A "New" Allele of the Mallard Plumage Pattern in Ducks

A "New" Allele of the Mallard Plumage Pattern in Ducks R. R. CAMPBELL, 1 B. S. REINHARD, and F. N. JEROME 2 Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario NIG 2Wl (Received for publication September 20, 1982) ABSTRACT Crosses of Rouen and White Pekin ducks produced a new black color pattern, which was distinct in the down of the ducklings and the plumage of the adults. Res"tricted and Mallard color patterns were also evident as well as a dus~ pattern at a very low frequency. The results indicate that black (MB) is allelic to restricted (M ), Mallard (M), and probably dusky (md ) with the existence of a quadruplet allelic series in the following order of dominance: MB>MR>M>md. (Key words: duck (Anas platyrhynchos), plumage colour inheritance, multiple alleles) INTRODUCTION Evidence indicates that the common domesticated duck originated from the Mallard (Ana$ platyrynchos) (Delacour, 1956). The Mallard can be readily tamed and was one of the earliest avian species to be domesticated with several independent domestications likely throughout the history of modern man. Despite the long period of domestication, the mutant color patterns extant in present breeds of ducks are fewer and less complicated than in fowl (Lancaster, 1963). The search for improved meat characteristics continues in domestic ducks, and fanciers of waterfowl are always interested in the production of new varieties of exotic color. The crossing of meat type varieties with colored plumage may lead to progress in the selection of the aforementioned color patterns. Because "domesticated wild birds" are common on game farms, and because wild Mallards frequently visit farmyards, it is important to understand the inheritance of plumage colors. These two groups frequently interbreed (Delacour, 1964), which could result in the introduction of new plumage color, adding to the problems of wildlife enforcement personnel. The purpose of this report is to present the inheritance of three colors, black (MB), restricted (MR), and Mallard (M), observed in research with wild Mallards and domestic Rouens. Jaap (1934) observed a multiple allelic 1 Department of Fisheries and Oceans, Resource Research Branch, 6th Floor, 240 Sparks Street, Ottawa, Ontario KIA OE6. 2299 Edinburgh Road S, Guelph, Ontario. 1984 Poultry Science 63: 19-24 series, which he referred to as the "restricted Mallard-dusky" group. Similar findings were reported by Campbell (1973) with Rouen-Pekin and Rouen-Mallard crosses, except only two dusky pattern ducks, as described by J aap (1934), were noted in over 3,000 progeny. In addition, a color pattern referred to as "black" was reported by Campbell (1973). This color pattern has not been previously described except for a mention of two individuals by Goodall (1911). The inheritance of this color pattern appeared to differ from the autosomal extended black described by Phillips (1915), J aap and Milby (1944), and Lancaster (1963) in the East Indian Runner or the Cayuga duck, although plumage descriptions were somewhat similar to those of the former variety. MATERIALS AND METHODS Initial reciprocal crosses of Rouen and Pekins produced offspring that phenotypically demonstrated three different color patterns of the Mallard plumage, i.e., Mallard, restricted and a "new" black pattern. Subsequently, the black offspring from these matings were intermated, the black and restricted offspring were reciprocally mated, and reciprocal matings of black offspring were made with Rouens. For the next three years matings were performed between the different color combinations originally derived from the Rouen-Pekin crosses to assess the inheritance of the three color patterns, black, restricted, and Mallard. The color markings were examined from progeny at one day of age and at sexual maturity, and from those that died after Day 20 of incubation. Samples of each color pattern were 19

20 CAMPBELL ET AL. '0..,..,.'.... FIG. 1. A) Day-old ducklings demonstrating the Mall ard (M), restricted (MR), and black (MB) down patterns. The light bird on the upper right is restricted. The dark bird upper middle is black and the remaining two d ucklings Mallard. The yellow area of t he black duckling will be white in the adult. B) Adult restricted drake and black hen from Pekin srock. C) Three-monch-old black drake and restric ted hen of Pekin srock. D) Mall ard drakes and hens with two bl ack individuals from the black (Rauen) X Mallard backcross. retained, and in all instances adult classification was found to agree with that of the downy young. All ducklings were vent sexed and those retained for rearing and breeding purposes were identified with numbered wing bands. In matings involving the changing of drakes during the breeding seaso n, an interim period of 14 days was granted prior to the introduction of new drakes. RESULTS AND DISCUSSION The original crossing of Rouens (typifyi ng the Mallard pattern) and Pekins (w hite) resulted in the production of all colored offspring in agreement with the hypothesis that in all common breeds of whi te ducks, self white plumage is due to an autosomal recessive gene (c/e) (Jaap, 1933; Mazing, 1933 ; Jaap and Holl ander, 1954). A " new" black down color, which must have been carried but was unexpressed in the Pekin parents, appeared in the offspring in addition to the restricted and Mallard patterns (Fig. 1). Reciprocal matings of the offspring produced all three down colors and so me white resulting from recombination of the e genes from the cle genot ype. The Mallard, restricted, and dusky patterns have been described previo usly (J aap, 1934; Lancaster, 1963). The uniform black pattern expressed in the downy young and adult of our birds was broken only by the presence or absence of yellow on the neck, bill, legs, and feet. In most cases, the dorsal and ventral surfaces were black with yellow appearing only on the ventral surface of the neck. Some birds could be distinguished by the presence of yell ow on the feet, legs, and bill, an extension of yellow fro m the breast around to the d orsal area of the neck, and on the distal, dorsal wing surface. Adults of both sexes displayed black plumage, except for areas that were yellow in

