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Genome size, known also as the C-value, has been proposed as an important determinant of life-history variation in numerous animal taxa. We assessed the relationships between genome size and fitness-related life-history traits in six species of interstitial marine annelids of the genus Ophryotrocha. Life-history traits and genome size data obtained from 18 additional annelid species were included in our analyses to have a broader phylogenetic scope. Unexpectedly, genome sizes assessed here by flow cytometry in four Ophryotrocha species were three times larger than previously reported values obtained using Feulgen densitometry. This has implications for the hypothesis that harsh interstitial habitats select for small genomes in meiofaunal annelids. Within the genus Ophryotrocha, significant and positive relationships were found between genome size and nucleus size, and between genome size, age at first egg mass deposition, body size and lifespan. These relationships held up in the broader phylogenetic comparison. Our study provides evidence for the important role played by genome size in the evolution of life-history traits in annelids. [ABSTRACT FROM AUTHOR]

The biology and seasonal phenology of Aacanthocnema dobsoni (Froggatt) were studied at a single site in Victoria over a 2 year period between 2013 and 2015. This species is monophagous on the dioecious host, Allocasuarina verticillata (Lam.) L. Johnson (Casuarinaceae). Laboratory studies found that females attained reproductive maturity 24 h post‐eclosion, lived for 28.6 ± 2.8 (mean ± SE) days and laid 182 ± 23 (mean ± SE) eggs each. Egg development was most rapid at 26 °C, ceased below 7 °C and above 33 °C; hatching required 188 degree‐days. Nymphs could not be reared to adulthood on excised host branchlets maintained under controlled conditions, so no developmental data were obtained for these life stages. Seasonal phenology data revealed pronounced developmental asynchrony, i.e. with overlapping generations and multiple life stages occurring simultaneously. Three generations per year were observed, and there was no evidence of either developmental (egg and nymph) or reproductive diapause. A 4 day heat wave in January 2014 drastically reduced psyllid abundance at the study site and the size of the adults that eclosed from the surviving nymphs. These smaller adults produced substrate‐borne vibrational signals with altered characteristics, i.e. with significantly higher intensities and power. The altered signals might have facilitated communication over longer distances and increased mate finding opportunities when populations were low. The abundance of adults had recovered to preheat wave levels 3 months after the heat wave. High fecundity, multivoltinism and effective mate attraction signalling are life history traits that may mitigate against localised extinction of populations as a consequence of extreme weather events. [ABSTRACT FROM AUTHOR]

Abstract: Previous work revealed that Harmonia axyridisPallas (Coleoptera: Coccinellidae) in Beijing, China, were capable of regenerating a forelimb amputated in the fourth instar; 75% of surviving individuals fully regenerated the limb during pupation. In this study, we tested a population of H. axyridis invasive in North America and found that virtually 100% of beetles surviving the operation successfully regenerated the limb. Ablated/regenerated beetles spent longer in pupation, and emerging females were smaller than controls. However, reproductive success was unaffected in all pairwise crosses of control/regenerated adults; there were no differences in pre‐oviposition period, the time required to produce 10 clutches, 10‐day fecundity, or the fertility of eggs, whereas ablated/regenerated parents paid a developmental cost, their progeny obtained benefits. Offspring of crosses that included a regenerated parent tended to have faster larval development than the control cross, although not all were significantly different from controls. However, when either or both parents were ablated and regenerated, their daughters were heavier than controls at emergence. Limb regeneration during pupation appears to activate a physiological cascade which increases the magnitude of beneficial parental effects normally conferred to progeny, possibly via pleiotropic effects. The invasive North American H. axyridis population appears to have higher regeneration capacity than the Chinese population tested previously, although how regeneration capacity might be associated with invasiveness remains unclear. Limb regeneration ability may be a side effect of selection on other traits that confer high fitness under either natural or sexual selection, as it seems unlikely to confer fitness benefits directly in this species. [ABSTRACT FROM AUTHOR]

