These aquaculture- and conservation-oriented commentaries are not abstracts written by the original authors.  They reflect the opinions of someone else -- usually Roger Doyle.  Direct quotations from the papers or abstracts are marked with inverted commas.

359.  Frankentilapia for treating diabetes
        Cell therapy for diabetes using piscine islet tissue. 2001. Wright, J.R. Jr., and B. Pohajdak. Cell Transplantation 10:125-143.
        Insulin-producing tissue is much easier to collect from tilapia than from mammals. The authors of this paper have developed procedures for encapsulating and implanting fish tissue into diabetic mice, where it accurately regulates blood glucose levels. In the ordinary course of things tilapia evolved to produce tilapia insulin, not human insulin, but this careless & inconvenient flaw in the Great Chain of Being has been corrected.
        "Because tilapia and human insulin differ by 17 amino acids, we have cloned, sequenced, and modified the tilapia insulin gene by site-directed mutagenesis resulting in a tilapia insulin gene that codes for "humanized" insulin while still maintaining all of the tilapia regulatory (noncoding) sequences." The authors proceeded to develop a strain of transgenic O. niloticus which produces the humanized insulin along with its normal insulin.
        Work still needs to be done to replace the normal tilapia gene with the humanized gene (by homologous recombination), to make the newly humanized gene homozygous and to adjust the genetic background by breeding and selection. The goal of this work is a new therapy for sick people. "Islets from the resulting transgenic fish, after extensive characterization, could be harvested, encapsulated, and then transplanted into diabetic patients." jwright@iwkgrace.ns.ca 

358.  Loss of fitness in captive populations
        Rapid genetic deterioration in captive populations: Causes and conservation implications. 2002. Woodworth, L.M., M.E. Montgomery, D.A. Briscoe, and R. Frankham. Conservation Genetics 3 (3):277-288.
        This experiment with Drosophila was designed to find out which of two consequences of cultivation in a comfortable artificial environment causes the worse long-term conservation problem: inbreeding depression or adaptation to the domestic life. The answer is, they both cause problems and each is worse than the other.
        Various population sizes of fruit flies were maintained for 50 generations in a benign environment intended to represent supportive breeding or a live gene bank. When the populations were subsequently returned to an environment more closely resembling their natural one all the populations showed a marked decrease in reproductive fitness relative to controls. This was especially evident in the smallest populations (Ne = 25) and largest populations (Ne = 500). The authors attribute this to inbreeding depression and adaptation to the benign environment, respectively, in small and large populations.
        "Reproductive fitness showed a curvilinear relationship with population size, the largest and smallest population size treatments being the worst." There are a lot of lessons to be learned from this experiment about the relative importance of drift and local adaptation in smallish populations. "Consequently, genetic deterioration in captivity is likely to be a major problem when long-term captive bred populations of endangered species are returned to the wild. A regime involving fragmentation of captive populations of endangered species is suggested to minimize the problems" rfrankha@els.mq.edu.au 

357.  Genetics of color variation in scallops
        Inheritance of the general shell color in the scallop Argopecten purpuratus (Bivalvia: Pectinidae). 2002. Winkler, F.M., B.F. Estévez, L.B. Jollán, and J.P. Garrido. The Journal of Heredity 92 (6):521-525.
        The genetics of shell colour in molluscs is usually rather simple. Molluscan color polymorphism has been used in several classic studies of the interaction between selection and drift in natural populations (bird predation on land snails). The authors of this paper have worked out the genetics of color in the Chilean scallop Argopecten purpuratus and found that it is also rather simple. The various colors, purple, brown, orange, yellow, and white are controlled by one locus and a white line on the shell is controlled at another. fwinkler@ucn.cl 

