Data_Sheet_3_Ecology and Evolution of Gall-Inducing Arthropods: The Pattern From the Terrestrial Fossil Record.docx

Insect and mite galls on land plants have a spotty but periodically rich and abundant fossil record of damage types (DTs), ichnotaxa, and informally described gall morphotypes. The earliest gall is on a liverwort of the Middle Devonian Period at 385 million years ago (Ma). A 70-million-year-long absence of documented gall activity ensues. Gall activity resumes during the Pennsylvanian Period (315 Ma) on vegetative and reproductive axial organs of horsetails, ferns, and probably conifers, followed by extensive diversification of small, early hemipteroid galler lineages on seed-plant foliage during the Permian Period. The end-Permian (P-Tr) evolutionary and ecological crisis extinguished most gall lineages; survivors diversified whose herbivore component communities surpassed pre-P-Tr levels within 10 million years in the mid-to late Triassic (242 Ma). During the late Triassic and Jurassic Period, new groups of galling insects colonized Ginkgoales, Bennettitales, Pinales, Gnetales, and other gymnosperms, but data are sparse. Diversifying mid-Cretaceous (125–90 Ma) angiosperms hosted a major expansion of 24 gall DTs organized as herbivore component communities, each in overlapping Venn-diagram fashion on early lineages of Austrobaileyales, Laurales, Chloranthales, and Eurosidae for the Dakota Fm (103 Ma). Gall diversification continued into the Ora Fm (92 Ma) of Israel with another 25 gall morphotypes, but as ichnospecies on a different spectrum of plant hosts alongside the earliest occurrence of parasitoid attack. The End-Cretaceous (K-Pg) extinction event (66 Ma) almost extinguished host–specialist DTs; surviving gall lineages expanded to a pre-K-Pg level 10 million years later at the Paleocene-Eocene Thermal Maximum (PETM) (56 Ma), at which time a dramatic increase of land surface temperatures and multiplying of atmospheric pCO2 levels induced a significant level of increased herbivory, although gall diversity increased only after the PETM excursion and during the Early Eocene Climatic Optimum (EECO). After the EECO, modern (or structurally convergent) gall morphotypes originate in the mid-Paleogene (49–40 Ma), evidenced by the Republic, Messel, and Eckfeld floras on hosts different from their modern analogs. During subsequent global aridification, the early Neogene (20 Ma) Most flora of the Czech Republic records several modern associations with gallers and plant hosts congeneric with their modern analogs. Except for 21 gall DTs in New Zealand flora, the gall record decreases in richness, although an early Pleistocene (3 Ma) study in France documents the same plant surviving as an endemic northern Iran but with decreasing associational, including gall, host specificity.

陆生植物上的昆虫与螨类虫瘿（gall）拥有一套零散但时而丰富充沛的化石记录，涵盖损伤类型（damage types, DTs）、遗迹分类群（ichnotaxa）以及非正式描述的虫瘿形态型（gall morphotypes）。已知最早的虫瘿发现于距今3.85亿年前（Ma）的中泥盆世苔类植物上，随后出现了长达7000万年的虫瘿活动记录空白期。宾夕法尼亚亚纪（3.15亿年前，Ma）时，虫瘿活动重现，当时木贼类、蕨类以及可能的松柏类植物的营养与生殖轴器官上均出现虫瘿；随后在二叠纪，种子植物叶片上出现了小型早期半翅类造瘿昆虫支系的大规模辐射演化。二叠纪末（P-Tr，二叠纪-三叠纪灭绝事件）的演化与生态危机导致绝大多数虫瘿昆虫支系灭绝；幸存支系在中晚三叠世（2.42亿年前，Ma）的1000万年内实现辐射演化，其植食性组分群落规模超过了二叠纪末灭绝前的水平。晚三叠世至侏罗纪时期，新的造瘿昆虫类群相继侵染银杏目（Ginkgoales）、本内苏铁目（Bennettitales）、松杉目（Pinales）、买麻藤目（Gnetales）以及其他裸子植物，但相关化石记录十分匮乏。处于辐射演化阶段的早白垩世中期（1.25亿~0.90亿年前，Ma）被子植物（angiosperm），承载了24种虫瘿损伤类型的大规模扩张，这些损伤类型构成了植食性组分群落，且以重叠的维恩图模式分布于木兰藤目（Austrobaileyales）、樟目（Laurales）、金粟兰目（Chloranthales）以及真双子叶植物（Eurosidae）的早期支系上，该记录来自达科他组（Dakota Formation, Dakota Fm，1.03亿年前，Ma）。虫瘿的辐射演化延续至以色列的奥拉组（Ora Formation, Ora Fm，0.92亿年前，Ma），当时又出现了25种新的虫瘿形态型，但这些形态型是以遗迹种（ichnospecies）的形式出现在不同类群的寄主植物上，同时伴随有已知最早的寄生性攻击（parasitoid attack）记录。白垩纪末（K-Pg，白垩纪-古近纪灭绝事件，0.66亿年前，Ma）灭绝事件几乎彻底消灭了寄主专化性的虫瘿损伤类型；幸存的虫瘿昆虫支系在1000万年后的古新世-始新世极热事件（Paleocene-Eocene Thermal Maximum, PETM，0.56亿年前，Ma）时恢复至白垩纪末灭绝前的规模，彼时地表温度急剧升高、大气二氧化碳分压（pCO₂）倍增，引发了植食性活动的显著增强，但虫瘿多样性仅在极热事件波动期及始新世早期气候最适宜期（Early Eocene Climatic Optimum, EECO）后才实现增长。始新世早期气候最适宜期过后，现代（或结构趋同的）虫瘿形态型在古近纪中期（0.49亿~0.40亿年前，Ma）开始出现，相关化石证据来自美国共和植物群、德国梅塞尔植物群以及埃克费尔德植物群，其寄主植物与现生对应类群并不相同。在随后的全球干旱化过程中，捷克共和国早中新世（0.20亿年前，Ma）的莫斯特植物群（Most flora）记录了多组现代造瘿昆虫与寄主植物的共生关系，其寄主植物属于与现生同类同属的类群。除新西兰植物群中记录的21种虫瘿损伤类型外，全球虫瘿化石记录的丰富度均呈下降趋势；尽管法国早更新世（0.03亿年前，Ma）的一项研究记录到，一种在伊朗北部为特有种的植物仍存活至今，但该植物的共生关系（包括虫瘿相关的寄主专一性）正逐渐减弱。