Population density during nymphal development affects body size, developmental rate and wing polymorphism in semiaquatic bugs. Nymphs from crowded habitats grow faster and thus gain an advantage in the later stadia. Rapid development results in smaller body size in several gerrids. Macropterous adults develop more frequently at high population densities in most species, which enables the bugs to leave crowded habitats. Three European widespread species Mesovelia furcata Mulsant & Rey, 1852 (Mesoveliidae), Microvelia reticulata Burmeister, 1835 and Velia caprai Tamanini, 1947 (Veliidae) were reared individually and simultaneously either at a low or high population density. Duration of postembryonic development, wing morph, body size and length of distal oocyte in females were recorded. High population density accelerates development in Mesovelia furcata and Microvelia reticulata. However, there was no trade-off between developmental rate and body size. Accelerated development without a decrease in body size was probably because maturation was delayed. Individually reared nymphs developed faster than nymphs from communal cohorts. No long-winged Microvelia reticulata specimen developed in any treatment. However, more macropterous individuals developed in high-density treatments in Mesovelia furcata (significant) and Velia caprai (not significant). All the nymphs of the species that were reared individually developed into apterous adults. The results suggest that population density strongly influences the life history of semiaquatic bugs. However, the only commonly shared response seems to be an increase in developmental rate when reared at high population densities. Other traits such as wing dimorphism, body size and rate of oogenesis differ at the species level.

The article presents a study which showed that faster developing populations have evolved higher haemocyte density and phenol oxidase (PO) activity in the larval haemolymph. Topics include possible reason for the evolution of reduced competitive ability in the faster developing populations, correlation between rapid development and reduced adult body size, and three types of the haemolymph of Drosophila larvae. The bacterial density measurement in the larval food medium is also included.

Body size, developmental rate, and metabolic rate were examined as potential phenotypic correlates of genome size using all 51 named species of Lepidoptera with recorded genome sizes. Genome sizes ranged 0.29-1.94 pg. Because no direct comparative measures were available, surrogates were used: wingspan for body size, voltinism for developmental rate, and grades of adult diel activity and adult feeding for metabolic rate. Analyses consisted of plotting genome size on surrogate values and fitting least-squares trend lines. At the order level, empirical - correlates of genome size with wingspan and voltinism were essentially null or flat. At family and subfamily levels, striking associations were found for wingspan and voltinism, but not for surrogates of metabolic rate, for which data were limited and surrogate validity uncertain. Geometrid species, nearly all of which were ennomiines, showed a sharp positive association between genome size and wingspan, Arctiidae a sharp negative association, and Noctuidae a flat association. Geometridae showed a sharp negative association between genome size and voltinism, Arctiide a sharp positive association, and Noctuidae a mild negative association. No phenotypic correlates of lepidopteran genome size were previously known. Suppositions were confirmed that phenotypic correlates are most likely to be detected at family and lower taxonomic levels. [ABSTRACT FROM AUTHOR]

Population density during nymphal development affects body size, developmental rate and wing polymorphism in semiaquatic bugs. Nymphs from crowded habitats grow faster and thus gain an advantage in the later stadia. Rapid development results in smaller body size in several gerrids. Macropterous adults develop more frequently at high population densities in most species, which enables the bugs to leave crowded habitats. Three European widespread species Mesovelia furcata Mulsant & Rey, 1852 (Mesoveliidae), Microvelia reticulata Burmeister, 1835 and Velia caprai Tamanini, 1947 (Veliidae) were reared individually and simultaneously either at a low or high population density. Duration of postembryonic development, wing morph, body size and length of distal oocyte in females were recorded. High population density accelerates development in Mesovelia furcata and Microvelia reticulata. However, there was no trade-off between developmental rate and body size. Accelerated development without a decrease in body size was probably because maturation was delayed. Individually reared nymphs developed faster than nymphs from communal cohorts. No long-winged Microvelia reticulata specimen developed in any treatment. However, more macropterous individuals developed in high-density treatments in Mesovelia furcata (significant) and Velia caprai (not significant). All the nymphs of the species that were reared individually developed into apterous adults. The results suggest that population density strongly influences the life history of semiaquatic bugs. However, the only commonly shared response seems to be an increase in developmental rate when reared at high population densities. Other traits such as wing dimorphism, body size and rate of oogenesis differ at the species level. [ABSTRACT FROM AUTHOR]

