The expression of an intraspecific aggressive reaction in the face of a stressor agent alters the immune response in rats

The repercussion on the immune response of the expression of intraspecific aggressiveness in the face of a stressor agent was investigated in rats. Ninety-day-old animals were divided into three groups: the control group (only immunological measurements were performed), the foot-shock (FS) (animals individually receiving FS), and the intraspecific aggressive response (IAR) group (animals receiving FS and presenting IAR). For immunological measurements, blood samples were collected promptly at 7 and 15 days after FS or IAR. The FS reduced the total leukocyte amount presented. However, aggressiveness triggered not only reduction of the leukocytes, but also lymphocyte decrease and neutrophil increase. Moreover, an elevation in total leukocytes associated with an increase in the humoral immune response was also observed one week after IAR. In this study, the expression of intraspecific aggressiveness in the face of a stressor seemed to activate the immune system and to potentiate the antigen specific humoral response.

Relative Intraspecific Aggressiveness of Pedal Disc Colour Phenotypes of the Beadlet Anemone, Actinia Equina

Anemones of the genus Actinia exhibit a well documented, stereotyped aggressive sequence (Bonnin, 1964; Brace & Pavey, 1978; Brace et ah, 1979) involving specialized, nematocyst-bearing structures called acrorhagi, which can be directed against an opponent. Experiments on the Australian species, A. tenebrosa Farquhar, and on the clonal anemone, Anthopleura elegantissima (Brandt) (which similarly bears acrorhagi), indicate that aggression occurs principally between genetically dissimilar (allogeneic) opponents (Ayre, 1982; Francis, 1973a, b; Bigger, 1980). Once acrorhagial contact has been made with an allogeneic individual, massive discharges of nematocysts ensue, which can cause severe necrotic lesions.

Interspecific Aggression By Barrow's Goldeneye: a Descriptive and Functional Analysis

We describe interspecific aggression and territoriality by a diving duck, the Barrow's goldeneye. Males of this species are strongly interspecifically territorial early during the breeding season, and in winter. Females are interspecifically territorial while tending broods of ducklings. Aggression was strongest against conspecifics, and against the con-generic bufflehead, which shares the same breeding habitat. Other diving ducks, which overlap in diet with goldeneyes, were frequently attacked, while dabbling ducks, with differing feeding habits, were generally tolerated, and were seldom attacked. One dabbling duck, the blue-winged teal, in which the drake resembles the Barrow's goldeneye drake in plumage, was attacked more strongly than other dabblers. We propose that the strong interspecific aggressiveness exhibited by the Barrow's goldeneye, and its congeners the bufflehead and common goldeneye, is a consequence of the strong intraspecific aggressiveness of these species. Selectivity in aggression towards victims of different species can be explained by two hypotheses. Species that have (1) similar diets, and (2) similar plumages to Barrow's goldeneye are selectively attacked.