Biogeographic distribution of three phylotypes (T1, T2 and T6) of <i>Ammonia</i> (foraminifera, Rhizaria) around Great Britain: new insights from combined molecular and morphological recognition

Abstract

Abstract. Ammonia is one of the most widespread foraminiferal genera worldwide. Three phylotypes (Ammonia sp. T1, T2 and T6), commonly encountered in the northeast Atlantic, are usually associated with the morphospecies Ammonia tepida. The biogeographic distribution of these three types was previously investigated in coastal environments around Great Britain based on genetic assignations. A new method was recently developed to recognize these three phylotypes based on morphological criteria (i.e. pore size and suture elevation on spiral side), avoiding the need to use molecular analyses to identify them. The results presented here allow us to validate the consistency of the morphometric determination method but also to define more precisely the pore size variability of each of the three phylotypes, which is a main criterion for their recognition. Moreover, these results, combined with earlier molecular and morphological data, enable us to refine the biogeographic distribution previously established by genetic analyses alone. The biogeographical distribution pattern presented here supports the putatively invasive character of Ammonia sp. T6, by suggesting that this phylotype is currently spreading out over large areas and is supplanting autochthonous phylotypes (T1 and T2) along the coastlines of the British Isles and northern France. In fact, only the southwest coast of England and Ireland and the northwest coast of France have not been colonized by Ammonia sp. T6 yet. Our results also suggest that within the areas colonized by phylotype T6, T2 may find refuges in the inner parts of estuaries. We further suggest that the absence of Ammonia sp. T6 in the western part of the English Channel may be explained by the general surface current circulation pattern, which impedes further expansion. The high reliability of the determination method of phylotypes T1, T2 and T6 based on morphology also allows us to quickly generate large datasets for sub-recent and fossil material. This new method will make it possible to gain an understanding of the ecological differences between the three phylotypes and of the historical changes in their distribution patterns (for example due to changing anthropogenic factors). Finally, it will allow us to confirm or invalidate the putative invasive character of phylotype T6.

Biometry and taxonomy of Adriatic <i>Ammonia</i> species from Bellaria–Igea Marina (Italy)

“…Ranges of morphometric characteristics useful for species determination were provided (Hayward et al, 2004). Other biometric approaches assessed the same characteristics and demonstrated that only the pore diameter and the suture elevation in the central part of the spiral side may facilitate a secure species differentiation, in particular among three morphologically similar genotypes (Richirt et al, 2019(Richirt et al, , 2021.…”

Newly designed foraminifera primers identify habitat‐specific lineages through metabarcoding analyses

“…For example, shared genotypes (e.g., Type IIa Hastigerina and Type IIIb Globigerinella) are present in the Indian and Southern Atlantic oceans (reviewed in Weiner et al, 2012Weiner et al, , 2014. There are also a few studies that estimate gene flow for benthic species (Hayward et al, 2004(Hayward et al, , 2021Richirt et al, 2021), although more work is needed here. Below we discuss the communities observed in each of these habitats.…”

“…Despite the progress in characterizing foraminifera biodiversity, the presence of cryptic diversity and different genotypes in different localities are the subject of recent debate, with the suggestion that foraminifera may show patchy distribution across a broader spatial scale (Gooday & Jorissen, 2012; Richirt et al, 2021). One reason for this is that previous molecular studies only focused on foraminiferal diversity in specific environments (Cordier et al, 2019; Lecroq et al, 2011; Shi et al, 2020).…”

Fast and Reliable Identification of Ammonia Phylotypes T1, T2 and T6 Using a Stereomicroscope: Implication for Large-Scale Ecological Surveys and Monitoring Programs

“…To ensure an objective assessment of the stereomicroscope and the SEM methods, independent identifications were made by two different investigators. First, specimens were identified with a stereomicroscope using the two criteria proposed by Richirt et al [5,12]. For the first criterium, the elevation of the sutures on the spiral side, i.e., either flush…”

“…Despite the considerable efforts made by taxonomists to link morphology-based (e.g., morphospecies) and molecular-based (e.g., phylotypes) taxonomy [3][4][5], the complexity of the taxonomy of Ammonia has not yet been totally disentangled and the genus still suffers from taxonomical uncertainties [2,4]. One of the most exhaustive recent publications recognizes 67 Ammonia and related taxa that can be morphologically discriminated, with possibly 30 or more additional living species uniquely distinguishable by molecular sequencing [2].…”