1. Although there is a great deal of theoretical and empirical data about the life history responses of time constraints in organisms, little is known about the latitude-compensating mechanism that enables northern populations' developmental rates to compensate for latitude. To investigate the importance of photoperiod on development, offspring of the obligatory univoltine damselfly Lestes sponsa from two populations at different latitudes (53°N and 63°N) were raised in a common laboratory environment at both northern and southern photoperiods that corresponded to the sites of collection. 2. Egg development time was shorter under northern photoperiod regimes for both populations. However, the northern latitude population showed a higher phenotypic plasticity response to photoperiod compared with the southern latitude population, suggesting a genetic difference in egg development time in response to photoperiod. 3. Larvae from both latitudes expressed shorter larval development time and faster growth rates under northern photoperiod regimes. There was no difference in phenotypic plastic response between northern and southern latitude populations with regard to development time. 4. Data on field collected adults showed that adult sizes decreased with an increase in latitude. This adult size difference was a genetically fixed trait, as the same size difference between populations was also found when larvae were reared in the laboratory. 5. The results suggest phenotypic plasticity responses in life history traits to photoperiod, but also genetic differences between north and south latitude populations in response to photoperiod, which indicates the presence of a latitudinal compensating mechanism that is triggered by a photoperiod. [ABSTRACT FROM AUTHOR]

Large body size confers a reproductive advantage to adults of the wood-boring beetlePhoracantha semipunctata(F.) (Cerambycidae: Cerambycinae: Phoracanthini). Larvae of this species feed subcortically in stressed and dying eucalypt trees and logs. We evaluated the influence of the larval environment on larval performance and adult body size by manipulating the post-felling age of host logs (from freshly cut to 2-weeks-old) and the density of colonizing neonates (low density with minimal competition for resources vs. high density with intense competition). Adult beetles emerged in greater numbers from logs that had been subjected to the aging treatment which reduced bark moisture content and favored colonization by neonates. Survival was greatest in larger logs having lower densities of neonates, but was greatly diminished in all treatments by mortality during pupation. Development time varied from 2 months to more than a year and was shortest in smaller logs having high densities of larvae. The size of adult beetles emerging from a log was not influenced by larval density, but was positively correlated with the age of logs when the neonates colonized, and log size. These findings suggest that the optimal developmental conditions forP. semipunctatalarvae, in terms of larval performance and adult body size, are available in large, aged host logs having low densities of larvae. Manipulation of the larval environment in this study resulted in a considerable variation in adult body size, but large individuals were relatively more common in the wild population that was the source of neonates for the experiment. Potential body size may have been constrained by our use of only one host species and a narrow range of log dimensions. [ABSTRACT FROM AUTHOR]

Freshwater cyclopoid copepods exhibit at least a fivefold range in somatic genome size and a mechanism, chromatin diminution, which could account for much of this interspecific variation. These attributes suggest that copepods are well suited to studies of genome size evolution. We tested the nucleotypic hypothesis of genome size evolution, which poses that variation in genome size is adaptive due to the ‘bulk’ effects of both coding and noncoding DNA on cell size and division rates, and their correlates. We found a significant inverse correlation between genome size and developmental (growth) rate in five freshwater cyclopoid species at three temperatures. That is, species with smaller genomes developed faster. Species with smaller genomes had significantly smaller bodies at 22 °C, but not at cooler and warmer temperatures. Species with smaller genomes developed faster at all three temperatures, but had smaller bodies only at 22 °C. We propose a model of life history evolution that adds genome size and cell cycle dynamics to the suite of characters on which selection may act to mold life histories and to influence the distribution of traits among different habitats. [ABSTRACT FROM AUTHOR]

Abstract To detect divergence of the introduced fall webworm, Hyphantria cunea , within its trivoltine area in Japan, developmental traits were determined in the Kobe (34°41′N) and Kumamoto (32°48′N) populations. The lower threshold temperature for development was not different between these two populations. The thermal constant for larval development was considerably smaller in the Kobe population than in the Kumamoto population. Two types of larva occurred in these populations, one with six instars and the other with seven. In the six-instar type, the developmental period was not different between the populations in males, but the pupal weight was greater and the forewing was longer in both sexes in the Kumamoto population than in the Kobe population. In the Kumamoto population, the seven-instar type had a longer developmental period, heavier pupa and longer forewing than the six-instar type. The proportion of the seven- to the six-instar type was greater in the Kumamoto population than in the Kobe population, resulting in the longer developmental time and greater body size of the former. [ABSTRACT FROM AUTHOR]