viii CONTENTS 8.4 ANOVA diagnostics 194 8.5 Robust ANOVA 195 8.5.1 Tests with heterogeneous variances 8.5.2 Rank-based ("non-parametric") tests 195 8.5.3 Randomization tests 8.6 Specific comparisons of means 8.6.1 Planned comparisons or contrasts 197 8.6.2 Unplanned pairwise comparisons 199 8.6.3 Specific contrasts versus unplanned pairwise comparisons 201 8.7 Tests for trends 202 8.8 Testing equality of group variances 8.9 Power of single factor ANOVA 204 8.10 General issues and hints for analysis 206 8.10.1 General issues 206 8.10.2 Hints for analysis 206 9 Multifactor analysis of variance 208 9.1 Nested (hierarchical) designs 208 9.1.1 Linear models for nested analyses 210 9.1.2 Analysis of variance 214 9.1.3 Null hypotheses 215 9.1.4 Unequal sample sizes (unbalanced designs) 216 9.1.5 Comparing ANOVA models 216 9.1.6 Factor effects in nested models 216 9.1.7 Assumptions for nested models 218 9.1.8 Specific comparisons for nested designs 219 9.1.9 More complex designs 219 9.1.10 Design and power 219 9.2 Factorial designs 221 9.2.1 Linear models for factorial designs 225 9.2.2 Analysis of variance 230 9.2.3 Null hypotheses 232 9.2.4 What are main effects and interactions really measuring? 237 9.2.5 Comparing ANOVA models 241 9.2.6 Unbalanced designs 241 9.2.7 Factor effects 247 9.2.8 Assumptions 249 9.2.9 Robust factorial ANOVAs 250 9.2.10 Specific comparisons on main effects 250 9.2.11 Interpreting interactions 251 9.2.12 More complex designs 255 9.2.13 Power and design in factorial ANOVA 259 9.3 Pooling in multifactor designs 260 9.4 Relationship between factorial and nested designs 261 9.5 General issues and hints for analysis 261 9.5.1 General issues 261 9.5.2 Hints for analysis 261

Spatial variation in the recruitment of sessile marine invertebrates with planktonic larvae may be derived from a number of sources: events within the plankton, choices made by larvae at the time of settlement, and mortality of juvenile organisms after settlement, but before a census by an observer. These sources usually are not distinguished.A study of the recruitment of four species of sessile invertebrates living on rock walls beneath a kelp canopy showed that both selection of microhabitats by settling larvae and predation by fish may be important. Two microhabitats were of interest; open, flat rock surfaces, and small pits and crevices that act as refuges from fish predators.The polychaete Spirorbis eximus and the cyclostome bryozoan Tubulipora spp. showed no preference for refuges, but settled apparently at random on the available substrata. Tubulipora was preyed upon heavily by fish, while Spirorbis was relatively unaffected. The bryozoans Celleporaria brunnea and Scrupocellaria bertholetti both recruited preferentially into refuges. Scrupocellaria were preyed upon, while Celleporaria juveniles seemed unaffected. Predation by fish modified the spatial distribution (Tubulipora), abundance (Tubulipora), or size distribution (Scrupocellaria) of the juvenile population, or had relatively little effect (Celleporaria, Spirorbis).All of the above events occur within three weeks of settlement. Since inferences about the effect of larval events on the population dynamics of adult organisms are often based on observations of the patterns of recruitment after one or two months, they are therefore likely to be misleading.

The connectivity of marine populations is often surprisingly lower than predicted by the dispersal capabilities of propagules alone. Estimates of connectivity, moreover, do not always scale with distance and are sometimes counterintuitive. Population connectivity requires more than just the simple exchange of settlers among populations: it also requires the successful establishment and reproduction of exogenous colonizers. Marine organisms often disperse over large spatial scales, encountering very different environments and suffering extremely high levels of post-colonization mortality. Given the growing evidence that such selection pressures often vary over spatial scales that are much smaller than those of dispersal, we argue that selection will bias survival against exogenous colonizers. We call this selection against exogenous colonizers a phenotypeenvironment mismatch and argue that phenotype-environment mismatches represent an important barrier to connectivity in the sea. Crucially, these mismatches may operate independently of distance and thereby have the potential to explain the counterintuitive patterns of connectivity often seen in marine environments. We discuss how such mismatches might alter our understanding and management of marine populations.

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