Fitzpatrick Courtney, Ciresi Colette M, Wade Michael J
Department of Biology Indiana University Bloomington IN USA.
Ecol Evol. 2021 Jan 12;11(3):1165-1174. doi: 10.1002/ece3.7058. eCollection 2021 Feb.
We investigate the evolution of a gene for paternal care, with pleiotropic effects on male mating fitness and offspring viability, with and without extrapair copulations (EPCs). We develop a population genetic model to examine how pleiotropic effects of a male mating advantage and paternal care are affected by "good genes" and EPCs. Using this approach, we show that the relative effects of each on fitness do not always predict the evolutionary change. We then find the line of combinations of mating success and paternal care that bisects the plane of possible values into regions of positive or negative gene frequency change. This line shifts when either good genes or EPCs are introduced, thereby expanding or contracting the region of positive gene frequency change and significantly affecting the evolution of paternal care. Predictably, a direct viability effect of "good genes" that enhances offspring viability constrains or expands the parameter space over which paternal care can evolve, depending on whether the viability effect is associated with the paternal care allele or not. In either case, the effect of a "good gene" that enhances offspring viability is substantial; when strong enough, it can even facilitate the evolution of paternal care, where males harm their young. When nonrandom mating is followed by random EPCs, the genetic regression between sire and offspring is reduced and, consequently, the relative strengths of selection are skewed away from paternal care and toward the male mating advantage. However, when random mating is followed by nonrandom EPCs, a situation called "trading up" by females, we show that selection is skewed in the opposite direction, away from male mating advantage and toward paternal care across the natural range of EPC frequencies.
我们研究了一种亲代抚育基因的进化情况，该基因对雄性交配适合度和后代存活力具有多效性，同时考虑了有无婚外交配（EPCs）的情况。我们建立了一个群体遗传模型，以检验雄性交配优势和亲代抚育的多效性如何受到“优质基因”和EPCs的影响。通过这种方法，我们表明它们各自对适合度的相对影响并不总是能预测进化变化。然后，我们找到了交配成功和亲代抚育的组合线，这条线将可能值的平面一分为二，形成基因频率正向或负向变化的区域。当引入优质基因或EPCs时，这条线会发生移动，从而扩大或缩小基因频率正向变化的区域，并显著影响亲代抚育的进化。可以预见，“优质基因”对后代存活力的直接影响会限制或扩大亲代抚育能够进化的参数空间，这取决于这种存活力影响是否与亲代抚育等位基因相关。在任何一种情况下，增强后代存活力的“优质基因”的影响都是巨大的；当这种影响足够强大时，甚至可以促进雄性伤害幼崽的亲代抚育的进化。当非随机交配之后是随机的EPCs时，父本与后代之间的遗传回归会降低，因此，选择的相对强度会偏离亲代抚育，而倾向于雄性交配优势。然而，当随机交配之后是非随机的EPCs时，即雌性所谓的“升级交配”情况，我们表明选择会向相反的方向倾斜，在EPC频率的自然范围内，从雄性交配优势转向亲代抚育。
