Abstract:
After environmental change, the trait evolution needed to rescue a population depends on the functional form of the plastic change (reaction norm) of that trait. Nearly all previous models of plasticity evolution for continuous traits have assumed that the functional form is linear, i.e., no limits on the range of plasticity. This paper examines the effect of developmental limits, modeled as a sigmoidal reaction norm, on evolutionary rescue after an abrupt environmental change and the subsequent evolution of plasticity, including genetic assimilation. We examined four different scenarios: (1) developmental limits only, (2) developmental limits plus a cost of plasticity, (3) developmental limits with developmental noise, and (4) developmental limits plus environmental variation. The probability of evolutionary rescue increased with an increase in phenotypic variation allowed by plastic development. With a smaller limit to the range of the plastic phenotype, the evolution of adaptive plasticity was limited, meaning the evolution of non-plastic genes was necessary. The addition of developmental constraints to the model did not speed up genetic assimilation, suggesting new theory is needed to understand empirical observations. The modeling framework presented here could be extended to different ecological and evolutionary conditions, alternative reaction norm shapes, the evolution of additional reaction norm parameters such as the range or the location of the inflection point on the environmental axis, or other function-valued traits.
摘要:
环境变化后,拯救种群所需的性状进化取决于该性状的可塑性变化(反应规范)的功能形式。几乎所有先前的连续性状可塑性演化模型都假设功能形式是线性的,即,对塑性的范围没有限制。本文研究了发育极限的影响,建模为S形反应范数,在环境突变和随后的可塑性进化后的进化拯救中,包括遗传同化。我们研究了四种不同的情况:(1)仅发育极限,(2)发育限制加上可塑性成本,(3)具有发育噪声的发育限制,(4)发育极限加环境变化。随着塑料发育所允许的表型变异的增加,进化拯救的可能性增加。塑料表型范围的限制较小,适应性可塑性的进化是有限的,这意味着非可塑性基因的进化是必要的。在模型中添加发育约束并没有加速遗传同化,建议需要新的理论来理解经验观察。这里提出的建模框架可以扩展到不同的生态和进化条件,替代反应范数形状,其他反应范数参数的演变,如拐点在环境轴上的范围或位置,或其他功能值特征。