Kin Discrimination and the Social Amoeba

Research recently published in PLoS Biology indicates that amoebas which are close to starvation will seek out genetically similar relatives.

We tested how widely social amoebae cooperate by mixing isolates from different localities that cover most of their natural range. We show here that different isolates partially exclude one another during aggregation, and there is a positive relationship between the extent of this exclusion and the genetic distance between strains. Our findings demonstrate that D. discoideum cells co-aggregate more with genetically similar than dissimilar individuals, suggesting the existence of a mechanism that discerns the degree of genetic similarity between individuals in this social microorganism.

It will be really interesting if/when a description of the mechanism discerning genetic similarity is given, and if there is any remnant of it still present in humans or to what extent it exists in other species.

Interestingly, this study seems to provide more evidence for the gene being the important unit of selection by nature. It is the very survival of these organisms that could explain what has been observed here on a genetic level: genes which are similar have evolved a mechanism for detecting one another because of the mutual (but ultimately selfish) benefit of doing so. The further from similarity they are, the more likely they are to discriminate in offering assistance, as was the case in this study. Aside from the reason of promoting different allelic versions of one’s self, one good reason for the evolution of this discrimination mechanism would be to weed out “cheaters”, or genes which take advantage of the ‘altruism’ of these genes to assist other amoebas in their time of need (starvation) by abusing their helpful nature. That is, if it is embedded in me, when I see a fellow organism of my species, ‘If starving, help fellow organism’, it will pay me to also have the command, ‘If distantly related, do not help’. In other words, if I see my brother and my 2nd cousin starving, it’s going to be worthwhile for my genes if I am able to detect which one is my brother since he shares more genetic material with me than my 2nd cousin. By helping him instead of the more distant relative, I am increasing the odds that my genes or genes very close to my own will be passed on to the next generation. My genes have limited interest in helping out other, distant genes.

By the by, the use of GFP makes this experiment all the more beautiful.

Darwin Wasn’t Right

Darwin Was Right About How Evolution Can Affect Whole Group

Evolutionary biologists at McGill University have discovered molecular signals that can maintain social harmony in ants by putting constraints on their fertility. Dr. Ehab Abouheif, of McGill’s Department of Biology, and post-doctoral researcher, Dr. Abderrahman Khila, have discovered how evolution has tinkered with the genes of colonizing insects like ants to keep them from fighting amongst themselves over who gets to reproduce.

“We’ve discovered a really elegant developmental mechanism, which we call ‘reproductive constraint,’ that challenges the classic paradigm that behaviour, such as policing, is the only way to enforce harmony and squash selfish behaviour in ant societies,” said Abouheif, McGill’s Canada Research Chair in Evolutionary Developmental Biology.

It’s unfortunate that group selectionism is gaining some traction once again. It almost never makes any sense and simply acts as a way of taking the easy explanation over the difficult answer.

This study found that evolution has changed the genetic make-up of ants to the point where social harmony is achieved through “reproductive constraint”. In other words, some worker ants have less or no fertility level relative to others because of particular gene regulations. Big deal. This doesn’t point to any group selectionism.

What makes far more sense is that ants which promote social harmony are more successful on average. Instead of looking toward the goal-oriented ideas of group selectionism, it’s more reasonably to view this as individual genes promoting their own fitness. That is, most ants in a colony, if not all, are going to share a high degree of genes. It isn’t that the vehicle for these genes – the organism, in this case, the ant – is important. The survival of the gene itself is important. With more harmony comes, perhaps, more reproduction and more success. And what’s being reproduced are a high number of shared genes.

Think of it this way. My brother and I share 50% of our genes. If I help him to reproduce, I have roughly 25% of my genes surviving to the next generation. Of course, if I simply reproduce on my own, that’s 50% of my genes that will be passed on. But if I’m fighting with my brother over the same woman, we decrease our reproduction odds. It may just benefit me on the level of the gene to help him reproduce at my own expense. Having assistance will help his odds (even if this assistance is passive, as in not fighting him). This will give 25% of my genes a better chance of surviving than the 50% of genes I ‘own’ have when there is conflict.

Rather than showing the notion of group selectionism to be valid (though it remains plausible), this research offers some interesting evidence which favors natural selection occurring at the level of the gene

Darwin Wasn't Right

Darwin Was Right About How Evolution Can Affect Whole Group

Evolutionary biologists at McGill University have discovered molecular signals that can maintain social harmony in ants by putting constraints on their fertility. Dr. Ehab Abouheif, of McGill’s Department of Biology, and post-doctoral researcher, Dr. Abderrahman Khila, have discovered how evolution has tinkered with the genes of colonizing insects like ants to keep them from fighting amongst themselves over who gets to reproduce.

“We’ve discovered a really elegant developmental mechanism, which we call ‘reproductive constraint,’ that challenges the classic paradigm that behaviour, such as policing, is the only way to enforce harmony and squash selfish behaviour in ant societies,” said Abouheif, McGill’s Canada Research Chair in Evolutionary Developmental Biology.

It’s unfortunate that group selectionism is gaining some traction once again. It almost never makes any sense and simply acts as a way of taking the easy explanation over the difficult answer.

This study found that evolution has changed the genetic make-up of ants to the point where social harmony is achieved through “reproductive constraint”. In other words, some worker ants have less or no fertility level relative to others because of particular gene regulations. Big deal. This doesn’t point to any group selectionism.

What makes far more sense is that ants which promote social harmony are more successful on average. Instead of looking toward the goal-oriented ideas of group selectionism, it’s more reasonably to view this as individual genes promoting their own fitness. That is, most ants in a colony, if not all, are going to share a high degree of genes. It isn’t that the vehicle for these genes – the organism, in this case, the ant – is important. The survival of the gene itself is important. With more harmony comes, perhaps, more reproduction and more success. And what’s being reproduced are a high number of shared genes.

Think of it this way. My brother and I share 50% of our genes. If I help him to reproduce, I have roughly 25% of my genes surviving to the next generation. Of course, if I simply reproduce on my own, that’s 50% of my genes that will be passed on. But if I’m fighting with my brother over the same woman, we decrease our reproduction odds. It may just benefit me on the level of the gene to help him reproduce at my own expense. Having assistance will help his odds (even if this assistance is passive, as in not fighting him). This will give 25% of my genes a better chance of surviving than the 50% of genes I ‘own’ have when there is conflict.

Rather than showing the notion of group selectionism to be valid (though it remains plausible), this research offers some interesting evidence which favors natural selection occurring at the level of the gene