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Many animals use color to signal their quality and/or behavioral motivations. Colorful signals have been well studied in the contexts of competition and mate choice; however, the role of these signals in nonsexual, affiliative relationships is not as well understood. Here, we used wild social groups of the cichlid fish Neolamprologus pulcher to investigate whether the size of a brightly colored facial patch was related to 1) individual quality, 2) social dominance, and/or 3) affiliative relationships. Individuals with larger patches spent more time foraging and tended to perform more aggressive acts against conspecific territory intruders. We did not find any evidence that the size of these yellow patches was related to social rank or body size, but dominant males tended to have larger patches than dominant females. Additionally, patch size had a rank-specific relationship with the number of affiliative interactions that individuals engaged in. Dominant males with large patches received fewer affiliative acts from their groupmates compared to dominant males with small patches. However, subordinates with large patches tended to receive more affiliative acts from their groupmates while performing fewer affiliative acts themselves. Taken together, our results suggest that patch size reflects interindividual variation in foraging effort in this cichlid fish and offer some of the first evidence that colorful signals may shape affiliative relationships within wild social groups. [ABSTRACT FROM AUTHOR]

Wood Frogs (Rana sylvatica LeConte, 1825 = Lithobates sylvaticus (LeConte, 1825)) exhibit one of the most extreme freeze tolerance responses found in vertebrates. While extensive work is continuing to resolve the physiological mechanisms involved, few have studied the effects of freezing on locomotor performance. The ability to mount an appropriate locomotor response is vital, as locomotion can affect both survivorship and reproductive success. To investigate how the biomechanical processes during locomotion are altered following freezing, stroke cycle timings and kinematic performance were measured prior to and immediately following a freeze--thaw cycle. Additionally, the effects of cooling rate (0.3 versus 0.8 [degrees]C/h) were also assessed. While jumping and swimming performance were both reduced post-freeze, the effects were more pronounced during swimming, with observed reductions in velocity and distance travelled. Interestingly, these changes occurred largely independent of cooling rate. Altered stroke cycle timings and highly variable muscle activation/deactivation patterns suggest an impairment in muscle function as frogs continued to recover from the effects of freezing. This was supported by the physiology of frogs post-freeze, specifically, the persistence of elevated glucose levels in muscles important during locomotion. Collectively, these findings suggest that reductions in locomotor performance observed immediately following a freeze--thaw cycle are driven by alterations in muscle function. Key words: Wood Frog, Rana sylvatica, freeze tolerance, cryoprotectants, cooling rate, biomechanics, locomotion. R?sum?: Les grenouilles des bois (Rana sylvatica LeConte, 1825 = Lithobates sylvaticus (LeConte, 1825)) pr?sentent une des r?actions de tol?rance au gel les plus importantes observ?es chez les vert?br?s. Si des efforts consid?rables visent ? ?lucider les m?-canismes physiologiques qui interviennent dans cette r?action, les effets du gel sur la performance locomotrice n'ont pas re?u beaucoup d'attention. La capacit? de produire une r?action locomotrice convenable est cruciale puisque la locomotion peut avoir une incidence tant sur la survie que sur le succ?s de reproduction. Pour examiner l'influence du gel sur les processus biom?caniques durant la locomotion, la chronologie et la performance cin?matique des cycles de battement des pattes ont ?t? mesur?es avant et imm?diatement apr?s un cycle de gel-d?gel. Les effets du taux de refroidissement (0,3 et 0,8[degrees] C/h) ont ?galement ?t? ?valu?s. Si les performances de saut et de nage ?taient toutes deux r?duites apr?s le gel, les effets ?taient plus prononc?s durant la nage, des baisses de la vitesse et de la distance parcourue ?tant observ?es. Fait ? noter, ces changements sont en bonne partie ind?pendants du taux de refroidissement. La modification de la chronologie des cycles de battement et les motifs tr?s variables d'activation et de d?sactivation des muscles indiqueraient une d?gradation de la fonction musculaire pendant que les grenouilles se remettent des effets du gel. Ces observations sont appuy?es par la physiologie des grenouilles apr?s le gel, plus pr?cis?ment la persistance de teneurs ?lev?es en glucose dans les muscles importants durant la locomotion. Collectivement, ces constatations donnent ? penser que les r?ductions de la performance locomotrice observ?es imm?diatement apr?s un cycle de gel--d?gel d?coulent de modifications de la fonction musculaire. [Traduit par la R?daction] Mots-cl?s: grenouille des bois, Rana sylvatica, tol?rance au gel, cryoprotecteurs, taux de refroidissement, biom?canique, locomotion., Introduction Many animals cope with seasonally subzero ( Certain species can tolerate freezing (Storey and Storey 1987, 1988), relying largely on amassing high levels of cryoprotectants in tissues to discourage [...]

