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The nest-holding grass goby (Zosterisessor ophiocephalus) male adjusts the spawning activity in relation to parasitic nest intrusions.
Full text linkThis study examines the temporal pattern of spawning behavior by the territorial (i.e. nest-holding) grass goby male, Zosterisessor ophiocephalus, in response to sneak intrusions by the small parasitic male under controlled laboratory conditions. The spawning activity of the territorial male consists of a sequence of upside-down movements on the ceiling of the nest accompanied by undulations of the body and sperm release. Five pairs of one territorial male and one parasitic male, each kept inside a large tank provided with an artificial buried nest (always occupied by the territorial male) and one small tunnel-shaped shelter (always occupied by the small male), were observed during one-female spawning taking place in the innermost part of the nest (i.e. the nest chamber). During the spawning, the presence of the small male nearby the nest openings elicited aggressive behavior and increased nest patrolling by the territorial male. In one spawn the small male never attempted to enter the nest. In four spawns the small male entered one to three times the nest chamber (sneaks), staying there from 2 to 203 s until the large male chased him away. The temporal patterning of the spawning activity by the territorial male (bouts of upside-down, U-D), and its changes following a sneak by the small male, were investigated using bout analysis and correlative tests. Results showed the length of bouts U-D did not change significantly after a sneak intrusion. whereas gap length (i.e. the period between subsequent bouts U-D) decreased significantly after each sneak intrusion. The mean duty cycle of bouts U-D tended to be positively correlated to the number of sneaker intrusions of each replicate. Results are discussed in the light of current knowledge on sperm competition among externally fertilizing teleosts
Parental Aggression Displayed by Female Mice in Relation to the Sex, Reproductive Status and Infanticidal Potential of Conspecific Intruders
No full textThe parental aggression of female mice (Mus domesticus Rutty) towards strange conspecifics known to vary in their tendency to commit infanticide was examined. Twenty-four hours after stud males removal, resident lactating females (with pups aged 3-5 days) were confronted with the following types of intruders: the reintroduced stud, i.e. the father of the pups, a strange father, sexually naive and recently sexually experienced (24 hr prior testing) males, virgin females. Parental attack was mainly elicited by sexually naive and recently sexually experienced males which were also most likely to kill and cannibalize pups. The stud males did not show infanticide and were never attacked. Remarkably, strange fathers were rarely attacked by lactating females and they rarely killed unrelated pups. The data seem to support the view that lactating female mice might be capable of assessing the infanticidal potential of conspecific intruders and of adopting the most appropriate behavioural strategy. Although parental attack was not very successful in thwarting infanticide, the data are discussed in terms of a possible counterstrategy to defend parental investment, and the situational cues females use to distinguish between males with or without parental experience. © Taylor & Francis Group, LLC
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Elongation of fin rays in parental males of Zosterisessor ophiocephalus (Pisces: Gobiidae)
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Ethology and animal ethics
No full textThe purpose of this round table is twofold. First, it aims at stimulating an appreciation of the role that ethologists play (or should play) in the ongoing debates on animal welfare. The second aim is to discuss some of the recent Italian laws concerning animals, such as that for example on animal experimentation which poses ethical obligations on researchers including those who study animal behaviour
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