Symbiosis, Selection, and Novelty: Freshwater Adaptation in the Unique Sponges of Lake Baikal
Symbiosis, Selection, and Novelty: Freshwater Adaptation in the Unique Sponges of Lake Baikal
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DOI：
10.1093/molbev/msz151
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发表时间：
2019-11-01
影响因子：
10.7
通讯作者：
Itskovich, Valeria B.
中科院分区：
文献类型：
--
作者：
Kenny, Nathan J.;Plese, Bruna;Itskovich, Valeria B.
淡水海绵（Spongillida）是一个独特的谱系demosponges，其次殖民湖泊和河流，现在在这些生态系统中无处不在。他们发展了对淡水系统的特定适应能力，包括在极端温度范围内生存的能力，长期干燥，缺氧和对各种污染物的抵抗力。虽然海绵动物已经在所有的淡水系统中定居，但Lubomirskiidae家族是贝加尔湖特有的，在这个生态系统中发挥着一系列关键作用。我们的工作比较了三种Lubomirskiidae个体的基因组内容和微生物组，为分子进化如何使它们适应其独特的环境提供了假设。我们已经对三种Lubomirskiidae的深（>92%的后生动物“基准通用单拷贝直系同源物”[BUSCO]集）转录组和Lubomirskia baikalensis的基因组资源草案进行了测序。我们注意到贝加尔海绵含有单细胞藻类和细菌共生体，以及甲藻Gyrodinium。我们研究了分子进化，基因复制，并在淡水海绵与海洋血统相比的新奇。61个正群具有一致的正选择证据。运输工具（例如，锌转运蛋白-2）、转录因子（aristaless-related homeobox）和结构蛋白（例如肌动蛋白-3），以及其他基因，在淡水中处于强大的进化压力下，在海绵动物中，尤其是在Lubomirskiidae中，复制驱动了新奇。淡水海绵遗传学知识的增加为理解分子生物学和未来的生态学提供了一系列工具（例如，移民和迁徙模式）。
Freshwater sponges (Spongillida) are a unique lineage of demosponges that secondarily colonized lakes and rivers and are now found ubiquitously in these ecosystems. They developed specific adaptations to freshwater systems, including the ability to survive extreme thermal ranges, long-lasting dessication, anoxia, and resistance to a variety of pollutants. Although spongillids have colonized all freshwater systems, the family Lubomirskiidae is endemic to Lake Baikal and plays a range of key roles in this ecosystem. Our work compares the genomic content and microbiome of individuals of three species of the Lubomirskiidae, providing hypotheses for how molecular evolution has allowed them to adapt to their unique environments. We have sequenced deep (>92% of the metazoan "Benchmarking Universal Single-Copy Orthologs" [BUSCO] set) transcriptomes from three species of Lubomirskiidae and a draft genome resource for Lubomirskia baikalensis. We note Baikal sponges contain unicellular algal and bacterial symbionts, as well as the dinoflagellate Gyrodinium. We investigated molecular evolution, gene duplication, and novelty in freshwater sponges compared with marine lineages. Sixty one orthogroups have consilient evidence of positive selection. Transporters (e.g., zinc transporter-2), transcription factors (aristaless-related homeobox), and structural proteins (e.g. actin-3), alongside other genes, are under strong evolutionary pressure in freshwater, with duplication driving novelty across the Spongillida, but especially in the Lubomirskiidae. This addition to knowledge of freshwater sponge genetics provides a range of tools for understanding the molecular biology and, in the future, the ecology (e.g., colonization and migration patterns) of these key species.