356.  How to monitor the quantitative genetic effects of domestication and other environmental change
        Comparing G matrices: a MANOVA approach. 2002. Roff, D. Evolution 56 (6):1286-1291.
        If the genetic relationships among traits in a managed population changes we would want to know about it. For example, one might speculate that the correlation between reproductive success and survival in the wild would be altered in domestic environments by strong artificial selection for growth, plus relaxed selection for mating behavior and fecundity. If so, the change would affect the long-term goal of using hatcheries to support natural populations. Changes in the G matrix can be produced by bottlenecking, by inbreeding and mutation in an extinction vortex (Mar 2000 #300), by strong selection for a single trait such as growth in aquaculture, by (in the case of salmon) hybridization between wild and farmed fish, by domestication selection (e.g. for tameness) in live gene banks, and by other means as well. The G matrix is important because it mediates the translation of multiple-trait selection into multiple-trait evolution.
        This paper describes a practical and statistically robust procedure for comparing G matrices as functions of categorical covariates such as sex, species, rearing conditions, habitat, before-and-after, etc. It is written with the author's usual clarity and intention to be helpful. "I have written coding [S-Plus] for the following designs: full-sib, nested full-sib, half-sib, mean offspring on parent, and simple phenotypic. This coding, available via email, is written as Word documents, color-coded to distinguish lines that need to be changed according to the particular data set. A detailed "Read me" file is also available."
        Pedigree information required for quantitative genetic analysis of wild and semi-wild populations is now relatively easy to obtain and analyse (for example #346 below), at least for full-sib and parent-offspring relationships. The essence of Roff's analysis is to combine MANOVA with a statistical procedure called the jackknife, which is easy to do in the SYSTAT statistical package among others. derek.roff@ucr.edu 

355.  Heritabilities and correlations of traits important in aquaculture
        Coupling body weight and its composition: a quantitative genetic analysis in rainbow trout. 2002. Kause, A., O. Ritola, T. Paananen, E. Mäntysaari, and U. Eskelinen. Aquaculture 211 (1-4):65-79.
        This is a useful genetic analysis of traits that are important to the cultivation of rainbow trout Oncorhynchus mykiss. Standard full- and half-sib experimental design and standard statistical procedures (animal model, REML) were used to estimate heritabilities and genetic correlations among numerous traits including body weight and condition factor, fillet weight, fat, flesh color, percent fillet protein, ash and water. The fish were three years old when measured.
        Percentages of fat, protein, ash and water showed low heritabilities but the heritability of body weight was 0.2 -- plenty high enough to justify a selection program. Percent fillet weight and percent fillet fat were also moderately heritable (0.3, 0.2). These traits could usefully be included with body weight in a selection index aimed at improving both productivity and consumer appeal.
        The authors emphasize the importance of including maturation status, sex and (for some traits) body weight as covariates in the statistical analyses. Genetic correlations among the traits also have to be watched and the authors include a very interesting discussion of genetic correlations in farmed animals and fish. In regard to their own findings they comment that "water percent could be utilised in selection programmes aiming to decrease fat content of the flesh, because recording of water percent is easy and cheap and it correlates very strongly, although negatively, with fat concentration. In contrast, condition factor seems to be an unsuitable predictor of body composition." Antti.Kause@mtt.fi 

354.  How to find QTL for logistic growth
        A logistic mixture model for characterizing genetic determinants causing differentiation in growth trajectories. 2002. Wu, R., C.-X. Ma, M. Chang, R.C. Littell, S.S. Wu, T. Yin, M. Huang, M. Wang, and G. Casella. Genetical Research 79:235-245.
        The quantitative genetics of growth at two different stages is easy to analyse if you don't think about it too much, nearly impossible if you do. A fundamental genetic problem is that early and late growth may be controlled by different sets or subsets of genes (Mar 2000 #20). A fundamental statistical problem is that the growth of individuals is cumulative and sequential measurements of size-at-age measured from birth are therefore spuriously correlated.
        In aquaculture, sequential correlations of size -at- age are usually moderate at best (see Sep 2000 #109 for observations on shrimp). This is an expensive nuisance for aquaculturists, who would like to select their animals as young as possible. One solution to the statistical autocorrelation is to slice the growth curves into non-overlapping intervals (Jun 2002 #330) but this is an arbitrary and ad hoc approach.
        It would be useful to work with the growth variables which are not spuriously correlated and which represent different aspects of the biology of the animal, i.e. the action of different sets of genes or genetic control elements. This thinking leads naturally to the classic logistic growth model, which has a parameter that characterizes growth in the absence of negative feedback (early growth) and another parameter that characterizes the sensitivity of growth to feedback, e.g. from size-dependent maturation status, crowding etc. (late growth). [My apologies to those who feel that this is a too-idiosyncratic description of the logistic model.] Anyway, the genetics of logistic growth parameters have indeed been studied to some extent by quantitative geneticists.
        Here, the quantitative genetic analysis is extended to the problem of QTL detection. In this paper the authors present a "statistical model for detecting major genes responsible for [S-shaped, logistic] growth trajectories. This model is incorporated with pervasive logistic growth curves under the maximum likelihood framework and, thus, is expected to improve over previous models in both parameter estimation and inference. The power of this model is demonstrated by an example using forest tree data, in which evidence of major genes affecting stem growth processes is successfully detected." rwu@stat.ufl.edu 

