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51.
Jay D. Evans 《Behavioral ecology and sociobiology》1996,39(4):275-284
In many polygynous ant species, established colonies adopt new queens secondarily. Conflicts over queen adoption might arise
between queens and workers of established colonies and the newly mated females seeking adoption into nests. Colony members
are predicted to base adoption decisions on their relatednesses to other participants, on competition between queens for colony
resources, and on the effects that adopted queens have on colony survivorship and productivity. To provide a better understanding
of queen-adoption dynamics in a facultatively polygynous ant, colonies of Myrmica tahoensis were observed in the field for 4 consecutive years and analyzed genetically using highly polymorphic microsatellite DNA markers.
The extreme rarity of newly founded colonies suggests that most newly mated queens that succeed do so by entering established
nests. Queens are closely related on average (rˉ = 0.58), although a sizable minority of queen pairs (29%) are not close relatives. An experiment involving transfers of queens
among nests showed that queens are often accepted by workers to which they are completely unrelated. Average queen numbers
estimated from nest excavations (harmonic mean = 1.4) are broadly similar to effective queen numbers inferred from the genetic
relatedness of colony members, suggesting that reproductive skew is low in this species. Queens appear to have reproductive
lifespans of only 1 or 2 years. As a result, queens transmit a substantial fraction of their genes posthumously (through the
reproduction of related nestmates), in comparison to direct and indirect reproduction while they are alive. Thus queens and
other colony members should often accept new queens when doing so will increase colony survivorship, in some cases even when
the adopted queens are not close relatives.
Received: 20 February 1996/Accepted after revision: 25 May 1996 相似文献
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Originally prenatal diagnosis was confined to the diagnosis of metabolic disorders and depended on assaying enzyme levels in amniotic fluid. With the development of recombinant DNA technology, molecular diagnosis became possible for some genetic conditions late in the 1970s. Here we briefly review the history of molecular prenatal diagnostic testing, using Duchenne muscular dystrophy as an example, and describe how over the last 30 years we have moved from offering testing to a few affected individuals using techniques, such as Southern blotting to identify deletions, to more rapid and accurate PCR-based testing which identifies the precise change in dystrophin for a greater number of families. We discuss the potential for safer, earlier prenatal genetic diagnosis using cell free fetal DNA in maternal blood before concluding by speculating on how more recent techniques, such as next generation sequencing, might further impact on the potential for molecular prenatal testing. Progress is not without its challenges, and as cytogenetics and molecular genetics begin to unite into one, we foresee the main challenge will not be in identifying the genetic change, but rather in interpreting its significance, particularly in the prenatal setting where we frequently have no phenotype on which to base interpretation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献