A Wednesday afternoon "TOOFER"

Hello kids...seeing as it is the middle of the trimester at school (work) and it is parent-teacher conferences, I will be doing a "TOOFER". That is I will be addressing two questions in this week's blog.

For those of you that are parents (or may be someday)...be nice to your kids teachers (especially at PTC time), we really aren't out to get your kids. Well, maybe some of them ;)

Anyway, let us discuss the question from the week our papers were due...

QUEENS VS. WORKERS:

Queens and workers...there is definitely a conflict between these two. Queen keeps a sister down by not letting her reproduce, yet sister has to help raise families that aren't theirs. However, there are instances where the worker bees may parasatize the next generation for their own benefit.

A recent study on bees in Brazil showed that worker bees are generally unable to mate, but are capable of laying unfertilized eggs which can develop into male offspring. To assure dominance over reproduction the Queen often selectively eats any worker laid eggs. In some species other workers may eat the eggs of fellow workers in what is known as 'worker policing'.

Even with these barriers there is much to gain for worker bees producing their own offspring, however the benefit is entirely for the individual and can be costly for the colony overall. The team found that workers who reproduce can live as much as three times longer, meaning that reproducing workers have a life expectancy almost matching the Queen herself.

This added life expectancy is thought to be because workers who reproduce do not usually carry out risky tasks such as foraging. However as worker bees who are reproducing are not working, an increase in individual workers who reproduce puts the collective production of the colony in jeopardy, hence a queen-worker conflict over the production of males ensues.

That sounds super technical...and it is. I found this information in the journal article: Alves, DA; Imperatriz-Fonseca, VL; Francoy, TM; Santos-Filho, PS; Billen, J; Wenseleers, T. The queen is dead-long live the workers: intraspecific parasitism by workers in the stingless bee Melipona scutellaris. Molecular Ecology, 2009; DOI:

So, who wins, loses and what are the consequences. Well, the worker that reproduces when the aren't "allowed" to is being selfish and benefits by gaining a longer life and having genes floating out in the world. The queen hurts due to increased competition and (according to the article) the colony can suffer as well, since all parts of the machine aren't working as they "should". It is a complex issue, and I can see where the selfish genes are really difficult to suppress.

Question #2 of your "toofer"...evolution of altruism, even in unrelated organisms...vampire bats in particular.

The background on this: Using the prisoner's dilemma, why do vampire bats share when they have a good night of hunting, when the best strategy for the individual seems like defecting? The way that I see it, is that if you are only facing ONE situation where you need to get some blood from a lucky bat, the best option is to defect. They payoff is very good and you don't reciprocate. However, in most cases, you aren't just living in a "one time" environment. You might not do well tonight, and someone helps you out. The next time you may have to help someone out. Even if you aren't related to that bat (according to the Wilkinson experiment in Dawkins) the others recognize who is an "old friend" and thus may hold a grudge (the grudger...from ch 10) and you are in danger of starving. Selfishness may be rewarded in the short term, but cooperation (in this case) seems to be a more effective strategy in the long term. You can't pass along genes when you are dead on the cave floor from starving!

A bit more info for the interested! From the website: http://brembs.net/ipd/ipd.html

Blood-sharing in vampire bats

Scientists working on cooperation among vampire bats (Desmondus rotundus) face the same difficulties in measuring all the essential parameters, but are in a somewhat better position. Some 8'%, of adult vampire bats fail to find food on any given night (Wilkinson 1984), but on such nights without a blood meal they are often fed by successful roostmates. This behaviour is vital for the recipients, since their energy budget leaves them 48-72 h of food deprivation before starvation (McNab 1973). Wilkinson (1984) showed that food sharing by regurgitation of blood "depends equally and independently on degree of relatedness and an index of opportunity for reciprocation". He suggested that w is probably high enough to fit the IPD due to the long lifespan of the individuals and the stable composition of groups in which the average coefficient of relatedness is comparatively low (0.08-0.11; Wilkinson 1988). Fig. 6 shows that b>c because the exponential postfeeding weightless enables a donor to lose less time to starvation by regurgitation of blood than the recipient gains. Hence, it is plausible that T>R>P>S. Furthermore, the cognitive abilities of vampire bats appear to be sufficiently well-developed to guarantee recognition of cooperators and defectors (Wilkinson 1984). While it is reported that bats do in fact deny feeding those roostmates that refused to regurgitate previously (i.e. act retaliatorily; Wilkinson 1984), it still remains to find out which strategy the bats actually use. An applicability of the IPD should be confirmed by further investigations.

Fig. 6. Predictive curve of post feeding weightlosses in vampire bats (Desmondus rotundus). A donation of 5% of pre-feeding weight when at weight D should cause a donor to lose C hours but provide the recipient at weight H with B hours. B >C for all E > F. See text for details. Redrawn from: Wilkinson, G. S. 1984. Reciprocal food sharing in the vampire bat. Nature 308: 183.

That is a lot for your "TOOFER" kiddies. Looking forward to input!

Black...tired and not ready to face parents.