Recent advances in techniques for obtaining molecular genetic markers have transformed research into biological and behavioral studies involving lineages and relationships. New types of DNA markers such as minisatellites, microsatellites and RAPDs have enormously increased the amount of genetic information over what was previously available from allozyme studies or phenotypic markers. This information, along with new computational techniques for its analysis, has ehanced the study of phylogenetics (species lineages), linkage analysis (co-transmission within families of traits and markers) and similar questions.
One area which stands to benefit greatly from the new techniques is that of genetic relatedness and pedigree determination. Inclusive fitness theory shows that relatedness is a major factor in the evolution of all kinds of social interactions, so its calculation is a necessary step in any study of such interactions. Obtaining genetic relatedness also yields information on demographics and population structure that may be of use in other evolutionary or ecological studies.
Social insects provide a unique system for the study of questions of inclusive fitness and social interaction. In the social insects, reproduction for an entire colony may be monopolized by one or a few individuals, with other individuals working to rear offspring that are not their own. To understand this extraordinary degree of cooperation among individuals with differing genetic interests, we must have detailed information about the demographics of social insect colonies and the differing relationships and conflicts of interest among individuals within them. Use of genetic markers to measure genetic relatedness yields such information. Another application of the new genetic markers, parentage analysis, will further enhance our understanding of how such conflicts are resolved, by telling us which individuals within a colony are actually obtaining the most reproduction, and thus whose inclusive fitness interests are best served.
I have been working on a study of one particular species, Parachartergus colobopterus, a neo-tropical swarm-founding wasp, using DNA microsatellite markers together with software I developed for measuring genetic relatedness and testing for specific pedigree relationships. With these tools I have been examining the potential conflicts of interest among colony members and how these are resolved and sociality maintained. I have been able to determine that queens of this species are singly-mated and that new colony foundation is uncoupled from new queen production, a pattern which allows the inclusive fitness interests of workers in the timing of queen production to be reconciled with ecological considerations in the best time for swarming.
The software tools I have used in this study have also been used for other studies in the David Queller / Joan Strassmann lab group and are distributed to other researchers who have a use for them. These programs have been developed with funding from NSF and the Keck Center for Computational Biology.
One program, called "Kinship", has been released and is in version 1.2 as of this writing. This program performs pairwise comparisons between individuals in a data set, carrying out likelihood calculations on hypothesized pedigree relationships. The program can also calculate a matrix of pairwise relatedness values, a feature long in demand from users of our "Relatedness" program, and can produce simulated data sets to test the power of the calculation with varying amounts of genetic information. Currently I am working on an upgrade to bring Kinship to version 2.0, with new features for controlling the choice of tests to be performed, and implementing a user interface matching that of "Relatedness", so that users of one program will be able to easily use both.
Another release is a major upgrade of "Relatedness", to version 5.0.4 (currently). "Relatedness" was originally written some years ago when allozymes were the best available genetic markers. Though it was still being widely used with the expanded genetic data sets now available, it was showing its age. The upgraded program includes greatly expanded data capacity and more sophisticated options for defining the relatedness calculation, as well as the output of 95% confidence intervals and significance testing for results, the ability to perform pairwise relatedness calculations, and new options for refining the statistical properties of the measure. Relatedness 5.0 was released in February 1998.
Besides social insects, this sort of information and the programs we are preparing will be of use in a variety of other types of organisms. Our existing relatedness program has been widely circulated and has been cited in more than forty publications (at last count), and our upgrade plans are based on suggestions received from the program's users, many of which accord with the new features we need for our own research. We have also received over a hundred expressions of interest in the new programs we intend to write. So we expect our programs will be useful not just in the study of social insects but to a wide variety of research.
All programs are available free for researchers interested in performing these type of calculations. The current versions are Relatedness 5.0.4 and Kinship 1.2 . For current information on all our programming projects, and to download available software, check the Goodnight Software WWW page.
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Last updated July 12, 1999 by Keith F. Goodnight