まとめ
分子データを用いた人間の起源の研究は,人間,チンパンジー,ゴリラとの間のより密接な関係を示唆しています. 新しいヘモグロビン配列データは,進化の減速を示し,より長い分岐時間を支持しています.
科学分野:
- 進化生物学の進化生物学について
- 分子人類学 分子人類学
- 霊長類の遺伝学
背景:
- 分子データは,ヒトの起源の理解を再構築し,チンパンジーやゴリラをオランウータンよりも人間に近い位置にしました.
- 以前の分子時計の推定では,ホモとパンの間の最近 (1〜150万年前) の分岐が示唆されており,化石の証拠と矛盾している.
研究 の 目的:
- チンパンジー (Pan troglodytes),ゴリラ (Gorilla gorilla),ピグミーチンパンジー (Pan paniscus) のアルファおよびベータヘモグロビンアミノ酸配列を厳密に決定する.
- 精密なヘモグロビン配列データを用いて,ホミノイドの分岐時間と進化速度を再評価する.
主な方法:
- チンパンジー,ピグミーチンパンジー,ゴリラからのアルファ・ベータ・ヘモグロビンのアミノ酸配列解析.
- 進化樹を構成するために得られた配列データを用いた系統遺伝分析.
- 新しいデータから得られた分子時計の推定値と,以前の発見値の比較.
主要な成果:
- 研究されたホミノイドにおける重要なヘモグロビンタンパク質のアミノ酸配列を正確に決定した.
- 発見は,ホミノイドのヘモグロビン配列における減速した進化速度を支持する.
- 新しいデータは,いくつかの分子データから以前に推定されたよりも,ホミノイド系統の間の分岐時間が長いことを示唆しています.
結論:
- 減速した配列進化は,分子時計の推定値と化石記録の間の不一致の説明がより可能である.
- 自然選択は,進化の過程で,高度に機能するヘモグロビン分子を保存する上で重要な役割を果たしたのかもしれません.
- 精密な分子配列データは,人間と霊長類の進化史の理解を洗練するために不可欠です.
関連する概念動画
What is Evolutionary History?
Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and provides evidence for evolution. However, both fossil and living organisms offer evidence that outlines Earth’s evolutionary history.Phylogenetic trees illustrate the evolutionary relationships among these organisms. Scientists infer organisms’ common ancestry by evaluating shared morphological and genetic characteristics. Together, the fossil...
The Evidence for Evolution
Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.The collection of fossils within sedimentary rocks give a record of common ancestry and often depicts the history of evolution.
Convergent Evolution
Evolution shapes the features of organisms over time, ensuring that they are suited for the environments in which they live. Sometimes, selection pressure leads to the rise of similar but unrelated adaptations in organisms with no recent common ancestors, a process known as convergent evolution.The structures that arise from convergent evolution are called analogous structures. They are similar in function even if they are dissimilar in structure. Further, structures can be analogous while also...
Gene Families
Gene families consist of groups of genes proposed to have originated from a common ancestor. Typically these arise through events in which a gene or genes are mistakenly duplicated during cell division. Unlike their parent genes (which are subject to selection pressure to maintain function), these gene copies do not need to preserve their sequences and may evolve at a relatively faster rate.
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Occasionally these regions can be adapted to take on new roles within the organism, becoming novel genes...
Synteny and Evolution
John H. Renwick first coined the term “synteny” in 1971, which refers to the genes present on the same chromosomes, even if they are not genetically linked. The species with common ancestry tend to show conserved syntenic regions. Therefore, the concept of synteny is nowadays used to describe the evolutionary relationship between species.
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
Around 80 million years ago, the human and mice lineages diverged from the common ancestor. During the course of evolution, the ancestral chromosome underwent...
Gene Duplication and Divergence
The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.


