THE EFFECT OF TEMPERATURE UPON THE FULL - EYED RACE OF DROSOPHILA By ROSELLE KARRER A. B. University of Illinois, 1921 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS IN ZOOLOGY IN THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS, 1922 URBANA, ILLINOIS i THE GRADUATE SCHOOL LIay 29 .192 i HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Roselle l_ Karrer ENTITLED — The Effect of Temp er a ture upon the Full-6yed Race of Drosophila. BE ACCEPTED AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF VaR ter of Arts, Recommendation concurred in* Committee on Final Examination* Required for doctor’s degree but not for master’s THE EFFECT OP TEMPERATURE UP OH THE PULL -EYED RACE OF DROSOPHILA CONTENTS . I. Introduction II. Materials and Methods 1) Stock used 2} Temperature control 3) Technique 4) Sources of Error 5) Method of Tabulation III. Results of Experiments IV. Discussion 1) Comparison of counts with the counts obtained by Krafka 2) Comparison of temperature effects on full with the temperature effects on its allelomorphs 3) Sexual Dimorphism V. Summary VI. Bibliography Digitized by the Internet Archive in 2015 https://archive.org/details/effectoftemperatOOkarr I. Introduction. Seyster and Krafka have shown that the effect which is produced by the bar gene in the reduction of facet number from full depends upon the temperature. At the same constant tempera.ture the same effect is produced while at different temperatures the amount of change in number of facets varies inversely with the temperature. ICrafka(l920) studied the effects of temperature upon the full -eyed race at 15° and 27° C . He states “The counts at hand show that temperature does not effect facet number in full eye to a marked degree'.’ It has been the purpose of the present study to find whether and how temperature does effect facet number in the full- eyed race by counting a greater number of flies at different tem- perature intervals than given by Krafka. The result of the study shows that facet number in full does vary with the temperature. The effect produced per degree is not however as great as the effect produced in the bar stocks. The earlier workers of note on temperature effects were a group of workers in the latter half of the nineteenth century. The most important of whom were Merrifield, V/eismann, Standfuss, Fischei Edwards and Dorfmeister, All of these workers studied the effect of temperature upon Lepidoptera larvae. The experiments however were carried on without an attempt to control other environmental conditions. Tower(l906) studied the effect of temperature upon Leptinotarsa keeping all other conditions as constant as possible. The results obtained were similar to those obtained by earlier workers, namely that an increase or decrease in temperature either -3- acceleratee or retards color development, modifying coloration either toward albinism or melanism. He found that between the o o temperatures of 16 and 28 there is an increase to melanism and above or below these temperatures there is a decrease to albinism. In a few known cases temperature determines certain characteristics of the animal. Thus Baur found that in Primula sinensis which under ordinary conditions produces red flowers when put at a temperature ranging from 30° to 35° white flowers are produced. Miss Hoge found that in a race of Drosophila, in which reduplication of legs occured, under ordinary conditions only 10 % of the offspring of a pure race showed this condition. When the eggs of these same flies are subjected to a temperature of 9° or 1C° the percentage is increased to almost 100. These experiments were not however suited for a quantita- tive analysis of temperature effects. It was van’t Hoff who show- ed that the speed of a chemical reaction for an interval of 10° is doubled or trebled. This is known as the temperature coefficient or Q,iq. It is found by the following formula, v t-ao = V t^lO _ - Vt +10° - ^ 10 “ - 2 or 3 for chemical reactions. Vt When a rise in temperature causes a decrea.se of an action then Q ,10 obtained by the use of the following formula v t-io s MlO ^io * Vt The quotient would thus become negative. In physical processes -4- q l0 has "been found to he negative or under 2. In chemical reactions is greater than 2 or 3 for the