353.  Marker identification of "nested" sibship relationships
        Sibship reconstruction in hierarchical population structures using Markov chain Monte Carlo techniques. 2002. Thomas, S.C., and W.G. Hill. Genetical Research 79:227-234.
        Markov chain Monte Carlo procedures developed by these authors "allow the reconstruction of nested full- within half-sib families, and present an efficient method for calculating the likelihood of the observed marker data in a nested family". These methods should be useful for genetic analysis of wild and semi-wild (e.g. aquacultural) populations -- see #356, above -- although the authors say that heritability and genetic variance values based on the reconstructed pedigrees can be biased if there are errors. This extends an earlier paper by these authors (Aug 2000 #88). (See also #346, below.) sthomas@srv0.bio.ed.ac.uk 

352.  Genetics of the fish that get away
        Rapid evolution of escape ability in Trinidadian guppies (Poecilia reticulata). 2002. O'Steen, S., A.J. Cullum, and A.F. Bennett. Evolution 56 (4):776-784.
        Guppies living in streams in Trinidad have been the subjects of many excellent studies on the selective effect of natural predators. The traits studied have usually been body color, mating behaviour and other traits affected by a trade-off between predation risk and reproductive success. Here the authors report on the ability of guppies to survive encounters with the pike cichlid Crenicichla alta in the laboratory.
        Guppies from environments in which natural predation is high showed superior survival, as did their F2 offspring. The descendents of a population of guppies which had previously been transplanted into high-and low-predation environments evolved significant changes in escapability in 26 - 36 generations or less. "Interestingly, we found rapid evolutionary loss of escape ability in populations introduced into low-predation environments, suggesting that steep fitness trade-offs may influence the evolution of escape traits".
        This work is reminiscent of the 20-year-old papers of Moav and his colleagues on the seine escapability of the European and Chinese strains of the common carp. European ponds are drained during harvest and Chinese ponds are seined. The carp in China have become very good at escaping seines. sosteen@bates.edu 

351.  Stocking changes the genetics of salmonid populations but they recover anyway
        The impact of stocking on the genetic integrity of Arctic charr (Salvelinus) populations from the Alpine region. 2002. Englbrecht, C.C., U. Schliewen, and D. Tautz. Molecular Ecology 11 (6):1017-1027.
        The charr population in one of the lakes in this study, Königssee in the Bavarian Alps, was heavily supplemented by stocking but nevertheless has changed very little genetically, as the authors found by comparing it with a near-by remnant of the ancestral population. The charr used for stocking another lake, Starnberger See, completely replaced the ancestral ones. Because Königssee has been ecologically stable while the charr in Starnberger See were almost wiped out by pollution this difference in the genetic effect of stocking is rather predictable.
         The really interesting part of this story is that a third lake, Ammersee, was just as heavily damaged by pollution as Starnberger See but was never stocked. Here, the original charr population recovered, genes and all, when the lake was cleaned up. The authors conclude "Our data suggest that the practice of artificial stocking should be reconsidered, or at least monitored for effectiveness".
        This paper could be used by partisans on both sides of the stocking controversy. Anti: using foreign fish to stock a population that is going extinct for ecological reasons causes irreparable genetic damage. Pro: it really does not matter what genotypes you use to re-establish a population when the ecological problems have been solved. tautz@uni-koeln.de 

