类群概述页面和类群页面上的特殊“地图标签”上都有地图显示。这些地图共有三种不同的数据来源:GBIF(全球生物多样性信息机构)、标本数据和类群描述数据。并非所有的地图都同时拥有三个数据源,但是三个数据源可以结合在一起并在同一张地图上显示。重要的是要认识到三个数据源的限制,以及每个数据源会在分布数据显示上引入何种不同的偏差。我们距离一个全面的蚂蚁物种分布数据显示还很遥远,这点反映在网站的地图上。
数据来源
GBIF. 这些数据是动态源自全球生物多样性信息机构的,它们显示为非常小的黄色到红色的小点,具体颜色是根据每个地方的物种密度记录而定的。地图的底部有一个选择框,它允许用户打开或关闭GBIF的数据。用户最好保持怀疑的眼光来使用GBIF的蚂蚁数据,因为他们主要来自于文献(而不是标本),而且没有严格的质量控制。
标本数据. 网站上的每个标本如果带有一个“位置”节点,都会显示在其类群页面的地图上,可以是作为一个单独的位置标记,或是作为一组地标(当一定范围内的区域内标本密度比较高的时候)。目前,所有的标本数据都是从Antweb导入的。这些标本数据的优点是高品质,但它的缺点是标本的特点依靠采样环境而定。例如,马达加斯加、哥斯达黎加和斐济的项目有大量的地理标本数据,而其它地区和国家只有很少的或者没有地理标本数据。这会形成许多地区并没有该物种的虚假印象,但其实是有的。
TDWG地区. TDWG生物多样性信息标准包括地理上划定的TDWG地区。Scratchpads界面允许网站的编辑者在编辑类群描述的时候,在地图上选择这些区域。之后,这些区域将在类群页地图上将被显示为阴影区域。这些区域还可以被大量导入。TDWG阴影区域使用户能够获得类群分布的大致印象,但并非在一个非常精确的水平。例如,如果一个物种的标本来自于巴西,那么整个巴西都会被阴影标出,用户请不要错误地认为该物种遍布巴西。
评论
TDWG Regions
None of the taxon pages currently display TDWG Regions. I expect this could be a fruitful avenue for future content development, especially if the data were imported. I used the map tool in the taxon description editor to select TDWG Regions for ~15 species. Unfortunately those changes were lost during subsequent development, but I had mixed feelings about the results. For example, how do you map a 'Neotropical distribution'? Does that include all of South America up through all of Mexico, or is it more accurate to exclude southern South America and northern Mexico? The TDWG regions do not allow for selection of administrative units below the province/state level, and species tend not to feel confined by political boundaries. However, when combined with specimen data, these coarse-scale maps have the advantage of at least being able to demonstrate the basic global distribution of a species even when specimen data is not available for particular portions of it. Also including the specimen data should help give the impression that the populations are much more localized than the shaded TDWG regions imply.
Why is the default view of Europe?
If there is no specimen/location data and no TDWG regions were selected for the taxon description, the default map view is of Europe. There might still be GBIF data, but the map does not automatically use that data to display its default extent. I suspect that the Scratchpad team made Europe the default extent because that project is based there. I've requested that the default extent be changed to a more global so as not to give the false impression that all species lacking distribution data occur in Europe.