lower temperatures and less than 2 for the higher. When a given process follows the van’t Iloff law it is an exponential function of the temperature and when plotted it is an exponential curve. Snyder and Arrhenius formulated two equations which make it possible to compare the constants of physiological processes with those of chemical reactions. Snyder’s formula is a.s follows, *0 10 ti-to a. ^ is the coefficient of increase in reaction velocity for a rise 10 of 10° Celsius, The symbols K-, and K represent the rate of the 1 0 physiological processes at the temperatures t-, and t r . The formula of Arrhenius is as follows, Nat. Log. ^ = (lUSl). K* 2 T 1 1 1 0 0 K and K represent the rates of the physiological orocesses at the 1 0 temperatures T-, and . The symbol indicates a constant value which is 13,500 for ordinary chemical reactions although it varies to some extent. When the temperature of vital tissue is altered there is a change in the physiological processes. This change can be accounted for partly upon the basis that the physiological processes are chemical in nature and therefore follow the same laws as chemical actions. The range of temperature at which these physiological processes are affected is approximately between 0° to 42°C. Hear f . i • -■ • i r j \ \ . ~ ( fc .i I I V - ■> ' V V i»V V. • : C - . v U ! s : , . j 1 t • r. • i : ^ ( .v ■. i-.'j m •- > t 5-i « * * * . i A t / -- N. ' - ’t 1 C J I 1 i ^ • 1 it ' . ^ i t". * i *V.» - ^ A* / •* * ^ \ ‘ , ^ i •• L « . !/• - %/ v* S • - ♦ « 4 • ’ 1 * * ’• •* ■* J J - ' t • * •* I \ . « * • ^ ^ ■ V. .. • >L< v J V>«* V • - - ‘ - . . f . 1 - „ w * *. • » w ? 4 . M ^ •» ... . o i _ ^ — J ~ 0° the aqueous solutions in the protoplasm freeze and the vital processes are retarded until death takes place. Above 40°vital processes also become hampered finally resulting in the death of the organism. There are however no definite temperatures at which death takes place, there are only temperature zones in which the physiological processes become more and more disturbed finally resulting in the death of the animal. The manner in which temper- ature affects the individual depends to a certain extent upon what its past history has been. Thus Dallinger was successful in raising Flagellata at 70° which under ordinary conditions died when brought from 15° to 23°. Davenport experimented with tadpoles and found that when they were reared at 15° went into heat rigor at 41° while if raised at 24° or 25° they died at 43°. The temperature coefficients of the physiological processes diminish from the lower to the higher temperatures in the same manner as for chemical reactions. The variations of are however greater for the vital processes than for the chemical ones. This variation as has been suggested by workers is due to the enzymes acting as catalytic agents thus affecting the speed of the reaction The first application of the van’t Hoff law for tem- perature effect upon living matter was made by Cohen. He pointed out that the output of C0 o in Claussen’s experiments with germinat- ing seeds of lupine and wheat and by the blossoms of Syringa chinensis followed the same law. Between the range of 0° to 25° an increase of 10° caused an increase of 2 ^> times the amount of CO. . Among the biologists Oscar Hertwig while working upon the changes of the rate of development of frogs eggs at different - 6 - temperatures was the first to note that even here chemical re- actions were affected by temperature. It was Cohen however who Showed that the effect produced by the temperatures followed the same law as that for chemical reactions. Since the year 1905 much work has been done upon the application of the van’t Hoff rule to physiological processes in general. It has been applied to processes as heart beat, contrac- tion of the vacuoles in protozoa, muscular contraction and digest- ion. Temperatures effects have also been applied to rate of growth and development. Peter worked upon the Echinoderms eggs and has shown that the rate of development follows the same temperature law. Snyder found that the rate of heart beat of the Pacific terrapin is in- fluenced by the temperature changes. He found that the minimum 0 o c contraction occurs at 0 C and the maximum rate between 35 and 3V. 5. The temperature