地區間尼泊爾埋葬蟲之偏好溫度與區域適應

Abstract

在氣候變遷加劇的背景下，物種如何選擇棲息環境並調整其分布，成為生態學的核心議題。然而，除了生理耐受性外，行為偏好是否也會隨環境而演化、進而影響物種分布，仍鮮少被實證探討。本研究聚焦於一個關鍵問題：環境如何影響物種溫度偏好的演化？本研究以尼泊爾埋葬蟲（Nicrophorus nepalensis）為模式物種，選取合歡山、陽明山與四川三地族群，透過運動表現、生殖表現與繁殖偏好溫度實驗，結合野外分布資料，探討溫度偏好的形成機制與族群間是否存在區域適應，以測試兩項假說：（1）生理表現優先假說：生物偏好其運動能力最佳之溫度；（2）生殖表現優先假說：生物偏好有利繁殖之溫度。研究結果顯示，三個族群在實驗室中繁殖出的個體，運動表現皆於低溫（14°C）下最佳，但偏好溫度不盡相同：合歡山族群偏好14°C，四川與陽明山族群則偏好17°C，且此偏好具有遺傳基礎。偏好差異可由各地族群在野外所面對之種間競爭壓力解釋：雖然三個族群在無競爭環境下的繁殖表現在溫度間沒有顯著差異，合歡山族群因在野外17°C時面臨高度種間競爭，繁殖成功主要集中於較低溫條件，進而偏好14°C；相較之下，四川與陽明山族群在17°C時所受的種間競爭壓力相對較小，因此偏好此最適繁殖溫度。這些結果顯示，各族群的溫度偏好反映其在野外種間競爭下最佳的繁殖溫度，且此偏好具遺傳基礎，是反映其對當地環境的區域適應，支持生殖表現優先假說。本研究結果指出，行為偏好是連結生態互動與物種分布的重要機制，未來評估物種對氣候變遷的反應時，應將行為偏好與區域適應納入考量，以提升物種分布預測的準確性，並加強不同族群層級的保育規劃與管理效益。

As climate change intensifies, uncovering the mechanisms that drive species distributions has become a central goal in ecology, especially for improving predictions of future range shifts. However, whether behavioral preferences evolve with environmental conditions and influence species distributions remains rarely tested. In this study, I investigated how environmental factors shape the evolution of thermal preferences in species. Using the burying beetle Nicrophorus nepalensis, I studied three populations from Hehuanshan (Taiwan), Yangmingshan (Taiwan), and Sichuan (China). Through experiments on locomotor performance, reproductive performance, and thermal preference, combined with field distribution data, I examined the mechanisms behind thermal preference and tested for local adaptation. I focused on two hypotheses: (1) the physiological performance priority hypothesis, where organisms prefer temperatures maximizing locomotor performance; and (2) the reproductive performance priority hypothesis, where organisms prefer temperatures enhancing reproduction. My results showed that although all populations performed best at low temperatures (14°C) in locomotion tests, their thermal preferences differed. The Hehuanshan population preferred 14°C, while the Sichuan and Yangmingshan populations preferred 17°C, with these preferences having a genetic basis. This difference reflects varying interspecific competition in the wild. While all populations shared similar performance of reproductive between temperatures under laboratory conditions, the Hehuanshan population experienced strong competition at this temperature in the wild and achieved higher reproductive success at lower temperatures. In contrast, the other two populations faced less competition at 17°C and maintained this preference. These findings demonstrate that thermal preferences reflect reproductive performance under natural competition and represent local adaptation, supporting the reproductive performance priority hypothesis. I highlight behavioral preference as a key mechanism linking ecological interactions to species distributions and emphasize its importance in predicting species’ responses to climate change and improving conservation planning.