Adult emergence phenology in checkerspot butterflies: the effects of macroclimate, topoclimate, and population history

• Published in: Oecologia Vol. 96; no. 2; pp. 261 - 270
• Main Authors: Weiss, S.B. (Stanford Univ., CA (USA). Dept. of Biological Sciences), Murphy, D.D, Ehrlich, P.R, Metzler, C.F
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01-11-1993; Springer
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; BIOMASA; BIOMASSE; Butterflies; Demecology; ECOLOGIA; ECOLOGIE; Emergence; ESTRUCTURA DE LA POBLACION; ETAPAS DEL DESARROLLO ANIMAL; Euphydryas editha bayensis; Euphydryas insolation; FACTEUR CLIMATIQUE; FACTORES CLIMATICOS; FENOLOGIA; FORMAS JUVENILES; Fundamental and applied biological sciences. Psychology; Habitat conservation; Insect larvae; Insolation; Instars; Invertebrates; JUVENILE; Larvae; Larval development; LARVAS; LARVE; LEPIDOPTERA; Microclimate; MODELE; MODELOS; Nymphalidae; PHENOLOGIE; Phenology; Protozoa. Invertebrata; STADE DE DEVELOPPEMENT ANIMAL; STRUCTURE DE LA POPULATION; TEMPERATURA AMBIENTE; TEMPERATURE AMBIANTE; Thermal ecology; Topography; Weather; USA, California; Euphydryas editha; Temperature; Endangered species; Insecta; Environmental factor; Microclimate; Phenology; Arthropoda; Topography; Lepidoptera; Emergence; Nymphalidae; Population dynamics; Simulation model; Invertebrata; Euphydryas insolation; Thermal ecology
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/bf00317740

The prediction of adult emergence lines 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 accounts for both solar exposure of the habitat and cloud cover. Instar-specific larval mass gains per unit of insolation were determined from mark-recapture experiments. A small correction for daily low temperatures was used to calibrate the model to five years of field data on larval mass. The model predicted mean mass of 90% of larval samples within 4 clear days over a 70-120 day growing season. The magnitude of spatial variation in emergence times across habitat slopes is greater than annual variation in emergence times due to yearly weather conditions. Historical variation (yearly shifts in larval distributions across slopes) is an important determinant of mean population emergence dates. All of these factors need to be considered in understanding adult emergence phenology in this butterfly and in other insects inhabiting heterogeneous thermal environments. Such an understanding can be useful in managing insect populations for both pest control and conservation.