MALLARD PLUMAGE IN DUCKS 21 the down and appeared as white in the adults. The white areas on the wings and breast may be under the influence of genes for recessive white bib (b) and recessive white primaries (w), all black birds being heterozygous (Bib, Wlw) or homozygous (BIB, WIW). Ducklings with yellow on the bill and legs displayed orange on legs, feet, and bills in the adults, all other adults had black legs and feet and greenish-black bills. The black of the adults was a rich, deep, black, which had an irridescent greenish sheen more evident in the male than in the female. The speculum of both sexes was obscured, and the contours did not show the pencilling as described for the wild Black Duck (Anas rubripes). The pattern and color of this "black" variety is somewhat similar to the black patterns detailed for the Indian Runner and Cayuga Ducks by Ives (1947) and Lancaster (1963) but did not seem to follow the inheritance of extended black in these varieties as reported by Lancas~er (1963). Also, white bib and white primaries were found in many of our black individuals, which according to Lancaster (1963), are not expressed in extended black with the black East Indian and Cayuga because of modifiers. This provided another clue that our black was not the autosomal extended black of these varieties. Although we have not conducted a complete study of the white areas on these black birds, results to date suggest that their white bib and primaries are due to the genes for recessive white bib (b) and autosomal recessive white primaries (w) (Jaap, 1933). The relationship of the triple allelic seriesrestricted (MR), Mallard (M), and dusky (md) was described by Jaap (1934). Dusky appeared to occur at a very low frequency in the original Rouen stock used in our studies. Only two dusky progeny were observed during the course of the investigations and these were in the F 1 in the original Pekin-Rouen crosses and were not retained. The results of matings involving restricted and Mallard are presented in Table 1. With the exception of Matings 5 (four males X eight females) and 18 (five males X five females), both parents were known. Mating 5 represents the cross of the restricted individuals of the F 1 progeny of the original Pekin-Rauen matings. Mating R 1 consisted of a restricted male and female from the BR 1 cross of Table 3 and provides a confirmation of their genotype. Matings R2 and 21 were crosses of F 3 and F 4 individuals to provide a further check on the genotype of the parents. These matings demonstrated a close relationship to the expected 3: 1 ratio. Restricted segregates mated together in matings R3 and R4 produced all restricted progeny as expected. The backcrosses of F 4 individuals to Mallard resulted in the expected 1: 1 ratio of restricted to Mallard (Mating 18, Table 1, part c.) The results of these matings substantiate the single gene difference between restricted and Mallard as shown by Jaap (1934) with Mallard recessive to restricted. TABLE 1. Matings showing the relationship of restricted (MR) to Mallard (M) Mating Type of mating number (Male X female) Restricted Mallard a) 5 MR/M MR/M 138 51 R, MR/M MR/M 32 13 R2 MR/M MR/M 38 14 21 MR/M MR/M 159 59 Total 367 137 Expected 378 126 x 2 = 1.17.30>P >.20 b) R3 MR/M MR/MR 41 R. MR/M MR/MR 45 c) 18 MIM MR/M 53 57 Expected 55 55 X 2 =.08.80>P>.70

