High Gene Expression Predicts Extremely Low Segregation of Deleterious Mutations in Large Penguin Populations.

Purifying selection is the most pervasive type of selection, as it constantly removes deleterious mutations arising in populations, directly scaling with population size. Highly expressed genes appear to accumulate fewer nonsynonymous mutations between divergent species' lineages (known as E-R anticorrelation), pointing toward gene expression as an additional component modulating the selection coefficient of protein-coding mutations. However, estimates of the effect of gene expression on segregating deleterious variants in natural populations are scarce, as is an understanding of the relative contribution of population size and gene expression to purifying selection.

Evolutionary Dynamics of Transposable Element Activity and Regulation in the Apennine Yellow-Bellied Toad (Bombina pachypus).

Transposable elements (TEs) expansion and accumulation represent one of the main drivers of genomic gigantism. Different host genome silencing mechanisms have evolved to counteract TE amplification, leading to a genomic arms race between them. Nevertheless, the evolutionary relationship between TEs and host genome silencing pathways remains poorly understood.

Selection-driven adaptation to the extreme Antarctic environment in the Emperor penguin.

The eco-evolutionary history of penguins is characterised by shifting from temperate to cold environments. Breeding in Antarctica, the Emperor penguin appears as an extreme outcome of this process, with unique features related to insulation, heat production and energy management. However, whether this species actually diverged from a less cold-adapted ancestor, more ecologically similar to its sister species, the King penguin, is still an open question.