Ethology最新文献

A well-established paradigm to assess fear sensing is the exposure to alarm substances (AS) from conspecifics in Ostariophysi fish, such as zebrafish, which causes several physiological and behavioral changes associated with distress. Although exposure to AS has been increasingly used to study various aspects related to threat perception, the general effect of fear sensing on agonistic behavior is understudied. Interestingly, while consecutive agonistic encounters modulating aggressive behavior are well studied in males, the extent to which social behavior can be altered by fear sensing during consecutive agonistic encounters remains unexplored. The aim of the present work is to examine whether fear sensing after two consecutive exposures to AS alters agonistic behavior in female zebrafish. Moreover, since female aggression is understudied when compared to males, this study also assesses possible differences according to the reproductive stage. We performed intrasexual dyadic encounters between female zebrafish to determine if agonistic behavior is altered during two consecutive contests and by the presence of AS. To control for the biological effect of the AS, individual behavioral parameters such as distance, mean velocity and freezing were determined during a first and a second exposure to AS. We then quantified agonistic behaviors during dyadic encounters, such as the latency to the first aggressive display, freezing (a well-established behavior associated with fear response after one acute AS exposure) and time of aggression, as the total time in which opponents engage in agonistic interaction. When comparing agonistic behavior in different reproductive stages, results suggest there are no differences in latency and in freezing. Regarding time of aggression, while there are no differences between contests in prespawning or postspawning, significant differences are detected between postspawning dyads and mixed dyads with both females in different reproductive stages. Results suggest that exposure to AS reduces female motivation to engage in an agonistic encounter while aggressive behavior is still maintained despite sensing AS as a potential threat, regardless of corresponding to the first or second contest. To the best of our knowledge, this is the first evidence assessing how consecutive agonistic encounters with a real opponent can be altered by repeated exposure to AS.

In birds, vocal interactions are essential during reproduction. However, the majority of studies on vocalisation discrimination and mate preferences in birds are biased in favour of females. Indeed, few studies have focused on male perception and preferences for female vocalisations. Thus, this study aims to determine male preferences for a type of female vocalisation in the domestic canary, Serinus canaria. To do this, we tested sexually receptive males in an operant conditioning test. The males tested were given the opportunity to choose between two keys and pressing the keys triggered the broadcast of female-specific copulation solicitation trills (CST) with a different number of notes per second. This experiment did not reveal preferences that could be generalised to the group but individual preferences could be highlighted. Further studies will be needed to explain these results and to better understand male preference in monogamous species.

Facilitative interactions between invertebrates and vertebrates are rarely documented, especially those involving trophic mechanisms. Here, we report a novel case of facilitation between the stingless bee Trigona spinipes and the nectarivorous bat Glossophaga soricina, observed in an urban coastal area in southeastern Brazil. Bees were seen wounding pedicels of Senna macranthera trees during the day, inducing sap exudation. At night, bats visited these sap sources, licking the exudate without creating wounds themselves. This observation represents a rare case of indirect trophic facilitation involving distantly related taxa and expands our understanding of cross-taxon interactions in urban ecological contexts.

Cichlid fishes have long been a popular model for ecology and evolutionary biology. Not only do they exhibit nearly unparalleled taxonomic diversity, but their community structures are both complex and extremely dense. Niche partitioning along dietary axes has been credited with maintaining cichlid biodiversity in a broad sense; however, it is common for cichlid species with overlapping diets to co-exist, leading to the search for other mechanisms to explain the maintenance of cichlid biodiversity. Behavioral variation has the potential to drive fine-scale (i.e., micro-) habitat partitioning, but analyzing complex animal behavior poses several challenges, including time, cost, and reproducibility. Modern tools, such as Machine learning (ML), ease the burden of behavioral analyses and are increasingly used in the field. Here, we present the application of tools from a well-developed sub-field of ML, Computer vision (CV), to extract locomotor behavioral data from four Lake Malawi cichlid species. Our dataset consisted of low-resolution (320 × 240), 24 h infrared videos of activity in 4 cichlid species. We first analyzed a pair of species with divergent behaviors, diets, and habitats (i.e., Abactochromis labrosus versus Tropheops kumwera), representing a proof-of-concept comparison. Next, we analyzed activity in two closely related species with broadly similar behaviors and overlapping diets and habitats (i.e., Maylandia sp. “daktari” versus Maylandia fainzilberi). In both comparisons, our analysis involved the quantification of tank usage patterns and stop/rest activity, as well as the statistical testing for differences in these behaviors between species and between times of day within species. Our data align with the known ecologies and behaviors of the species in our proof-of-concept comparison and also reveal novel behavioral differences between all species, especially as related to variation in tank usage from day to night. Our approach provides a window into potential cryptic patterns in behavioral niche partitioning, as well as a foundation for future, high-throughput analyses to study the genetic basis and evolution of behavior.

Reciprocity is one of the evolutionary mechanisms explaining cooperation between individuals and explains behaviors where individuals follow the rules “help who helped you before” (direct reciprocity) or “help anyone if helped by someone” (generalized reciprocity). In direct reciprocity, decisions require individual recognition and the ability to remember the outcome of past interactions with individual partners. In contrast, in generalized reciprocity, decisions only require that individuals remember if they received help in previous interactions, irrespective of partner identity. Some species of outcrossing, simultaneous hermaphrodites trade eggs as predicted by a reciprocity mechanism, that is one individual offers its eggs to the partner conditionally upon receiving eggs from the partner before. As a first step toward understanding the decision rules used by egg-traders, we tested whether they discriminate between familiar, previously cooperative partners and unfamiliar partners. We asked this question in the marine annelid worm Ophryotrocha diadema, where monogamous partners engage in egg trading by exchanging eggs every 4 days. By switching partners between pairs (thus exposing them to unfamiliar partners), we show that worms did not delay egg donations nor diminish clutch size compared to control (sham switched) pairs, where worms were kept with the same (familiar) partners. These results suggest that worms do not discriminate between familiar and unfamiliar partners and reciprocate eggs irrespective of partner identity.