Sex-linked Inheritance In Drosophila Part 7

LINKAGE OF VERMILION, BAR, AND FUSED.

Males from the stock of (red) bar fused were mated to vermilion (not-bar, not-fused) females, and produced bar females and vermilion males. The bar F_1 daughters were back-crossed to vermilion fused males and produced the cla.s.ses of offspring shown in table 34.

TABLE 34.--P_1 _vermilion_ [female] [female] _bar fused_ [male] [male].

_B. C. F_1 bar_ [female] _vermilion fused_ [male] [male].

+----------+-------------------+---------------------+------------------+ v v B' f_u v f_u ----------------- ----+-------------- -----------+---- B' f_u B' Reference.+----------+--------+----------+----------+-----------+------+ Vermilion Vermilion. Bar bar Wild-type. Vermilion Bar. fused. fused. fused. +----------+----------+--------+----------+----------+-----------+------+ 140 I 137 130 35 40 5 8 ~ 141 I 144 137 38 41 4 2 ~ 142 I 153 120 43 58 6 7 143 I 153 92 44 41 3 7 145 I 69 62 29 19 1 .. 146 I 96 103 30 34 7 3 156 I 62 45 25 27 1 4 157 I 93 57 11 31 2 2 +----------+--------+----------+----------+-----------+------+ Total. 907 746 255 291 29 33 +----------+----------+--------+----------+----------+-----------+------+

+--------------------+--------+--------------------------------+ v B' ----+--------+---- Cross-over values. f_u +-----------+--------+ +-----------+--------+-----------+ Total. Vermilion Fused. Vermilion Bar Vermilion bar. bar. fused. fused. +-----------+--------+--------+-----------+--------+-----------+ ~ .. .. 355 21 4 25 ~ .. .. 366 22 2 23 1 .. 388 26 4 29 3 1 344 26 4 28 1 .. 181 27 1 27 .. .. 273 23 4 26 .. .. 164 32 3 35 .. 2 198 22 3 23 +-----------+--------+--------+-----------+--------+-----------+ 5 3 2,269 24 3 27 +-----------+--------+--------+-----------+--------+-----------+

The data show that the factor for fused lies about 3 units to the right of bar. This is the furthest point yet obtained to the right. The reasons for locating fused to the right of bar are that, if it occupies such a position, then the double cross-over cla.s.ses (which are expected to be the smallest cla.s.ses) should be vermilion bar and fused, and these are, in fact, the smallest cla.s.ses. The order of factors is, then, vermilion, bar, fused. This order is confirmed by the result that the number of cross-overs between fused and vermilion is greater than that between bar and vermilion.

In order to obtain data to balance viability effects, the following experiment was made:

Vermilion (not-bar) fused males were bred to (red) bar (not-fused) females.

The daughters and sons were bar. The daughters were back-crossed, singly, to vermilion fused males and gave the results shown in table 35. Each female was also transferred to a second culture bottle, so that for each female there are two broods given consecutively (82, 82', etc.) in table 35.

The results given by the two broods of the same female are similar. The values are very near to those given in the last experiment, and confirm the conclusions there drawn. The combined data give the results shown in table 36. {56}

TABLE 35.--_P_1 bar [female] [female] vermilion fused [male] [male]. B.

C. F_1 bar [female] vermilion fused [male] [male]._

A - Vermilion fused.

B - Bar.

C - Vermilion bar.

D - Fused.

E - Vermilion.

F - Bar fused.

G - Vermilion bar fused.

H - Wild type.

------------------------------------------------------------------------- v f_u v B' v v B' f_u Cross- -------- ----+---- ----+---- -+---+--- over B' f_u B' f_u Total. values.

