カンブリア期に由来する管状腸内膜
Jean-Bernard Caron1, Simon Conway Morris, Christopher B Cameron
1Department of Natural History (Palaeobiology), Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada. jcaron@rom.on.ca
Nature
|March 15, 2013
まとめ
新しく発見されたカンブリア時代の化石,Spartobranchus tenuisは,虫のような祖先から進化したヘミコルドを明らかにしています. この発見は,エンテロプネウストとペトロブランクとの間の進化的つながりを明らかにし,初期デウテロストームの発達に光を当てます.
科学分野:
- パレオントロジー・パレオントロジー
- 進化生物学の進化生物学について
- マリン・バイオロジー マリン・バイオロジー
背景:
- エントロプネウストとペトロブランクを含むヘミコルド類は,初期の動物の進化を理解するために不可欠な海洋デウテロストームです.
- ヘミコルド類内の系統遺伝的関係と,エンテロプネウスト類とペトロブランク類の間の移行は,歴史的に議論されてきた.
- ヘミコルド類,特にエンテロプネウスト類の化石記録は稀で,進化論的な洞察を妨げています.
研究 の 目的:
- ブルゲス・シェイルの新しい中カンブリア期の腸肺化石,Spartobranchus tenuisを記述する.
- 化石の証拠を用いて,エンテロプネウストとペトロブランクとの進化的つながりを調査する.
- ヘミコーダテスの起源と初期の進化についての洞察を提供するためです.
主な方法:
- 化石のSpartobranchus tenuis.の詳細な形態学的記述と分析について
- 化石の形状を,現存するヘミコルド群 (エンテロプネウスト,ペトロブランク) と比較.
- 形態学的特徴と推論された進化的移行に基づく系統遺伝的解釈.
主要な成果:
- Spartobranchus tenuisは,現存するハリマニド・エンテロプネウストに著しい類似性を示しています.
- 化石は繊維状の管と関連しており,ペテロブランク型ペリデルムの前身であると解釈されています.
- この発見は,ペトロブランクが,小型化と食する触角の発達を通じて,より大きくて,腸鼻状の祖先から進化したという仮説を裏付けている.
結論:
- Spartobranchus tenuisは,ハリマニド-ペトロブランク移行の重要な証拠を提供し,ペトロブランクがエンテロプネウストから派生したと示唆しています.
- 周皮は,大きさの縮小と触角の獲得がペテロブランクスに起こる前に進化した.
- カンブリア期中期におけるエンテロプネウストとペトロブランクの両方の存在は,カンブリア爆発の開始時のヘミコルド系の起源を示唆する.
関連する概念動画
01:26Bacterial Phylum Planctomycetes
564
Planctomycetes are a group of morphologically distinct bacteria predominantly classified into two orders: Planctomycetales and Brocadiales. These gram-negative bacteria exhibit unique features, including division by budding and the presence of stalks or appendages. Their cells are often found in rosette arrangements, and they are notable for possessing an S-layer in their cell envelope, which is relatively uncommon among bacteria. Additionally, Planctomycetes frequently exhibit intracellular...
564
01:30Bacterial Phylum Spirochaetes
1.5K
Spirochetes, unique bacteria in the phylum Spirochaetes, are gram-negative, motile, tightly coiled, slender, and flexible. They inhabit aquatic sediments and animals, with some causing diseases like syphilis. Spirochetes are classified into eight genera based on habitat, pathogenicity, phylogeny, and characteristics.Their distinctive motility arises from endoflagella, located within the cell’s periplasm. These endoflagella anchor at the cell poles and extend along the cell length, encased...
1.5K
01:30Bacterial Phylum Actinobacteria
854
Coryneform bacteria are gram-positive, aerobic, nonmotile rods that exhibit irregular, club-shaped, or V-shaped arrangements. Their V-shape results from snapping division, where the inner cell wall layer forms the cross-wall, while the outer layer remains intact until it ruptures on one side, causing the daughter cells to bend away.The primary genera are Corynebacterium and Arthrobacter. Corynebacterium includes diverse species, ranging from saprophytes to pathogens like Corynebacterium...
854
01:15Diversity of Protists I
2.3K
Excavata is a diverse group of protists that includes both chemoorganotrophic and phototrophic species, with some thriving in anaerobic environments. Among the key groups within Excavata are diplomonads and parabasalids, which are flagellated protists that lack mitochondria and chloroplasts. These microorganisms typically inhabit anoxic environments, such as the intestines of animals, where they exist either symbiotically or as parasites, relying on fermentation for energy production. Some...
2.3K
01:27Diversity of Protists II
2.3K
Alveolates are a group of organisms recognized by the presence of alveoli, which are cytoplasmic sacs located beneath the cell membrane. While their function remains uncertain, alveoli may help regulate water balance by controlling how much water enters and leaves the cell. In dinoflagellates, these structures may serve as armor plates. There are three major types of alveolates: ciliates, which move using cilia; dinoflagellates, which use flagella for movement; and apicomplexans, which are...
2.3K
01:27Diversity of Protists III
2.1K
Rhizaria are a diverse group of unicellular protists characterized by their threadlike cytoplasmic extensions known as pseudopodia. These structures aid in both locomotion and feeding, giving Rhizaria an amoeboid appearance. Their amoeboid morphology once led to taxonomic confusion, but molecular phylogenetics has clarified their evolutionary placement and emphasized their shared use of pseudopodia despite divergent lineages.This clade comprises diverse lineages such as Chlorarachniophyta,...
2.1K