Egg weights and total eggs produced by nine Speyeria spp. (Nymphalidae) in California allowed estimates of per-egg and lifetime reproductive effort. Interpopulation reproductive effort in four species and intrapopulation reproductive effort of two species in different years were documented. Female body weight was uncorrelated with either individual egg weight or total lifetime egg weight. Smallest eggs (mean dry wt/egg = 0.05-0.06 ug), and the greatest number of eggs, were from S. coronis (Skinner) and S. zerene (Boisduval) whose females undergo summer reproductive diapause in dry habitats. Largest eggs (mean dry wt/egg = 0.10 ug) were from S. nokomis (Skinner), a wet habitat species. The greatest relative reproductive effort was made by dry habitat species lacking reproductive diapause. Reproductive effort and duration of first instar exposure to summer temperatures were positively correlated. Intrayear variation in total egg weight did not vary significantly among populations of S. callippe (Boisduval), S. hesperis (Boisduval), S. nokomis, or S. zerene but mean total egg weights were significantly different in females from the Donner Pass, CA population of S. mormonia (Boisduval) in two years. S. zerene from high elevations lacked the reproductive diapause characteristic of lower elevation populations. The reproductive strategies of Speyeria spp. are adaptive responses to the desiccation stress that their habitats impose on diapausing first instars.

Egg weights of Speyeria (Nymphalidae) species from California were measured to estimate relative sizes of first-instar larvae. First-instar larvae were compared for diapause intensity and for their physiological and behavioral responses to atmospheric humidity and free water. Diapause intensity, measured by number of days between first instar and molt to second instar, ranged from 7.6 d (Speyeria nokomis) to 40.7 d (Speyeria callippe). Among species, diapause intensity was uncorrelated with egg weight, but within three species (S. nokomis, Speyeria mormonia, and Speyeria zerene), diapause intensity was positively correlated to egg weight. There was significant interspecific variability in the desiccation tolerance of diapause larvae to low (11% RH) humidity. The least and most desiccation-tolerant species, respectively, were S. nokomis (LT50= 1.9 d) and S. callippe (LT50 = 13.6 d). Interspecific desiccation tolerance was uncorrelated with egg weight. Larvae of S. nokomis moved from lower to higher humidity within a humidity gradient, whereas larvae of S. callippe did not move toward higher humidity. Desiccated larvae of S. callippe and S. zerene rehydrated by imbibing free water. Exposure of S. callippe and S. zerene larvae to 100% RH in the absence of free water did not result in a body weight increase, but high humidity conditions reduced the rate of water loss. © 2014 Entomological Society of America.

Understanding the spatial and temporal scales at which environmental variation affects populations of plants and animals is an important goal for modern population biology, especially in the context of shifting climatic conditions. The El Niño Southern Oscillation (ENSO) generates climatic extremes of interannual variation, and has been shown to have significant effects on the diversity and abundance of a variety of terrestrial taxa. However, studies that have investigated the influence of such large-scale climate phenomena have often been limited in spatial and taxonomic scope. We used 23 years (1988-2010) of a long-term butterfly monitoring data set to explore associations between variation in population abundance of 28 butterfly species and variation in ENSO-derived sea surface temperature anomalies (SSTA) across 10 sites that encompass an elevational range of 2750 m in the Sierra Nevada mountain range of California. Our analysis detected a positive, regional effect of increased SSTA on butterfly abundance (wetter and warmer years predict more butterfly observations), yet the influence of SSTA on butterfly abundances varied along the elevational gradient, and also differed greatly among the 28 species. Migratory species had the strongest relationships with ENSO-derived SSTA, suggesting that large-scale climate indices are particularly valuable for understanding biotic-abiotic relationships of the most mobile species. In general, however, the ecological effects of large-scale climatic factors are context dependent between sites and species. Our results illustrate the power of long-term data sets for revealing pervasive yet subtle climatic effects, but also caution against expectations derived from exemplar species or single locations in the study of biotic-abiotic interactions.

Gene flow and hybridization among species dramatically affect our understanding of the species as a biological unit, species relationships, and species adaptations. In North American Colias eurytheme and Colias eriphyle, there has been historical debate over the extent of hybridization occurring and the identity of phenotypically intermediate individuals as genetic hybrids. This study assesses the population structure of these two species to measure the extent of hybridization and the genetic identity of phenotypic intermediates as hybrids. Amplified fragment length polymorphism (AFLP) marker analysis was performed on 378 specimens collected from northern California and Nevada. Population structure was inferred using a Bayesian/Markov chain Monte Carlo method, which probabilistically assigns individuals to genetic clusters. Three genetic clusters provided the best fit for the data. C. eurytheme individuals were primarily assigned to two closely related clusters, and C. eriphyle individuals were mostly assigned to a third, more distantly related cluster. There appeared to be significant hybridization between the two species. Individuals of intermediate phenotype (putative hybrids) were found to be genetically indistinguishable from C. eriphyle, indicating that previous work based on the assumption that these intermediate forms are hybrids may warrant reconsideration.

