The haplochromine cichlids of Lake Victoria constitute a classical example of explosive speciation. Extensive intra- and interspecific variation in male nuptial coloration and female mating preferences, in the absence of postzygotic isolation between species, has inspired the hypothesis that sexual selection has been a driving force in the origin of this species flock. This hypothesis rests on the premise that the phenotypic traits that underlie behavioural reproductive isolation between sister species diverged under sexual selection within a species. We test this premise in a Lake Victoria cichlid, by using laboratory experiments and field observations. We report that a male colour trait, which has previously been shown to be important for behavioural reproductive isolation between this species and a close relative, is under directional sexual selection by female mate choice within this species. This is consistent with the hypothesis that female choice has driven the divergence in male coloration between the two species. We also find that male territoriality is vital for male reproductive success and that multiple mating by females is common.

Aim This study furthers the documentation of the geographical distribution of two divergent (c. 3%) mitochondrial DNA clades in the threespine stickleback (Gasterosteus aculeatus) and tests the hypotheses that the northeastern Pacific distribution has been influenced by post-glacial colonization and lake elevation and that clade identity is associated with certain morphological attributes such as reduction in body armour.Location Lakes and nearshore marine environments of the eastern Pacific Basin from southcentral Alaska to southeastern British Columbia, (BC) Canada.Methods Restriction enzyme analysis of polymerase chain reaction-amplified mitochondrial DNA fragments (cytochrome b) from a total of 45 new populations combined with existing data for a further 45 populations. Lake elevation data were collected for 78 localities and tested for an association with mtDNA clade by contingency table analyses. Morphological data were collected on sticklebacks from eight samples representing four lake-stream systems and tested for differentiation among populations with different mtDNA clade identities using analyses of variance. ResultsWe extend the known distribution of the haplotypes diagnostic of the Trans-North Pacific Clade (TNPC) southward to mid-Vancouver Island and, for the first time, on mainland BC, in other island populations far from putative refugia, and in nearby anadromous populations. A morphological analysis indicated that the mainland population with the TNPC was not characterized by reduced spine or lateral plate ('armour') traits that characterize some putative relict populations on the Queen Charlotte Islands. We found a significant association between lake elevation and the presence of the TNPC; the TNPC was present more often in lakes located at or lower than 42 m than in higher elevation lakes.Main conclusions Our data support the hypothesis that post-glacial colonization by TNPC-bearing marine sticklebacks and aspects of lake 'accessibility' were important in determining the distribution of mtDNA clades in the eastern Pacific Ocean basin. More generally, our study demonstrates how processes acting both across immense geographic scales (e.g. pan-Pacific dispersal) and local scales (lake accessibility contingent on timing and extent of isostatic rebound) may interact to explain biogeographical patterns.

This article analyzes the findings from a three-state study of teacher induction policy. It looks within and across Illinois, Ohio, and Wisconsin to explore the landscape and experience of teacher induction. Although the orientation and conception of each state’s policy is similar, the states represent three different structural approaches to induction policy. Based on interviews with state-level and urban district respondents and a review of relevant documents, this article explores the evolution of state-level induction policy and finds that states need to strike a balance between specificity and autonomy in crafting policy that supports effective and equitable induction policy.

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This article calls into question recent research on induction and mentoring and illustrates the effects of comprehensive induction programs on new teacher motivation, satisfaction, and retention. This analysis contradicts recent research and suggests that comprehensive induction can positively influence the retention and development of new teachers, specifically teachers in urban, hardto-staff schools. An understanding of the unique nature of and supports necessary to help new teachers navigate the complexity of teaching in today's urban diverse settings is offered. Implicationsfor successful induction support for urban educators conclude the article.