1. The causes of lagged population and geographical range expansions after species introductions ... more 1. The causes of lagged population and geographical range expansions after species introductions are poorly understood, and there are relatively few detailed case studies. 2. We document the 29-year history of population dynamics and structure for a population of Euphydryas gillettii Barnes that was introduced to the Colorado Rocky Mountains, USA in 1977. 3. The population size remained low ( < 200 individuals) and confined to a single habitat patch ( ∼ 2·25 ha) to 1998. These values are similar to those of many other populations within the natural geographical range of the species. 4. However, by 2002 the population increased dramatically to > 3000 individuals and covered ∼ 70 ha, nearly all to the south of the original site. The direction of population expansion was the same as that of predominant winds. 5. By 2004, the butterfly's local distribution had retracted mainly to three habitat patches. It thus exhibited a 'surge/contraction' form of population growth. Searches within 15 km of the original site yielded no other new populations. 6. In 2005, butterfly numbers crashed, but all three habitat patches remained occupied. The populations within each patch did not decrease in the same proportions, suggesting independent dynamics that are characteristic of metapopulations. 7. We postulate that this behaviour results, in this species, in establishment of satellite populations and, given appropriate habitat structure, may result in lagged or punctuated expansions of introduced populations.
We tested empirically whether microclimate and relative timing of oviposition affected prediapaus... more We tested empirically whether microclimate and relative timing of oviposition affected prediapause larval survival and development rates in the federally threatened Bay checkerspot butterfly, Euphydryas editha bayensis (Nymphalidae). Most mortality in Bay checkerspot butterflies occurs among prediapause larvae. Because phenology of the butterfly's larval hostplant, Plantago erecta, has been thought to drive prediapause larval survival patterns, we also tested whether
Radiotracer studies on three butterfly species showed that nutrients contributed by males through... more Radiotracer studies on three butterfly species showed that nutrients contributed by males through mating are used by females for egg production and possibly for somatic maintenance.
... For example, in a short-lived caddis fly species, Odontocerum albicorne (Tri-choptera: Odonto... more ... For example, in a short-lived caddis fly species, Odontocerum albicorne (Tri-choptera: Odontoceridae), increased investment in larval defence results in shifts in ... (Boggs & Freeman 2005), and the caddisfly Agrypnia deflate (Trichoptera: Phryganeidae) (Jannot et al. ...
We investigated the genetic background of intraspecific variation in wing color across an elevati... more We investigated the genetic background of intraspecific variation in wing color across an elevational gradient in the butterfly Colias philodice eriphyle. The degree of wing melanization was an accelerating function of elevation, and differences in wing melanization persisted in a common environment. Full-sibling analysis and parent-offspring regression yielded consistent, moderate to high heritabilities for the degree of wing melanization. The breeding experiments also demonstrated that wing melanization is strongly sex linked. Because traits that differentiate sister species also tend to be sex linked, our results suggest that the genetic mechanisms underlying intraspecific differences in wing melanization are not fundamentally different from those that have been shown to differentiate sister species.
Correlated evolution of mate signals and mate preference may be constrained if selection pressure... more Correlated evolution of mate signals and mate preference may be constrained if selection pressures acting on mate preference differ from those acting on mate signals. In particular, opposing selection pressures may act on mate preference and signals when traits have sexual as well as nonsexual functions. In the butterfly Colias philodice eriphyle, divergent selection on wing color across an elevational gradient in response to the thermal environment has led to increasing wing melanization at higher elevations. Wing color is also a long-range signal used by males in mate searching. We conducted experiments to test whether sexual selection on wing melanization via male mate choice acts in the same direction as natural selection on mate signals due to the thermal environment. We performed controlled mate choice experiments in the field over an elevational range of 1500 meters using decoy butterflies with different melanization levels. Also, we obtained a more direct estimate of the relation between wing color and sexual selection by measuring mating success in wild-caught females. Both our experiments showed that wing melanization is an important determinant of female mating success in C. p. eriphyle. However, a lack of elevational variation in male mate preference prevents coevolution of mate signals and mate preference, as males at all elevations prefer lessmelanized females. We suggest that this apparently maladaptive mate choice may be maintained by differences in detectability between the morphs or by preservation of species recognition.
