Molecular status of the dusky Canada goose (Branta canadensis occidentalis): A genetic assessment of a translocation effort

Until recently, the dusky Canada goose (Branta canadensis occidentalis) was managedas one breeding population from the CopperRiver Delta (CRD), Alaska. Population numberson the CRD have declined precipitously over thelast three decades, due in part to changes inhabitat. In 1981, a pair of Canada geese,presumably B.c. occidentalis, wasreported nesting on Middleton Island (MID), inthe Gulf of Alaska. Numbers of Canada geese onthe island increased in the decade subsequentto a translocation of geese from CRD to MID,but it is unclear whether the increase isattributable to the translocation effort. Weused genetic data derived from three classes ofgenetic markers to clarify relationships ofCanada geese breeding in south-coastal Alaska. Geese were sampled from 5 populations: CRD,MID, Anchorage (ANC), Admiralty Island (ADM) insoutheastern Alaska, and Green Island (GRN) inPrince William Sound (PWS). Mitochondrial DNAanalyses demonstrate Canada geese from MID arenearly monomorphic for a unique haplotype fixedon GRN but not found in CRD or any otherbreeding population. Furthermore, nuclearmarkers consistently cluster MID with GRN tothe exclusion of CRD. We suggest the currentpopulation on MID is not derived from birdstranslocated from CRD, but rather that MID wasmost likely colonised by birds inhabiting otherisland habitats within the PWS. Furthermore,since geese from the CRD share mtDNA haplotypeswith geese from other breeding locales, theyapparently share recent common ancestry and/orgene flow with populations representing othersubspecies. Our genetic data raise questionsabout the validity of current management unitsof Canada geese.     

Genomic dynamics of brown trout populations released to a novel environment

Population translocations occur for a variety of reasons, from displacement due to climate change to human‐induced transfers. Such actions have adverse effects on genetic variation and understanding their microevolutionary consequences requires monitoring. Here, we return to an experimental release of brown trout (Salmo trutta) in order to monitor the genomic effects of population translocations. In 1979, fish from each of two genetically (F _ST = 0.16) and ecologically separate populations were simultaneously released, at one point in time, to a lake system previously void of brown trout. Here, whole‐genome sequencing of pooled DNA (Pool‐seq) is used to characterize diversity within and divergence between the introduced populations and fish inhabiting two lakes downstream of the release sites, sampled 30 years later (c. 5 generations). Present results suggest that while extensive hybridization has occurred, the two introduced populations are unequally represented in the lakes downstream of the release sites. One population, which is ecologically resident in its original habitat, mainly contributes to the lake closest to the release site. The other population, migratory in its natal habitat, is genetically more represented in the lake further downstream. Genomic regions putatively under directional selection in the new habitat are identified, where allele frequencies in both established populations are more similar to the introduced population stemming from a resident population than the migratory one. Results suggest that the microevolutionary consequences of population translocations, for example, hybridization and adaptation, can be rapid and that Pool‐seq can be used as an initial tool to monitor genome‐wide effects.     

Mottled Duck introductions to South Carolina: The ugly,the bad,and the good?

Translocations or other movements of wildlife sometimes accomplish their intended objectives, but unforeseen consequences may arise and disrupt locally adapted ecological communities, restructure or dilute genetic integrity of populations or subspecies of the moved organism, and otherwise negatively influences a species’ long‐term fitness. Two historical populations of Mottled Ducks (Anas fulvigula) exist and are endemic to (1) Mexico and the West‐Gulf Coast (A. f. maculosa) regions of the United States and (2) Florida (A. f. fulvigula). From 1975 to 1983, 1285 Mottled Ducks from Florida, Louisiana, and Texas were released to coastal South Carolina, primarily to ultimately establish a legally harvestable population. This movement stirred mixed reactions amid the conservation community. Contemporary information suggests an increasing Mottled Duck population in South Carolina and possibly dispersing into Georgia. Herein, I objectively discuss the potential consequences of this new population per the birds’ evolution, ecology, and management. Ultimately, I suggest that this translocation is a long‐term benefit to the species.     

