Local and regional species richness y = 0.54x R 2 = Species of regional pool Species of local pool Species richness on bracken is higher at richer sites At species poorer sites there seem to be many empty niches Local habitats are not saturated with species Bracken occurs whole over the world Species numbers of phytophages on bracken differ Is this difference an effect of competitive exlusion or do empty niches exist? John H.Lawton The common brushtail Possum Trichosurus vulpecula is at its introduced sites often free of natural parasites. There are empty niches

Cynipid gall wasps in Norh America (Cornell 1985) Lacutrine fish in North America (Gaston 2000) Relationship between local species richness and the regional species pool size for 14 vegetation types in Estonia (Pärtel et al. 1996) Dry grasslandsMoist grasslands y = 0.49x R 2 = Number of species regionally Number of species locally y = 0.36x R 2 = Regional number of species Local number of species y = 0.27x R2 = Number of species regionally Number of species locally y = 16Ln(x) - 49 R2 = Number of species regionally Number of species locally Local and regional species richness

Four possible relations between local and regional species numbers Regional number of species Local number of species

Abundance – range size relationships Freshwater gyrinid beetles in temporary pools (Svensson 1992)Regional distribution of 21 Bombus species in northern Spain (Obeso 1992) Local abundance in relation to regional distribution of soil mites (Karppinen 1958) D: Local abundance in relation to regional distribution of bumblebees in Poland (Anasiewicz 1971) Diptera colonising dead snails in a beech forest (Ulrich 2001) Parasitic Hymenoptera of these Diptera (Ulrich 2001) y = 0.95e 2.58x R 2 = Fraction of pools occupied Mean abundance y = 0.067e 6.97x R 2 = % 5% 10% 15% 20% 25% 30% Fraction of sites occupied Percentage of total Abundance y = 3.06e 0.11x R 2 = Number of sites occupied log rel. abundance y = 1.0e 0.33x R 2 = Number of sites occupied log rel. abundance y = 1.35e 3.674x R 2 = %20%40%60%80%100% Percentage of site occupied Mean density per occupied patch y = 1.57e 2.97x R 2 = %20%40%60% Percentage of site occupied Mean density per occupied patch

Patch occupancy models A matrix of cells refers to a metacommunity scale Each cell represents one local community Cells might have different sizes Individuals of different species of the meta- community are now placed at random or according to certain predefined rules into the cells A random placement is called a passive sampling model The spatial distribution patterns are then compared to observed ones. Individuals of 100 species were placed at random into a 100x100 matrix. Species had different individual numbers Matrix cells had different capacities The model produces an abundance - range size relationship This relationship follows an exponential model as observed in reality Abundance - range size relationships are most parsimonous explained from passive sampling in heterogeneous environments

Core and satellite species Insects on small mangrove islands (Simberloff 1976) Plant species in Russian Karelia (Linkola 1916) In an assemblage of species distributed over many sites we can often differentiate a group of core species, which occur in most or even all of the sites, and a group of satellite species, which occur only in a few or even only in one site Number of sites occupied Number of species Number of sites occupied Number of species

Core and satellite species Ground beetles species on Mazuran lake island Satellite (infrequent, tourist) species Core (frequent, permanent) species Random pattern of temporal or spatial occurrence High dispersal ability Log-series rank abundance distributions Weak species interactions Forming random assemblages Non-random pattern of temporal or spatial occurrence Lower dispersal ability Log-normal rank abundance distributions Importance of species interactions Forming true ecological communities Importance of ecological interactions

Nestedness Speciesgilfullipsoskorguc3pogheldabwronmilwil2pogterwrosswi1pog Occurren- ces Carabus granulatus Pterostichus melanarius Pterostichus strennus (Panzer) Oxypselaphus obscurus (Herbst) Pterostichus diligens (Sturm) Synuchus vivalis (Illiger) Patrobus atrorufus (Stroem) Carabus nemoralis Muller Pterostichus antracinus Pterostichus minor (Gyllenhal) Notiophilus palustris (Duftshmid) Stomis pumicatus (Panzer) Clivina fossor (Linnaeus) Epaphius secalis (Paykull) Leistus rufomarginatus (Duftshmid) Notiophilus biguttatus (Fabricius) Calathus melanocephalus (Linnaeus) Carabus hortensis Linnaeus Calathus mollis (Marsham) Calathus micropterus (Duftschmid) Dischirius globosus (Herbst) Leistus ferrugineus (Linnaeus) Calathus fuscipes (Goeze) Carabus cancelatus Illiger Occurrences Ground beetles species with limited dispersal ability on Mazuran lake island Core and satellite species