The butterfly tribe Melitaeini [Nymphalidae] contains numerous species that have been the subjects of a wide range of biological studies. Despite numerous taxonomic revisions, many of the evolutionary relationships within the tribe remain unresolved. Utilizing mitochondrial and nuclear gene regions, we produced a time-calibrated phylogenetic hypothesis for 222 exemplars comprising at least 178 different species and 21 of the 22 described genera, making this the most complete phylogeny of the tribe to date. Our results suggest that four well-supported clades corresponding to the subtribes Euphydryina, Chlosynina, Melitaeina, and Phyciodina exist within the tribe. This analysis is also represents the most complete phylogenetic analysis of the Chlosynina to date, and includes several genera and species that have been previously excluded from published phylogenies of this group.

Checkerspot butterflies in the genera Euphydryas and Chlosyne exhibit phenotypic polymorphisms along a well-defined latitudinal and elevational gradient in California. The patterns of phenotypic variation in Euphydryas chalcedona, Chlosyne palla, and Chlosyne hoffmanni suggest a mimetic relationship; in addition, the specific patterns of variation in C. palla suggest a female-limited polymorphic mimicry system (FPM). However, the existence of polymorphic models runs counter to predictions of mimicry theory. Palatability trials were undertaken to assess whether or not the different color morphs of each species were distasteful or toxic to a generalized avian predator, the European starling (Sturnus vulgaris). Results indicate that the black morph of E. chalcedona is distasteful, but not toxic, to predators, while the red morph is palatable. C . hoffmanni and both color morphs of C. palla are palatable to predators. Predators that learn to reject black E. chalcedona also reject black C. palla, suggesting that the latter is a FPM of the former. C. hoffmanni does not appear to be involved in this mimetic relationship.

Understanding the spatial and temporal scales at which environmental variation affects populations of plants and animals is an important goal for modern population biology, especially in the context of shifting climatic conditions. The El Niño Southern Oscillation (ENSO) generates climatic extremes of interannual variation, and has been shown to have significant effects on the diversity and abundance of a variety of terrestrial taxa. However, studies that have investigated the influence of such large-scale climate phenomena have often been limited in spatial and taxonomic scope. We used 23 years (1988-2010) of a long-term butterfly monitoring data set to explore associations between variation in population abundance of 28 butterfly species and variation in ENSO-derived sea surface temperature anomalies (SSTA) across 10 sites that encompass an elevational range of 2750 m in the Sierra Nevada mountain range of California. Our analysis detected a positive, regional effect of increased SSTA on butterfly abundance (wetter and warmer years predict more butterfly observations), yet the influence of SSTA on butterfly abundances varied along the elevational gradient, and also differed greatly among the 28 species. Migratory species had the strongest relationships with ENSO-derived SSTA, suggesting that large-scale climate indices are particularly valuable for understanding biotic-abiotic relationships of the most mobile species. In general, however, the ecological effects of large-scale climatic factors are context dependent between sites and species. Our results illustrate the power of long-term data sets for revealing pervasive yet subtle climatic effects, but also caution against expectations derived from exemplar species or single locations in the study of biotic-abiotic interactions.

Since the phenomenon of mimicry was first described by Bates in 1862 it has become one of the foundational examples of adaptive evolution. Numerous subcategories of mimicry and dozens of hypotheses pertaining to its evolution and maintenance have been proposed. Many of these hypotheses, however, are difficult to test in experimental settings, and data from natural observations are often inadequate. Here we use data from a long-term survey of butterfly presence and abundance to test several hypotheses pertaining to Batesian and female-limited polymorphic mimicry (FPM; a special case of Batesian mimicry). We found strong evidence that models outnumber mimics in both mimicry systems, but no evidence for an increase in relative abundance of FPM mimics to their Batesian counterparts. Tests of the early-emergence/model first hypothesis showed strong evidence that the Batesian mimic routinely emerges after the model, while emergence timing in the FPM system was site specific, suggesting that other ecological factors are at play. These results demonstrate the importance of long-term field observations for testing evolutionary and ecological hypotheses.

An important and largely unaddressed issue in studies of biotic-abiotic relationships is the extent to which closely related species, or species living in similar habitats, have similar responses to weather. We addressed this by applying a hierarchical, Bayesian analytical framework to a long-term data set for butterflies which allowed us to simultaneously investigate responses of the entire fauna and individual species. A small number of variables had community-level effects. In particular, higher total annual snow depth had a positive effect on butterfly occurrences, while spring minimum temperature and El Niño-Southern Oscillation (ENSO) sea-surface variables for April-May had negative standardized coefficients. Our most important finding was that variables with large impacts at the community-level did not necessarily have a consistent response across all species. Species-level responses were much more similar to each other for snow depth compared to the other variables with strong community effects. This variation in species-level responses to weather variables raises important complications for the prediction of biotic responses to shifting climatic conditions. In addition, we found that clear associations with weather can be detected when considering ecologically delimited subsets of the community. For example, resident species and non-ruderal species had a much more unified response to weather variables compared to non-resident species and ruderal species, which suggests local adaptation to climate. These results highlight the complexity of biotic-abiotic interactions and confront that complexity with methodological advances that allow ecologists to understand communities and shifting climates while simultaneously revealing species-specific variation in response to climate.