Bilateral symmetry has evolved from radial symmetry in several floral lineages, and multiple hypotheses have been proposed to account for the success of this floral plan. One of these hypotheses posits that bilateral symmetry (or, more generally, a reduced number of planes of floral symmetry) allows for more precise pollen placement on pollinators. Greater precision would maximize the efficacy of pollen transfer to conspecifics, while minimizing reproductive interference amongst plant species. Despite the intuitiveness of this hypothesis, it has little experimental support. Here, we tested whether a reduction in the number of floral planes of symmetry (as in the transition from radial to bilateral symmetry) increases the potential precision of pollen placement. We analyzed video recordings of bumblebees (Bombus impatiens ) visiting artificial flowers to determine whether consistency in flower entry angle differed between radial (round) and disymmetric (rectangular) "flowers". We observed more consistent entry angles for disymmetric flowers than for radial flowers, with entry angles to radial flowers 43% more variable on average (standard deviations of 30° vs. 21°). Bees trained on flowers with an intermediate (square) morphology exhibited a slight, non-significant preference for radial symmetry over disymmetry. Our results show that disymmetry--an evolutionarily intermediate form of floral symmetry--has the potential to increase pollen transfer to conspecific stigmas, relative to radial symmetry. Thus, evolutionary reduction in the number of planes of floral symmetry likely provides benefits in terms of pollen delivery, as suggested by the pollen-placement-accuracy hypothesis. These findings offer insight into the evolution of floral symmetry. [ABSTRACT FROM AUTHOR]

Understanding how animals select their mates requires knowing the factors that shape mate preferences. Recent theoretical and empirical considerations suggest that female mating status can influence the degree to which a female engages in mate choice, with virgin females predicted to be less choosy than mated females. In this study, we investigated mate choice in both virgin and mated females in the pygmy halfbeak Dermogenys collettei . Halfbeaks are small, live-bearing, internally fertilizing freshwater fish that live in mixed-sex groups where females have ample opportunity to engage in mate choice. Using a dichotomous choice assay, we quantified and contrasted in virgin and mated females mate preferences for differences in male body size, beak size, and area of yellow and red coloration. We also examined how mating status influenced the amount of time a female associated with the first male encountered and the relative amount of time a female associated with each male. We demonstrate that mate preferences of female halfbeaks are driven primarily by the size of red coloration present on males. Females showed contrasting preferences based on mating status, with virgin females preferentially associating with drab males whereas mated females preferentially associate with males possessing large areas of red. Contrary to expectations, female mating status did not influence how females associate with the first males encountered or how females biased their association time among males. Although the precise drivers of these effects need further studying, our finding highlights a possible explanation for how variation in male ornamentation can be maintained., (© The Author(s) (2019). Published by Oxford University Press on behalf of Editorial Office, Current Zoology.)

Juvenile rainbow trout ( Oncorhynchus mykiss) confined in pairs form social hierarchies in which socially subordinate fish display characteristic traits, including reduced growth rates and altered glucose metabolism. These effects are, in part, mediated by chronically elevated cortisol levels and/or reduced feeding. To determine the effects of social status on lipid metabolism, trout were held in pairs for 4 days, following which organismal and liver-specific indexes of lipid metabolism were measured. At the organismal level, circulating triglycerides were elevated in dominant trout, whereas subordinate trout exhibited elevated concentrations of circulating free fatty acids (FFAs) and lowered plasma total cholesterol levels. At the molecular level, increased expression of lipogenic genes in dominant trout and cpt1a in subordinate trout was identified, suggesting a contribution of increased de novo lipogenesis to circulating triglycerides in dominant trout and reliance on circulating FFAs for β-oxidation in the liver of subordinates. Given the emerging importance of microRNAs (miRNA) in the regulation of hepatic lipid metabolism, candidate miRNAs were profiled, revealing increased expression of the lipogenic miRNA-33 in dominant fish. Because the Akt-TOR-S6-signaling pathway is an important upstream regulator of hepatic lipid metabolism, its signaling activity was quantified. However, the only difference detected among groups was a strong increase in S6 phosphorylation in subordinate trout. In general, the changes observed in lipid metabolism of subordinates were not mimicked by either cortisol treatment or fasting alone, indicating the existence of specific, emergent effects of subordinate social status itself on this fuel.