22 CAMPBELL ET AL. TABLE 2, Matings showing the relationship of black (MB) to Mallard (M) Mating Type of,mating number (Male X female) Black Restricted Mallard a) 6 MB/M MB/M 81 33 Expected 85,S 28,S X 2 =,75,50>P>,30 b) BI MB/M MIM 20 16 B2 MIM MB/M 19 21 Total 39 37 Expected 38 38 X2 =,02,90>P>,80 c) B3 MB/MB MB/MB 25 B. MB/MB MB/MB 31 Bs MB/MB MB/MB 41 22 MB/MB MB/MB 84 Total Expected The heritable relationship of black to Mallard is demonstrated in the matings shown in Table 2, Mating 6 in Table 2 is the cross of F 1 black individuals (three males and five females), which segregated into the expected 3: 1 ratio of black to Mallard, The reciprocal back crosses of F 1 black progeny to Mallard (Matings Bland B2, single male and female) produced the expected 1: 1 ratio (Table 2, part b), Table 2, part c shows the genotype check of black males 01 (mating B3) and 02 (matings B3 and B 4 ) mated to a black female (22) known to 181 181 be homozygous, These matings indicate a single gene difference between black and Mallard with Mallard a simple recessive to black, Matings Bs and 22 were genotype checks on the males 01 and 02 and consisted of a black male and black female from the progeny of mating B3 and a black male and 2 black females from the progeny of B 4, Table 3 presents the data showing the relationship of black to restricted and Mallard, Matings BR 1 and BR2 are reciprocal F 1 crosses of black and restricted individuals from the TABLE 3, Matings showing the relationship of black (MB) to restricted (MR) Mating Type of Mating number (Male X female) Black Restricted Mallard a) BRI MB/M MR/M 19 8 6 BR2 MR/M MB/M 42 18 32 Total 61 26 38 Expected 62,50 31.25 31.25 X2 = 2,38,50>P>,30 b) BR4 MB/M MR/MR 31 30 BRs MR/MR MB/M 17 13 Total 48 43 Expected 45,S 45,S X2 =,18,70>P>,50

MALLARD PLUMAGE IN DUCKS 23 TABLE 4. Observed and expected results of matings testing the hypothesis of three allelic genes: MB (black), MR (restricted), and M (Mallard) in decreasing order of dominance on two factor pairs at different loci' Mating Type of mating number (Male X female) Black Restricted Mallard a) BR. MB/M MRIMR 31 30 (MB/MR) (MRIM) Expected 30.5 30.5 x 2 =.02.70>P>.50 BR. MIM MB/MR 35 26 (MB/M) (MRIM) Expected 30.5 30.5 X 2 = 1.04.50>P>.30 b) BR. Ele mlm ele MIM 31 30 (Ele Mlm) (ele Mlm) Expected 30.5 30.5 X2 =.02.70>P>.50 BR. e/e mlm Ele Mlm 35 26 0 (Ele Mlm (ele Mlm) (ele mlm) or Ele mlm) Expected 30.5 15.25 15.25 X2 = 23.49 P<'Ol, E = black, e = not black, M = restricted, m = Mallard. E is assumed to be epistatic over M and m. original Pekin-Rouen matings. As expected, the type of offspring produced showed a good fit to the expected 2: 1: 1 ratio of black to restricted to Mallard. The male of mating BR 1 and the female of mating BR2 were further tested in BR4 and BRs demonstrating their heterozygosity for black. The results of matings BR4 and BRs in Table 3, part b demonstrated the expected equality of black and restricted offspring. The results of these matings (Tables 1 to 3) show that black is due to either a dominant allele or to an independent factor pair on a different locus, the dominant number being epistatic to restricted and Mallard. Jaap (1934) has shown that restricted is a dominant allele over Mallard and our results are in agreement. To test the alternate hypothesis, a black male (MB/M) was mated to a homozygous, restricted female (MR/MR) and a black female MB/MR from the progeny mated to a Mallard male (matings BR4, BR6, Table 4). 1 black were due to an independent factor pair mating, BR6 should produce a ratio of 2 black:1 restricted: 1 Mallard (Table 4 part b) while if due to an allele we should expect half black and half restricted in the offspring (Table 4, part a). Because no Mallard offspring were produced, the allelic hypothesis is accepted. The results of the matings suggested that the black color pattern (MB) may be allelic to restricted (MR) and Mallard (M) and dominant to both. J aap (1934) has shown that restricted (MR) and Mallard (M) and dusky (md ) are of an allelic series in which (MR) is dominant to (M) and dusky (md ) and (M) dominant to (md ). Our studies to date have indicated that black (M B) is dominant to all these alleles, and thereby a quadruplet allelic series may be operating in the following order of dominance; MB>MR>M>md. The lack of the dusky pattern occurring in this investigation was probably the result of a low frequency in the original Rouen stock. The breeder who supplied the foundation Rouen stock reported an incidence of only one dusky pattern in approximately 1000 birds. ACKNOWLEDGMENT This research was in part supported by Ontario Ministry of Agriculture and Food (Research Project A-04-77).

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