2024-01-03 ニューサウスウェールズ大学(UNSW)
It turns out that male southern elephant seals like to stick with their own favourite foods. Photo: Andrea Cormack.
◆遺伝子の化学的手がかりを解析するためにアザラシのヒゲサンプルを使用し、これまでにない範囲でオスの食事を分析した結果、ほとんどのオスは同じ食物を一貫して摂取しており、極端な専門家とみなされることがわかりました。これにより、南ゾウアザラシオスは食物の種類を限定せず、各オスが独自の好物を持っていることが確認されました。
◆研究者たちは、これらの気難しい食事療法が、気温の変化や気候変動によって南極の食物の供給に影響を与え、将来的な繁殖の成功にどのような影響を与えるかを調査する必要があると考えています。
<関連情報>
- https://newsroom.unsw.edu.au/news/science-tech/male-southern-elephant-seals-are-picky-eaters-study-suggests
- https://www.int-res.com/abstracts/meps/v725/p185-199/
ミナミゾウアザラシの成体オスにおける極端な食餌の特殊化:栄養食個体間の変動を決定する Extreme dietary specialisation in adult male southern elephant seals: determining variation between individual trophic diets
Andrea Cormack, Eve Slavich, Javier Negrete, Horst Bornemann, Gustavo A. Daneri, Tracey L. Rogers
Marine Ecology Progress Series Published:December 21, 2023
DOI: https://doi.org/10.3354/meps14472
ABSTRACT
Although dietary studies have provided important insights into the causes and ramifications of diet variation for the southern elephant seal (SES) (Mirounga leonina), adult males are comparatively underrepresented within that literature. Individual males can vary morphologically as well as behaviourally, leading to differences in their life history trajectories and outcomes. Therefore, to improve our understanding of the male diet, we sought to determine the degree of dietary variation between as well as within individuals from the West Antarctic Peninsula. Secondly, we investigated whether individual morphological traits, seasonality, and year influenced their dietary variation. Whiskers were sampled from 31 adult male seals and used to measure the bulk stable isotope nitrogen (δ15N). We sequentially segmented each whisker to create a time series of datapoints for each individual, allowing us to compare δ15N variation within each seal as well as assess variation between the seals. We then investigated the relationships between male dietary variation and body length, girth, season, and year. We found that adult male SESs maintained an extremely specialised diet. Variation between individuals was strongly correlated with their body size, with larger seals feeding higher up the trophic web. Interestingly, seasonality and year both influenced variation within the seals’ diets, but only year was seen to influence the variability between seals. We discuss the possible causes and ramifications of dietary specialisation for the SES and highlight the need for combined tracking and stable isotope investigations to improve our understanding of the ontogeny of the seals’ dietary specialisation.
