グレゴールメンデル植物学者

理論的解釈

メンデルはさらに彼の結果を受精の細胞理論に関連付けました。それによれば、新しい生物は2つの細胞の融合から生成されます。優性型と劣性型の両方の純粋な繁殖形態をハイブリッドに導入するために、ハイブリッド内の2つの異なる特性の一時的な調整と、花粉細胞の形成における分離プロセスが必要でした。卵細胞。言い換えれば、ハイブリッドは、1つの特性または他の特性のいずれかを生み出す可能性がある生殖細胞を形成しなければなりません。これは、分離の法則、または生殖細胞の純度の法則として説明されてきました。 1つの花粉細胞が1つの卵細胞と融合するため、異なる花粉と卵細胞の考えられるすべての組み合わせは、メンデルの組み合わせ理論によって示唆された結果のみを生み出します。

メンデルは最初に1865年に2つの別々の講義で彼の結果をブレンの自然科学協会に発表しました。彼の論文「植物ハイブリッドに関する実験」は、翌年のブリュンの社会誌、Verhandlungen des naturforschenden Vereinesに掲載されました。多くの図書館がそれを受け取り、再版を送りましたが、それはほとんど注目を集めませんでした。それを読んだ人の傾向は、メンデルがすでに広く想定されていることをより正確に実証しただけであると結論する傾向にありました。彼らは変動の可能性と、形質の組み換えの彼の実証が可能にした進化的含意を見落としていた。最も注目に値するのは、スイスの植物学者カールヴィルヘルムフォンネーゲリが実際にメンデルと通信したことです。彼の結果の重要性に関して懐疑的であり続け、雑種の生殖細胞が純粋であるかもしれないことを疑ったにもかかわらず。

Latter years

Mendel appears to have made no effort to publicize his work, and it is not known how many reprints of his paper he distributed. He had ordered 40 reprints, the whereabouts of only eight of which are known. Other than the journal that published his paper, 15 sources are known from the 19th century in which Mendel is mentioned in the context of plant hybridization. Few of these provide a clear picture of his achievement, and most are very brief.

By 1871 Mendel had only enough time to continue his meteorological and apicultural work. He traveled little, and his only visit to England was to see the Industrial Exhibition in 1862. Bright disease made his last years painful, and he died at the age of 61. Mendel’s funeral was attended by many mourners and proceeded from the monastery to the monastery’s burial plot in the town’s central cemetery, where his grave can be seen today. He was survived by two sisters and three nephews.

Rediscovery

In 1900 Dutch botanist and geneticist Hugo de Vries, German botanist and geneticist Carl Erich Correns, and Austrian botanist Erich Tschermak von Seysenegg independently reported results of hybridization experiments similar to Mendel’s, though each later claimed not to have known of Mendel’s work while doing their own experiments. However, both de Vries and Correns had read Mendel earlier—Correns even made detailed notes on the subject—but had forgotten. De Vries had a diversity of results in 1899, but it was not until he reread Mendel in 1900 that he was able to select and organize his data into a rational system. Tschermak had not read Mendel before obtaining his results, and his first account of his data offers an interpretation in terms of hereditary potency. He described the 3:1 ratio as an “unequal valancy” (Wertigkeit). In subsequent papers he incorporated the Mendelian theory of segregation and the purity of the germ cells into his text.

In Great Britain, biologist William Bateson became the leading proponent of Mendel’s theory. Around him gathered an enthusiastic band of followers. However, Darwinian evolution was assumed to be based chiefly on the selection of small, blending variations, whereas Mendel worked with clearly nonblending variations. Bateson soon found that championing Mendel aroused opposition from Darwinians. He and his supporters were called Mendelians, and their work was considered irrelevant to evolution. It took some three decades before the Mendelian theory was sufficiently developed to find its rightful place in evolutionary theory.

The distinction between a characteristic and its determinant was not consistently made by Mendel or by his successors, the early Mendelians. In 1909 Danish botanist and geneticist Wilhelm Johannsen clarified this point and named the determinants genes. Four years later American zoologist and geneticist Thomas Hunt Morgan located the genes on the chromosomes, and the popular picture of them as beads on a string emerged. This discovery had implications for Mendel’s claim of an independent transmission of traits, for genes close together on the same chromosome are not transmitted independently. Moreover, as genetic studies pushed the analysis down to smaller and smaller dimensions, the Mendelian gene appeared to fragment. Molecular genetics has thus challenged any attempts to achieve a unified conception of the gene as the elementary unit of heredity. Today the gene is defined in several ways, depending upon the nature of the investigation. Genetic material can be synthesized, manipulated, and hybridized with genetic material from other species, but to fully understand its functions in the whole organism, an understanding of Mendelian inheritance is necessary. As the architect of genetic experimental and statistical analysis, Mendel remains the acknowledged father of genetics.