Changes in the functional structures of communities are rarely examined along multiple large-scale environmental gradients. Here, we describe patterns in functional beta diversity for New Zealand marine fishes versus depth and latitude, including broad-scale delineation of functional bioregions. We derived eight functional traits related to food acquisition and locomotion and calculated complementary indices of functional beta diversity for 144 species of marine ray-finned fishes occurring along large-scale depth (50–1200 m) and latitudinal gradients (29°–51°S) in the New Zealand Exclusive Economic Zone. We focused on a suite of morphological traits calculated directly from in situ Baited Remote Underwater Stereo-Video (stereo-BRUV) footage and museum specimens. We found that functional changes were primarily structured by depth followed by latitude, and that latitudinal functional turnover decreased with increasing depth. Functional turnover among cells increased with increasing depth distance, but this relationship plateaued for greater depth distances (>750 m). In contrast, functional turnover did not change significantly with increasing latitudinal distance at 700–1200 m depths. Shallow functional bioregions (50–100 m) were distinct at different latitudes, whereas deeper bioregions extended across broad latitudinal ranges. Fishes in shallow depths had a body shape conducive to efficient propulsion, while fishes in deeper depths were more elongated, enabling slow, energy-efficient locomotion, and had large eyes to enhance vision. Environmental filtering may be a primary driver of broad-scale patterns of functional beta diversity in the deep sea. Greater environmental homogeneity may lead to greater functional homogeneity across latitudinal gradients at deeper depths (700–1200 m). We suggest that communities living at depth may follow a ‘functional village hypothesis’, whereby similar key functional niches in fish communities may be maintained over large spatial scales.

中文翻译：

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新西兰鱼类的功能β多样性：表征沿深度和纬度梯度的形态转换，以及功能生物区的推导

很少沿着多个大规模环境梯度检查社区功能结构的变化。在这里，我们描述了新西兰海洋鱼类的功能β多样性与深度和纬度之间的模式，包括功能生物区域的大尺度划定。我们推导出了与食物获取和运动相关的 8 个功能性状，并计算了 144 种沿大尺度深度（50-1200 m）和纬度梯度（29°-51°S ) 在新西兰专属经济区。我们专注于直接从原位计算的一组形态特征诱饵远程水下立体视频 (stereo-BRUV) 镜头和博物馆标本。我们发现功能变化主要由深度其次是纬度构成，并且纬度功能周转随着深度的增加而减少。细胞之间的功能周转随着深度距离的增加而增加，但这种关系随着深度距离的增加（>750 m）而趋于稳定。相比之下，在 700-1200 m 深度，随着纬度距离的增加，功能周转没有显着变化。浅层功能生物区（50-100 m）在不同纬度上是不同的，而更深的生物区则跨越广阔的纬度范围。浅水区的鱼体型有利于有效推进，而深水区的鱼更细长，能够进行缓慢、节能的运动，并有大眼睛以增强视力。环境过滤可能是深海功能性β多样性广泛模式的主要驱动因素。更大的环境同质性可能导致更深深度（700-1200 m）的纬度梯度上更大的功能同质性。我们建议生活在深处的社区可能遵循“功能村庄假设”，即鱼类社区中类似的关键功能生态位可以在大空间尺度上保持。