Publications

population genetics of euphydryas butterflies. i genetic variation and the neutrality hypothesis.	twenty-one populations of the checkerspot butterfly, euphydryas editha, and ten populations of euphydryas chalcedona were sampled for genetic variation at eight polymorphic enzyme loci. both species possessed loci that were highly variable from population to population and loci that were virtually identical across all populations sampled. our data indicate that the neutrality hypothesis is untenable for the loci studied, and therefore selection is indicated as the major factor responsible for pr ...	1975	1205135
a direct assessment of the role of genetic drift in determining allele frequency variation in populations of euphydryas editha.	estimates of allele frequencies at six polymorphic loci were collected over eight generations in two populations of euphydryas editha. we have estimated, in addition, the effective population size for each generation for both populations with results from mark-recapture and other field data. the variation in allele frequencies generated by random genetic drift was then studied using computer simulations and our direct estimates of effective population size. substantial differences between observ ...	1985	4018569
the dispersal system of a butterfly: a test of source-sink theory suggests the intermediate-scale hypothesis.	theory predicts source-sink dynamics can occur in species with the ideal preemptive distribution but not with the ideal free distribution. source-sink dynamics can also occur in species with passive dispersal, in which a fixed fraction of the population disperses each generation. however, in nature, dispersal often approximates random diffusion rather than ideal choices or fixed probabilities. here, i ask which dispersal system occurred in a butterfly (euphydryas editha) known to have source-sin ...	2000	10856197
on parameter estimation in population models.	we describe methods for estimating the parameters of markovian population processes in continuous time, thus increasing their utility in modelling real biological systems. a general approach, applicable to any finite-state continuous-time markovian model, is presented, and this is specialised to a computationally more efficient method applicable to a class of models called density-dependent markov population processes. we illustrate the versatility of both approaches by estimating the parameters ...	2006	16984803
complex components of habitat suitability within a butterfly colony.	the microdistribution of adult euphydryas editha changes from year to year, and the colony is subdivided into three populations that fluctuate independently in size. these observations are attributed largely to fluctuations in time and space of three complex larval resources associated with the availability of food. this cotnplexity also entails selection pressure favoring the observed low dispersal tendency of adults.	1972	17784423
intrinsic barriers to dispersal in checkerspot butterfly.	capture-recapture studies revealed that the checkerspot butterfly euphydryas editha is extraordinarily sedentary. since no physical barriers prevent interchange between various portions of the study colony, it is concluded that intrinsic factors play the major role in limiting movement. the few available data on dispersal are discussed.	1961	17807397
the difficulty of deducing behavior from resource use: an example from hilltopping in checkerspot butterflies.	resource preferences of individuals cannot be deduced from patterns of resource use at the population level. for example, a particular pattern of resource use can be produced by a variety of preference distributions in an animal population. the strength of the association between resource preference (a behavioral parameter) and resource use (an ecological parameter) detemines the extent to which natural selection acting on resource use translates into selection acting on preference. however, the ...	1992	19426037
multitrait, host-associated divergence among sets of butterfly populations: implications for reproductive isolation and ecological speciation.	when populations use different resources, they tend to diverge in traits that affect performance on those resources. the extent and complexity of divergence that is achieved will depend on gene flow, genetic constraints, and the character of divergent selection. we describe divergent host adaptation among californian populations of the melitaeine butterfly, euphydryas editha. divergence in seven traits created parallel phenotypic suites, each suite associated with the use of a different host spe ...	2010	19817847
rapid microsatellite isolation from a butterfly by de novo transcriptome sequencing: performance and a comparison with aflp-derived distances.	the isolation of microsatellite markers remains laborious and expensive. for some taxa, such as lepidoptera, development of microsatellite markers has been particularly difficult, as many markers appear to be located in repetitive dna and have nearly identical flanking regions. we attempted to circumvent this problem by bioinformatic mining of microsatellite sequences from a de novo-sequenced transcriptome of a butterfly (euphydryas editha).	2010	20585453
phenological asynchrony between herbivorous insects and their hosts: signal of climate change or pre-existing adaptive strategy?	climate change alters phenological relations between interacting species. we might expect the historical baseline, or starting-point, for such effects to be precise synchrony between the season at which a consumer most requires food and the time when its resources are most available. we synthesize evidence that synchrony was not the historical condition in two insect-plant interactions involving edith's checkerspot butterfly (euphydryas editha), the winter moth (operophtera brumata) and their ho ...	2010	20819810
