Disentangling Positive Selection from Relaxed Selection in Animal Mitochondrial Genomes.

AbstractDisentangling different types of selection is a common goal in molecular evolution. Elevated dN/dS ratios (the ratio of nonsynonymous to synonymous substitution rates) in focal lineages are often interpreted as signs of positive selection. Paradoxically, relaxed purifying selection can also result in elevated dN/dS ratios, but tests to distinguish these two causes are seldomly implemented. Here, we reevaluated seven case studies describing elevated dN/dS ratios in animal mitochondrial DNA (mtDNA) and their accompanying hypotheses regarding selection. They included flightless lineages versus flighted lineages in birds, bats, and insects and physiological adaptations in snakes, two groups of electric fishes, and primates. We found that elevated dN/dS ratios were often not caused by the predicted mechanism, and we sometimes found strong support for the opposite mechanism. We discuss reasons why energetic hypotheses may be confounded by other selective forces acting on mtDNA and caution against overinterpreting singular molecular signals, including elevated dN/dS ratios.

Trust over the transition to parenthood: Links to attachment, perception of partner's caregiving, and parenting.

We examined couples' dyadic trust profiles over the transition to parenthood and their associations with couples' attachment representations, perceptions of partner's caregiving, and parenting quality. We followed 125 couples from pregnancy to 24 months postpartum and applied the latent profile analysis (LPA) to examine whether distinct dyadic patterns of trust would emerge among couples. We then examined couples' attachment representations and perceptions of partner's caregiving as factors that might explain their trust profiles. Finally, we examined how couples' trust profiles would be related to their parenting quality 24 months postpartum. The dyadic LPA yielded three trust profiles: a both high profile (N = 64), a mother high, father moderate profile (N = 42), and a mother moderate to low, father moderate profile (N = 19). Mothers with dismissing attachment were able to hold high-stable trust when their partner also held high trust toward them, whereas mothers with preoccupied attachment, in general, were likely to have low and declining trust over time. Mothers' more positive perceptions of their husband's caregiving quality were also related to their high-stable trust over time. Mothers' high trust, in turn, was associated with their less emotionally disengaged and less role-reversed parenting. The findings highlight mothers' important role in couples' dyadic trust over the transition to parenthood. Implications of study findings are discussed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).