ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup ... more ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup species produced high-frequency clicking sounds when courting females. At the beginning of the courtship, the males may semaphore or vibrate their wings with a large amplitude, producing no audible sounds. After these ‘preliminary’ wing vibrations the males set their wings backwards in a normal resting position and vibrate them with a small amplitude, producing loud clicking sounds (up to 15000 cps), which differ from all Drosophila sounds described so far in both their spectral and their temporal structure. When producing these sounds the males always touch the abdomen of the female with their front legs, which might help the females receive the sounds as vibrational signals.
In the Drosophila virilis group the males of the virilis phylad species produce courtship song co... more In the Drosophila virilis group the males of the virilis phylad species produce courtship song consisting of pulse trains with no pauses between successive sound pulses, whereas the males of the montana phylad species produce songs with clear pauses between the sound pulses. We obtained song data for F 1 hybrids between D. virilis (representing the virilis phylad) or D.
Photoperiodic regulation of the circadian rhythms in insect locomotor activity has been studied i... more Photoperiodic regulation of the circadian rhythms in insect locomotor activity has been studied in several species, but seasonal entrainment of these rhythms is still poorly understood. We have traced the entrainment of activity rhythm of northern Drosophila montana flies in a climate chamber mimicking the photoperiods and day and night temperatures that the flies encounter in northern Finland during the summer. The experiment was started by transferring freshly emerged females into the chamber in early and late summer conditions to obtain both non-diapausing and diapausing females for the studies. The locomotor activity of the females and daily changes in the expression levels of two core circadian clock genes, timeless and period, in their heads were measured at different times of summer. The study revealed several features in fly rhythmicity that are likely to help the flies to cope with high variation in the day length and temperature typical to northern summers. First, both the non-diapausing and the diapausing females showed evening activity, which decreased towards the short day length as observed in the autumn in nature. Second, timeless and period genes showed concordant daily oscillations and seasonal shifts in their expression level in both types of females. Contrary to Drosophila melanogaster, oscillation profiles of these genes were similar to each other in all conditions, including the extremely long days in early summer and the cool temperatures in late summer, and their peak expression levels were not locked to lights-off transition in any photoperiod. Third, the diapausing females were less active than the non-diapausing ones, in spite of their younger age. Overall, the study showed that D. montana clock functions well under long day conditions, and that both the photoperiod and the daily temperature cycles are important zeitgebers for seasonal changes in the circadian rhythm of this species.
... female in the "head-under-wings" (HUW) position (Spieth, 1978 ... The songs of the ... more ... female in the "head-under-wings" (HUW) position (Spieth, 1978 ... The songs of the males of the Y14 laboratory stock established in 1987 had lower carder frequencies (Wilcoxon Mann-Whitney test, z = 6.5962, P < 0.0001) and longer sound bursts (Wil-coxon Mann-Whitney test, z ...
ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup ... more ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup species produced high-frequency clicking sounds when courting females. At the beginning of the courtship, the males may semaphore or vibrate their wings with a large amplitude, producing no audible sounds. After these ‘preliminary’ wing vibrations the males set their wings backwards in a normal resting position and vibrate them with a small amplitude, producing loud clicking sounds (up to 15000 cps), which differ from all Drosophila sounds described so far in both their spectral and their temporal structure. When producing these sounds the males always touch the abdomen of the female with their front legs, which might help the females receive the sounds as vibrational signals.
The males of six species of the Drosophila virilis group (including D. virilis) keep their wings ... more The males of six species of the Drosophila virilis group (including D. virilis) keep their wings extended while producing a train of sound pulses, where the pulses follow each other without any pause. The males of the remaining five species of the group produce only one sound pulse during each wing extension/vibration, which results in species-specific songs with long pauses (in D. littoralis about 300 ms) between successive sound pulses. Genetic analyses of the differences between the songs of D. virilis and D. littoralis showed that species-specific song traits are affected by genes on the X chromosome, and for the length of pause, also by genes on chromosomes 3 and 4. The X chromosomal genes having a major impact on pulse and pause length were tightly linked with white, apricot and notched marker genes located at the proximal third of the chromosome. A large inversion in D. littoralis, marked by notched, prevents more precise localization of these genes by classical crossing methods.
