Sexual conflict and sexual pleiotropy.

Abstract

Natural selection might favour brightly coloured males and drab females. A male and a female might disagree about whether to mate. Such tensions are often described as 'sexual conflict' of two forms: intralocus and interlocus. However, this framing unites two very different evolutionary processes: genetic constraint and social conflict, in which male and female fitness are linked by shared genetics or by shared social interactions, respectively. We suggest that coupling both under the banner of 'sexual conflict' is not justified and impedes progress. This problem has become acute as researchers explore the mechanistic underpinnings of both phenomena and as conflation emerges in other research. We propose that a conceptual uncoupling of 'sexual conflict' into true sexual conflict and sexual pleiotropy is needed. Here, we (i) clarify the distinction between conflict and pleiotropy, using evolutionary theory; (ii) show how current conceptual coupling has led to faulty predictions, misdirected research efforts and missed opportunities; (iii) detail how interlocus and intralocus terms have added to confusion; and (iv) establish links with other areas of biology. We show the potential scientific advances that can emerge from disentangling conflict and pleiotropy in biodiversity, molecular genetic and ecological research.