A Function of the Subelytral Chamber of Tenebrionid Beetles

1. The subelytral chamber is an air space between the elytra and the dorsum of the abdomen of some Tenebrionid beetles. Postulated functions for the subelytral chamber have been a reduction of transpiratory water loss and a thermal buffer for heat flow from the elytra to the abdomen. 2. We show that there is a significant correlation between water loss and the depth of the subelytral chamber. 3. This implies that the chamber may be a structure that permits the rapid expansion of the abdomen, providing the beetles with a mechanism by which they can quickly drink large quantities of water from an ephemeral source such as a rain puddle. As the beetles drink, the abdomen greatly expands, and the chamber shrinks

Habitat structure and alarm call dialects in Gunnison\u27s prairie dog (Cynomys gunnisoni)

We examined the relationship between habitat structure and alarm call characteristics in six colonies of Gunnison’s prairie dogs (Cynomys gunnisoni) near Flagstaff, Arizona, before and after a mid-summer vegetation change. We found significant differences in alarm call characteristics between colonies, confirming the existence of alarm call dialects. Differences in frequency components but not temporal components of calls were associated with differences in habitat structure. Playback experiments revealed that differences in alarm call structure affected acoustic transmission of calls through the local habitat. Thus, we identify habitat structure as one factor that may contribute to alarm call differences between colonies of Gunnison’s prairie dogs. Relationships between call characteristics and habitat structure changed over seasons. Playback experiments suggested that this changing relationship could reflect a change in the purpose of the alarm call between early and late summer. Some components of alarm calls seem tailored for attenuation over short distances in the early summer but for long-distance transmission at summer’s end. These differences might arise because pups stay close to their natal burrows in the early summer and disperse throughout a colony in late summer. Alternatively, these differences in alarm call transmission between seasons could be caused by the increase in vegetation in the mid-summer. At the end of the summer prairie dogs could be more dependent on long-distance antipredator calls to offset the loss of visibility caused by the increase in vegetation in the late summe

Acoustic Structures in the Alarm Calls of Gunnison’s Prairie Dogs

Acoustic structures of sound in Gunnison’s prairie dog alarm calls are described, showing how these acoustic structures may encode information about three different predator species (red-tailed hawk—Buteo jamaicensis; domestic dog—Canis familaris; and coyote—Canis latrans). By dividing each alarm call into 25 equal-sized partitions and using resonant frequencies within each partition, commonly occurring acoustic structures were identified as components of alarm calls for the three predators. Although most of the acoustic structures appeared in alarm calls elicited by all three predator species, the frequency of occurrence of these acoustic structures varied among the alarm calls for the different predators, suggesting that these structures encode identifying information for each of the predators. A classification analysis of alarm calls elicited by each of the three predators showed that acoustic structures could correctly classify 67% of the calls elicited by domestic dogs, 73% of the calls elicited by coyotes, and 99% of the calls elicited by red-tailed hawks. The different distributions of acoustic structures associated with alarm calls for the three predator species suggest a duality of function, one of the design elements of language listed by Hockett [in Animal Sounds and Communication, edited by W. E. Lanyon and W. N. Tavolga (American Institute of Biological Sciences, Washington, DC, 1960), pp. 392–430]

Vigilance and Predation Risk in Gunnison’s Prairie Dogs (Cynomys gunnisoni)

Group living in animals is believed to confer advantages related to a decrease in predation risk and an energetic trade-off between vigilance and foraging efficiency. Eight Gunnison’s prairie dog, Cynomys gunnisoni, colonies in Flagstaff, Arizona (elevation 2300 m), were studied from April to August 2000 to examine the adaptive significance of colonial living in the context of predation risk and antipredator behavioral strategies. Each colony was sampled once every 10 days for a period of 3 h. Upright and quadrepedal vigilance was recorded using scan samples. All predation events were recorded. Results suggest that vigilant behavior in Gunnison’s prairie dogs is an antipredator strategy because the animals oriented more frequently towards the periphery of the colony while vigilant. Gunnison’s prairie dogs engaged in posting, an upright bipedal posture, more frequently than scanning, a quadrepedal posture. Furthermore, there was no relationship between either form of vigilance and population size. The proportion of animals vigilant decreased significantly only on the two smallest colonies as colony size increased. On larger colonies there was no relationship between the proportion of animals vigilant and colony size. The lack of change in the proportion of animals vigilant in larger populations may be a function of perceived risk rather than actual individual risk

Male Territoriality in a Social Sciurid, Cynomys gunnisoni: What do Patterns of Paternity Tell Us?

