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101.
Asymmetrical thermal constraints on the parapatric species boundaries of two widespread generalist butterflies 总被引:1,自引:0,他引:1
Abstract. 1. The sibling species Papilio glaucus and Papilio canadensis meet in a narrow hybrid zone believed to be maintained by temperature thresholds acting independently on both species. The present study tests if this assertion is true for the cold-adapted species, P. canadensis , which is presumed to be limited by the effect of high temperatures in late summer and/or autumn on pupal survival.
2. Three experiments were conducted examining the effects of: (i) short periods of high temperature stress in autumn, (ii) prolonged warm temperatures in autumn, and (iii) temperatures simulating warmer winters/longer springs upon the survival of P. canadensis and P. glaucus.
3. Results indicated that short periods of high temperatures did not induce the high mortality rates required to be the key factor limiting the range of P. canadensis . However, P. canadensis did exhibit a considerably lower tolerance to high temperature extremes, prolonged warm temperatures in autumn, and conditions simulating shorter/warmer winters than P. glaucus .
4. Differences in temperature tolerance throughout the pupal stage are likely to be a significant factor in maintaining the southern range limit of P. canadensis . Further warming as may occur during climate change, particularly in winter and spring, will likely affect the dynamics of southerly populations of P. canadensis. 相似文献
2. Three experiments were conducted examining the effects of: (i) short periods of high temperature stress in autumn, (ii) prolonged warm temperatures in autumn, and (iii) temperatures simulating warmer winters/longer springs upon the survival of P. canadensis and P. glaucus.
3. Results indicated that short periods of high temperatures did not induce the high mortality rates required to be the key factor limiting the range of P. canadensis . However, P. canadensis did exhibit a considerably lower tolerance to high temperature extremes, prolonged warm temperatures in autumn, and conditions simulating shorter/warmer winters than P. glaucus .
4. Differences in temperature tolerance throughout the pupal stage are likely to be a significant factor in maintaining the southern range limit of P. canadensis . Further warming as may occur during climate change, particularly in winter and spring, will likely affect the dynamics of southerly populations of P. canadensis. 相似文献
102.
Nelson G. Hairston Jr Stephen P. Ellner Monica A. Geber Takehito Yoshida Jennifer A. Fox 《Ecology letters》2005,8(10):1114-1127
Recent studies have documented rates of evolution of ecologically important phenotypes sufficiently fast that they have the potential to impact the outcome of ecological interactions while they are underway. Observations of this type go against accepted wisdom that ecological and evolutionary dynamics occur at very different time scales. While some authors have evaluated the rapidity of a measured evolutionary rate by comparing it to the overall distribution of measured evolutionary rates, we believe that ecologists are mainly interested in rapid evolution because of its potential to impinge on ecological processes. We therefore propose that rapid evolution be defined as a genetic change occurring rapidly enough to have a measurable impact on simultaneous ecological change. Using this definition we propose a framework for decomposing rates of ecological change into components driven by simultaneous evolutionary change and by change in a non‐evolutionary factor (e.g. density dependent population dynamics, abiotic environmental change). Evolution is judged to be rapid in this ecological context if its contribution to ecological change is large relative to the contribution of other factors. We provide a worked example of this approach based on a theoretical predator–prey interaction [ Abrams, P. & Matsuda, H. (1997) . Evolution, 51, 1740], and find that in this system the impact of prey evolution on predator per capita growth rate is 63% that of internal ecological dynamics. We then propose analytical methods for measuring these contributions in field situations, and apply them to two long‐term data sets for which suitable ecological and evolutionary data exist. For both data sets relatively high rates of evolutionary change have been found when measured as character change in standard deviations per generation (haldanes). For Darwin's finches evolving in response to fluctuating rainfall [ Grant, P.R. & Grant, B.R. (2002) . Science, 296, 707], we estimate that evolutionary change has been more rapid than ecological change by a factor of 2.2. For a population of freshwater copepods whose life history evolves in response to fluctuating fish predation [ Hairston, N.G. Jr & Dillon, T.A. (1990) . Evolution, 44, 1796], we find that evolutionary change has been about one quarter the rate of ecological change – less than in the finch example, but nevertheless substantial. These analyses support the view that in order to understand temporal dynamics in ecological processes it is critical to consider the extent to which the attributes of the system under investigation are simultaneously changing as a result of rapid evolution. 相似文献
103.
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105.
