Biogeographic distribution and habitat association of Ammonia genetic variants around the coastline of Great Britain

Abstract

High morphological variation and the lack of clearly defined morphological criteria for identification have led to difficulties in the identification of species in the foraminiferal genus Ammonia. It is often difficult to decide if morphological variability is genetic or ecophenotypic and more than 40 species, subspecies and varieties have been described worldwide under the generic name Ammonia. This study aimed to add new insight into the genetic diversity, biogeographical distribution and the impact of different environmental conditions in Ammonia populations around the coastline of Great Britain. A total of 164 Ammonia specimens were examined from 19 different populations. Genetic analysis revealed three distinct large subunit (LSU) ribosomal (r) RNA gene genetic types T1, T2 and T6 in Ammonia populations around Great Britain. T6 is the most common genetic type around Great Britain occurring in 14 of the 19 populations. T2 was represented in 6 of the 19 populations and T1 was found in only 5 of the 19 populations. These genetic types were not ubiquitously distributed around the coastline of Great Britain and instead their pattern of biogeographical distribution revealed evidence of geographic structuring of Ammonia populations. However, their distribution does not seem to be correlated with habitat. The ability of genetic types to inhabit contrasting intertidal ecosystems is indicative of a non-specific ecological preference. Comparing the Ammonia genetic types from Great Britain to those in other regions around the world revealed geographical connectivity. The large scale distribution of Ammonia genetic types could result from either passive transport of propagules with Ocean currents or by the anthropogenic transportation of individuals with ships ballast water.