Animal and plant species exhibit an astonishing diversity of sexual systems, including environmental and genetic determinants of sex, with the latter including genetic material in the mitochondrial genome. In several hermaphroditic plants for example, sex is determined by an interaction between mitochondrial cytoplasmic male sterility (CMS) genes and nuclear restorer genes. Specifically, CMS involves aberrant mitochondrial genes that prevent pollen development and specific nuclear genes that restore it, leading to a mixture of female (male‐sterile) and hermaphroditic individuals in the population (...) (gynodioecy). Such a mitochondrial‐nuclear sex determination system is thought to be rare outside plants. Here, we present one possible case of CMS in animals. We hypothesize that the only exception to the strict maternal mtDNA inheritance in animals, the doubly uniparental inheritance (DUI) system in bivalves, might have originated as a mitochondrial‐nuclear sex‐determination system. We document and explore similarities that exist between DUI and CMS, and we propose various ways to test our hypothesis. (shrink)

The current work builds a definition of irritability from both academic definitions and lay perspectives. In Study 1, a quantitative content analysis of academic definitions resulted in eight main content categories (i.e., behaviour, emotion or affect, cognition, physiological, qualifiers, irritant, stability or endurance, and other). In Study 2, a community sample of 39 adults participated in qualitative interviews. A deductive thematic analysis resulted in two main themes. The first main theme dealt with how participants positioned irritability in relation to other (...) negative states. The second dealt with how participants constructed irritability as both a loss of control and as an experience that should be controlled. The discussion integrates the findings of both studies and provides a concise, but comprehensive definition. (shrink)