InDrosophila montana andD. littoralis (species of theD. virilis group), females use male courtshi... more InDrosophila montana andD. littoralis (species of theD. virilis group), females use male courtship song in their mate choice in wild preferring males which produce short and dense sound pulses (Aspi and Hoikkala, 1995). In the present study these song characters were found to be repeatable among overwintered males. Male progenies of wild-caught flies reared in the laboratory, and inD. montana
The courtship sounds of five strains ofDrosophila virilis and three strains ofD. lummei were anal... more The courtship sounds of five strains ofDrosophila virilis and three strains ofD. lummei were analyzed and the sounds of the two species were found to differ from each other by the number of pulses in a pulse train. The mean number of pulses in a pulse train varied from 5.8 to 9.1 inD. virilis and from 12.3 to 13.3 inD. lummei. TheD. virilis marker stockb, sv t tb gp2,cd, pe was crossed to the wild-typeD. lummei and the courtship sounds of reciprocal F1 hybrids and backcross hybrids were analyzed. Genes affecting the number of pulses in a pulse train were found to exist on each of the major autosomes but not on the X chromosome. The contributions of the second, third, fourth, and fifth chromosomes to the number of pulses in a pulse train were 0.513, 0.534, 0.430, and 0.841, respectively, the heterozygous condition increasing and the homozygous (both chromosomes fromD. virilis) decreasing the number of pulses in a pulse train by the number given. The interactions between chromosomes varied between 0.250 and -0.255. Thus genes causing the difference between the courtship sounds ofD. virilis andD. lummei are autosomal and the character truly polygenic.
Annals of the Entomological Society of America, Oct 31, 1997
... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-es... more ... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-established laboratory strain of C ... Courtship element Description Male No courting (noc) Calling (cal) Vibrating (vib) Fanning (fan) Attempting copulation (att) Female No courting (nof ...
Correct timing of the induction of photoperiodic reproductive diapause has been found to play an ... more Correct timing of the induction of photoperiodic reproductive diapause has been found to play an important role in the life cycle of several northern insect species. However, even when the environmental conditions are favorable for diapause, the switch to diapause can only take place when the females are in a proper developmental and physiological stage, referred to as the sensitive period (SP) for diapause. We have previously shown that in a northern fly species, Drosophila montana, the developmental pathway of the ovaries (direct maturation vs. diapause) is determined by photoperiodic cues that the females receive after eclosion. Here, we have studied the effects of temperature on the duration of the sensitive period, and on the number of short day cycles that the females have to experience before half of them will enter diapause (RDN = required day number). Ovarian development rate of the females was first traced under long and short day conditions in 16(°)C and 19(°)C, and then ...
Most northern insect species experience a period of developmental arrest, diapause, which enables... more Most northern insect species experience a period of developmental arrest, diapause, which enables them to survive over the winter and postpone reproduction until favorable conditions. We studied the timing of reproductive diapause and its long-term effects on the cold tolerance of Drosophila montana, D. littoralis and D. ezoana females in seasonally varying environmental conditions. At the same time we traced expression levels of 219 genes in D. montana using a custom-made microarray. We show that the seasonal switch to reproductive diapause occurs over a short time period, and that overwintering in reproductive diapause has long-lasting effects on cold tolerance. Some genes, such as Hsc70, Jon25Bi and period, were upregulated throughout the diapause, while others, including regucalcin, couch potato and Thor, were upregulated only at its specific phases. Some of the expression patterns induced during the sensitive stage, when the females either enter diapause or not, remained induce...
Annals of the Entomological Society of America, 1997
... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-es... more ... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-established laboratory strain of C ... Courtship element Description Male No courting (noc) Calling (cal) Vibrating (vib) Fanning (fan) Attempting copulation (att) Female No courting (nof ...
Seasonally changing environments at high latitudes present great challenges for the reproduction ... more Seasonally changing environments at high latitudes present great challenges for the reproduction and survival of insects, and photoperiodic cues play an important role in helping them to synchronize their life cycle with prevalent and forthcoming conditions. We have mapped quantitative trait loci (QTL) responsible for the photoperiodic regulation of four life-history traits, female reproductive diapause, cold tolerance, egg-to-eclosion development time and juvenile body weight in Drosophila montana strains from different latitudes in Canada and Finland. The F2 progeny of the cross were reared under a single photoperiod (LD 16:8), which the flies from the Canadian population interpret as early summer and the flies from the Finnish population as late summer. The analysis revealed a unique QTL for diapause induction on the X-chromosome and several QTL for this and the other measured traits on the 4(th) chromosome. Flies' cold tolerance, egg-to-eclosion development time and juvenile...
ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup ... more ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup species produced high-frequency clicking sounds when courting females. At the beginning of the courtship, the males may semaphore or vibrate their wings with a large amplitude, producing no audible sounds. After these ‘preliminary’ wing vibrations the males set their wings backwards in a normal resting position and vibrate them with a small amplitude, producing loud clicking sounds (up to 15000 cps), which differ from all Drosophila sounds described so far in both their spectral and their temporal structure. When producing these sounds the males always touch the abdomen of the female with their front legs, which might help the females receive the sounds as vibrational signals.
In the Drosophila virilis group the males of the virilis phylad species produce courtship song co... more In the Drosophila virilis group the males of the virilis phylad species produce courtship song consisting of pulse trains with no pauses between successive sound pulses, whereas the males of the montana phylad species produce songs with clear pauses between the sound pulses. We obtained song data for F 1 hybrids between D. virilis (representing the virilis phylad) or D.
Photoperiodic regulation of the circadian rhythms in insect locomotor activity has been studied i... more Photoperiodic regulation of the circadian rhythms in insect locomotor activity has been studied in several species, but seasonal entrainment of these rhythms is still poorly understood. We have traced the entrainment of activity rhythm of northern Drosophila montana flies in a climate chamber mimicking the photoperiods and day and night temperatures that the flies encounter in northern Finland during the summer. The experiment was started by transferring freshly emerged females into the chamber in early and late summer conditions to obtain both non-diapausing and diapausing females for the studies. The locomotor activity of the females and daily changes in the expression levels of two core circadian clock genes, timeless and period, in their heads were measured at different times of summer. The study revealed several features in fly rhythmicity that are likely to help the flies to cope with high variation in the day length and temperature typical to northern summers. First, both the non-diapausing and the diapausing females showed evening activity, which decreased towards the short day length as observed in the autumn in nature. Second, timeless and period genes showed concordant daily oscillations and seasonal shifts in their expression level in both types of females. Contrary to Drosophila melanogaster, oscillation profiles of these genes were similar to each other in all conditions, including the extremely long days in early summer and the cool temperatures in late summer, and their peak expression levels were not locked to lights-off transition in any photoperiod. Third, the diapausing females were less active than the non-diapausing ones, in spite of their younger age. Overall, the study showed that D. montana clock functions well under long day conditions, and that both the photoperiod and the daily temperature cycles are important zeitgebers for seasonal changes in the circadian rhythm of this species.
... female in the "head-under-wings" (HUW) position (Spieth, 1978 ... The songs of the ... more ... female in the "head-under-wings" (HUW) position (Spieth, 1978 ... The songs of the males of the Y14 laboratory stock established in 1987 had lower carder frequencies (Wilcoxon Mann-Whitney test, z = 6.5962, P < 0.0001) and longer sound bursts (Wil-coxon Mann-Whitney test, z ...
ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup ... more ABSTRACT In this study, it is shown that the males of several picture-winged Drosophila subgroup species produced high-frequency clicking sounds when courting females. At the beginning of the courtship, the males may semaphore or vibrate their wings with a large amplitude, producing no audible sounds. After these ‘preliminary’ wing vibrations the males set their wings backwards in a normal resting position and vibrate them with a small amplitude, producing loud clicking sounds (up to 15000 cps), which differ from all Drosophila sounds described so far in both their spectral and their temporal structure. When producing these sounds the males always touch the abdomen of the female with their front legs, which might help the females receive the sounds as vibrational signals.
The males of six species of the Drosophila virilis group (including D. virilis) keep their wings ... more The males of six species of the Drosophila virilis group (including D. virilis) keep their wings extended while producing a train of sound pulses, where the pulses follow each other without any pause. The males of the remaining five species of the group produce only one sound pulse during each wing extension/vibration, which results in species-specific songs with long pauses (in D. littoralis about 300 ms) between successive sound pulses. Genetic analyses of the differences between the songs of D. virilis and D. littoralis showed that species-specific song traits are affected by genes on the X chromosome, and for the length of pause, also by genes on chromosomes 3 and 4. The X chromosomal genes having a major impact on pulse and pause length were tightly linked with white, apricot and notched marker genes located at the proximal third of the chromosome. A large inversion in D. littoralis, marked by notched, prevents more precise localization of these genes by classical crossing methods.
