スズメの繁殖を成功させるために、友好的でありながら、友好的過ぎないこと(Being friendly but not too friendly helps sparrows breed successfully)

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2023-03-09 インペリアル・カレッジ・ロンドン(ICL)

スズメの異性の友達が多い個体ほど遺伝子プールに寄与することが多いという新しい研究結果が出たが、長期的には「平均的な」社交性が勝利する。
イギリスのランディ島のスズメの集団を用いた遺伝子学的研究により、スズメが異性の友達が多い場合、その繁殖期に遺伝子を遺伝させることに成功しやすく、これが短期的にはメリットを生むことがわかった。しかし、長期的には、極端に内向的でも外向的でもない「普通」の社交性を持つスズメが繁殖成功に優位であることも明らかになった。

<関連情報>

異性間の付き合いは年間の体力と連動するが、社会性は生涯にわたって安定する Opposite-sex associations are linked with annual fitness, but sociality is stable over lifetime

Jamie Dunning, Terry Burke, Alex Hoi Hang Chan, Heung Ying Janet Chik, Tim Evans, Julia Schroeder
Behavioral Ecology  Published:08 March 2023
DOI:https://doi.org/10.1093/beheco/arac124

Three versions of a simulated event (A, B, and C) show the interval over which five individuals (1–5, black/gray bars) spent at a resource over time (t), and the derived social networks from each approach: A = gambit of the group, which links all individuals in a discrete group equally; B = time-window overlap (by ∆t), which links individuals who overlap at a resource; and C = arrival time (developed for this study), which links individuals who arrive together to a resource. Shaded boxes denote the time period during which individuals are considered to be associated, and overlaps represent an association: A, all individuals within a group; B, where they are physically present at the same time (shaded box), or shortly after they depart to account for birds which were present, but not currently being recorded by the antenna, in that case, over-lapping by ∆t (shaded over-hanging box, typically a few seconds); or, C, where they arrive within ∆t of each other, but the subsequent time spent at a feeder is irrelevant. However, note that the function of ∆t differs between B and C; Where in B, ∆t functions to detect when birds are in the same place but where one (or more) are not currently being detected by the antenna, in C the function is to link all individuals which arrive together while ignoring those already present at the resource, which has the potential to link two separate groups in A and B. In the case of C, an additional interval (∆i) is required to define when birds have left the resource, after which they can be recorded as arriving again.

Abstract

Animal sociality, an individual’s propensity to associate with others, has fitness consequences through mate choice, for example, directly, by increasing the pool of prospective partners, and indirectly through increased survival, and individuals benefit from both. Annually, fitness consequences are realized through increased mating success and subsequent fecundity. However, it remains unknown whether these consequences translate to lifetime fitness. Here, we quantified social associations and their link to fitness annually and over lifetime, using a multi-generational, genetic pedigree. We used social network analysis to calculate variables representing different aspects of an individual’s sociality. Sociality showed high within-individual repeatability. We found that birds with more opposite-sex associates had higher annual fitness than those with fewer, but this did not translate to lifetime fitness. Instead, for lifetime fitness, we found evidence for stabilizing selection on opposite-sex sociality, and sociality in general, suggesting that reported benefits are only short-lived in a wild population, and that selection favors an average sociality.

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生物環境工学
インペリアル・カレッジ・ロンドン(ICL)スズメ繁殖優位社会性
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テック・アイ生命科学
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