350.  Low fitness of stressed-out inbred finches
        Environmental conditions affect the magnitude of inbreeding depression in survival of Darwin's finches. 2002. Keller, L.F., P.R. Grant, B.R. Grant, and K. Petrena. Evolution 56 (6):1229-1239.
        The finches of the Galapagos which stimulated Darwin's imagination are still a major source of knowledge about how evolution works. In this study several traits of two species of Geospiza were studied in relation to variation among individuals in their level of inbreeding. Individuals with inbreeding equivalent to the offspring of brother-sister mating had such poor survival and mating success that they left essentially no offspring. As has often been reported in other cases the depressive effects of inbreeding were much worse in a stressful environment (see Mar 2000 #32, Sep 2000 #101, Mar-Apr 2001 #185, Apr-May 2002 #312.) "In juveniles, inbreeding depression was only present in years with low food availability, and in adults inbreeding depression was five times more severe in years with low food availability and large population sizes." l.keller@bio.gla.ac.uk 

349.  Frankenfish that survive Pseudomonas and Vibrio
        Production of transgenic medaka with increased resistance to bacterial pathogens. 2002. Sarmasik, A., G. Warr, and T.T. Chen. Marine Biotechnology 4:310-322.
        The authors used electroporation to introduce the silk-moth cecropin gene into medaka. (For more about cecropin and anti-microbial polypeptides see May 2000 #55). "F2 transgenic fish from different families and control fish were challenged with Pseudomonas fluorescens and Vibrio anguillarum at a 60% lethal dose. Challenge studies showed that while about 40% of the control fish were killed by both pathogens, only up to 10% of the F2 transgenic fish were killed by P. fluorescens and about 10% to 30% by V. anguillarum." tchen@uconnvm.uconn.edu 

348.  Frankencatfish that resist pathogenic bacteria in ponds
        Enhanced bacterial disease resistance of transgenic channel catfish Ictalurus punctatus possessing cecropin genes. 2002. Dunham, R.A., G.W. Warr, A. Nichols, P.L. Duncan, B. Argue, D. Middleton, and H. Kucuktas. Marine Biotechnology 4:338-344.
        This paper describes a field test of a cecropin gene construct (see #349, above) inserted into catfish. In earthen ponds 100% of the transgenic catfish survived a natural exposure to Flavobacterium columnare, versus 27% survival of normal fish. When challenged in tanks with Edwardsiella ictaluri, a bacterium which causes enteric septicemia in catfish, survival of the transgenic fish was 41% versus 15% for the controls. rdunham@acesag.auburn.edu 

347.  Inbred populations are especially receptive to immigrant genes
        Rapid spread of immigrant genomes into inbred populations. 2002. Saccheri, I.J., and P.M. Brakefield. Proceedings of the Royal Society (U.K.) Ser. B. 269 (1495):1073-1078.
        There is a problem with the way immigration is handled in standard population genetic models. The initial spread of immigrant genes ini the recipient population is supposed to be a purely random process unless the gene confers some gene-specific fitness advantage. Consequently weakly selected or neutral immigrant genes have a high risk of being lost in the early generations while they are still extremely rare.
        Experimental work on the butterfly Bicyclus anynana which is reported here shows that if the recipient population is somewhat inbred, the offspring of the immigrant can have a fitness advantage (heterosis) which increases the probability that the whole immigrant genome will survive. This non-specific advantage persists for several generations. "Our result suggests that effective migration rates may often be much higher than the numbers of individual migrants assumed by classical population genetics models, with implications for the persistence and evolution of metapopulations."
        It may happen quite often that endangered population remnants, or indeed aquacultural broodstocks, are sufficiently inbred so that they have an enhanced receptivity to immigrant genomes. saccheri@liverpool.ac.uk 

346.  Computer program for estimating relatedness and inbreeding
        An estimator for pairwise relatedness using molecular markers. 2002. Wang, J. Genetics 160:1203-1215.
        The marker-based statistical procedures developed by Jinliang Wang for estimating inbreeding (in one individual) and genetic relatedness (between two individuals) were described in Apr-May 2002 #320. The author is now kindly providing a Fortran program for doing the calculations on a PC. The executable files can be downloaded from http://www.zoo.cam.ac.uk/ioz/software.htm#MER  along with a test data set and instructions. Users are requested to send an email to jinliang.wang@ioz.ac.uk to register after downloading the package.