InDrosophila montana andD. littoralis (species of theD. virilis group), females use male courtshi... more InDrosophila montana andD. littoralis (species of theD. virilis group), females use male courtship song in their mate choice in wild preferring males which produce short and dense sound pulses (Aspi and Hoikkala, 1995). In the present study these song characters were found to be repeatable among overwintered males. Male progenies of wild-caught flies reared in the laboratory, and inD. montana
The courtship sounds of five strains ofDrosophila virilis and three strains ofD. lummei were anal... more The courtship sounds of five strains ofDrosophila virilis and three strains ofD. lummei were analyzed and the sounds of the two species were found to differ from each other by the number of pulses in a pulse train. The mean number of pulses in a pulse train varied from 5.8 to 9.1 inD. virilis and from 12.3 to 13.3 inD. lummei. TheD. virilis marker stockb, sv t tb gp2,cd, pe was crossed to the wild-typeD. lummei and the courtship sounds of reciprocal F1 hybrids and backcross hybrids were analyzed. Genes affecting the number of pulses in a pulse train were found to exist on each of the major autosomes but not on the X chromosome. The contributions of the second, third, fourth, and fifth chromosomes to the number of pulses in a pulse train were 0.513, 0.534, 0.430, and 0.841, respectively, the heterozygous condition increasing and the homozygous (both chromosomes fromD. virilis) decreasing the number of pulses in a pulse train by the number given. The interactions between chromosomes varied between 0.250 and -0.255. Thus genes causing the difference between the courtship sounds ofD. virilis andD. lummei are autosomal and the character truly polygenic.
Annals of the Entomological Society of America, Oct 31, 1997
... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-es... more ... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-established laboratory strain of C ... Courtship element Description Male No courting (noc) Calling (cal) Vibrating (vib) Fanning (fan) Attempting copulation (att) Female No courting (nof ...
Correct timing of the induction of photoperiodic reproductive diapause has been found to play an ... more Correct timing of the induction of photoperiodic reproductive diapause has been found to play an important role in the life cycle of several northern insect species. However, even when the environmental conditions are favorable for diapause, the switch to diapause can only take place when the females are in a proper developmental and physiological stage, referred to as the sensitive period (SP) for diapause. We have previously shown that in a northern fly species, Drosophila montana, the developmental pathway of the ovaries (direct maturation vs. diapause) is determined by photoperiodic cues that the females receive after eclosion. Here, we have studied the effects of temperature on the duration of the sensitive period, and on the number of short day cycles that the females have to experience before half of them will enter diapause (RDN = required day number). Ovarian development rate of the females was first traced under long and short day conditions in 16(°)C and 19(°)C, and then ...
Most northern insect species experience a period of developmental arrest, diapause, which enables... more Most northern insect species experience a period of developmental arrest, diapause, which enables them to survive over the winter and postpone reproduction until favorable conditions. We studied the timing of reproductive diapause and its long-term effects on the cold tolerance of Drosophila montana, D. littoralis and D. ezoana females in seasonally varying environmental conditions. At the same time we traced expression levels of 219 genes in D. montana using a custom-made microarray. We show that the seasonal switch to reproductive diapause occurs over a short time period, and that overwintering in reproductive diapause has long-lasting effects on cold tolerance. Some genes, such as Hsc70, Jon25Bi and period, were upregulated throughout the diapause, while others, including regucalcin, couch potato and Thor, were upregulated only at its specific phases. Some of the expression patterns induced during the sensitive stage, when the females either enter diapause or not, remained induce...
Annals of the Entomological Society of America, 1997
... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-es... more ... 1994, Shelly and Whittier 1996) conducted in Hawaii suggest that sterile males from a long-established laboratory strain of C ... Courtship element Description Male No courting (noc) Calling (cal) Vibrating (vib) Fanning (fan) Attempting copulation (att) Female No courting (nof ...
Seasonally changing environments at high latitudes present great challenges for the reproduction ... more Seasonally changing environments at high latitudes present great challenges for the reproduction and survival of insects, and photoperiodic cues play an important role in helping them to synchronize their life cycle with prevalent and forthcoming conditions. We have mapped quantitative trait loci (QTL) responsible for the photoperiodic regulation of four life-history traits, female reproductive diapause, cold tolerance, egg-to-eclosion development time and juvenile body weight in Drosophila montana strains from different latitudes in Canada and Finland. The F2 progeny of the cross were reared under a single photoperiod (LD 16:8), which the flies from the Canadian population interpret as early summer and the flies from the Finnish population as late summer. The analysis revealed a unique QTL for diapause induction on the X-chromosome and several QTL for this and the other measured traits on the 4(th) chromosome. Flies' cold tolerance, egg-to-eclosion development time and juvenile...
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