Fin whale song evolution in the North Atlantic.

Animal songs can change within and between populations as the result of different evolutionary processes. When these processes include cultural transmission, the social learning of information or behaviours from conspecifics, songs can undergo rapid evolutions because cultural novelties can emerge more frequently than genetic mutations. Understanding these song variations over large temporal and spatial scales can provide insights into the patterns, drivers and limits of song evolution that can ultimately inform on the species' capacity to adapt to rapidly changing acoustic environments. Here, we analysed changes in fin whale (Balaenoptera physalus) songs recorded over two decades across the central and eastern North Atlantic Ocean. We document a rapid replacement of song INIs (inter-note intervals) over just four singing seasons, that co-occurred with hybrid songs (with both INIs), and a clear geographic gradient in the occurrence of different song INIs during the transition period. We also found gradual changes in INIs and note frequencies over more than a decade with fin whales adopting song changes. These results provide evidence of vocal learning in fin whales and reveal patterns of song evolution that raise questions on the limits of song variation in this species.

Administration of loperamide and addition of wheat bran to the diets of weaner pigs decrease the incidence of diarrhoea and enhance their gut maturation.

The influence of fibre inclusion and transit time regulation on the performance, health status, microbial activity and population, physico-chemical characteristics of the hindgut digesta and intestinal morphology in early weaned pigs were examined. For these experiments, wheat bran (WB) was used as fibre source and loperamide as a drug (LOP) to increase the digesta transit time. In Expt 1, a total of 128 early weaned pigs were randomly distributed in a 2 x 2 factorial combination of WB inclusion (0 v. 40 g/kg) and LOP administration (0 v. 0.07 mg/kg body weight) during 13 d. For Expt 2, a total of twenty-four piglets were allotted to three dietary treatments for 15 d with the same basal diet (control diet) as Expt 1; a diet with 80 g/kg of WB and the combination of WB and LOP. In Expt 1, LOP improved the average daily feed intake and average daily gain of the animals (P = 0.001 and 0.007, respectively). The same result was obtained when WB was combined with LOP. The WB-LOP group also showed a higher concentration of SCFA (P = 0.013), acetic acid (P = 0.004) and propionic acid (P = 0.093). On the other hand, WB inclusion reduced the organic matter and crude protein digestibility (P = 0.001) and tended to decrease the enterobacteria population (P = 0.089). In Expt 2, WB increased the butyric acid concentration (P = 0.086). We concluded that the inclusion of WB to modify the intestinal microbiota activity combined with LOP may be beneficial to animal health and performance.