Chemical patterns of colony membership and mother-offspring similarity in Antarctic fur seals are reproducible

Abstract

Replication studies are essential for evaluating the validity of previous research findings. However, it has proven challenging to reproduce the results of ecological and evolutionary studies, partly because of the complexity and lability of many of the phenomena being investigated, but also due to small sample sizes, low statistical power and publication bias. Additionally, replication is often considered too difficult in field settings where many factors are beyond the investigator’s control and where spatial and temporal dependencies may be strong. We investigated the feasibility of reproducing original research findings in the field of chemical ecology by performing an exact replication of a previous study of Antarctic fur seals (Arctocephalus gazella). In the original study, skin swabs from 41 mother-offspring pairs from two adjacent breeding colonies on Bird Island, South Georgia, were analyzed using gas chromatography-mass spectrometry. Seals from the two colonies differed significantly in their chemical fingerprints, suggesting that colony membership may be chemically encoded, and mothers were also chemically similar to their pups, hinting at the possible involvement of phenotype matching in mother-offspring recognition. In the current study, we generated and analyzed chemical data from a non-overlapping sample of 50 mother-offspring pairs from the same two colonies 5 years later. The original results were corroborated in both hypothesis testing and estimation contexts, with p-values remaining highly significant and effect sizes, standardized between studies by bootstrapping the chemical data over individuals, being of comparable magnitude. However, exact replication studies are only capable of showing whether a given effect can be replicated in a specific setting. We therefore investigated whether chemical signatures are colony-specific in general by expanding the geographic coverage of our study to include pups from a total of six colonies around Bird Island. We detected significant chemical differences in all but a handful of pairwise comparisons between colonies. This finding adds weight to our original conclusion that colony membership is chemically encoded, and suggests that chemical patterns of colony membership not only persist over time but can also be generalized over space. Our study systematically confirms and extends our previous findings, while also implying more broadly that spatial and temporal heterogeneity need not necessarily negate the reproduction and generalization of ecological research findings.

No evidence for a role of MHC class II genotype in the chemical encoding of heterozygosity and relatedness in Antarctic fur seals

“…Specifically, chemical similarity was not significantly associated with neither MHC relatedness (figure 2a) nor microsatellite relatedness (figure 2b). The best performing (null) model only included colony and age as fixed effects, as previously found by Stoffel et al [12] and Tebbe et al [46]. The best royalsocietypublishing.org/journal/rspb Proc.…”

“…[ 12 ] and Tebbe et al . [ 46 ]. The best model of chemical diversity (model b2; table 1 b ) included only sMLH as a fixed genetic effect ( p = 0.003; figure 2 c ; electronic supplementary material, table S2b) while no significant effects of MHC heterozygosity on chemical diversity were found ( figure 2 d ).…”

“…Fur seals in particular have a strong musky smell [ 41 ] that has been attributed to facial glands which hypertrophy during the breeding season [ 42 , 43 ], and naso-nasal inspection plays an important role in pup recognition [ 44 , 45 ], suggesting that olfactory communication plays an important role in fur seals during the peak reproductive period. In Antarctic fur seals ( Arctocephalus gazella ), chemical fingerprints (otherwise commonly referred to as ‘odour profiles’, ‘scent profiles’ or ‘semiochemical profiles’) robustly and repeatably encode various information that could be important for kin recognition, including colony membership and mother-offspring similarity [ 12 , 46 ]. Furthermore, heterozygosity is known to be positively associated with chemical diversity, defined as the total number of substances in an individual's chemical fingerprint [ 12 ].…”

Giant panda mothers can discriminate own neonates from others based on their squalls

“…, (Pitcher et al, 2010a, b); 也可防止幼仔受到陌生成 年个体或天敌的伤害, 提高幼仔的存活率 (Brown et al, 2021), 这对亲本和幼仔双方均有益处。 母幼识别 可以通过嗅觉 (Lévy et al, 2004;Tebbe et al, 2020)、 视觉 (Wierucka et al, 2017(Wierucka et al, , 2018和听觉 (Phan et al, 2006)等模态信号的通讯实现。 与嗅觉和视觉信号相 比, 听觉信号可反映信号发出者的性别、年龄、体 型大小、所处环境状态等信息 (Charlton et al, 2009a(Charlton et al, , b, 2012Stoeger et al, 2011), 其传输的信息较为可 靠 (Reby & McComb, 2003),…”

“…如种群密度、幼仔的扩散能力 (Sébe et al, 2008;Martin et al, 2022)。 研究表明, 群居哺乳动物具有母 幼识别的机制 (Volodin et al, 2017;Sibiryakova et al, 2018;Nuñez & Rubenstein, 2020;Martin et al, 2022), 因其具有较高的种群密度 (Masataka, 1985;Torriani et al, 2006;Blank & Yang, 2017;Charrier et al, 2017), 并且部分物种的幼仔具有较强的扩散能力 (Sébe et al, 2008;Martin et al, 2022) 野外, 大熊猫母兽产后立即进入2-3周的禁食期 (Lü et al, 1994;Zhu et al, 2001), 并将主要精力用于照顾 幼仔 (Zhu et al, 2001) 和个体间变异系数(CV b ), 计算公式如下:…”