field studies reveal strong postmating isolation between ecologically divergent butterfly populations.	gene flow between populations that are adapting to distinct environments may be restricted if hybrids inherit maladaptive, intermediate phenotypes. this phenomenon, called extrinsic postzygotic isolation (epi), is thought to play a critical role in the early stages of speciation. however, despite its intuitive appeal, we know surprisingly little about the strength and prevalence of epi in nature, and even less about the specific phenotypes that tend to cause problems for hybrids. in this study, ...	2010	21048982
a reexamination of hilltopping in euphydryas editha.		1990	22160120
microsatellites for the marsh fritillary butterfly: de novo transcriptome sequencing, and a comparison with amplified fragment length polymorphism (aflp) markers.	until recently the isolation of microsatellite markers from lepidoptera has proved troublesome, expensive and time-consuming. following on from a previous study of edith's checkerspot butterfly, euphydryas editha, we developed novel microsatellite markers for the vulnerable marsh fritillary butterfly, e. aurinia. our goal was to optimize the process in order to reduce both time and cost relative to prevailing techniques. this was accomplished by using a combination of previously developed techni ...	2013	23349956
geographic mosaics of species' association: a definition and an example driven by plant-insect phenological synchrony.	spatial mosaics occur in both evolutionary and ecological properties of species' interactions. studies of these patterns have facilitated description and prediction of evolutionary responses of interacting species to each other and to changing environments. we propose seeking complementary understanding of community assembly and dynamics by studying ecological and mechanistic properties of mosaics. we define "species' association mosaics" as deviations from a null model in which spatial variatio ...	2012	23431596
host-associated genomic differentiation in congeneric butterflies: now you see it, now you do not.	ecotypic variation among populations may become associated with widespread genomic differentiation, but theory predicts that this should happen only under particular conditions of gene flow, selection and population size. in closely related species, we might expect the strength of host-associated genomic differentiation (had) to be correlated with the degree of phenotypic differentiation in host-adaptive traits. using microsatellite and amplified fragment length polymorphism (aflp) markers, and ...	2013	23927539
apparent power-law distributions in animal movements can arise from intraspecific interactions.	lévy flights have gained prominence for analysis of animal movement. in a lévy flight, step-lengths are drawn from a heavy-tailed distribution such as a power law (pl), and a large number of empirical demonstrations have been published. others, however, have suggested that animal movement is ill fit by pl distributions or contend a state-switching process better explains apparent lévy flight movement patterns. we used a mix of direct behavioural observations and gps tracking to understand step-l ...	2015	25519992
grazing maintains native plant diversity and promotes community stability in an annual grassland.	maintaining native biodiversity in grasslands requires management and mitigation of anthropogenic changes that have altered resource availability, grazing regimes, and community composition. in california (usa), high levels of atmospheric nitrogen (n) deposition have facilitated the invasion of exotic grasses, posing a threat to the diverse plant and insect communities endemic to serpentine grasslands. cattle grazing has been employed to mitigate the consequences of exotic grass invasion, but th ...	2015	26485954
learning about colonization when managing metapopulations under an adaptive management framework.	adaptive management is a framework for resolving key uncertainties while managing complex ecological systems. its use has been prominent in fisheries research and wildlife harvesting; however, its application to other areas of environmental management remains somewhat limited. indeed, adaptive management has not been used to guide and inform metapopulation restoration, despite considerable uncertainty surrounding such actions. in this study, we determined how best to learn about the colonization ...	2016	27039525
food plant defoliation and larval starvation of euphydryas editha.	investigation of larval food plant relationships of populations of euphydryas editha boisduval throughout california demonstrated three striking phenomena. first, relationships between butterflies and plants were found to be highly variable among populations utilizing different (but related) food plants. second, defoliation of food plants was quite common and often extensive; this is contrary to the widely accepted generalization that herbivores rarely defoliate their food plants. third, larval ...	1974	28308656
the structure and genetics of a montane population of the checkerspot butterfly, chlosyne palla.	the population structure, genetics and ecology of the checkerspot butterfly, chlosyne palla, in an area of gunnison county, colorado were investigated. the population structure was found to be quite different from that of most butterflies and from all of those aspects known for its thoroughly studied relative, euphydryas editha. the population unit of chlosyne palla may cover an area some five to eight times the size of the largest known euphydryas population and twice the size of an erebia epip ...	1976	28308873
