take three years to run the PCR! It took that long to get sufficient samples of breeding individuals. The study with Saratoga will probably take longer because of the smaller number of breeders in Australia.

Inheritance --> I'm afraid I can't go too far into it because of publication issues, but we have techniques that can determine whether a parent is a male of female based on the genotypes of their offspring (think about it for a while and you may get it!). But yes, for any microsatellite work we need to know background levels of allelic diversity within the population, hence the study of wild fish.

Alex