Geographic variation in hybrid fertility in the field crickets Gryllus integer, G. rubens, and Gryllus sp.

1990 ◽  
Vol 68 (12) ◽  
pp. 2697-2700 ◽  
Author(s):  
William H. Cade ◽  
Michael G. Tyshenko

Hybridization was attempted between three geographically separated field cricket populations having males that produce distinct songs. Gryllus integer from central Texas and G. rubens from Arkansas produced many offspring in both reciprocal crosses. Gryllus sp. from New Mexico also produced hybrid offspring in matings with G. integer and G. rubens but at a very low frequency and only in crosses where the female was Gryllus sp. In previous experiments, G. integer from California was unable to hybridize with G. integer from Texas and G. rubens.

1989 ◽  
Vol 67 (10) ◽  
pp. 2540-2542 ◽  
Author(s):  
William H. Cade

Nightly and hourly rates of attraction of flying field crickets, Gryllus integer, to conspecific calling song were studied in an arena placed in the natural habitat of the species in central Texas. Calling of male G. integer in the arena and tape-recorded broadcasts of conspecific song were the sources of cricket song that subsequently attracted flying crickets. Observations were conducted for 10 h from approximately 1.5–2 h past sunset to 3 h past sunrise for 97 nights in 1983 and 1985–1988, using calling males, and for 4 nights in 1988, using taped song. The number of crickets attracted each night varied greatly, significantly more females were attracted, the numbers of males and females attracted decreased near sunrise, and significantly more crickets entered the arena from 2 to 6 h than from 7 to 11 h past sunset. Results are discussed in the context of mating behavior and sexual selection in this and other species.


2000 ◽  
Vol 78 (1) ◽  
pp. 140-143 ◽  
Author(s):  
David A Gray ◽  
William H Cade

The evolutionary theory of aging proposes that senescence is related to decreased selection against deleterious mutations acting late in life. Senescence, i.e., an increase in intrinsic mortality with age, should reflect levels of extrinsic mortality early in life. We tested these predictions using two species of field cricket, Gryllus integer and Gryllus pennsylvanicus. Gryllus integer males are host to a sex-biased parasitoid fly, which orients to the male calling song. As a result, males have reduced life expectancy compared with females in the field. In contrast, G. pennsylvanicus males and females appear to have similar life expectancies in the wild. Thus, we predicted that there would be a significant species × sex interaction, with G. integer males having the shortest life-span. In two replicates, we found that males of both species died at a significantly younger age than females. However, no evidence of a species × sex interaction was found: in the first replicate, G. integer males died earliest, in the second replicate, G. pennsylvanicus males died earliest.


1987 ◽  
Vol 65 (10) ◽  
pp. 2390-2394 ◽  
Author(s):  
Cynthia J. Smith ◽  
William H. Cade

Species-specific calling songs of male field crickets attract conspecific females. Each wing closure results in a pulse of sound, and the song is composed of pulses arranged in species-specific patterns of short chirps, long continuous trills, or intermediates between chirps and trills. California Gryllus integer has a song with pulses of sound delivered in groups of two or three to produce a chirp, but in central Texas, the G. integer song has a variable number of pulses delivered in long continuous trills. Gryllus rubens occurs from eastern Texas to Florida and has a trilling song with a slower pulse rate than that of Texas G. integer. Identification of these three groups in the laboratory was confirmed by recording and analyzing songs for California and Texas G. integer and G. rubens males. All possible crosses were performed in the laboratory between conspecifics and heterospecifics. No progeny resulted in California G. integer and Texas G. integer or California G. integer and G. rubens crosses. Hybrids were produced in G. rubens and Texas G. integer crosses. Results suggest that California and Texas G. integer are different species, or at least populations geographically separated enough to result in reproductive incompatibility and different song types. Texas G. integer and G. rubens are apparently closely related species.


