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We used nuclear genomic data and statistical models to evaluate the ecological and evolutionary processes shaping spatial variation in species richness in Calochortus (Liliaceae, 74 spp.). Calochortus occupies diverse habitats in the western United States and Mexico and has a center of diversity in the California Floristic Province, marked by multiple orogenies, winter rainfall, and highly divergent climates and substrates (including serpentine). We used sequences of 294 low-copy nuclear loci to produce a time-calibrated phylogeny, estimate historical biogeography, and test hypotheses regarding drivers of present-day spatial patterns in species number. Speciation and species coexistence require reproductive isolation and ecological divergence, so we examined the roles of chromosome number, environmental heterogeneity, and migration in shaping local species richness. Six major clades--inhabiting different geographic/climatic areas, and often marked by different base chromosome numbers (n = 6 to 10)--began diverging from each other ~10.3 Mya. As predicted, local species number increased significantly with local heterogeneity in chromosome number, elevation, soil characteristics, and serpentine presence. Species richness is greatest in the Transverse/Peninsular Ranges where clades with different chromosome numbers overlap, topographic complexity provides diverse conditions over short distances, and several physiographic provinces meet allowing immigration by several clades. Recently diverged sister-species pairs generally have peri-patric distributions, and maximum geographic overlap between species increases over the first million years since divergence, suggesting that chromosomal evolution, genetic divergence leading to gametic isolation or hybrid inviability/sterility, and/or ecological divergence over small spatial scales may permit species co-occurrence. [ABSTRACT FROM AUTHOR]

Aim: Natural selection typically results in the homogenization of reproductive traits, reducing natural variation within populations; thus, highly polymorphic species present unresolved questions regarding the mechanisms that shape and maintain gene flow given a diversity of phenotypes. We used an integrative framework to characterize phenotypic diversity and assess how evolutionary history and population genetics affect the highly polymorphic nature of a California endemic lily. Location: California, United States. Taxon: Butterfly mariposa lily, Calochortus venustus (Liliaceae). Methods: We summarized phenotypic diversity at both metapopulation and subpopulation scales to explore spatial phenotypic distributions. We sampled 174 individuals across the species range representing multiple samples for each population and each phenotype. We used restriction‐site‐associated DNA sequencing (RAD‐Seq) to detect population clusters, gene flow between phenotypes and between populations, infer haplotype networks, and reconstruct ancestral range evolution to infer historical migration and range expansion. Results: Polymorphic floral traits within the species such as petal pigmentation and distal spots are geographically structured, and inferred evolutionary history is consistent with a ring species pattern involving a complex of populations having experienced sequential change in genetic and phenotypic variation from the founding population. Populations remain interconnected yet have differentiated from each other along a bifurcating south‐to‐north range expansion, consequently indicating parallel evolution towards the white morphotype in the northern range. Thus, our phylogeographical analyses reveal morphological convergence with population genetic cohesion irrespective of phenotypic diversity. Main conclusions: Phenotypic variation in the highly polymorphic Calochortus venustus is not due to genetic differentiation between phenotypes; rather there is genetic cohesion within six geographically defined populations, some of which maintain a high level of within‐population phenotypic diversity. Our results demonstrate that analyses of polymorphic taxa greatly benefit from disentangling phenotype from genotype at various spatial scales. We discuss results in light of ring species concepts and the need to determine the adaptive significance of the patterns we report. [ABSTRACT FROM AUTHOR]

In response to the second California Supreme Court ruling in Serrano, the legislature has recently acted to make the financing of schools fiscally neutral, The neutrality provisions of the new law have been challenged as permitting unacceptably large variations in per pupil expenditure among districts. The author shows that even if the intent to comply fully were not at issue achieving fiscal neutrality would be a difficult and complex task. Other provisions of the law address intra- district financial practices and policies. Since equality of educational opportunity depends as much on intradistrict resource allocation as on fiscal neutrality, the author develops a research strategy to determine the efficacy of these intradistrict reforms. Drawing on recent theoretical work in the field of public-choice economics, he devises an analysis of decision making in school districts that yields testable hypotheses about the consequences of school-site councils and minimum performance requirements, two of the intradistrict reforms. While the testing must await the unfolding of events, the analysis shows how economic reasoning can be brought to bear in promising ways on political issues in education. [ABSTRACT FROM AUTHOR]