In many social sciurids, male territoriality confers significant mating advantages. We evaluated resident male paternity in Gunnison’s prairie dogs (Cynomys gunnisoni), a colonial ground-dwelling sciurid, where males and females cooperatively defend territories. Contrary to findings reported for other social sciurids, our results show that territorial resident males do not gain significant reproductive advantages. Resident males sired the majority of offspring from their respective territories only 10.5% of the time. A single non-resident male sired equal or greater number of offspring than any single resident male 71.2% of the time. While adult males were more likely to sire a greater number of offspring, standard heterozygosity, body mass, and territory size were not significant predictors of how many offspring a male sired. In addition, the number of other males present did not influence the number of offspring sired by any given resident male. However, territory size was significantly correlated with overall offspring number and mean litter size per female, suggesting a potential reproductive advantage for females that occupy larger, better quality territories. Previous work has demonstrated that the cooperative defence of territories by both males and females permits enhanced access to food resources critical to overwinter survival. Our results have important implications for studies that do not distinguish between social and mating systems, because they suggest that individual mating strategies may be different from the social strategies that emerge in response to resource availability

Social assemblages and mating relationships in prairie dogs: a DNA fingerprint analysis

Mating system characterizations have been hindered by difficulties in accurately assigning parentage to offspring. We investigated the relationship between social assemblages and mating relationships in a territorial harem polygynous mammal, the Gunnison\u27s prairie dog, using a combination of behavioral and molecular analyses. We demonstrate multiple paternity and an extraordinarily high incidence of extraterritorial fertilizations (i.e., 61% of all progeny), in combination with the existence of female kin groups. On this basis, we conclude that social assemblages alone provide a poor description of the Gunnison\u27s prairie dog mating system, and suggest several potential reasons for the maintenance of territoriality in this species

DNA Fingerprinting Reveals Low Genetic Diversity in Gunnison\u27s Prairie Dog (Cynomys gunnisoni)

The use of molecular techniques for the assessment of familial relationships among social species of mammals has become relatively commonplace. However, some species represent poor candidates for such studies due to naturally low levels of genetic diversity, leading to unacceptably large standard errors associated with estimates of relatedness. Here, we report on a preliminary study of genetic diversity within two populations of a social species of ground squirrel, Gunnison\u27s prairie dog (Cynomys gunnisoni) using DNA fingerprinting. We observed low levels of diversity in the form of large mean coefficients of genetic similarity among individuals occupying the same population. Overall similarity, determined from the combined data, yielded by three minisatellte probes, ranged from 55 to 61%. These values place Gunnison\u27s prairie dog at the extreme upper end of the range of similarity values reported for outbred species of mammals (ca. 0.20-0.50). As a partial means of explaining these results, and as a means of comparing our results to those of similar studies using allozymes, we determined the level of differentiation between our two study colonies in the form of an F-statistic analog. A value of 0.11 (± 2.26 × 10−3) was obtained and is similar to values reported from allozyme studies (0.07–0.12). A significance test of this value yielded a positive result (D = 5.63, d.f. = 1, P \u3c 0.025), demonstrating that gene flow between populations is limited, a factor that may help to maintain low levels of diversity

DNA Fingerprinting Reveals Low Genetic Diversity in Gunnison\u27s Prairie Dog (Cynomys gunnisoni)

The use of molecular techniques for the assessment of familial relationships among social species of mammals has become relatively commonplace. However, some species represent poor candidates for such studies due to naturally low levels of genetic diversity, leading to unacceptably large standard errors associated with estimates of relatedness. Here, we report on a preliminary study of genetic diversity within two populations of a social species of ground squirrel, Gunnison\u27s prairie dog (Cynomys gunnisoni) using DNA fingerprinting. We observed low levels of diversity in the form of large mean coefficients of genetic similarity among individuals occupying the same population. Overall similarity, determined from the combined data, yielded by three minisatellte probes, ranged from 55 to 61%. These values place Gunnison\u27s prairie dog at the extreme upper end of the range of similarity values reported for outbred species of mammals (ca. 0.20-0.50). As a partial means of explaining these results, and as a means of comparing our results to those of similar studies using allozymes, we determined the level of differentiation between our two study colonies in the form of an F-statistic analog. A value of 0.11 (± 2.26 × 10−3) was obtained and is similar to values reported from allozyme studies (0.07–0.12). A significance test of this value yielded a positive result (D = 5.63, d.f. = 1, P \u3c 0.025), demonstrating that gene flow between populations is limited, a factor that may help to maintain low levels of diversity