Not Bad For The Last Day Of The Year

Beinn Dubchraig (left), Ben Lomond (distance) Ben Oss (centre) and Ben Lui (right) from Ben Dorain

Ben More (centre left) Stob Binnien (centre right) and Cruach Ardrain (right) from Ben Dorain

The blackmount and Ben Nevis (centre right) from Beinn Dorain

Happy New year everyone

My Genome Project

Given the fact that many creationists accept evolution within rather vaguely defined kinds of animals but deny that man is the product of evolution, I’ve decided to go through our genomes and compare it with chimps (and other species). Firstly, I’ll define the genome. This is essentially the complete genetic sequence of an organism. Prokaryotes (eg bacteria) contain one copy of this sequence, and Eukaryotes (like ourselves) generally contain two copies of this information (some organisms are polyploid and contain many copies). In sexually reproducing organisms, there are often two separate sex chromosomes, so when a genome sequence is referred to in these organisms, it means all the different somatic (non sex) chromosomes plus a copy of each of the sex chromosomes (eg X and Y in humans).

In case anyone does not know, our genome has 96% identity with that of the chimp. That sounds a small difference for two easily distinguishable species. However, our genome is 3,200,000,000 base pairs (letters) long. However, that is equivalent to 128 million differences.

My plan is to go through the chromosomes from the first (largest) to the smallest (Y) and highlight the tell tale signs of evolution – signs shared with chimps – or derived from a common ancestor. Chromosomes often contain tell tale pieces of “junk” DNA (perhaps up to 50% of the genome is non functional junk acquired during our evolutionary past) or even fusions that show the ancestry of the organism. This will take some time, but I hope to learn a lot from it myself.

Interspecific Brood Care

I’ve been thinking about a few posts on cichlid evolution at the moment, but don’t have too much time. These fish make Darwin’s finches look like absolute beginners in evolutionary terms. Lake Malawi alone has at least 500 species and many geographical variations – all thought to have evolved from a single (maybe 2) common ancestor(s) in a few million years. For anyone with some spare time, this site provides some photos of them. A small section on trophic (feeding) adaptations can be found here.

Anyway, as a short post, I would like to introduce some Central American cichlids. Parachromis dovii is a rather large and nasty predator. One problem it faces is the predation of its fry by other fish. Next up is Theraps (aka Hypsophorys, aka Copora) nicaraguense. This is a medium sized fish, but is easily bullied and can be out competed for breeding sites by the aggressive Archocentrus nigrofasciatus. A 12 cm male is a very big fish for this species and I have had 6-8cm fish attack me and draw blood when looking after their fry. There is another smaller species, Neetroplus nematopus, which by all accounts is even more aggressive. So, T. nicaraguense has a problem, these little fish get all the good breeding sites. The solution is rather unexpected. See if you can guess: P. dovii is a major predator of N. nematopus and A. nigrofasciatus………


Give up?

T. Nicaraguense helps bring up the fry of P. dovii and is therefore tolerated by them. Their own fry also benefit from the numbers of P. dovii fry in the area – a predator is more likely to grab one of them as they are more numerous. Som studies estimate that P. dovii would face extinction in some areas if it was not for this interspecific co-operation. There are some costs though, as P. dovii will also eat some juvenile T. nicaraguense too. Thre have also been some recorded incidents of T. nicaraguense “cheating” on the deal too. However, that is evolution for you – cheating can be of benefit to the cheats until their numbers rise and make it disadvantageous – if P. dovii numbers drop, so do T. nicaraguense numbers. Natural selection will then start to select against the cheats and a new equilibrium will be reached – this may then allow another cycle of cheating……

There are obviously some implications for the evolution of moral behaviour here – by helping others, you are actually being selfish and helping yourself. This is something the religious just don’t get – they think being selfish means that you kill and eat every thing – not cooperate.