Comparative support for the expensive tissue hypothesis: Big brains are correlated with smaller gut and greater parental investment in Lake Tanganyika cichlids

This is the final version of the article. Available from the publisher via the DOI in this record.The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the energetic requirements of encephalization are suggested to impose considerable constraints on brain size evolution. Three main hypotheses concerning how energetic constraints might affect brain evolution predict covariation between brain investment and (1) investment into other costly tissues, (2) overall metabolic rate, and (3) reproductive investment. To date, these hypotheses have mainly been tested in homeothermic animals and the existing data are inconclusive. However, there are good reasons to believe that energetic limitations might play a role in large-scale patterns of brain size evolution also in ectothermic vertebrates. Here, we test these hypotheses in a group of ectothermic vertebrates, the Lake Tanganyika cichlid fishes. After controlling for the effect of shared ancestry and confounding ecological variables, we find a negative association between brain size and gut size. Furthermore, we find that the evolution of a larger brain is accompanied by increased reproductive investment into egg size and parental care. Our results indicate that the energetic costs of encephalization may be an important general factor involved in the evolution of brain size also in ectothermic vertebrates.The authors thank the staff of the Department of Fisheries of the Ministry of Agriculture and Cooperatives at Mpulungu, Zambia, for their cooperation during fieldwork, especially for collecting fishes from the deeper levels. They also thank H. Tanaka for collecting fish samples for us. This study was funded through the student exchange support program (scholarship for long-term study abroad) from the Japanese Student Services Organization (JASSO) to MT, the Zoologiska foundation to MT and AK, a Davis Expedition Fund grant, Helge Axelsson Johnson grant, and a Stiftelsen Hierta-Retzius stipendiefond grant to AH, the Austrian Science Fund (J 3304-B24) to AK, and a Swedish Research Council grant to NK. The authors have no conflict of interest to declare

Relatedness and age reduce aggressive male interactions over mating in domestic fowl

Altruistic behaviour represents a fundamental challenge in evolutionary biology. It is often best understood through kin selection, where favourable behaviour is directed towards relatives. Kin selection can take place when males cooperate to enhance the reproductive success of relatives. Here, we focus on reduced male–male competition over mating as a case of cooperation, by examining male tolerance of matings by related and unrelated competitors. A suitable model for exploring whether relatedness affects male–male interactions over mating is the domestic fowl, Gallus gallus domesticus. In this species, males form social hierarchies and dominant males commonly interrupt subdominant males’ copulation attempts. We investigated whether dominant male fowl differentially direct aggressive interactions towards unrelated and related subordinate males during mating attempts. Dominant male fowl were found to interrupt mating attempts of male relatives less often than those of unrelated males. We further tested whether male age mediates the magnitude of kin tolerance behaviour. However, we found no support for this as both young and old dominant males were less likely to interrupt related, compared to unrelated, subdominant males’ copulations during male–male interactions. Our results, consistent with kin selection, provide a rare experimental demonstration of relatedness relaxing male–male competition over mating

Relatedness and age reduce aggressive male interactions over mating in domestic fowl

Altruistic behaviour represents a fundamental challenge in evolutionary biology. It is often best understood through kin selection, where favourable behaviour is directed towards relatives. Kin selection can take place when males cooperate to enhance the reproductive success of relatives. Here, we focus on reduced male–male competition over mating as a case of cooperation, by examining male tolerance of matings by related and unrelated competitors. A suitable model for exploring whether relatedness affects male–male interactions over mating is the domestic fowl, Gallus gallus domesticus. In this species, males form social hierarchies and dominant males commonly interrupt subdominant males’ copulation attempts. We investigated whether dominant male fowl differentially direct aggressive interactions towards unrelated and related subordinate males during mating attempts. Dominant male fowl were found to interrupt mating attempts of male relatives less often than those of unrelated males. We further tested whether male age mediates the magnitude of kin tolerance behaviour. However, we found no support for this as both young and old dominant males were less likely to interrupt related, compared to unrelated, subdominant males’ copulations during male–male interactions. Our results, consistent with kin selection, provide a rare experimental demonstration of relatedness relaxing male–male competition over mating

Relatedness and age reduce aggressive male interactions over mating in domestic fowl

