Functional Ecology of the Ciliate Glaucomides bromelicola, and Comparison with the Sympatric Species Bromeliothrix metopoides

Abstract

We investigated the ecology and life strategy of Glaucomides bromelicola (family Bromeliophryidae), a very common ciliate in the reservoirs (tanks) of bromeliads, assessing its response to food quality and quantity and pH. Further, we conducted competition experiments with the frequently coexisting species Bromeliothrix metopoides (family Colpodidae). In contrast to B. metopoides and many other colpodean ciliates, G. bromelicola does not form resting cysts, which jeopardizes this ciliate when its small aquatic habitats dry out. Both species form bactivorous microstomes and flagellate-feeding macrostomes. However, only G. bromelicola has a low feeding threshold and is able to adapt to different protist food. The higher affinity to the local bacterial and flagellate food renders it the superior competitor relative to B. metopoides. Continuous encystment and excystment of the latter may enable stable coexistence of both species in their natural habitat. Both are tolerant to a wide range of pH (4–9). These ciliates appear to be limited to tank bromeliads because they either lack resting cysts and vectors for long distance dispersal (G. bromelicola) and/or have highly specific food requirements (primarily B. metopoides).

Ciliates in Planktonic Food Webs: Communication and Adaptive Response

“…it would be the superior competitor relative to species A at high food concentrations; however, species B would be outcompeted by species A at low food abundance and become extinct unless this is prevented by behavioural adaptations. Such a scenario was recently illustrated with two ciliate species from the reservoir of tank bromeliads: the colpodid ciliate Bromeliothrix metopoides needed high food concentration to thrive and was able to survive in the presence of the bromeliophryid Glaucomides bromelicola at low food levels only because, in contrast to the latter, it can encyst (Weisse et al 2013a). …”

Ciliates and the Rare Biosphere—Community Ecology and Population Dynamics

“…The life cycle and some ecophysiological peculiarities have been identified as the main reasons restricting the occurrence of these ciliates to their particular habitat (Weisse et al. ). For a detailed account on the morphology of rare ciliates in extreme environments, consult Hu ().…”

“…Foissner and colleagues recently described a highly specific ciliate fauna from tank bromeliads (Foissner 2010(Foissner , 2013Foissner and Wolf 2009;Foissner et al 2003). The life cycle and some ecophysiological peculiarities have been identified as the main reasons restricting the occurrence of these ciliates to their particular habitat (Weisse et al 2013a). For a detailed account on the morphology of rare ciliates in extreme environments, consult Hu (2014).…”

“…Inferior competitors may avoid being outcompeted via encystment and excystment. Recent laboratory experiments with two ciliate species from tank bromeliads demonstrated that stable coexistence can be mediated by continuous encystment and excystment of the inferior competitor (Weisse et al 2013a). In those experiments, only the inferior competitor was able to form cysts.…”

Predators and priority effects suggested as potential drivers of microfauna communities in a community transplantation experiment along an elevational gradient

“…Since we did find an elevational pattern for the communities that were not transplanted, it seems that a longer exposure to a certain set of environmental variables may deterministically drive community assembly and lead to spatial patterns in community structure, for example along elevational gradients, if environmental conditions remain more or less constant over longer periods (including constant disturbance regimes). However, if environmental changes, such as a climate change‐related prolongation of dry seasons, occur over longer time periods, community structure could experience lasting changes, for example caused by a higher drought prevalence in the bromeliad compartments (Zotz and Thomas ) negatively affecting the microfauna species that do not have resting stages (Weisse et al ). Thus, with regard to our initial question 1) on whether changes in environmental conditions affect microfauna community structure in bromeliads, we conclude that the changes we addressed here do not affect community structure on short time scales.…”