Lepidoptera feed at mud puddles, dung, and carrion in a behavior known as puddling. Sodium and so... more Lepidoptera feed at mud puddles, dung, and carrion in a behavior known as puddling. Sodium and sometimes protein are feeding cues, are actively collected, and play a potentially important role in lepidopteran nutritional and mating ecology. We showed that montane butterßy species have feeding preferences among mud, herbivore dung, and carnivore dung, and that these preferences differed among butterßy species. The puddling substrates varied in soluble sodium content, with mud having the lowest concentrations and carnivore dung having the highest. Within one species, Pieris napi L., visit frequencies to mud versus dung matched visit frequencies to sand trays Þlled with sodium solutions matching the concentrations seen in mud or dung. This suggests that the preference hierarchy of this species is driven by soluble sodium concentration. Overall, the results indicate that lepidopteran species specialize on different puddling substrates, likely obtaining different arrays of nutrients. This suggests that there are species-or family-speciÞc roles for puddling nutrients in the overall nutrient budget of the insects.
Allocation of stored and incoming nutrients to reproduction determines an organism's age-specific... more Allocation of stored and incoming nutrients to reproduction determines an organism's age-specific fecundity curve. In holometabolous insects, differences among species in the shape of the curve are correlated with differences in the potential importance of adult food to reproduction. I examined allocation patterns underlying this association. Specific changes throughout life in body mass and reproductive effort were predicted to result from use of stored vs. incoming nutrients for reproduction and other metabolic needs at each age. Data for three nymphalid butterfly species, Euphydryas editha, Speyeria mormonia, and Heliconius charitonius, were compared with the predictions. These three species differ in adult diet and fraction of oocytes mature at adult emergence (hence, potential for adult nutrients to be used to make eggs), with E. editha showing the least potential for use of adult nutrients in egg production and H. charitonius showing the greatest potential. For all three species, body mass declined with age, although nonlinearly for E. editha. This indicated that metabolic expenditures were greater than intake at all ages, and that a constant fraction of stored nutrients was allocated to reproduction and other metabolic uses at each age for E. editha. Reproductive effort also declined with age for all three species. The specific patterns seen suggested that incoming nutrients may be stored, to some extent, early in life and then used late in life by both S. mormonia and H. charitonius. The similarity between S. mormonia and H. charitonius is rather surprising, given the qualitative differences in adult diet and suggests either that qualitative age-specific allocation patterns for incoming vs. stored nutrients may be independent of adult diet quality, or that the observed patterns are constrained by phylogenetic relatedness of these two species.
Nutrients used in reproduction may come from adult feeding or reserves stored from the juvenile s... more Nutrients used in reproduction may come from adult feeding or reserves stored from the juvenile stage. The dynamics of allocation from these sources are predicted to differ among nutrient types, depending on the relative availability of each nutrient type from adult and juvenile feeding. Using radiotracer techniques, I examined reproductive allocation of glucose and amino acids from adult and juvenile sources in two nymphalid butterflies, Euphydryas editha and Speyeria mormonia. The species used were intermediate in expected importance of adult nutrients to egg production, with abundant carbohydrates but few nitrogenous compounds available from the adult diet. As predicted, for compounds abundantly available in the adult diet, incoming nutrients were used in preference to stored nutrients. For compounds present in low amounts in the adult diet, juvenile reserves were used throughout adult life, although adult sources were used if available. Nutrients received by the female from the male at mating, although expected to be treated as stored reserves, were immediately used in egg production. Thus, restriction of adult or juvenile feeding may cause different nutrient types (e.g., carbohydrates, nitrogenous compounds) to become limiting to reproduction. These results are consistent with earlier allocation studies examining age-specific changes in body mass and reproductive effort, and the effects on fecundity of quantitative adult food reduction. The work has implications for understanding the evolution of nutrient types donated by males to females, the effects of a holometabolous lifestyle on age-specific fecundity, and the effects of using stored reserves vs. income in reproduction. The present results allow further predictions concerning effects of food supply perturbation on fecundity and, hence, population dynamics, and suggest ways in which species and individuals will differ in sensitivity to those perturbations.
Daily egg number is not correlated with body size. In the central range of body size, egg weight ... more Daily egg number is not correlated with body size. In the central range of body size, egg weight is also not correlated with body size. However, exceptionally large or small females lay respectively heavier or lighter eggs than average.
... COLLEEN E. SCULLEY'v2~* and CAROL L. BOGGS1v3 ... This site contained a 6.25 x 1.5 m mud... more ... COLLEEN E. SCULLEY'v2~* and CAROL L. BOGGS1v3 ... This site contained a 6.25 x 1.5 m mud puddle created by a small stream crossing a road (after flowing through an old horse corral which was used infrequently during summers only) and a 60 x 120 m open fescue ...