Reference +-------------+---------+---------+---------+ +----------- A B C D E F G H C F A ----------+------+------+----+----+----+----+----+----+------+---+---+--- 82 165 165 63 57 8 7 1 .. 466 26 3 29 82' 104 87 26 24 .. 4 .. .. 245 20 2 22 83 128 164 51 39 6 4 .. .. 392 23 3 26 83' 100 94 28 30 4 4 .. .. 260 22 3 25 89 85 105 23 24 5 2 .. .. 244 19 3 22 89' 78 91 21 27 1 2 .. 1 221 22 2 23 90 86 85 30 28 5 .. .. .. 234 25 2 27 90' 33 38 22 14 4 1 .. 1 113 33 5 36 91 125 107 41 31 1 1 .. .. 306 24 1 24 91' 91 95 31 25 5 1 .. 2 250 23 3 25 92 109 136 41 24 4 2 .. .. 316 21 2 23 92' 100 105 29 29 .. 1 .. 1 265 22 1 22 93 75 67 19 20 .. 1 .. .. 182 21 1 22 93' 68 94 31 17 1 1 .. .. 212 23 1 24 94 84 96 31 35 8 1 .. .. 255 26 4 29 94' 61 73 20 22 5 4 .. .. 185 23 5 28 95 84 102 27 26 3 3 .. .. 245 22 2 24 96 144 148 43 34 1 2 .. 1 373 21 1 21 97 81 96 25 20 5 3 .. .. 230 20 4 23 98 107 112 39 33 1 2 .. .. 294 25 1 26 Firsts 1,273 1,383 433 371 47 28 1 1 3,537 23 2 25 Seconds 635 677 208 188 20 18 .. 5 1,751 23 3 25 ----------+------+------+----+----+----+----+----+----+------+---+---+--- Total. 1,908 2,060 641 559 67 46 1 6 5,288 23 2.3 25 ----------+------+------+----+----+----+----+----+----+------+---+---+---

TABLE 36.--_Linkage of vermilion, bar, and fused with balanced viability._

+------------+----------+-----------+-----------+-----------+--------+ v B' f_u v v B' v f_u -------- --+------ -----+--- -+---+--- Total. B' f_u f_u B' +------------+----------+-----------+-----------+-----------+--------+ 5,621 1,756 175 15 7,567 Percentage 74.3 23.19 2.31 0.2 +------------+----------+-----------+-----------+-----------+--------+

Some additional data bearing on the linkage of vermilion and fused were obtained. Males of (red) fused stock were bred to vermilion (not-fused) females, and gave wild-type females and vermilion males, which inbred gave the results shown in table 37.

The percentage of cross-overs between vermilion and fused is here 27, which is in agreement with the 26 per cent of the preceding experiment.

The converse experiment, namely, red (not-fused) females by vermilion fused males also gave, when the wild-type daughters were {57} back-crossed to vermilion fused males, a linkage value of 27 units. Two 10-day broods were reared from each female. The data given in table 38 show that the percentage of crossing-over does not change as the flies get older. The locus of fused on the basis of all of the data is at 59.5.

TABLE 37.--P_1 vermilion [female] [female] fused [male] [male]. F_1 wild-type [female] [female] F_1 vermilion [male] [male].

KEY: A: Non-cross-over [male] [male].

B: Cross-over [male] [male].

C: Females.

D: Vermilion.

E: Fused.

F: Vermilion fused.

G: Wild-type.

H: Total [male] [male].

I: Cross-over values.

+------------+-----+-----------+----------+-----+----+ A B +-----+-----+----+-----+ Reference. C D E F G H I +------------+-----+-----+-----+----+-----+-----+----+ 79 I 299 93 96 37 36 262 28 80 I 245 93 60 28 27 208 26 81 I 263 101 63 22 40 226 27 +-----+-----+-----+----+-----+-----+----+ Total. 807 287 219 87 103 696 27 +------------+-----+-----+-----+----+-----+-----+----+

TABLE 38.--P_1 wild [female] [female] vermilion fused [male] [male]. F_1 wild-type [female] F_1 wild-type [male] [male].

KEY: A: Wild-type [female] [female].

B: Non-Cross-over [male].

C: Cross-over [male].

D: Vermilion fused.

E: Wild-type.

F: Vermilion.

G: Fused.

H: Total [male] [male].

I: Cross-over values.

+------------+-------+------------+-----------+-----+----+ B C +-----+------+-----+-----+ Reference. A D E F G H I +------------+-------+-----+------+-----+-----+-----+----+ 52 96 25 30 16 11 82 33 52' 176 59 64 24 19 166 26 53 60 20 22 9 6 57 26 53' 76 21 27 11 10 69 31 54 88 35 38 14 16 103 29 54' 60 22 20 8 9 59 29 57 61 22 20 7 11 60 30 57' 170 47 54 24 19 144 30 58 128 37 55 14 10 116 21 58' 144 38 64 16 15 133 23 Firsts 433 139 165 60 54 418 27 Seconds 626 187 229 83 72 571 27 +-------+-----+------+-----+-----+-----+----+ Total 1,059 326 394 143 126 989 27 +------------+-------+-----+------+-----+-----+-----+----+

FORKED.

