種間競爭壓力對尼泊爾埋葬蟲繁殖偏離的影響

How Interspecific Competition Influences the Reproductive Skew of Burying Beetles (Nicrophorus nepalensis, Hope 1831)

詹勳承(Shiun-Cheng Chan)

指導教授 ： 沈聖峰

國立臺灣大學/理學院/氣候變遷與永續發展國際學位學程/碩士(2021年)

https://doi.org/10.6342/NTU202100579

摘要

繁殖偏離意指在合作生殖群體中，群體成員之間子代數量分配不均的現象。群體成員之間身體狀態的差異、親緣關係遠近和環境壓力等因素都有可能會影響繁殖偏離的程度。研究繁殖偏離的形成機制有助於理解社會行為的演化驅動力，理論生態學家為此發展出許多理論模型，試圖解釋生物形成群體的機制。然而，過往的研究往往著重在群體成員間的親緣關係如何影響群體形成的機制以及繁殖偏離，較少探討其他生態因子（例如：環境壓力）對繁殖偏離的影響。因此本研究以社會性的尼泊爾埋葬蟲為實驗物種，藉由控制實驗用蟲的親緣關係和體型大小，進行改變種間競爭壓力的室內操作實驗，來探討不同環境壓力對繁殖偏離的影響，並結合理論模型探討尼泊爾埋葬蟲繁殖偏離的形成機制。我們發現尼泊爾埋葬蟲在有麗蠅競爭壓力的環境下，群內成員的互動模式會改變。高位階個體較不會驅趕低位階個體，形成較大的合作生殖群體，且因為麗蠅的競爭壓力，各個位階的個體都將產卵時間提早至相近的時間點，消除了高位階個體的殺嬰線索（infanticide cue），間接使得低位階個體的子代存活機會提高，使得合作者的基因能被傳遞至下一代，促進合作行為的演化。除了會有較高程度的合作行為外，雌蟲之間的產卵時間和產卵數量也變得更平均，整體繁殖偏離程度降低，形成在行為和繁殖成果上都更為合作的群體。本研究透過操作環境壓力的室內實驗，深入了解尼泊爾埋葬蟲組成群體時的細節，使我們更加了解群體形成的機制以及社會群體演化的驅動力。

關鍵字

繁殖偏離 ； 合作生殖 ； 種間競爭 ； 殺嬰行為 ； 尼泊爾埋葬蟲

並列摘要

Reproductive skew means the uneven partitioning of members’ offspring among reproductive group. Differences in physical quality, relatedness, and environmental stress may affect the degree of reproductive skew. Studying the mechanisms that shape reproductive skew helps to understand the evolutionary driving force of social behavior.
To understand the evolutionary driving force of social behavior, theoretical ecologists have developed many theoretical models that attempt to explain the mechanisms by how organisms form groups. However, previous studies have tended to focus on how relatedness among group members affect the mechanisms of group formation and reproductive skew and have less examined the effects of other ecological factors (e.g., environmental stress) on reproductive skew. Therefore, in this study, the sub-social insects, Nicrophorus nepalensis, was used as the experimental species. By controlling the relatedness and size of the experimental insects, operation experiment are conducted to change the interspecific competition stress. Investigating the effects of interspecific competition stress on reproductive skew and to explain the mechanism of reproductive skew in burying beetles’ society by theoretical models.
We found that the interaction patterns of burying beetles changed in an environment where there was interspecific competition stress from flies. Dominant are less likely to drive away subordinate and form larger cooperative reproductive groups. In addition, due to the interspecific competition stress from flies, individuals of each hierarchy advance their spawning time to a similar time, eliminating the infanticide cue of dominant and indirectly increasing the chance of survival of the offspring of subordinate. Allowing the genes of cooperators to be passed on to the next generation and promoting the evolution of cooperative behavior. In addition to a higher degree of cooperative behavior, the timing and number of eggs laid by females became more even, and the overall reproductive skew index decreased, resulting in a more cooperative group in terms of behavior and reproductive success.
This research provides insight into the details of group formation in burying beetles by manipulating interspecific competition stress, allowing us to better understand the mechanisms of group formation and the evolutionary driving force of social behavior.

並列關鍵字

Reproductive skew ； Cooperatively breeding ； Interspecific competition ； Infanticide behavior ； Burying beetles (Nicrophorus nepalensis)

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