Variation in the degree of insect wing melanin affects thermoregulation, and is expected to be ad... more Variation in the degree of insect wing melanin affects thermoregulation, and is expected to be adapted to local environmental conditions, for example over an elevational gradient. The effects of melanization on flight activity and egg maturation rate were assessed in the closely related butterflies Colias philodice eriphyle and C. eurytheme using experimental manipulation of wing darkness and transplant experiments between high and low elevation sites. Experimental manipulation of wing darkness in C. p. eriphyle demonstrated that light males had reduced flight activity at high elevations, and darkened males had reduced flight activity at low elevations. In contrast, the transplant experiments revealed asymmetrical adaptation for male C. p. eriphyle . At high elevations darker, highelevation males had higher flight activity than lighter, low-elevation males, but there was no difference between the two groups at low elevation. For females, melanization had no effect on flight activity. However, an increase in female C. eurytheme wing darkness led to a significantly higher egg maturation rate at cold ambient temperatures, which may increase female reproductive output under natural conditions. Therefore, dispersers moving down in elevation may be more successful than those moving up.
... among members of another major insect order, the Hymenoptera. The available data suggest a si... more ... among members of another major insect order, the Hymenoptera. The available data suggest a similar trade-off occurs among caddis flies (order Trichoptera) (Novak & Sehnal, 1963; DJ Stevens and J. Jannot, unpubl. data). ...
New oocytes are generated throughout long lives in butterflies of the genus Heliconius, which as ... more New oocytes are generated throughout long lives in butterflies of the genus Heliconius, which as adults feed on amino acids from pollen. In Dryas julia, a related heliconiine that feeds only on nectar and is relatively short-lived, the original oocyte supply is eventually depleted. Such divergent ovarian dynamics in closely related organisms are significant in terms of both their evolutionary basis and their physiological controls.
1. The causes of lagged population and geographical range expansions after species introductions ... more 1. The causes of lagged population and geographical range expansions after species introductions are poorly understood, and there are relatively few detailed case studies. 2. We document the 29-year history of population dynamics and structure for a population of Euphydryas gillettii Barnes that was introduced to the Colorado Rocky Mountains, USA in 1977. 3. The population size remained low ( < 200 individuals) and confined to a single habitat patch ( ∼ 2·25 ha) to 1998. These values are similar to those of many other populations within the natural geographical range of the species. 4. However, by 2002 the population increased dramatically to > 3000 individuals and covered ∼ 70 ha, nearly all to the south of the original site. The direction of population expansion was the same as that of predominant winds. 5. By 2004, the butterfly's local distribution had retracted mainly to three habitat patches. It thus exhibited a 'surge/contraction' form of population growth. Searches within 15 km of the original site yielded no other new populations. 6. In 2005, butterfly numbers crashed, but all three habitat patches remained occupied. The populations within each patch did not decrease in the same proportions, suggesting independent dynamics that are characteristic of metapopulations. 7. We postulate that this behaviour results, in this species, in establishment of satellite populations and, given appropriate habitat structure, may result in lagged or punctuated expansions of introduced populations.
We tested empirically whether microclimate and relative timing of oviposition affected prediapaus... more We tested empirically whether microclimate and relative timing of oviposition affected prediapause larval survival and development rates in the federally threatened Bay checkerspot butterfly, Euphydryas editha bayensis (Nymphalidae). Most mortality in Bay checkerspot butterflies occurs among prediapause larvae. Because phenology of the butterfly's larval hostplant, Plantago erecta, has been thought to drive prediapause larval survival patterns, we also tested whether
Radiotracer studies on three butterfly species showed that nutrients contributed by males through... more Radiotracer studies on three butterfly species showed that nutrients contributed by males through mating are used by females for egg production and possibly for somatic maintenance.
... For example, in a short-lived caddis fly species, Odontocerum albicorne (Tri-choptera: Odonto... more ... For example, in a short-lived caddis fly species, Odontocerum albicorne (Tri-choptera: Odontoceridae), increased investment in larval defence results in shifts in ... (Boggs & Freeman 2005), and the caddisfly Agrypnia deflate (Trichoptera: Phryganeidae) (Jannot et al. ...
We investigated the genetic background of intraspecific variation in wing color across an elevati... more We investigated the genetic background of intraspecific variation in wing color across an elevational gradient in the butterfly Colias philodice eriphyle. The degree of wing melanization was an accelerating function of elevation, and differences in wing melanization persisted in a common environment. Full-sibling analysis and parent-offspring regression yielded consistent, moderate to high heritabilities for the degree of wing melanization. The breeding experiments also demonstrated that wing melanization is strongly sex linked. Because traits that differentiate sister species also tend to be sex linked, our results suggest that the genetic mechanisms underlying intraspecific differences in wing melanization are not fundamentally different from those that have been shown to differentiate sister species.
