Cichlid fish- biodiversity, speciation & conservation

18/02/2020

The final talk I attended for my Science and Employability module was one held by Bangors zoological society.

This talk was by Prof. George Turner and focused on cichlid fish biodiversity, speciation and conservation.

The largest numbers of cichlid fish are found in lake Malawi, Tanganyika and Victoria. With as many as 1000 species in lake Malawi,
The species are all unique to the lakes in which they’re found.
There are small radiations in other lakes and lower levels of diversity in rivers.

The fish all vary in colour, morphology, feeding and behaviour.
Variety of colour likely comes from female sexual selection.

Rivers in South Africa are particularly rich in cichlids, most likely due to the now extinct lake Magadikadi.
Showing that what happens in these large lakes has an effect on the surrounding areas.

Recently Prof. Turner has been sequencing the lake Malawi radiation.
Full genome sequencing gave very different results to MtDNA. The big message here being that using mitochondrial sequencing DNA to look at differences doesn’t work for cichlids. Therefore, its important to get into genome wide data to properly look at the differences between the organisms.
One possibility for this is that cichlids don’t go through species bottlenecks and they also sometimes hybridise with themselves again, even after speciation.

One species, Astatotilapia Calliptera, isn’t found in just lake Malawi but also in the rivers that flow in and out of it and in rivers that aren’t connected to the lake at all.
Morphologically, the A.calliptera is similar to the other Astatotilapias. However, this species isn’t basal in the Malawi tree. A possible reason for this could be that it was there before the lake was formed. It doesn’t come out as basal because its still integrating with everything else but still doing what it was doing from the start.
This assumes basic sympatric speciation.
You would assume that the ancestral species gives rise to everything else but its not the case here.

One study Prof. Turner has been involved with since 2011, is sorting out the fishes that lives in the lakes and rivers of Tanzania. This proved difficult because of the old and often short descriptions of these species.
This found new distributions of “old” fishes and ones that have gone by several names.
Also it found 4 new species not described yet.

Prof. Turner rounded up his talk by discussing some problems cichlids are facing such as extinction of some species due to the Nile perch and there is also a problem with oil drilling under some of the lakes.

This was a very passionate and captivating talk and even almost tempted me to go into researching fish. This was the first time that morphology seemed interesting to me as it’s something that I tend to forget about most of the time. Unfortunately I don’t think researching fish will be a path a choose to follow any time soon.