世界の博物館の生物標本、雄に偏り　英研究

【パリＡＦＰ＝時事】世界の博物館に所蔵されている鳥や哺乳類などの生物標本が雄に偏っていると指摘する研究結果が23日、明らかになった。（写真は資料写真）
　英ロンドン自然史博物館生命科学部門の研究員ナタリー・クーパー氏のチームは、世界５か所の博物館が所蔵する標本約２５０万点を分析した。中には１００年以上前に作製されたものも含まれていた。
　鳥類の標本のうち約半数は性別が確認されていなかったが、識別されていた中では雌は４０％だけだった。一方、哺乳類の標本では、性別が確認されているもののうち雌は４８％だった。
　クーパー氏はＡＦＰに対し「雄を標本にしようという傾向がいくらかあったのではないか。科学を行っているのは人間で、人間は男性への固有バイアスを持っているからだ」と述べた。
　クーパー氏は１３０年前に作製された標本と最近の標本を比べて、雌と雄の比率がほとんど変わっていない事実に驚いたという。「１９世紀の博物館では標本の収集者はほとんど男性だったが、それは変わりつつある。しかし今でも男性中心の分野だ」
　標本の作製方法が、問題の一部を担っている可能性もある。雄は体がより大きかったり、より目立ったりするために、見つけやすく採取されやすい場合があるからだ。
　しかし今回の研究によると、雌の方が雄よりも大きかったり、派手な姿をしたりしている種でも、雌の標本が占める平均比率は４４．６％にすぎなかった。角、枝角、牙などの「飾り」を持つ哺乳類では、雌が同様の飾りを持つ場合でも、標本の収集者は雄を選んでいた。
　収集者が「飾りを持つ雄」を好む傾向は鳥類でもみられた。雌よりも色彩が豊かだったり、飾りが目立ったりする雄が、特に熱帯地方に生息する鳥などで標本として好まれていた。
　クーパー氏は「雌を無視した研究では、生物の全体像が描けない」と指摘。雌の習性が明らかになれば、雌と雄でよりバランスの取れた標本の収集に役立つのではないかと述べた。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2019/10/24-08:28）

Museum collections of birds and mammals may be disproportionately skewed to favour males, even if female members of the species outnumber males in the wild, according to research published Wednesday.
Natalie Cooper, a researcher in the department of life sciences at the Natural History Museum in London, and her colleagues analysed the sex of almost 2.5 million specimens from five international collections, some dating back over a century.
Although as many as half of the bird specimens were not labelled by sex, of the ones that were, only 40 percent were female. Female mammals represented 48 percent of the collections identified by sex.
We suspected that some bias towards males would be found because science is done by people, and people have inherent biases towards males, Cooper told AFP.
What surprised the researcher, though, was that there was no change in the ratios from collections dating back 130 years to more recent collections.
In museums, collectors in the 19th century were mostly male, and though this is changing, it's still a male-dominated field, she added.
Collection methods may be part of the problem. In some species, the males may be larger or showier, making them easier to spot and collect.
Hunters are more likely to see and target these individuals, Cooper said.
So it's important to ensure smaller female individuals are not being overlooked.
When scientists disproportionately collect male deer, for example, which are larger than their female counterparts, the specimens studied represent a larger average size than in the wild.
By ignoring females we don't get a full picture of life, said Cooper.
- 'Macho' collection culture -
Even when female specimens were larger or showier than males, the study found the median percentage of females was still only 44.6 percent.
The same trend applied for male mammals with ornaments, such as horns, antlers or tusks.
But even in species where females also have ornaments, collectors preferred males.
The trend carried over to bird collections, too. Male birds that are significantly more colourful or ornamental than females -? birds of paradise, for example -- were preferred by collectors, the author said.
The males in these species were also more likely to be selected for exhibits.
Recognising the habits of female specimens may be useful in trapping and collecting a more balanced sex ratio, the author noted.
It would be useful to identify the sex of the unknown specimens in collections. It is possible females are simply harder to identify than males -? they may appear similar to juveniles, for example.
If this is the case, many of our unsexed specimens may be female, said the study, published in the journal Proceedings of the Royal Society B.
Cooper said having more female collectors may also be beneficial.
I have hope that by acknowledging the problem and by hiring more women in the traditionally 'macho' field of collections we can make a positive change in the future, she said.