coefficients varied to a considerable extent rang- ing from 10.2 for the temperature interval of 0° to 10°C and de- o o creasing to 2.2 for the interval of 10 to 20 , 1.9 for the in- terval of 20° to 30°, and finally falling to 1 for the range be- tween 30° to 40°C. He found the same thing in the mollusc, Phyllerrhoe, and in a crustacean. Kobertsonf 1906 ) found the same thing in Laphnia. Martin, Applegarth, Langendorff and Lehmann found that temperature effects were similar in the hearts of dogs, cats and rabbits as the temperature effects described by Snyder. Rogers(191l) worked upon the contractions of the dorsal blood vessel in Nereis and Tubifex and the heart of Eundulus. He found that these contractions were altered in response to tempera- -7- ture. The slower rates were always at the lower temperatures and the faster rates were at the higher. The values of Q]_q were found to he higher for the lower temperatures and lower for the higher, temperatures, Riddle(1909) in his work upon digestion in cold-blooded animals showed that this process followed the same trend. He attributes the increase of the coefficient of the reaction velocity as the temperature 0 is approached as due to the destructive effect of the temperature upon the digestive secretions. The temperature effects upon the pulsation of medusae have been worked out by E. Veresso and Harvey. The forms Cotylorihiza and :>.hizostoma which the former worker used went into heat rigor at 24° or 25°, as a result the temperatures were confined to a narrow range. His results are as follows: Temperature Pulsations 14 17.5 20 21.5 80 112 140 155 Q 10 2.6 2.3 Harvey working upon Cassiopia obtained the following results, Temperature Pulsations Q-^q 16 20 25 30 8 17 26 33 6.5 2.3 1.6 The first work on the application of the temperature law upon the rhythm of breathing was done on different species of fish by Baglionia( 1907 ) . The work was carried on in August and the beginning of December at the Haples Zoological Gardens. The tem- perature of the water at these times was 23° and 14° respectively. ■ ■ - 8 - In all cases the frequency was greater at the higher temperatures. QlO varied from 1.8 to 4.5. The work of this nature upon warm blooded animals was carried on by Sciglianos. The latter investi- gator subjected guinea-pigs to temperatures of 39° and 47°. At the lower temperature the frequency of breathing was 66 per minute and at the higher temperature it was 144 per minute. The temperature coefficient was 2.7. He also collected data of fever patients. The Q 10 ranged from 1.8 to 2.8. In 1872 Rossback worked upon the temperature effect on the rhythm of vacuole contraction in Infusoria. He found that the rhythm was constant at a given temperature but changed to a marked degree at different temperatures. Kanitz within recent years has found that the law of temperature coefficients also holds here. This work was carried on under the direction of Doctor Charles ^eleny, whom I wish to thank for his interest in the problem and for his many valuable suggestions. - 9 “ II. Materials and Methods. The stock which was obtained from Doctor Zeleny was number 2054.1. This number refers to the stock which arose from a reverse mutation of low selected bar 80 forked number 1961.5. All of the matings made were mass matings. The flies were raised on banana agar inoculated with yeast. Temperature Control: The temperatures used ranged from 15° to 31°. Each temperature interval was 2°. Constant temperatures of 15° and 25° are maintained in the cold and warm rooms respectively by forcing air over brine coils and redistributing it to the rooms. Steam pipes are also present in the warm room. The temperature of 27° is maintained in a Chicago Surgical Supply incubator in the 25° room. A similar incubator gives a temperature of 17° in the 15° room. Aquaria were used to maintain temperatures of 19°, 21°, 23° and 31°. In these aquaria regulators controlled the flow of hot and cold water. A temperature of 29°was obtained by the use of a Chicago Electrical Supply incubator in the laboratory. The temperature records at 17° and 27° are kept by a Tycos recording thermometer while Tycos thermographs keep the records for the 15° and 25° rooms. All records of the aquaria were kept by the Eriez soil and water thermographs. Technique : The flies were etherized and then placed in 2 to 3$ caustic potash solution for a period of 24 to 36 hourB. They were then placed in a solution of 70$ alcohol for dissection. The cornea was removed under a binocular and then placed on a slide and separat- ed into parts to obtain a flattened surface. A coverglass was then J II II . - 10 - placed over it. The facets were counted under a Leitz objective number 3 and a number 4 ocular. Spider web cross hairs were used to mark off the ocular field into parts to facilitate counting. Sources of Error: The chief sources of error are 1) those due to counting and 2). variations in temperature. The sources of error due to countimg are of extreme import- ance here because of the number of facets to be counted. To deter- mine the personal error of counting slides were made and then numbered. The first count was then made, after several hours or a day these same slides were recounted. Six corneas were recounted in this manner. The difference in facet counts ranged from 4 to 16. The following are the first and second counts made 1st counts 2nd counts 695 703 716 720 630 621 745 740 672 683 650 634 Counts were also made with a number 7 objective to deter- mine whether a marked difference would result from a higher magnification. In these cases the number of facets was first counted under a number 3 objective. The slides were then put away for a time and recounted under a number 7 objective. The difference in thq counts were 4, 6, 14. This difference was therefore no greater than the difference found in the personal error. - 11 - The temperatures of 15° , 17°, 25° and 27° were the most constant. In all four cases they did not vary more than -0.5°C. The other temperatures varied to a greater extent. At 19° while the flies were developing the temperature varied from 18° to 20°. The 21° aquarium at one time was 19.8° and at another 22°; the 31° aquarium varied from 30° to 32°. Since the facet reaction period has not been determined for full, the assumption that it is when 32$ to 45$ of the development has been completed as for ultra- "bar (Krafka 1920) may involve a considerable error. Method of Tabulation: It was at first determined whether the decrease is an exponential or a linear one. For this purpose tables 1 and 2 were made for females and males respectively. In these tables the average observed facet counts at each temperature are given, also the calculated exponential decrease of 2.5$, and a linear decrease of 2.5$ of the mean at 23°. In all the calculated data the mean facet value at 23° was used. The 2.5$ decrease was found by finding the logarithms of the mean facet counts of two temperatures, subtracting then and dividing by the temperature interval. The natural number was then found corresponding to this logarithm. For example, the mean facet number for the females at 17 ( was found to be 895.1, at 27° it was found to be 698.5. The log- arithms of these numbers are 2.951872 and 2.844166 respectively. Subtracting these we get 0.107706, dividing by the temperature o interval which is 10 the logarithm 0.010770 is obtained which is the logarithm of 1.025. The percent of change for the interval is thus 2.5$, -15- Table 2. Temperature in °C. Observed Means Calculated 2.5 % exponential de- crease. Calculated 2.5$ linear de crease. 15 955.9 941.1 949.9 17 908.5 895.7 910.5 19 855.2 852.6 870.7 21 827.6 851.8 851.1 25 791.5 791.5 791.5 25 751.1 752.5 751.9 27 710.1 715.2 712.5 29 687.7 679.9 672.7 51 678.5 646.4 655.1 Facet number in full- eyed males. - 14 ' The last columns in the tables represent a 2.5$ of the mean o at 23 . This was found to be 39.0 for the females and 39.6 for the males for an interval of 2°. By the comparison of the observed facet counts with those which were calculated it can be easily seen that the exponential and the linear decrease of 2.5$ of the mean at 23° correspond to a certain extent to the observed facet counts. Prom the irregular- ities in the facet counts obtained it was impossible to determine with any marked degree of certainty whether the decrease is an exponential or a linear decrease. The observed counts show however one characteristic of the exponential decrease, that is that the highest counts were obtained at the lower temperatures and the lowest