population biology of the checkerspot butterfly, euphydryas chalcedona structure of the jasper ridge colony.	euphydryas chalcedona at jasper ridge consists of two independently varying major demographic units, similar in scale but not in structure to those of euphydryas editha. in contrast, however, jasper ridge e. chalcedona represent just a portion of a deme-while e. editha occurs as two partially connected demes. the life history and general ecology of e. chalcedona is described and compared with those of its intensively-studied congener. various problems of mark-release-recapture estimation of popu ...	1980	28309478
the role of adult feeding in egg production and population dynamics of the checkerspot butterfly euphydryas editha.	carbohydrate intake increases longevity, body weight maintenance and egg production in female euphydryas editha. amino acid intake leads to heavier eggs, larvae from which are more likely to survive. females fed nectar produce more eggs in later masses than females which are not fed. during years of normal and below normal precipitation, larvae emerging from these later eggs are unlikely to reach obligatory size for diapause before their food dries up. on jasper ridge, where mortality is density ...	1983	28310203
ecological determinants of food plant choice in the checkerspot butterfly euphydryas editha in colorado.	the larvae of euphydryas editha in gunnison county, colorado, feed on castilleja linariifolia. two related plants, c. chromosa and penstemon strictus, occur in the same area and are equally nutritious, but are not eaten. restriction to c. linariifolia appears to be a case of ecological monophagy - survival on the other two species is less likely not because of their biochemical make-up but because of their ecological characteristics, primarily their phenologies.	1982	28310406
quantification of host preference by manipulation of oviposition behavior in the butterfly euphydryas editha.	this paper describes a novel method of measuring host specificity and determining host rank order. as applied to oviposition behavior of the butterfly euphydryas editha, the rank order of preference is the order in which plants become acceptable as the insect searches, while specificity is quantified in terms of the rate at which searching insects become less discriminating. the information obtained is different from that gleaned from other preference testing techniques. it is useful in helping ...	1982	28310512
butterfly larvae reduce host plant survival in vicinity of alternative host species.	mortality of an annual plant. collinsia torreyi, was increased in the vicinity of pedicularis semibarbata plants. this was a consequence of feeding by euphydryas editha, a herbivore which feeds on both plant species. mortality of c. torreyi was better predicted by distance from p. semibarbata than by density of c. torreyi. since not all herbivores are monophagous, interactions involving distance and density effects on plant survival and on vegetational diversity need to be considered with respec ...	1986	28311294
rainfall and the interaction of microclimate with larval resources in the population dynamics of checkerspot butterflies (euphydryas editha) inhabiting serpentine grassland.	the interaction of host plant phenology and microclimatic heterogeneity was examined to determine its role in the population dynamics of checkerspot butterflies, euphydryas editha, inhabiting serpentine grassland in california's outer coast range.within the 2-3 hectares inhabited by a population of e. editha (jasper ridge area h), microclimatic differences resulting from topographic heterogeneity largely determine the temporal and spatial pattern of senescence of the larval host plants, plantago ...	1987	28312241
population structure of a hilltopping butterfly.	the hilltopping behavior of individuals in a closed demographic unit ofeuphydryas editha is examined. both males and females hilltop but the behavior differs between the sexes. most males appear to hilltop throughout their reproductive lives. females hilltop only as virgins. the occurrence of hilltopping in a population is influenced by the density and age structure of the population. in addition, some males appear not to hilltop, but instead "patrol" below the hilltop, a strategy which may be f ...	1988	28312436
adult emergence phenology in checkerspot butterflies: the effects of macroclimate, topoclimate, and population history.	the prediction of adult emergence times in insect populations can be greatly complicated by microclimatic gradients, especially in circumstances where distributions of juveniles along those gradients vary from year to year. to investigate adult emergence patterns in topographically heterogeneous habitats, we built a model of postdiapause development of the bay checkerspot butterfly, euphydryas editha bayensis. the model uses slope-specific insolation as the rate-controlling variable, and account ...	1993	28313423
estimating female reproductive success of a threatened butterfly: influence of emergence time and hostplant phenology.	we estimated lifetime reproductive success of euphydryas editha bayensis (nymphalidae), a federally listed threatened butterfly, based on age-specific fecundity and both adult and offspring survival. our results indicate that the relative timing of adult emergence and larval hosplant senescence strongly influenced reproductive success of females. for 1992, we estimated that only 8-21% of the eggs laid by females emerging on the 1st day of the 4-week flight season would produce larvae that reach ...	1994	28313966