Correlated evolution of mate signals and mate preference may be constrained if selection pressure... more Correlated evolution of mate signals and mate preference may be constrained if selection pressures acting on mate preference differ from those acting on mate signals. In particular, opposing selection pressures may act on mate preference and signals when traits have sexual as well as nonsexual functions. In the butterfly Colias philodice eriphyle, divergent selection on wing color across an elevational gradient in response to the thermal environment has led to increasing wing melanization at higher elevations. Wing color is also a long-range signal used by males in mate searching. We conducted experiments to test whether sexual selection on wing melanization via male mate choice acts in the same direction as natural selection on mate signals due to the thermal environment. We performed controlled mate choice experiments in the field over an elevational range of 1500 meters using decoy butterflies with different melanization levels. Also, we obtained a more direct estimate of the relation between wing color and sexual selection by measuring mating success in wild-caught females. Both our experiments showed that wing melanization is an important determinant of female mating success in C. p. eriphyle. However, a lack of elevational variation in male mate preference prevents coevolution of mate signals and mate preference, as males at all elevations prefer lessmelanized females. We suggest that this apparently maladaptive mate choice may be maintained by differences in detectability between the morphs or by preservation of species recognition.
Lepidoptera feed at mud puddles, dung, and carrion in a behavior known as puddling. Sodium and so... more Lepidoptera feed at mud puddles, dung, and carrion in a behavior known as puddling. Sodium and sometimes protein are feeding cues, are actively collected, and play a potentially important role in lepidopteran nutritional and mating ecology. We showed that montane butterßy species have feeding preferences among mud, herbivore dung, and carnivore dung, and that these preferences differed among butterßy species. The puddling substrates varied in soluble sodium content, with mud having the lowest concentrations and carnivore dung having the highest. Within one species, Pieris napi L., visit frequencies to mud versus dung matched visit frequencies to sand trays Þlled with sodium solutions matching the concentrations seen in mud or dung. This suggests that the preference hierarchy of this species is driven by soluble sodium concentration. Overall, the results indicate that lepidopteran species specialize on different puddling substrates, likely obtaining different arrays of nutrients. This suggests that there are species-or family-speciÞc roles for puddling nutrients in the overall nutrient budget of the insects.
Allocation of stored and incoming nutrients to reproduction determines an organism's age-specific... more Allocation of stored and incoming nutrients to reproduction determines an organism's age-specific fecundity curve. In holometabolous insects, differences among species in the shape of the curve are correlated with differences in the potential importance of adult food to reproduction. I examined allocation patterns underlying this association. Specific changes throughout life in body mass and reproductive effort were predicted to result from use of stored vs. incoming nutrients for reproduction and other metabolic needs at each age. Data for three nymphalid butterfly species, Euphydryas editha, Speyeria mormonia, and Heliconius charitonius, were compared with the predictions. These three species differ in adult diet and fraction of oocytes mature at adult emergence (hence, potential for adult nutrients to be used to make eggs), with E. editha showing the least potential for use of adult nutrients in egg production and H. charitonius showing the greatest potential. For all three species, body mass declined with age, although nonlinearly for E. editha. This indicated that metabolic expenditures were greater than intake at all ages, and that a constant fraction of stored nutrients was allocated to reproduction and other metabolic uses at each age for E. editha. Reproductive effort also declined with age for all three species. The specific patterns seen suggested that incoming nutrients may be stored, to some extent, early in life and then used late in life by both S. mormonia and H. charitonius. The similarity between S. mormonia and H. charitonius is rather surprising, given the qualitative differences in adult diet and suggests either that qualitative age-specific allocation patterns for incoming vs. stored nutrients may be independent of adult diet quality, or that the observed patterns are constrained by phylogenetic relatedness of these two species.