counts were obtained at the higher temperatures. Prom this fact and also that the decrease in the number of facets of the bar and ultra-bar stocks has been found to be exponential, the same system of tabulation as for these stocks was used. Zeleny(1920) has shown that the difference of the average mean facet values is not a good measure of temperature effect but that the change should be expressed in units affecting the differ- ence in facet number. Upon this bases the factorial unit system was made for bar and ultra-bar. This system is based upon the compound interest law. In the particular case given the mean facet values of each class represent & difference of 10$. Upon this basis that the decrease in full is an exponent- ial deorease of 2.5$, a system was made on the same order as that for the bar stocks. Since there was a slight difference between -15- the counts obtained for the females and males at all temperatures, different zero points were used. These zero points were taken as the average of the counts at 25°. This average was obtained by finding the logarithms of the observed counts at that temperature, dividing by the number of flies counted and finding the natural number of the logarithm thus obtained* For the females, the zero point was found to be 740 and for the males 750* The facet classes containing these points would thus be 731-749 for the females and 741-759 for the males. Tables 3 and 4 give the distribution of the counts in facet classes at the different temperatures for females and males respectively. Table 3, Classes units in 2.5$ Classes in facets. 15 17 19 21 23 25 27 29 31 -7 606-622 1 -6 623 639 1 1 -5 640-656 1 1 4 -4 657-674 1 2 3 3 -3 675-692 3 1 1 • 2 693-711 1 2 1 -1 712-730 1 2 2 1 0 731-749 1 3 + 1 750-769 1 3 2 + 2 770-789 2 2 1 - 3 790-810 2 1 1 2 +4 811-831 2 2 •'5 832-853 3 3 1 2 +6 854-875 1 1 2 +7 876-898 1 3 3 1 +8 899-921 1 -'9 922-945 3 1 *'10 946-970 1 til 971-995 3 0.2 996-1021 1 +13 1022-1047 +14 1048-1074 1 Data of full females, showing the distribution in olasses at different temperatures. : - r . , : ■ <■ - 13 - III* Results of Experiments. The results of the experiments are summarized in tables 5 and 6 for the females and males respectively. In these tables the temperatures, the number of flies counted at these temperatures, the arithmetical means, the means in terms of factorial units and the differences for the intervals are given. It can readily be seen that temperature causes a decrease in facet number from 15° o to 31. The differences between the means are not constant. The greater differences are found between the means of the lower temperatures and the least difference is produced at the higher o o temperatures. Thus the interval of 15 to 17 produces a change of 2.2 factorial units for the females and 2.1 factorial units for the males. The interval from 29° to 31° produces a change of 0.9 factorial units for the females and 0.6 factorial units for the males. Figures 1 and 2 give the facets in facet classes plotted in terms of the temperature. Sexual Dimorphism: A slight sexual difference was found at all temperatures. The average ratio between the mean facet number of the males and females was found to be 0.984. _ _ . . 9 :'U| ' - 20 - Table 6. Temperature in 0 C. Number of flies counted. Mean facet values. Means in factorial units. Difference in factorial units for interval. 15 10 953.9 + 9.4 2.1 17 10 908.3 7.3 2.4 19 10 855.2 + 4.9 1.2 21 10 827.6 + 3.7 1.7 22 10 791.5 + 2.0 2.0 25 10 751.1 0.0 2.1 27 10 710.1 -2.1 1.1 29 10 687.7 -3.2 0.6 3.1 10 678.5 -2.9 Summary of the effect of temperature upon full- eyed males. . r •- % -25- IV, Discussion, The counts for full at 27° as given "by Krafka give a mean facet value of 810.6 for the females and 849.9 for the males. His counts at 15° are insufficient in number to give a mean facet value, however 2 females gave an average of 1,084 and 1 male a count of 1,016. In this experiment the counts obtained at 27° were o 6S8.5 for the females and 954.9 for the males. At 15 the counts were 943.3 for the females and 954.9 for the males. The difference in the facet counts in the two sets of data may be due to the different stocks used. Krafka used the wild full- eyed flies while the ones used in this experiment were mutants. The conditions