Harman V.S. Peeke

Maternal aggression in red swamp crayfish (Procambarus clarkii, Girard): the relation between reproductive status and outcome of aggressive encounters with male and female conspecifics

A series of experiments investigated intraspecific aggression by maternal (carrying eggs and/or hatched young) and non-maternal female red swamp crayfish (Procambarus clarkii) residents against intrusions by non-maternal female and Form I (reproductively active) male conspecifics. Each resident occupied an aquarium containing a shelter for 24 hours prior to the initial intrusion. The winner of each encounter was determined, as well as the pair member that initiated the aggressive interaction, and the relation between the initiation of aggression and contest outcome. The results showed that: (1) Maternal female residents were winners in 92% of the encounters with male intruders, and initiated aggression in a significantly higher proportion of encounters than the male intruders. (2) Maternal female residents were the winners in 75% of the encounters with non-maternal female intruders. The maternal residents also initiated aggression in a significantly higher proportion of the encounters than the non-maternal intruders. (3) Non-maternal female residents lost 77% of the encounters with non-maternal intruders. Also, the non-maternal intruders initiated aggression in a significantly higher proportion of the encounters than did the non-maternal residents. (4) Non-maternal female residents lost all of their encounters with male intruders. However, there was no significant difference in the proportion of the encounters in which aggression was initiated by residents or intruders. (5) For all experiments combined, maternal residents won a significantly higher proportion of their encounters than did non-maternal residents, regardless of whether the intruders were males or non-maternal females. (6) For the three experiments combined, the initiation of aggression reliably predicted contest outcome (i.e. the initiator of aggression ultimately won). The present results provide the first empirical demonstration, with appropriate non-maternal controls, of maternal aggression in decapod crustaceans. Also, the direct relation between reproductive status and contest outcome in both ovigerous and post-hatch P. clarkii are the first such data reported in crustaceans, in general. Finally, the findings of these experiments bear notable similarities to the results of maternal aggression research in other taxonomic groups.

Mother's identification of their infant's odors☆

Abstract Human mothers can identify their infants by smell alone at 6 hours post partum after a single exposure to their babies. This ability persists to 48 hours post partum with no improvement with additional experience. Fathers were not able to make the same discrimination.

Shelter competition between resident male red swamp crayfish Procambarus clarkii (Girard) and conspecific intruders varying by sex and reproductive status

The shelter defense dynamics of reproductively active (Form I) male red swamp crayfish Procambarus clarkii (Girard) were investigated by staging serial intrusions by male, maternal or non-maternal female conspecifics after one day of residence. The male residents showed a direct contest advantage only against non-maternal females, and won a significantly higher proportion of the encounters against non-maternal females than against either male or maternal female intruders. However, there was no significant difference in success against male or maternal female intruders. Further experiments against male intruders showed that increasing male prior residence to either 2 or 4 days did not significantly improve the residents’ proportion of successful encounters. A final experiment revealed extremely low shelter fidelity in male P. clarkii, the most likely reason why male shelter defense against conspecific males and maternal females is not successful. These results, combined with those of past research, suggest that non-maternal females, juveniles and recently molted conspecifics are most vulnerable to predation and cannibalism, since males and maternal females easily out-compete non-maternal females for shelter, and adults out-compete juveniles. These findings may have implications for P. clarkii aquaculture and general management.

Cocaine exposure prebreeding to weaning : maternal and offspring effects

In a model emphasizing prebreeding cocaine administration, rats exposed to cocaine (50 mg/kg) daily were compared to saline-injected and noninjected controls with respect to weight changes, food and water intake, maternal behavior, offspring weight, and activity. During the first 21 days cocaine-treated dams lost weight, while the control dams gained. Throughout gestation and the first 14 days of lactation all groups gained weight, but the cocaine-exposed dams never completely recovered from the initial anorectic effect. Except during the first week of exposure, cocaine dams ate and drank more than the normal controls and drank more than the saline group. During gestation there was no difference in food intake, although the cocaine dams continued to drink more than controls. During lactation there were no differences in food and water consumption across groups. However, the cocaine dams exhibited more nursing behavior. From birth to day 21, the offspring of cocaine-treated dams were smaller than those of either control group. By 51 days of age, group differences had disappeared. Cocaine-exposed pups and saline offspring tested at days 28 and 85 were more active than those of noninjected controls. The results indicate that administration of cocaine for a period prior to breeding and during gestation and lactation, a protocol which closely resembles human drug abuse patterns, is more devastating than the administration during gestation.

