Asexual reproduction changes predator population dynamics in a life predator–prey system

Abstract

Many organisms display oscillations in population size. Theory predicts that these fluctuations can be generated by predator–prey interactions, and empirical studies using life model systems, such as a rotifer‐algae community consisting of Brachionus calyciflorus as predator and Chlorella vulgaris as prey, have been successfully used for studying such dynamics. B. calyciflorus is a cyclical parthenogen (CP) and clones often differ in their sexual propensity, that is, the degree to which they engage into sexual or asexual (clonal) reproduction. Since sexual propensities can affect growth rates and population sizes, we hypothesized that this might also affect population oscillations. Here, we studied the dynamical behaviour of B. calyciflorus clones representing either CPs (regularly inducing sex) or obligate parthenogens (OPs). We found that the amplitudes of population cycles to be increased in OPs at low nutrient levels. Several other population dynamic parameters seemed unaffected. This suggests that reproductive mode might be an important additional variable to be considered in future studies of population oscillations.

Predator coevolution and prey trait variability determine species coexistence

“…We found predation to be highly important as an ecological force affecting coexistence of the two bacteria. This result is in line with previous studies showing the effect of predation on the coexistence of species [21,37,43,44,47]. A naive predator equalizes species proportions [21], although this also depends on growth -defence trade-offs [19,45].…”

Co-evolution as an important component explaining microbial predator-prey interaction

“…Consequently, the shape of the functional response may change ( Gentleman et al, 2003 ). Such changes may lead to complex but sustained coexistence of the prey and predator ( Mougi, 2010 ;Scheuerl and Stelzer, 2019 ).…”

The effect of dilution on eco‐evolutionary dynamics of experimental microbial communities

“…This, however, means that populations reach limiting conditions quickly. To keep the growth conditions constant, populations are commonly either maintained in chemostat systems (Fussmann et al., 2003 ; Scheuerl & Stelzer, 2019 ; Stelzer, 2009 ) or a proportion of the population is transferred to fresh conditions regularly (often between 24 hr and 72 hr) (Fiegna, Scheuerl, et al., 2015 ; Good et al., 2017 ; Hiltunen et al., 2017 ; Lawrence et al., 2012 ; Scheuerl et al., 2019 ; Scheuerl & Stelzer, 2017 ). Diluting a small part of the populations every few days is a classical approach to keep populations constantly growing and to avoid growth plateaus, for example, reaching carrying capacity, once nutrient limitation occurs (Bennett et al., 1990 ).…”

“…Further, prey populations may not be under strong selection to defend because rarely, or only shortly before the next transfer, they encounter predators (Friman et al, 2008;Fussmann et al, 2000;Scheuerl & Stelzer, 2019). Contrarily, extending the transfer interval (e.g., every 48 hr instead of every 24 hr) should increase final densities so that prey and predator encounter each other more often, which may intensify evolutionary changes in the defense of prey.…”