under which they were raised were also different. Thus Krafka raised the wild fulls on a culture of fermented banana while the stock in the present experiment was raised on banana agar as previously pointed out. The range in the counts is greater in the wild flies. At 27° this range was from 632 to 924 for the females and 700 to 980 for the males. The same temperatures gave a range of 653 to 757 for the females and 662 to 773 for the males in the stock used in the present experiment. This difference may be explained upon the basis that germinal diversities have been selected out. Although temperature affects the facet number in full the change produoed is not as great as that of its allelomorphs. Thus the exponential decrease for full is 2.5$ or a linear deorease of 39.6 facets for the males and 39.0 facets for the females. In bar - . . . - . ... - -24- and ultra-bar it is 9.6 $ and 8.7 $ respectively. The change per degree however shows one feature in common in all three cases, that is that the greater change occurs at the lower temperatures while 0 the least change occurs at the temperature interval of 29 to 31 • Here the oounts show a very small difference and the curves tend to flatten out indicating that there is a critical temperature for o facet reaction. This critical temperature is 27 for all stocks. The sex coefficients for the bar stocks as determined by Krafka is 0.791 while for full it is 0.984. Zeleny(1920) has shown that the probable cause of sex dimorphism in the bar stocks is due to accessory factors. Since these seem to be sex-linked the stock would consist of heterozygous females. The result of selection for facet number would cause a decrease in the heterozygous factors. The greater this decrease would become the closer the sex coeffic- ient would approach unity. If it wo\ild be unity the counts of the males and females would be the same. The close approach of the sex coefficient of full to unity may thus be explained upon the basis that there has been a decrease in accessory factors due to select- ion. , . < I -25- V. Summary. 1. Temperature causes a decrease in facet number in the full-eyed race between the experimental temperatures of 15° to 31°. 2. It can not be definitely determined from the counts whether the decrease is of an exponential or linear order. The fact that the effect is greater at the lower and least at the higher temperatures seems to indicate that it is an exponential decrease. 3. The temperature effect in full is not as marked as the temperature effects on the bar stocks. In full the effect is approximately a 2.5 % exponential decrease while in bar it is 9.5% and in ultra-bar it is 8.7%. 4. The critical temperature for change in facet number is at 27° as in all bar stocks. 5. The sex dimorphism in the full- eyed race is 0.984 while in the bar stocks it is 0.791. - 26 - Bibliography. Hoge, M. A. 1915. The Influence of Temperature on the develop- ment of a Mendelian Character. Journ. Exp. Zool., 18:241- 286. Aanitz, Aristides 1915. Temperatur und Lebensvorgange. Krafka, Joseph 1920. The Effect of Temperature upon Facet Number in the Bar-eyed Mutant of Drosophila. Journ. Gen. Phys., 2:409-464. Rogers, Charles 1911. Studies upon the Temperature coefficient of the Pate of Heart Beat in certain Living Animals. Amer. Journ. Phys. 28:81-93. Seyster, E. W. , 1919. Eye Facet dumber as Influenced by Temperature in the Bar- eyed Mutant of Drosophila melano- gasterf ampelophila) . Biol. Bull., 37:168-181. Snyder, Charles 1906. The Influence of Temperature upon the Hate of Heart Beat in the night of the Law for Chemical Reactions. Amer. Journ. Phys. 17:350-361. 1911. On the Meaning of Variation in the Magnitude of Temperature Coefficients of Physiological Processes. Amer. Journ. Phys. 28J167-175. Zeleny, Charles 1917. Germinal Changes in the Bar- eyed Race of Drosophila during the Course of Selection for Facet Humber. Proc. Ind. Acad. Sci., 73-77. - 27 - 1920, The Tabulation of Factorial Values, Amer, Nat., 54:358-376, 1920. A Change in the Dar Gene of Drosophila melanogaster Involving further Decrease in Facet Humber and Increase in Dominance. Journ. Exp. Zool., 30:293-324. 1921. Decrease in Sexual Dimorphism of Bar Eye during the Course of Selection for Low and High Facet Dumber. Amer. Nat., 55:404-411.