Sex differences and prior residence effects in shelter competition in juvenile lobsters, Homarus americanus Milne-Edwards

Using a resident–intruder paradigm, a four-experiment study of competition for a single shelter between same- and mixed-sex dyads of juvenile lobsters, Homarus americanus Milne-Edwards, revealed a significantly greater advantage for male residents than female residents against intruders of either sex. However, there was no significant direct competitive advantage for residents of one sex over intruders of the other, as occurs for adult males over females in this species. There was a prior residence effect only in the male–male dyad condition. Unexpectedly, there was a reliable intruder advantage in female–female dyads. The methods employed showed that the shelter-seeking response of the juvenile lobster is a phylogenetic adaptation and that juvenile aggressive behavior differs little in form from that of adult lobsters but appears to be more intense.

Sex differences and asymmetries of catecholamines: Relation to turning preferences☆

Male and female Sprague-Dawley rats were tested for turning preferences in a multiple alley maze. The left and right caudate-putamen were dissected and assayed for norepinephrine and dopamine. Dopamine was not found to be lateralized contralateral to turning preference for females as a group. However, dopamine was significantly lateralized contralateral to the females turning preference if a strong turning bias was present. No relationship between dopamine asymmetry and turning preference was evident for males. Females were found to have norepinephrine significantly lateralized to the left caudate-putamen; in males greater striatal norepinephrine levels were equally distributed between left and right sides. This sexual dimorphism in norepinephrine lateralization was not related to turning preference.

Brain stimulation and behavior: Controls and consequences

Groups of rats ranging from unimplanted controls to caudate-putamen (CPU) stimulated experimental animals were compared in terms of the number of trials required to acquire a brightness discrimination habit. The results indicated that the degree of deficit produced was a function of the magnitude of experimental intervention imposed. Animals with headplugs and cables, but without electrodes required significantly more trials to learn than unimplanted controls. The addition of electrodes without a headcable produced no greater deficit, while electrodes with attached cable resulted in significantly greater disruption than plug and cable alone. Stimulation of the PCU with one or three bilateral pulses following each discrimination produced significantly greater interference than did the electrode lesion and headcable. The results are discussed in terms of the control conditions required for studies of the effects of brain stimulation on behavior.

NOCTURNAL FEEDING IN THE MARINE THREESPINE STICKLEBACK (GASTEROSTEUS ACULEATUS L.): MODULATION BY CHEMICAL STIMULATION

Contrary to previous understanding, sticklebacks in our laboratory were observed, with night vision goggles, feeding on live brine shrimp in total darkness. The response was greatly enhanced by pre-feeding stimulation with water that had previously held brine shrimp. The response pattern elicited by the brine shrimp water was characteristic of feeding responses directed toward benthic organisms rather than a pelagic crustacean such as the brine shrimp. This suggests a general, non-prey specific feeding activation function for the chemicalolfactory cues used in this study. is no literature that demonstrates other forms of sensory input, such as chemoreception or mechanoreception, to be important in stickleback prey detection or feeding. Sticklebacks have shown preferences for their preys

The effects of pargyline, scopolamine, and imipramine on territorial aggression in the convict cichlid (Cichlasoma nigrofasciatum).

Scopolamine, pargyline, and imipramine reduce territoral aggression in the convict cichlid. Imipramine is effective at much lower doses than either scopolamine or pargyline. None of the drugs affected activity or predation/feeding, indicating that the observed drug effects are relatively specific.