On November 19, 1912 there appeared in a stock of a double recessive eye-color, vermilion maroon, a few males which showed a novel form of the large bristles (macrochaetae) upon the head and thorax. In this mutation (text-fig. E) the first of several which affect the shape and distribution of the bristles, the macrochaetae, instead of {58} being long, slender, and tapered (see Plate 1, fig. I), are greatly shortened and crinkled as though scorched. The ends are forked or branched, bent sharply, or merely thickened. The bristles which are most distorted are those upon the scutellum, where they are sometimes curled together into b.a.l.l.s.

LINKAGE OF VERMILION AND FORKED.

[Ill.u.s.tration: FIG. E.--Forked bristles.]

Since forked arose in vermilion stock, the double recessive for these two s.e.x-linked factors could be used in testing the linkage relations of the mutation. Vermilion forked males were crossed to wild females and gave wild-type males and females, which inbred gave in F_2 the results shown in table 39. Forked reappeared only in the males in the following proportion: not-forked [female], 742; not-forked [male], 346; forked [male], 301. The result shows that the character is a s.e.x-linked recessive.

TABLE 39.--_P_1 wild_ [female] [female] _vermilion-forked_ [male] [male].

_F_1 wild-type_ [female] [female] _F_1 wild-type_ [male] [male].

+----------+----------+----------------+---------------+--------+-------+ Non-cross-over Cross-over Wild-type [male] [male]. [male] [male]. Total Cross- Reference. [female] +--------+-------+-------+-------+ [male] over [female]. Ver- Wild- Ver- Forked. [male]. values. milion type. milion. forked. +----------+----------+--------+-------+-------+-------+--------+-------+ 9 I 366 113 123 49 41 326 28 11 I 376 116 150 42 31 339 22 +----------+--------+-------+-------+-------+--------+-------+ Total. 742 229 273 91 72 665 25 +----------+----------+--------+-------+-------+-------+--------+-------+

In table 39 vermilion forked and wild-type are non-cross-overs, and vermilion and forked are cross-overs, giving a cross-over value of 25 units. The locus, therefore, is 25 units to the right or to the left of vermilion, that is, either about 58 or 8 units from the yellow locus.

LINKAGE OF CHERRY AND FORKED.

Forked males were crossed to cherry females (cherry has the same locus as white, which is about 1 unit from yellow) and gave wild-type females and cherry males. These gave in F_2 the results shown in table 40. The non-cross-overs (cherry and forked) plus the cross-overs (cherry forked and wild type) divided into the cross-overs give a cross-over value of 46 units, which shows that the locus lies to the right of vermilion, because if it had been to the left, the value would have been 8 (_i. e._, 33-25) instead of 33+25=58. The difference between 58 {59} and 46 is due to the expected amount of double crossing-over. In fact, for a distance as long as 58 an almost independent behavior of linked gens is to be expected.

TABLE 40.--_P_{1} cherry_ [female] [female] _forked_ [male] [male].

_F_{1} wild-type_ [female] [female] _F_{1} cherry_ [male] [male].

+----------+--------------+---------------+-------------+-------+-------+ Reference. Females. Non-cross-over Cross-over [male] [male]. [male] [male] Total Cross- +-------+------+-------+-------+-------+-----+[male] over Cherry. Wild- Cherry. Forked. Cherry Wild- [male]. values. type. forked. type. +----------+-------+------+-------+-------+-------+-----+-------+-------+ 25 129 145 73 70 65 68 276 48 25' 167 148 74 82 66 88 310 50 36 96 88 52 52 35 51 190 45 36' 57 76 41 32 24 30 127 43 84 76 86 40 34 38 26 138 46 84' 62 71 24 39 25 28 116 46 85 114 86 43 78 41 53 215 44 85' 98 95 48 63 52 46 209 47 86 307 323 152 144 118 165 579 49 87 351 341 183 213 160 147 703 45 88 244 246 142 142 107 104 495 43 +----------+-------+------+-------+-------+-------+-----+-------+-------+ Total. 1,701 1,705 872 949 731 806 3,358 46 +----------+-------+------+-------+-------+-------+-----+-------+-------+