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An investigation of species sorting and neutral processes during early colonisation of aquatic microcosms. Jack Lee Lincoln University, Canterbury, New Zealand . Bacterial Immigration. About 54,000 Kiwi’s migrated to Australia last year.
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An investigation of species sorting and neutral processes during early colonisation of aquatic microcosms. Jack Lee Lincoln University, Canterbury, New Zealand .
Bacterial Immigration.... • About 54,000 Kiwi’s migrated to Australia last year. • However, c. 1.34 x 1015 (1.34 quadrillion) bacterial cells enter NZ on Australian dust particles each year! • Limited knowledge of the impact! 134000 metric tonnes of dust from Oz to NZ each year (Marx et al .,2009). Very conservative estimate of 104 bacterial cells per gram = 1338550000000000 bacterial cells a year!
Neutral Processes Vs Species Sorting… Neutral Processes- Random migration, deaths, births, ‘speciation’. Species Sorting- Niche based sorting. Deterministic environmental selection
Investigate the effects of different immigration times in both pre-sterilised and non-sterilised microcosms. A 23L pH 7.8 B 150L pH 7.4 C 550L pH 7.1 Water = PS NS Inoculate = PS NS PS NS Time = Water x 3 (A,B,C), Inoculate x 2 (PS, NS), Time x 7, Rep x 3 = 108 microcosms
Methods All samples collected after 7 days. All water filtered. ARISA PCR DNA Extraction Ordination diagrams generated and experimental treatments compared (MDS plots). ARISA performed
Neutral theory predicts... Pre-Sterilised microcosms will show no significant differences in community structure relating to pond water source (A,B or C). Key: = A = B = C = Rain Non-Sterilised Pre-Sterilised 2D stress 0.2 Based on a Bray-Curtis similarity matrix
Neutral theory predicts... There will be no significant differences in community evenness relating to pond water source. Lorenz Curve Contrast results (comparing the effects of water (A,B, C) based on permutational ANOVA of Gini Coefficient data Glossary: Community Evenness is a measure of the equality or distribution of individuals among species
Pre-Sterilised Non-Sterilised Neutral theory predicts... 45 45 12h 167 h 45 12h 167 h 45 A A There will be fewer differences in community composition between the Pre-Sterilised microcosms and the rain water samples than between the Non-Sterilised microcosms and rain water. 45 45 45 45 Relative abundance of taxon (percent of total community) B B 45 45 45 45 C C Taxon (ARISA peak)
Neutral Model... • Makes predictions using only three parameters: J (total community size), m (which describes the fraction of recruits coming into the local community from the source pool), Ɵ (the fundamental biodiversity number).
Neutral theory predicts... That mwill increase with increased immigration times. Generated using Etienne, 2005.
Conclusions….. • Both neutral processes and species sorting appear to be important during the colonisation of aquatic environments. • However, species sorting seems more important in previously colonised environments!