Altruistic behaviour represents a fundamental challenge in evolutionary biology. It is often best understood through kin selection, where favourable behaviour is directed towards relatives. Kin selection can take place when males cooperate to enhance the reproductive success of relatives. Here, we focus on reduced male–male competition over mating as a case of cooperation, by examining male tolerance of matings by related and unrelated competitors. A suitable model for exploring whether relatedness affects male–male interactions over mating is the domestic fowl, Gallus gallus domesticus. In this species, males form social hierarchies and dominant males commonly interrupt subdominant males’ copulation attempts. We investigated whether dominant male fowl differentially direct aggressive interactions towards unrelated and related subordinate males during mating attempts. Dominant male fowl were found to interrupt mating attempts of male relatives less often than those of unrelated males. We further tested whether male age mediates the magnitude of kin tolerance behaviour. However, we found no support for this as both young and old dominant males were less likely to interrupt related, compared to unrelated, subdominant males’ copulations during male–male interactions. Our results, consistent with kin selection, provide a rare experimental demonstration of relatedness relaxing male–male competition over mating

‘Friends call me racist’: Experiences of repercussions from writing comments on newspaper websites

acceptedVersio

Playing Games with Tito:Designing Hybrid Museum Experiences for Critical Play

This article brings together two distinct, but related perspectives on playful museum experiences: Critical play and hybrid design. The article explores the challenges involved in combining these two perspectives, through the design of two hybrid museum experiences that aimed to facilitate critical play with/in the collections of the Museum of Yugoslavia and the highly contested heritage they represent. Based on reflections from the design process as well as feedback from test users, we describe a series of challenges: Challenging the norms of visitor behaviour, challenging the role of the artefact, and challenging the curatorial authority. In conclusion, we outline some possible design strategies to address these challenges

Macroalgal morphogenesis induced by waterborne compounds and bacteria in coastal seawater

Axenic gametes of the marine green macroalga Ulva mutabilis Foyn (Ria Formosa, locus typicus) exhibit abnormal development into slow-growing callus-like colonies with aberrant cell walls. Under laboratory conditions, it was previously demonstrated that all defects in growth and thallus development can be completely abolished when axenic gametes are inoculated with a combination of two specific bacterial strains originally identified as Roseo-bacter sp. strain MS2 and Cytophaga sp. strain MS6. These bacteria release diffusible morphogenetic compounds (= morphogens), which act similar to cytokinin and auxin. To investigate the ecological relevance of the waterborne bacterial morphogens, seawater samples were collected in the Ria Formosa lagoon (Algarve, Southern Portugal) at 20 sampling sites and tidal pools to assess their morphogenetic effects on the axenic gametes of U. mutabilis. Specifically the survey revealed that sterile-filtered seawater samples can completely recover growth and morphogenesis of U. mutabilis under axenic conditions. Morphogenetic activities of free-living and epiphytic bacteria isolated from the locally very abundant Ulva species (i.e., U. rigida) were screened using a multiwell-based testing system. The most represented genera isolated from U. rigida were Alteromonas, Pseudoalteromonas and Sulfitobacter followed by Psychrobacter and Polaribacter. Several naturally occurring bacterial species could emulate MS2 activity (= induction of cell divisions) regardless of taxonomic affiliation, whereas the MS6 activity (= induction of cell differentiation and cell wall formation) was species-specific and is probably a feature of difficult-to-culture bacteria. Interestingly, isolated bacteroidetes such as Algoriphagus sp. and Polaribacter sp. could individually trigger complete Ulva morphogenesis and thus provide a novel mode of action for bacterial-induced algal development. This study also highlights that the accumulation of algal growth factors in a shallow water body separated from the open ocean by barrier islands might have strong implications to, for example, the wide usage of natural coastal seawater in algal (land based) aquacultures of Ulva

Sex in the morning or in the evening? Females adjust daily mating patterns to the intensity of sexual harassment.

Selection on males to mate at a higher rate than females often results in male harassment of females and counteracting female responses. When the reproductive value of copulation changes over time, these mating strategies are expected to be time dependent. Here, we demonstrate that variation in the intensity of male harassment leads to drastic changes in female daily mating patterns. In feral populations of fowl Gallus gallus domesticus, male harassment is intense, particularly in the evening when inseminations are most likely to result in fertilization. We experimentally manipulated the intensity of male harassment through similar-sized groups of different sex ratios. Male mating propensity was always higher than females', particularly in male-biased groups and in the evening, when males were closer to and more likely to approach females. Females counteracted male harassment by escalating resistance to mating and--crucially--by shifting their daily mating pattern: in strongly female-biased groups with relaxed sexual harassment, females solicited sex in the evening, while in male-biased groups, they solicited sex in the morning, thus avoiding harassment in the evening. Together, these results indicate that intersexual conflict may occur not only over mating rates but also over when in the day to copulate