Significance of Adaptive Radiations in an Environmentally Transmitted Symbiosis

短尾乌贼与其发光细菌共生体(弧菌属)之间的互惠共生关系是研究动物-非生物共生关系进化的极好模型。由于共生细菌每次都会通过周围的海水传播到新的宿主，这提供了一个唯一的机会来解决自由生活细菌的生态如何影响这些鱿鱼发光细菌伙伴的组成，特别是与盐度和温度等因素有关的影响。由于弧菌很容易适应不断变化的环境条件，这可能导致这些细菌的范围扩大到不同的鱿鱼种群，并可能最终导致弧菌新物种的进化。这项建议将在实验室的各种条件(盐度、温度)下检查自由生活和共生弧菌，以确定非生物因素是否有助于弧菌在广泛的宿主群体中的分布。同时，将在实验室监测不同宿主物种中各种弧菌的遗传变化，以确定宿主是否对弧菌进化有任何影响。这些实验将通过对培养中的细菌或在实验室饲养的鱿鱼幼体的生长研究来完成。显然，有必要了解细菌等生物适应不同环境的速度；随着全球气候的显著变化，确定这些变化是否会在更大范围内增加或减少生物多样性将是有益的。这项研究的预期结果是，由于环境的波动，适应发生的频率要高得多，这随后允许不同寄主物种的成功定居，为细菌物种形成提供了新的轨迹。这项提案的结果将通过出版物、教学、网站和外联活动传播，以便对公众和研究界产生更大的影响。

Mutualistic associations between bobtail squids and their luminescent bacterial symbionts (genus Vibrio) make excellent models to study the evolution of animal-acterial associations. Since symbiotic bacteria are transmitted through the surrounding seawater to new hosts with every tion, it provides a uniqe opportunity to resolve how the ecology of free-living bacteria effects the make-up of these squid-luminous bacterial partnerships, particularly with respect to factors such as salinity and temperature. Since Vibrio bacteria are quite easily adaptable to changing environmental conditions, this may lead to the possibility of range expansion of these bacteria to different squid populations, and may eventually lead to the evolution of new species of Vibrio. This proposal will examine both free-living and symbiotic vibrios under a variety of conditions in the laboratory (salinity, temperature) to determine if abiotic factors contribute to the distribution of Vibrio among wide ranging host populations. Simultaneously, monitor genetic changes of various Vibrio bacteria in different squid host species will be monitered in the lab to determine if the host has any influence upon Vibrio evolution. These experiments will be completed via growth studies of the bacteria in culture or in juvenile squids that are raised in the laboratory. Clearly, there is a need to understand how quickly organisms such as bacteria can adapt to different environments; with the noticeable change in global climate, it will be a benefit to determine if these changes will increase or decrease biodiversity on a much larger scale. The expected outcome of this research is that adaptation occurs at a much higher frequency due to fluctuations in the environment, which then allows successful colonization of different host species, providing a new trajectory for bacterial speciation to occur. Results from this proposal will be disseminated through publications, teaching, web sites, and outreach to have a greater impact for both the public and research communities.