Ferreira Mafalda S, Alves Paulo C, Callahan Colin M, Giska Iwona, Farelo Liliana, Jenny Hannes, Mills L Scott, Hackländer Klaus, Good Jeffrey M, Melo-Ferreira José
CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos InBIO Laboratório Associado Universidade do Porto Vairão Portugal.
Departamento de Biologia Faculdade de Ciências da Universidade do Porto Porto Portugal.
Ecol Evol. 2020 Jan 15;10(3):1180-1192. doi: 10.1002/ece3.5956. eCollection 2020 Feb.
Color molts from summer brown to winter white coats have evolved in several species to maintain camouflage year-round in environments with seasonal snow. Despite the eco-evolutionary relevance of this key phenological adaptation, its molecular regulation has only recently begun to be addressed. Here, we analyze skin transcription changes during the autumn molt of the mountain hare () and integrate the results with an established model of gene regulation across the spring molt of the closely related snowshoe hare (). We quantified differences in gene expression among three stages of molt progression-"brown" (early molt), "intermediate," and "white" (late molt). We found 632 differentially expressed genes, with a major pulse of expression early in the molt, followed by a milder one in late molt. The functional makeup of differentially expressed genes anchored the sampled molt stages to the developmental timeline of the hair growth cycle, associating anagen to early molt and the transition to catagen to late molt. The progression of color change was characterized by differential expression of genes involved in pigmentation, circadian, and behavioral regulation. We found significant overlap between differentially expressed genes across the seasonal molts of mountain and snowshoe hares, particularly at molt onset, suggesting conservatism of gene regulation across species and seasons. However, some discrepancies suggest seasonal differences in melanocyte differentiation and the integration of nutritional cues. Our established regulatory model of seasonal coat color molt provides an important mechanistic context to study the functional architecture and evolution of this crucial seasonal adaptation.
在一些物种中，毛色从夏季的棕色转变为冬季的白色，以便在有季节性降雪的环境中全年保持伪装。尽管这种关键的物候适应具有生态进化意义，但其分子调控直到最近才开始得到研究。在此，我们分析了山兔秋季换毛期间皮肤的转录变化，并将结果与已建立的关于近缘种雪靴兔春季换毛的基因调控模型相结合。我们量化了换毛过程三个阶段——“棕色”（换毛早期）、“中间期”和“白色”（换毛后期）之间的基因表达差异。我们发现了632个差异表达基因，换毛早期有一个主要的表达脉冲，随后在换毛后期有一个较温和的脉冲。差异表达基因的功能构成将所采样的换毛阶段与毛发生长周期的发育时间线联系起来，将生长期与换毛早期相关联，而向退行期的转变与换毛后期相关联。毛色变化的进程以参与色素沉着、昼夜节律和行为调控的基因的差异表达为特征。我们发现山兔和雪靴兔季节性换毛过程中差异表达基因之间存在显著重叠，特别是在换毛开始时，这表明跨物种和季节的基因调控具有保守性。然而，一些差异表明黑素细胞分化和营养信号整合存在季节性差异。我们建立的季节性毛色换毛调控模型为研究这种关键的季节性适应的功能结构和进化提供了重要的机制背景。