Nutrients used in reproduction may come from adult feeding or reserves stored from the juvenile s... more Nutrients used in reproduction may come from adult feeding or reserves stored from the juvenile stage. The dynamics of allocation from these sources are predicted to differ among nutrient types, depending on the relative availability of each nutrient type from adult and juvenile feeding. Using radiotracer techniques, I examined reproductive allocation of glucose and amino acids from adult and juvenile sources in two nymphalid butterflies, Euphydryas editha and Speyeria mormonia. The species used were intermediate in expected importance of adult nutrients to egg production, with abundant carbohydrates but few nitrogenous compounds available from the adult diet. As predicted, for compounds abundantly available in the adult diet, incoming nutrients were used in preference to stored nutrients. For compounds present in low amounts in the adult diet, juvenile reserves were used throughout adult life, although adult sources were used if available. Nutrients received by the female from the male at mating, although expected to be treated as stored reserves, were immediately used in egg production. Thus, restriction of adult or juvenile feeding may cause different nutrient types (e.g., carbohydrates, nitrogenous compounds) to become limiting to reproduction. These results are consistent with earlier allocation studies examining age-specific changes in body mass and reproductive effort, and the effects on fecundity of quantitative adult food reduction. The work has implications for understanding the evolution of nutrient types donated by males to females, the effects of a holometabolous lifestyle on age-specific fecundity, and the effects of using stored reserves vs. income in reproduction. The present results allow further predictions concerning effects of food supply perturbation on fecundity and, hence, population dynamics, and suggest ways in which species and individuals will differ in sensitivity to those perturbations.
Daily egg number is not correlated with body size. In the central range of body size, egg weight ... more Daily egg number is not correlated with body size. In the central range of body size, egg weight is also not correlated with body size. However, exceptionally large or small females lay respectively heavier or lighter eggs than average.
... COLLEEN E. SCULLEY'v2~* and CAROL L. BOGGS1v3 ... This site contained a 6.25 x 1.5 m mud... more ... COLLEEN E. SCULLEY'v2~* and CAROL L. BOGGS1v3 ... This site contained a 6.25 x 1.5 m mud puddle created by a small stream crossing a road (after flowing through an old horse corral which was used infrequently during summers only) and a 60 x 120 m open fescue ...
Variation in the degree of insect wing melanin affects thermoregulation, and is expected to be ad... more Variation in the degree of insect wing melanin affects thermoregulation, and is expected to be adapted to local environmental conditions, for example over an elevational gradient. The effects of melanization on flight activity and egg maturation rate were assessed in the closely related butterflies Colias philodice eriphyle and C. eurytheme using experimental manipulation of wing darkness and transplant experiments between high and low elevation sites. Experimental manipulation of wing darkness in C. p. eriphyle demonstrated that light males had reduced flight activity at high elevations, and darkened males had reduced flight activity at low elevations. In contrast, the transplant experiments revealed asymmetrical adaptation for male C. p. eriphyle . At high elevations darker, highelevation males had higher flight activity than lighter, low-elevation males, but there was no difference between the two groups at low elevation. For females, melanization had no effect on flight activity. However, an increase in female C. eurytheme wing darkness led to a significantly higher egg maturation rate at cold ambient temperatures, which may increase female reproductive output under natural conditions. Therefore, dispersers moving down in elevation may be more successful than those moving up.
... among members of another major insect order, the Hymenoptera. The available data suggest a si... more ... among members of another major insect order, the Hymenoptera. The available data suggest a similar trade-off occurs among caddis flies (order Trichoptera) (Novak & Sehnal, 1963; DJ Stevens and J. Jannot, unpubl. data). ...
New oocytes are generated throughout long lives in butterflies of the genus Heliconius, which as ... more New oocytes are generated throughout long lives in butterflies of the genus Heliconius, which as adults feed on amino acids from pollen. In Dryas julia, a related heliconiine that feeds only on nectar and is relatively short-lived, the original oocyte supply is eventually depleted. Such divergent ovarian dynamics in closely related organisms are significant in terms of both their evolutionary basis and their physiological controls.
FULL TEXT FREELY AVAILABLE AT www.escholarship.org/uc/item/6837k4gc . . . Both means and year-to-... more FULL TEXT FREELY AVAILABLE AT www.escholarship.org/uc/item/6837k4gc . . . Both means and year-to-year variances of climate variables such as temperature and precipitation are predicted to change. However, the potential impact of changing climatic variability on the fate of populations has been largely unexamined. We analyzed multiyear demographic data for 36 plant and animal species with a broad range of life histories and types of environment to ask how sensitive their long-term stochastic population growth rates are likely to be to changes in the means and standard deviations of vital rates (survival, reproduction, growth) in response to changing climate. We quantified responsiveness using elasticities of the long-term population growth rate predicted by stochastic projection matrix models. Short-lived species (insects and annual plants and algae) are predicted to be more strongly (and negatively) affected by increasing vital rate variability relative to longer-lived species (perennial plants, birds, ungulates). Taxonomic affiliation has little power to explain sensitivity to increasing variability once longevity has been taken into account. Our results highlight the potential vulnerability of short-lived species to an increasingly variable climate, but also suggest that problems associated with short-lived undesirable species (agricultural pests, disease vectors, invasive weedy plants) may be exacerbated in regions where climate variability decreases.
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Papers by Carol Boggs