U Abstract Extra-pair paternity (EPP) is extremely variable among species of birds, both in its frequency and in the behavioral events that produce it. A flood of field studies and comparative analyses has stimulated an array of novel ideas, but the results are limited in several ways. The prevailing view is that EPP is largely the product of a female strategy. We evaluate what is known about the behavioral events leading to EPP and find the justification for this view to be weak. Conflict theory (derived from selection theory) predicts that adaptations in all the players involved will influence the outcome of mating interactions, producing complex and often highly variable patterns of behavior and levels of EPP. Data support some of these predictions, but alternative hypotheses abound. Tests of predictions from conflict theory will require better information on how males and females encounter one another, behave once they have met, and influence fertilization once insemination has occurred. 1543-592X/03/1215-0365$14.00 365 366 WESTNEAT n STEWART of offspring and thereby uncover actual mating patterns. To date, parentage studies have been published for more than 150 species of birds, and the results have been stunning. In more than 70% of species, at least some offspring are sired by a male other than the social father (reviewed by Griffith et al. 2002).The genetic studies of extra-pair paternity (EPP) in birds have transformed the study of avian monogamy from what was once termed a "bland" area of research (Mock 1985) into one teeming with intriguing, confusing, and contradictory results. An array of new theoretical and empirical questions has emerged since Gowaty (1985) first outlined the potential impact of EPP, much of which remains controversial. In this review, we summarize some of these new areas of research, critically examine some of the approaches and conclusions to date, and advocate a conceptual approach that emphasizes a balanced perspective of the sexes and stimulates new areas for future research. COMPARATIVE APPROACHES TO DIVERSITYOne obvious and provocative result emerging from the burgeoning dataset on EPP frequency is the magnitude of interspecific variation. Some of the patterns behind this variation are strikingly evident, whereas others prove more elusive. It is clear, for example, that EPP levels are higher and more variable among passerines than among nonpasserines [15% ± 16% (SD) versus 3% ± 5%, calculated from appendix A of Griffith et al. 2002]. Indeed, interspecific variation in EPP levels clearly has a large phylogenetic component, with more than 55% of the variation occurring at or above the level of family (Arnold & Owens 2002). Nevertheless, substantial variation exists within related birds, as illustrated by the range of EPP found in the swallows, a group of socially monogamous aerial insectivores (Figure la). Variation in EPP is also inversely related to the estimated branch lengths of the avian phylogeny, indicating more than a phylogenetic influence (Westneat & Sherman Figure 1...

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The design of artificial nestboxes for the study of secondary hole-nesting birds: a review of methodological inconsistencies and potential biases. Acta Ornithol. 45: 1-26.

We have developed a new approach to create microsatellite primer sets that have high utility across a wide range of species. The success of this method was demonstrated using birds. We selected 35 avian EST microsatellite loci that had a high degree of sequence homology between the zebra finch Taeniopygia guttata and the chicken Gallus gallus and designed primer sets in which the primer bind sites were identical in both species. For 33 conserved primer sets, on average, 100% of loci amplified in each of 17 passerine species and 99% of loci in five non-passerine species. The genotyping of four individuals per species revealed that 24-76% (mean 48%) of loci were polymorphic in the passerines and 18-26% (mean 21%) in the non-passerines. When at least 17 individuals were genotyped per species for four Fringillidae finch species, 71-85% of loci were polymorphic, observed heterozygosity was above 0.50 for most loci and no locus deviated significantly from Hardy-Weinberg proportions. This new set of microsatellite markers is of higher cross-species utility than any set previously designed. The loci described are suitable for a range of applications that require polymorphic avian markers, including paternity and population studies. They will facilitate comparisons of bird genome organization, including genome mapping and studies of recombination, and allow comparisons of genetic variability between species whilst avoiding ascertainment bias. The costs and time to develop new loci can now be avoided for many applications in numerous species. Furthermore, our method can be readily used to develop microsatellite markers of high utility across other taxa.

Despite the many studies that have investigated the genetic mating system of socially monogamous birds, very little is known about the underlying causes of extra‐pair paternity and few studies have attempted to test those hypotheses which have been suggested. This study describes die analysis of die genetic mating system of two populations of the house sparrow [Passer domesticus), and uses the results from four other populations to test existing hypodieses using an intra‐specific comparative approach. The parentage analysis was conducted using a combination of published and newly presented microsatellite loci isolated from the house sparrow. One population in Kentucky, U.S.A. was found to contain what may be considered to be a typical level of extra‐pair paternity for mis species (10.5%, 19/185 offspring). The second, a population on the island of Lundy, UK, exhibited a very low level (1.3%, 4/305 offspring), significandy lower dian that in all the other populations studied so far. The finding of such diverse rates of extra‐pair paternity, along with the existing estimates from ofher populations, has allowed us to test the effects of breeding density and genetic variation on die level of extra‐pair paternity. We found no effect of either factor on the frequency of extra‐pair paternity in the house sparrow, leaving the cause of this variation open to fresh ideas.

In this paper and its sequel we study arrays of coupled identical cells that possess a 'global' symmetry group G, and in which the cells possess their own 'internal' symmetry group L. We focus on general existence conditions for symmetry-breaking steady-state and Hopf bifurcations. The global and internal symmetries can combine in two quite different ways, depending on how the internal symmetries affect the coupling. Algebraically, the symmetries either combine to give the wreath product L G of the two groups or the direct product L × G.Here we develop a theory for the wreath product: we analyse the direct product case in the accompanying paper (henceforth referred to as II).The wreath product case occurs when the coupling is invariant under internal symmetries. The main objective of the paper is to relate the patterns of steady-state and Hopf bifurcation that occur in systems with the combined symmetry group L G to the corresponding bifurcations in systems with symmetry L or G. This organizes the problem by reducing it to simpler questions whose answers can often be read off from known results.The basic existence theorem for steady-state bifurcation is the equivariant branching lemma, which states that under appropriate conditions there will be a symmetry-breaking branch of steady states for any isotropy subgroup with a one-dimensional fixed-point subspace. We call such an isotropy subgroup axial. The analogous result for equivariant Hopf bifurcation involves isotropy subgroups with a two-dimensional fixed-point subspace, which we call C-axial because of an analogy involving a natural complex structure. Our main results are classification theorems for axial and C-axial subgroups in wreath products.We study some typical examples, rings of cells in which the internal symmetry group is O(2) and the global symmetry group is dihedral. As these examples illustrate, one striking consequence of our general results is that systems with wreath product coupling often have states in which some cells are performing nontrivial dynamics, while others remain quiescent. We also discuss the common occurrence of heteroclinic cycles in wreath product systems.

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