1980 ◽  
Vol 58 (3) ◽  
pp. 404-411 ◽  
Author(s):  
Scott K. Sakaluk ◽  
William H. Cade

Many female insects mate more than once although the adaptive significance is often unclear. We studied the frequency of mating, the fate of the spermatophore, and progeny production of individual females as a function of single or double matings in the house cricket, Acheta domesticus, and the field cricket, Gryllus integer. Females of both species may mate repeatedly and often eat the externally attached spermatophore. In A. domesticus, doubly mated females produced significantly more offspring than did single maters, the difference resulting largely from the failure of 12.5% of the single maters to leave progeny. Singly and doubly mated G. integer did not differ regarding nymph production, but 50% of the singly mated females did not reproduce. Remating by female crickets partly functions in offsetting the probability of a failed initial mating. Nymph production increased significantly with the time the spermatophore was attached in singly mated A. domesticus. Spermatophore consumption by the female was not affected by male "guarding" behaviour, and the interval between mating and eating of the spermatophore may often be shorter than the time required for maximum insemination. It is suggested that acquisition of nutrition may be an additional function of female repeated matings.


1992 ◽  
Vol 70 (5) ◽  
pp. 950-955 ◽  
Author(s):  
Konstantine Souroukis ◽  
William H. Cade ◽  
Gareth Rowell

The structure of the calling song of the Texas field cricket, Gryllus integer, was studied. Pulse rates, percentage of missed pulses within a trill, numbers of pulses per trill or trill lengths, and intertrill intervals were measured for males singing in the field and in the laboratory. All song parameters were variable and were distributed normally. Intertrill intervals were longer in the laboratory, but all other parameters were similar in laboratory and field populations. Pulse rates varied in a linear fashion with ambient temperature in the laboratory and field. The percentage of missed pulses in a trill decreased with increasing temperature in the field and in the laboratory; intertrill intervals varied inversely with temperature only in the field. In field populations, immediately before and after sunrise male songs had fewer pulses per trill and a greater frequency of missed pulses than songs produced for a few hours following sunset. Song structure did not vary with age, weight, or hind-wing dimorphism. Most song parameters were correlated with each other. The data are discussed in terms of female choice and attraction to male song, male competition by way of acoustical interaction, and underlying genetic variation in G. integer.


2009 ◽  
Vol 23 (4) ◽  
pp. 191-198 ◽  
Author(s):  
Suzannah K. Helps ◽  
Samantha J. Broyd ◽  
Christopher J. James ◽  
Anke Karl ◽  
Edmund J. S. Sonuga-Barke

Background: The default mode interference hypothesis ( Sonuga-Barke & Castellanos, 2007 ) predicts (1) the attenuation of very low frequency oscillations (VLFO; e.g., .05 Hz) in brain activity within the default mode network during the transition from rest to task, and (2) that failures to attenuate in this way will lead to an increased likelihood of periodic attention lapses that are synchronized to the VLFO pattern. Here, we tested these predictions using DC-EEG recordings within and outside of a previously identified network of electrode locations hypothesized to reflect DMN activity (i.e., S3 network; Helps et al., 2008 ). Method: 24 young adults (mean age 22.3 years; 8 male), sampled to include a wide range of ADHD symptoms, took part in a study of rest to task transitions. Two conditions were compared: 5 min of rest (eyes open) and a 10-min simple 2-choice RT task with a relatively high sampling rate (ISI 1 s). DC-EEG was recorded during both conditions, and the low-frequency spectrum was decomposed and measures of the power within specific bands extracted. Results: Shift from rest to task led to an attenuation of VLFO activity within the S3 network which was inversely associated with ADHD symptoms. RT during task also showed a VLFO signature. During task there was a small but significant degree of synchronization between EEG and RT in the VLFO band. Attenuators showed a lower degree of synchrony than nonattenuators. Discussion: The results provide some initial EEG-based support for the default mode interference hypothesis and suggest that failure to attenuate VLFO in the S3 network is associated with higher synchrony between low-frequency brain activity and RT fluctuations during a simple RT task. Although significant, the effects were small and future research should employ tasks with a higher sampling rate to increase the possibility of extracting robust and stable signals.


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