John J. Gilbert 《Freshwater Biology》2004,49(11):1505-1515
1. In the heterogonic life cycle of monogonont rotifers, amictic (female‐producing) females develop from two types of eggs: fertilised resting (diapausing) eggs and parthenogenetic subitaneous eggs. Females hatched from resting eggs initiate clonal populations by female parthenogenesis and are called stem females. This study compares females from resting and parthenogenetic eggs that were produced under identical culture conditions and were of similar birth order. 2. Newborn stem females had many more lipid droplets in their tissues than similar‐sized, newborn females from parthenogenetic eggs. When neonates were stained with Nile Red and viewed under epifluorescent illumination, these droplets were shown to be sites of neutral‐lipid storage products. 3. Stem females had no posterolateral spines and short anterior spines, while their mothers and offspring in subsequent, parthenogenetic generations typically had long posterolateral spines and elongated anterior spines. 4. Newborn stem females survived starvation significantly longer than newborn females from parthenogenetic eggs. 5. When females from resting and parthenogenetic eggs were cultured from birth to death at a high food concentration, the reproductive potential (r day?1) of the stem females was significantly higher (0.82–0.88 versus 0.70), primarily because of egg production at an earlier age. The mean lifetime fecundity (Ro) of stem females was significantly greater than that of females from parthenogenetic eggs. 6. Extensive lipid reserves should increase the ability of stem females to colonise new habitats. Firstly, compared with females from parthenogenetic eggs, stem females are more likely to experience starvation or food limitation. Resting eggs hatch in response to physical and chemical factors that are not directly related to food availability, and from sediments that may be far from food‐rich surface waters. Secondly, when food is abundant, stem females have a greater reproductive potential. 相似文献
106.
Abstract 1. Under natural conditions in Kyoto, Japan, the reproductive activities of Nicrophorus quadripunctatus Kraatz (Coleoptera: Silphidae) decreased in summer and the species showed a bimodal life cycle.
2. In the laboratory, most adult pairs raised at 20 °C under a LD 12:12 h regime reproduced when provided with a piece of chicken. In adults raised at 20 °C under a LD 16:8 h regime, however, both reproductive behaviour and ovarian development were reduced. It is concluded that these adults entered a reproductive summer diapause.
3. High temperature (25 °C) also suppressed the reproductive behaviour even under a favourable LD 12:12 h regime. In the field, therefore, adults reduce their reproductive activity in summer because of diapause induced by long-day photoperiods and direct inhibition of reproduction by high temperatures.
4. When the temperature was changed from 20 °C to 25 °C immediately after hatching of larvae, they reached the wandering stage in 95% of adult pairs. When the temperature was changed from 20 °C to 25 °C immediately after oviposition, however, no larvae hatched in 85% of pairs. Egg mortality was significantly higher at 25 °C than at 20 and 22.5 °C; no eggs hatched at 27.5 °C. The physiological mechanisms for reducing reproduction probably prevent the beetles from inefficient oviposition in summer. 相似文献
2. In the laboratory, most adult pairs raised at 20 °C under a LD 12:12 h regime reproduced when provided with a piece of chicken. In adults raised at 20 °C under a LD 16:8 h regime, however, both reproductive behaviour and ovarian development were reduced. It is concluded that these adults entered a reproductive summer diapause.
3. High temperature (25 °C) also suppressed the reproductive behaviour even under a favourable LD 12:12 h regime. In the field, therefore, adults reduce their reproductive activity in summer because of diapause induced by long-day photoperiods and direct inhibition of reproduction by high temperatures.
4. When the temperature was changed from 20 °C to 25 °C immediately after hatching of larvae, they reached the wandering stage in 95% of adult pairs. When the temperature was changed from 20 °C to 25 °C immediately after oviposition, however, no larvae hatched in 85% of pairs. Egg mortality was significantly higher at 25 °C than at 20 and 22.5 °C; no eggs hatched at 27.5 °C. The physiological mechanisms for reducing reproduction probably prevent the beetles from inefficient oviposition in summer. 相似文献
107.
关于昆虫休眠和滞育的关系之浅见 总被引:8,自引:3,他引:5
本文简要介绍描述昆虫生长发育中断现象的名词术语的由来、目前文献中常见的几个术语的含义以及作者对这些术语之间关系的理解 相似文献
108.
109.
Akira Mizoguchi 《Physiological Entomology》2017,42(3):239-245
Many insects undergo diapause to survive adverse seasons. Although the mechanism of diapause induction is the subject of extensive study, that of diapause termination remains poorly understood. In the present study, we show the endocrine processes leading to the termination of pupal diapause in Mamestra brassicae. Diapause of this insect is terminated if the pupae are exposed to a low temperature for several weeks. During this period, the prothoracic glands (PGs) of pupae acquire the potential to secrete sufficient ecdysteroids necessary for inducing adult development. The main endocrine changes observed under the low temperature conditions are: (i) the increase in activity of the PGs in two steps; (ii) the increase in responsiveness of the glands to prothoracicotropic hormone (PTTH); and (iii) two‐step increase in PTTH gene expression in the brain. The timing of the first and second increases in PG activity roughly coincides with that of the two steps of increase in PTTH gene expression, and the timing of the increase in the responsiveness of the PGs to PTTH coincides with the second, larger increase in PTTH gene expression. The ablation of the PGs prior to cooling pupae does not affect the increase in PTTH gene expression, whereas brain removal results in a failure to increase PG activity, strongly suggesting that PTTH is the master regulator of diapause development and termination. 相似文献
110.
ABSTRACT. From a Japanese population of Chymomyza costata which has been known to have a photoperiodic larval diapause, we selected a mutant strain which did not respond to photoperiod. However, about 70% of the individuals of this strain entered diapause at 11o C irrespective of photoperiod, and about the same percentage of those of the photoperiod-sensitive strain also did so in continuous illumination at 11o C. This indicates that low temperature induces diapause independently of photoperiod. On the other hand, a temperature drop from 18 or 25o C to 15o C and chilling at 4o C did not induce diapause. 相似文献