Speciesgilfullipsoskorguc3pogheldabwronmilwil2pogterwrosswi1pog Occurren- ces Carabus granulatus Pterostichus melanarius Pterostichus strennus (Panzer) Oxypselaphus obscurus (Herbst) Pterostichus diligens (Sturm) Synuchus vivalis (Illiger) Patrobus atrorufus (Stroem) Carabus nemoralis Muller Pterostichus antracinus Pterostichus minor (Gyllenhal) Notiophilus palustris (Duftshmid) Stomis pumicatus (Panzer) Clivina fossor (Linnaeus) Epaphius secalis (Paykull) Leistus rufomarginatus (Duftshmid) Notiophilus biguttatus (Fabricius) Calathus melanocephalus (Linnaeus) Carabus hortensis Linnaeus Calathus mollis (Marsham) Calathus micropterus (Duftschmid) Dischirius globosus (Herbst) Leistus ferrugineus (Linnaeus) Calathus fuscipes (Goeze) Carabus cancelatus Illiger Occurrences The matrix sorted according to row and column totals (numbers of occurrences) containes two triangles. One contain species and site with very high matrix fill (numbers of occurrences, the second contains species and site with very low matrix fill. We call such a matrix nested.

ASites SpeciesACFDGEBHSum Sum A perfectly nested matrix A perfectly nested (ordered) matrix can be divided into a completely filled and an empty part. ASites SpeciesACFDGEBHSum Sum Imperfectly nested matrices have holes (unexpected absences) and outliers (unexpected occurrences). The number of holes and outlier with respect to the perfectly ordered state is a measure of the degree of nestedness. The discrepancy metric counts the number of holes that have to be filled by outliers of the same row or column to form a perfectly nested matrix.

Speciesgilfullipsoskorguc3pogheldabwronmilwil2pogterwrosswi1pog Occurren- ces Carabus granulatus Pterostichus melanarius Pterostichus strennus (Panzer) Oxypselaphus obscurus (Herbst) Pterostichus diligens (Sturm) Synuchus vivalis (Illiger) Patrobus atrorufus (Stroem) Carabus nemoralis Muller Pterostichus antracinus Pterostichus minor (Gyllenhal) Notiophilus palustris (Duftshmid) Stomis pumicatus (Panzer) Clivina fossor (Linnaeus) Epaphius secalis (Paykull) Leistus rufomarginatus (Duftshmid) Notiophilus biguttatus (Fabricius) Calathus melanocephalus (Linnaeus) Carabus hortensis Linnaeus Calathus mollis (Marsham) Calathus micropterus (Duftschmid) Dischirius globosus (Herbst) Leistus ferrugineus (Linnaeus) Calathus fuscipes (Goeze) Carabus cancelatus Illiger Occurrences Nestedness analysis surves to find idiosyncratic species that means species that deviate from the general trend of community organization..Often these species do not belong to the guild of species under study while having different habitat requirements.

Variable 3pogsos2pogdabwrosgilter1pogwilmilswikorhellipwron Organic matter content Temperature Species 3pogsos2pogdabwrosgilter1pogwilmilswikorhellipwron Occurren ces Carabus granulatus Pterostichus melanarius Pterostichus strennus (Panzer) Oxypselaphus obscurus (Herbst) Pterostichus diligens (Sturm) Synuchus vivalis (Illiger) Patrobus atrorufus (Stroem) Pterostichus antracinus Pterostichus minor (Gyllenhal) Carabus nemoralis Muller Notiophilus palustris (Duftshmid) Clivina fossor (Linnaeus) Stomis pumicatus (Panzer) Leistus rufomarginatus (Duftshmid) Epaphius secalis (Paykull) Notiophilus biguttatus (Fabricius) Calathus melanocephalus (Linnaeus) Calathus mollis (Marsham) Dischirius globosus (Herbst) Leistus ferrugineus (Linnaeus) Carabus hortensis Linnaeus Calathus micropterus (Duftschmid) Calathus fuscipes (Goeze) Carabus cancelatus Illiger Analysis of ecological gradients Nestedness analysis helps to identify species that run counter to ecological gradients Nestedness analysis is particulalry an analysis of ecological gradients

ASites SpeciesACFDGEBHSum Sum Statistical inference using null models SpeciesACFDGEBHSum Sum We have to infer how many discrepancies are expected just by chance. Checkerboards We randomize the matrix switching checkerboards. This retains row and column totals and therefore basic matrix properties. Observed discrepancy D = 11 Nested Antinested Lower 5% CL Upper 5% CL Observed 1. Use 10*sites*species checkerboard swaps per matrix to randomize. 2. Calculate discrepancy. 3. Repeat steps 1 and times to get the null distribtuion. 4. Compare the observed discepancy with the expected one.

Both matrices are not significantly nested. There are not more idiosyncratic sites and species than expected just by chance. Low dispersal Carabidae do not colonize lake island according to organic matter content (soil fertility). Our first eysight impression was wrong. Always ask whether an observed pattern or process might exist just by chance.

Today’s reading Local and regional species richness: m / m / Nestedness and null models: UlrichConsumersGuide.pdf UlrichConsumersGuide.pdf Community assembly: nity%20Assembly1.ppt nity%20Assembly1.ppt