Circadian rhythms play an essential role in the adaptation of organisms to the environment and may show species-specific or sex-specific differences even within a closely related taxonomic group. Although spiders (Araneae) are sexually dimorphic in several morphological and behavioural features, there are very few studies on the sex-specific differences in their biological rhythms. This study evaluated the circadian rhythm in the locomotor activity of two agrobiont hunting species of spider, Carrhotus xanthogramma (Latreille, 1819) (Salticidae) and Philodromus cespitum (Walckenaer, 1802) (Philodromidae), under natural photoperiod conditions. Particular attention was paid to possible differences between the sexes in both species. We found that C. xanthogramma is a strictly diurnal species with a mean activity peak in the morning in both sexes and the females are more active than males. The locomotor activity rhythm of males was richer in ultradian (shorter than a day but longer than an hour) components, although the relative power of these components was negligible compared to the main, 24-h period component. In accordance with these results, the diel pattern of locomotor activity of C. xanthogramma can be described by a unimodal cosine curve. In contrast to C. xanthogramma, both sexes of Ph. cespitum showed cathemeral activity (i.e., activity occur within both the light and dark portions of the daily cycle) and females and males follow quite different activity schedules: females were most active at night, shortly before nautical dawn, whereas males were most active early in the morning. Unlike C. xanthogramma, Ph. cespitum has more ultradian components, with higher relative power especially in females, where besides the 24-h circadian component there is a particularly strong 12-h ultradian period. Based on these factors, females of Ph. cespitum show a bimodal and males a unimodal pattern.
The cerambycid borers Callidiellum rufipenne (Motschulsky) and Semanotus bifasciatus (Motschulsky) infest coniferous logs in Japan, with the latter distributed in the north and at high altitudes, where both species occur sympatrically. Semanotus bifasciatus adults were active at low temperatures and very active after sunset, and less active but never inactive in the daytime, whereas C. rufipenne adults were usually active at high temperatures and almost only in the daytime. At an almost constant temperature, C. rufipenne adults were almost inactive at night, whereas S. bifasciatus adults showed only an obscure decline in activity in the morning. Of a horizontal log, the upper surface tended to be drier and lower surface wetter, and C. rufipenne larvae grew large if they were in the upper part of a log, whereas S. bifasciatus larvae grew large if in the lower part. Thus, the coexistence of these two species can be ascribed to two major segregation factors: adult segregation based on temperature and sunshine, and larval segregation associated with the moisture content of the wood.
The thermal relations, diel, and annual activity and microhabitat use of Lacerta agilis were studied in the Pyrenean isolated range of this species. Although, this heliothermic lizard demonstrated thermoregulatory capability, thermal constraints attributable to the mountain climate were observed. The activity pattern was that typical of cold temperate lizards but the beginning of activity was delayed in comparison with lowland populations. The reproductive cycle determined different activity patterns for males and females. The ontogenetic and seasonal changes in microhabitat use detected suggest influence of body size, reproductive condition in adults, and interference with other individuals in juveniles.
The spawning migration from Moravka reservoir to the Moravka river tributary of brown trout in autumn (October – November) lasted 22, 24, and 27 days respectively in the seasons 2002–2004. In 2002, 187 fish were trapped, while the number of trapped spawners increased to 447 in 2003 and 2230 in 2004. Spawning males were significantly longer than females (PoC in the reservoir. The peak of spawning, in all three seasons, took place between 28 October and 3 November, and the river water temperature varied from 6 to 8oC. The spawning in 2002 was more nocturnal (between 8:00 p.m. to 6:00 a.m.) than diurnal (P<0.01) and the diel activity showed the multimodal distribution. There were no large or significant differences between the diurnal and nocturnal migrations in 2003 and 2004. Single environmental variables and their interaction were significantly related to the spawning migration only in 2003 and 2004 (P<0.001).