Effects of genealogical relationship and colony age on the dominance hierarchy in the primitively eusocial bee Lasioglossum zephyrum

A preliminary experiment with sheep in pens demonstrated that wheat grain could be labelled with tritiated water so that when fed it could provide data that would allow accurate calculation of individual feed consumption. This techinque was used with two groups of sheep fed supplementary wheat grain in paddocks. Half of the animals had previous experience of grain feeding some eight months earlier and the others had not eaten grain. Individual diversity of intake could be estimated usefully by tritium labelling of wheat, which was fed to the sheep in a group. The experiment showed that there was a threefold difference in the amount of wheat eaten between the lowest and highest intakes. Further, animals with previous experience of grain feeding consumed the entire ration initially, but those without previous experience did not consume all of the ration until two weeks after wheat feeding began. Over the period of measurement the experienced sheep consumed about 13% more wheat than the non-experienced group. There were insufficient aggressive acts to establish a dominance hierarchy in either group, although the experienced sheep were more aggressive than the others. Aggressiveness by one sheep towards other sheep did not result in higher wheat intakes by the former compared with other sheep in the group. The results are discussed in terms of the variability in acceptance of such supplements by animals, and of the value, later in life, of early introduction of supplementary feeding.

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Non-random associations in group housed rats (Rattus norvegicus)

Scientific Reports ◽

10.1038/s41598-021-94608-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Leanne Proops ◽

Camille A. Troisi ◽

Tanja K. Kleinhappel ◽

Teresa Romero

Keyword(s):

Network Analysis ◽

Empirical Evidence ◽

Rattus Norvegicus ◽

Dominance Hierarchy ◽

Group Living ◽

Ecological Factors ◽

Limited Evidence ◽

Rat Strains ◽

Social Species ◽

Over Time

AbstractEcological factors, such as predation, have traditionally been used to explain sociability. However, it is increasingly recognised that individuals within a group do not associate randomly, and that these non-random associations can generate fitness advantages. The majority of the empirical evidence on differentiated associations in group-living mammals, however, comes from a limited number of taxa and we still know very little about their occurrence and characteristics in some highly social species, such as rats (Rattus spp.). Here, using network analysis, we quantified association patterns in four groups of male fancy rats. We found that the associations between rats were not randomly distributed and that most individuals had significantly more preferred/avoided associates than expected by random. We also found that these preferences can be stable over time, and that they were not influenced by individuals’ rank position in the dominance hierarchy. Our findings are consistent with work in other mammals, but contrast with the limited evidence available for other rat strains. While further studies in groups with different demographic composition are warranted to confirm our findings, the occurrence of differentiated associations in all male groups of rats have important implications for the management and welfare of captive rat populations.

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