Propagule pressure and persistence in experimental populations

Abstract

Average inoculum size and number of introductions are known to have positive effects on population persistence. However, whether these factors affect persistence independently or interact is unknown. We conducted a two-factor experiment in which 112 populations of parthenogenetic Daphnia magna were maintained for 41 days to study effects of inoculum size and introduction frequency on: (i) population growth, (ii) population persistence and (iii) time-to-extinction. We found that the interaction of inoculum size and introduction frequency—the immigration rate—affected all three dependent variables, while population growth was additionally affected by introduction frequency. We conclude that for this system the most important aspect of propagule pressure is immigration rate, with relatively minor additional effects of introduction frequency and negligible effects of inoculum size.

Invasion genetics of Pacific oyster Crassostrea gigas shaped by aquaculture stocking practices

“…Since Büsum reflects the current frontier of the Southern expansion, this is somewhat surprising as this population must have gone through several colonization events during the expansion (Brandt et al, 2008). Haplotype diversity was however as large as on Texel (Table 2) indicating that sequential sites were colonized by a large inocculum stemming from undifferentiated populations with little importance of genetic drift or several rounds of colonization from a common source (Drake et al, 2005). Since recruitment is usually stronger during warm years large inocculum sizes are likely and thus genetic drift during colonization might not have lead to a substantial loss of genetic variability or differentiation between populations.…”

How do freshwater organisms cross the “dry ocean”? A review on passive dispersal and colonization processes with a special focus on temporary ponds

“…Along with viability, the number of resting stages (both considering the reproductive potential of single individuals and of populations) has been found to have a role in promoting a successful dispersal, since larger inocula have a higher probability to successfully colonize a new environment (e.g. Drake et al, 2005 and literature therein). In addition, their ability to sink, to float or to remain attached to plants or sediment particles (Brendonck & De Meester, 2003;Van Damme & Sinev, 2013) actually contribute to determine the dispersal vector(s) and thus the range of dispersal.…”

Manipulating the intrinsic parameters of propagule pressure: implications for bio‐invasion

“…This would restrict the relevance of total propagule pressure, since greater propagule numbers of less size may be a better predictor of a species colonisation than larger propagule sizes arriving less frequently. This distinction is important, as propagule number (or immigration frequency) has recently been implicated as a strong driver of persistence and survival in laboratory model populations (Drake et al 2005).…”