The Effects of Varying Chromosome Arm Dosage on Maize Plant Morphogenesis

Maize is an especially well-suited species for studying the effects of aneuploidy on plant development. We used B-A translocations and testers that were crossed seven times into inbred W22 to generate a dosage series for 14 chromosome arms. This is the first report of dosage effects on maize morphogenesis using inbred B-A stocks and inbred tester stocks. We compared plants containing one dose or three doses of each of the 14 chromosome arms with plants containing two doses for seven measured traits. These were leaf width, leaf length, plant height, ear height, internode length, ear node circumference, and tassel branch number. We observed the typical maize aneuploid syndrome wherein one dose was more widespread and more severe in its effects than three doses. All but two of the one-dose effects were negative, and all of the three-dose effects were negative. The occurrence of positive responses by hyperploid plants in our earlier B-A-A study and the absence of any positive responses among the hyperploids reported for the 14 simple B-A translocations tested for dosage effects in the present study and previously may reflect gene dosage interaction between the two chromosome arm segments present in the B-A-A translocations. The overall congruence of our results with those of previous studies suggests that the traits measured are quantitative traits controlled by multiple genes whose activities provide a balanced regulation that transcends individual inbred lines or diverse genetic backgrounds and that such genes may be especially abundant in chromosome arm 1L.     

Production of multiple wheat-rye 1RS translocation stocks and genetic analysis of LMW subunits of glutenin and gliadins in wheats using these stocks

Summary A triple (1AL.1RS/1BL.1RS/1DL.1RS) and three double (1AL.1RS/1BL.1RS, 1AL.1RS/1DL.1RS, 1BL.1RS/1DL.1RS) wheat-rye 1RS translocation stocks were isolated from a segregating population using the Gli-1, Tri-1 and Sec-1 seed proteins as genetic markers. These stocks carried 42 chromosomes and formed the expected multivalents (frequency of 14–25%) at metaphase 1. They gave floret fertility ranging from 40–60%. These stocks were subsequently used to determine the genetic control of low-molecular-weight (LMW) glutenin subunits in Chinese Spring and Gabo by means of two-step one-dimensional SDS-PAGE. All of the B subunits and most of the C subunits of glutenin were shown to be controlled by genes on the short arms of group-1 chromosomes in these wheats. The other C subunits were not controlled by group-1 chromosomes. The triple translocation line served as a suitable third parent in producing test-cross seeds for studying the inheritance of the LMW glutenin subunits and gliadins in wheat cultivars, e.g. Chinese Spring and Orca. The segregation patterns of the LMW glutenin subunits in these cultivars revealed that the subunits were inherited in clusters and that their controlling genes (Glu-3) were tightly linked with those controlling gliadins (Gli-1). The LMW glutenin patterns d, d and e in Orca segregated as alternatives to the patterns a, a and a in Chinese Spring controlled by Glu-A3, Glu-B3 and Glu-D3 loci on chromosome arms 1AS, 1BS and 1DS, respectively, thus indicating that these patterns were controlled by allelic genes at these loci.     

Quality and biochemical effects of a IBL/IRS wheat-rye translocation in wheat

Wheat (Triticum aestivum L.) breeders world-wide have used rye (Secale cereale L.) as a source of genes for agronomic improvement. The 1BL/1RS wheat-rye chromosomal translocation derived from the Russian cultivars Kavkaz and Aurora has been among the most common means of accessing useful rye genes. Unfortunately, deleterious wheat quality effects are often associated with the presence of 1RS. The identification of genetic backgrounds capable of alleviating the deleterious effects of 1RS is crucial for its continued exploitation. End-use quality parameters and flour protein composition, as measured by size-exclusion high-performance liquid chromatography (SE-HPLC) of 373 wheat lines, derived from seven 1BL/1RS breeding populations, were analyzed. In all populations, significant quality defects were detected in 1BL/1RS lines compared to non-1RS sister lines. The detrimental quality effects resulted from alteration of the ratio of flour protein composition, especially, decreased glutenin concentrations, and increased salt-water soluble protein concentrations. The end-use quality of 1BL/1RS lines, however, was highly dependent on genetic backgrounds. The potential exists for improvement in quality through crosses between 1RS lines with high glutenin, or low salt-water soluble protein concentrations, and non-1RS lines with strong dough properties.Joint contribution of the U.S. Department of Agriculture, Agricultural Research Service and Department of Agronomy, University of Nebraska-Lincoln, as Journal Series Paper No. 10598. Mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture or the University of Nebraska over other firms or products not mentioned     

