Biology Reference
In-Depth Information
bees have a very high rate of breaking and recombining along their
chromosomes.
Recombination rates are measured in centimorgans (cM). One cen-
timorgan distance between two places on a chromosome means that
roughly 1 percent of the time there is recombination between those
points. h e distance between two points along a chromosome can be
expressed as the physical distance measured by the number of nucleo-
tide base pairs (bp), the building blocks of DNA, or the recombina-
tional distance in cM. Another measure is the number of base pairs per
cM of recombination. h is is a way to compare genomes of dif erent
species. h e honey bee has roughly 45,000 base pairs per cM. h e
mouse has about 2 million bp per cM, and humans have about 1 mil-
lion bp per cM. h e honey bee has about 20 times more recombination
than humans.
Recombination breaks up gene combinations inherited from indi-
vidual parents and builds new combinations in the gametes, thereby
increasing the genotypic variation of the of spring produced. h ere-
fore, it appears that genotypic variation is very important for honey
bees. Why? h ere are two ways to approach this question. One is to
look at the consequences of genotypic variation on individual and col-
ony behavior. h e other is to ask whether higher genotypic diversity
results in higher i tness for colonies, higher survival and reproductive
success (successful queens and drones), and the evolution of higher
rates of recombination and polyandry. I have tried to keep these ques-
tions separate. In the rest of this chapter, I will discuss genetic variation
for individual behavior and its consequences. In particular, I will dis-
cuss how the genotype of a worker places constraints on her behavioral
l exibility (plasticity), and the ef ects of genetic variation and polyandry
on colony plasticity and resilience, the ability to respond to environ-
mental changes and return to “normal.” In Chapter 4, I will discuss the
evolution of polyandry.