Spontaneous transformation of a cloned cell line of normal diploid bovine vascular endothelial cells

Summary We report here the spontaneous transformation of a normal diploid bovine fetal aortic endothelial cell line. This cell line showed a period of rapid proliferation, followed by a period of declining proliferative activity, as judged by both a decline in the number of population doublings achieved from seeding to subcultivation and a decrease in the fraction of cells incorporating [³H]thymidine. During the decline in proliferation, foci of small cells appeared amid a background of larger senescent-appearing cells. The cultures then regained proliferative activity and have been maintained in our laboratory for more than 22 months. The transformants are characterized by (a) an indefinite life span, (b) a morphology that is more spindle shaped as compared to pretransformants, and (c) heteroploidy with chromosome translocations. This work was supported by the U.S. National Institute of Health (NIH) Grant AG-00378. S. D. G. is a predoctoral trainee supported by U.S. Public Health Service Grant CA-09191-06, E. H. is supported under NIH Grant AG0-2100, and W. W. N. is the S. Emlen Stokes Professor of Genetics at the Institute for Medical Research.     

Chromosomal evolution inEpilobium sect.Epilobium (Onagraceae)

WithinEpilobium sect.Epilobium, a cytological analysis of 121 experimental hybrids, involving 40 species, indicates the presence of a widespread BB chromosome arrangement in Eurasia, Africa, and Australasia, as well as in North and South America less commonly. The AA chromosome arrangement, which differs from BB by one reciprocal translocation, occurs in North America, South America, and in at least three European species. The CC arrangement, which differs from AA by two reciprocal translocations, characterizes theAlpinae, a circumboreal group. Distinctive or only partly worked out chromosome arrangements occur in the EuropeanE. duriaei andE. nutans and in the North AmericanE. luteum, E. obcordatum, E. oregonense, andE. rigidum. With earlier results, the chromosome arrangements of some 65 of the estimated 185 species of the section have been established fully or partly.     

Introduction of two chromosomal translocations of Sus scrofa nigripes and Sus scrofa scrofa into the genome of Sus scrofa domestica

Summary Hybrids between wild and domestic pigs with two types of translocations in the karyotype were studied. The translocations of type I were first detected in a population of the Middle Asian wild boars. Type II was identified in a populations of the Central European subspecies. A large number of Middle Asian and Central European hybrids and their F₁-F₃ hybrids from crosses with domestic pigs were viable. By means of differential chromosome staining, the mechanism of the formation of synthetic karyotypes, as well as some features of translocation inheritance, were established.The introduction of two translocations into a single genome and the same chromosome set of these hybrids not only modified chromosome number, but also the composition of the linkage groups. The hybrids heterozygous for two translocations and their hybrid progeny are characterized by an obligatory heterozygozity for a large number of genes, gene complexes and linked genes. It is suggested that this heterozygozity may be associated with heterotic events. The use of such hybrids in pig breeding may provide heterosis for viability and productivity.     

Population structure of red-cockaded woodpeckers in south Florida: RAPDs revisited

Six south Florida populations of the endangered red-cockaded woodpecker (Picoides borealis) were sampled to examine genetic diversity and population structure in the southernmost portion of the species' range relative to 14 previously sampled populations from throughout the species range. Random amplified polymorphic DNA (RAPD) analyses were used to evaluate the populations (n= 161 individuals, 13 primers, one band/primer). Results suggested that south Florida populations have significant among-population genetic differentiation (F_ST= 0.17, P < 0.000), although gene flow may be adequate to offset drift (N_m= 1.26). Comparison of Florida populations with others sampled indicated differentiation was less in Florida (F_ST for all populations = 0.21). Cluster analyses of all 20 populations did not reflect complete geographical predictions, although clustering of distant populations resulted in a significant correlation between genetic distance and geographical distance. Overall, results suggest populations in south Florida, similar to the remainder of the species, have low genetic diversity and high population fragmentation. Exact clustering of distant populations supports the ability of RAPDs to differentiate populations accurately. Our results further support past management recommendations that translocations of birds among geographically proximate populations is preferable to movement of birds between distant populations.