Differences In Population Dynamics Research Articles

Population dynamics of natural colonies of Aurelia sp. scyphistomae in Tasmania, Australia

The aim of this study was to identify potential environmental controls of the asexual phases of reproduction by measuring the rates of asexual reproduction (budding and strobilation) and mortality in naturally occurring populations of Aurelia sp. scyphistomae at different spatial and temporal scales. The percentage cover, density of colonies of Aurelia sp. scyphistomae, and density of the population of two naturally occurring colonies of Aurelia sp. scyphistomae were examined over 2 years in southern Tasmania. Artificial substrates were also deployed to investigate colony dynamics when density dependent effects were reduced. Clear spatial and temporal differences in the population dynamics of the colonies were observed. Density dependent effects controlled budding and recruitment of new scyphistomae to the substrate when populations were dense and space limiting. In contrast, environmental controls of budding and strobilation were more apparent in a colony with significantly greater area of bare substrate and hence room for expansion. Water temperature and rainfall (as a proxy for salinity) were linked to changes in population size. Annual and seasonal differences in population dynamics were not observed in a colony limited by space but were apparent in a colony where space was not limited. When space was removed as a limiting factor by deploying artificial substrates, a seasonal environmental effect on the rate of growth of the colony was observed. These studies suggest that the growth, survival and reproduction of the sessile colonial phase of Aurelia sp. is regulated by a combination of density dependent factors and environmental conditions, which are consequently important to the formation of jellyfish blooms.

Growth, secondary production and gonad development of two co-existing amphioxus species ( Branchiostoma belcheri and B. malayanum) in subtropical Hong Kong

The present study investigated the growth, secondary production and gonad development of two co-existing amphioxus species Branchiostoma belcheri and B. malayanum in subtropical Hong Kong from June 2005 to June 2006. Based on the modal progression analysis, amphioxus populations were decomposed into separate cohorts. The von Bertalanffy growth models were also estimated according to the size incremental data. From the growth models, the size ranges of one, two and three-year-old B. belcheri were estimated to be 5–28 mm, 28–38 mm and 38–45 mm BL, respectively; while the one and two-year-old B. malayanum were estimated to be 7–30 mm and 30–35 mm BL, respectively. The secondary production was calculated at 1.15 g m − 2 yr − 1 DW or 0.63 g m − 2 yr − 1 AFDW for B. belcheri with density 424 ind m − 2 , and 0.51 g m − 2 yr − 1 DW or 0.40 g m − 2 yr − 1 AFDW for B. malayanum with density 121 ind m − 2 . The production to biomass ratio ( P/ B) was 1.13 for B. belcheri and 0.98 for B. malayanum. Changes in the gonad length index indicated that B. belcheri spawned mainly in June and July, while B. malayanum mainly in April and August. As compared with B. belcheri, B. malayanum was characterized by rapid growth, shorter life span, early maturity and lower population density. Such differences in population dynamics may allow both species to share a similar habitat and co-exist in subtropical waters of Hong Kong.

First record of males of Encentrum mucronatum Wulfert, 1936 and Encentrum martes Wulfert, 1939 (Rotifera: Dicranophoridae) including notes on males across Rotifera Monogononta

A detailed description is given of the males of Encentrum mucronatum Wulfert, 1936 and Encentrum martes Wulfert, 1939. The degree of miniaturisation relative to the corresponding females is assessed and compared to males in selected planktonic rotifers. Different degrees of miniaturisation are related to differences in population dynamics.

IDENTIFYING INTERACTIONS AMONG SALMON POPULATIONS FROM OBSERVED DYNAMICS

A simple direct correlation analysis of individual counts between different populations often fails to characterize the true nature of population interactions; however, the most common data type available for population studies is count data, and one of the most important objectives in population and community ecology is to identify interactions among populations. Here, I examine the dynamics of the spawning abundance of fall-run chinook salmon spawning within the California Central Valley and the Klamath Basin, California, and the Columbia River Basin, Oregon. I analyzed multiple time series from each watershed using a multivariate time-series technique called maximum autocorrelation factor analysis. This technique was used for finding common underlying trends in escapement abundance within each watershed. These trends were further investigated to identify potential resource-mediated interactions among the three groups of salmon. Each group is affected by multiple trends that are likely to be affected by environmental factors. In addition, some of the trends are coherent with each other, and the differences in population dynamics originate from variations in the relative importance of these trends among the three watershed groups.

Diverse population dynamics of three Anopheles species belonging to the Triannulatus Complex (Diptera: Culicidae)

The Triannulatus Complex of Anopheles (Nyssorhynchus) consists of at least three sibling species, namely Anopheles triannulatus s.s., Anopheles halophylus and a third undescribed member herein referred to as An. triannulatus "C". Sympatric anophelines belonging to species complexes, even though closely related, may exploit different environments such as larval habitats. In this paper we hypothesize that rainfall and seasonal flooding would distinctly influence the availability of larval habitats and consequently the seasonal population dynamics of sympatric members of the Triannulatus Complex. A reflection of this is distinct seasonal biting frequencies exhibited by three members of the Triannulatus Complex at a site in Central Brazil. Population dynamics seem to be influenced by the water level in the local rivers, although biting frequency of all three species was negatively influenced by rainfall. An. triannulatus s.s. was more abundant following the end of the rainy season, but notably 30 to 60 days after flooding. On the other hand, An. halophylus and An. triannulatus C peaked during the middle of the dry season, when water impoundments have no inflow, are somewhat reduced in size and the water becomes brackish. Differences in population dynamics were greater between An. triannulatus s.s. and An. halophylus and An. triannulatus C than between An. halophylus and An. triannulatus C. This might reflect differences in larval habitat exploitation and therefore spatial segregation among these members of the complex.

Population dynamics of diploid and hexaploid populations of a perennial herb.

Despite the recent enormous increase in the number of studies on polyploid species, no studies to date have explored the population dynamics of these taxa. It is thus not known whether the commonly reported differences in single life-history traits between taxa of different ploidy levels result in differences in population dynamics. This study explores differences in single life-history traits and in the complete life cycle between populations of different ploidy levels and compares these differences with differences observed between different habitat types and years. Diploid and hexaploid populations of a perennial herb, Aster amellus, are used as the study system. Transition matrix models were used to describe the dynamics of the populations, and population growth rates, elasticity values and life-table response experiments were used to compare the dynamics between populations and years. The results indicate that between-year variation in population dynamics is much larger than variation between different ploidy levels and different habitat conditions. Significant differences exist, however, in the structure of the transition matrices, indicating that the dynamics of the different ploidy levels are different. Strong differences in probability of extinction of local populations were also found, with hexaploid populations having higher probability than diploid populations, indicating strong potential differences in persistence of these populations. This is the first study on complete population dynamics of plants of different ploidy levels. This knowledge will help to understand the ability of new ploidy levels to spread into new areas and persist there, and the interactions of different ploidy levels in secondary contact zones. This knowledge will also contribute to understanding of interactions of different ploidy levels with other plant species or other interacting organisms such as pollinators or herbivores.

Genetic structure of black rat populations in a rural plague focus in Madagascar

The genetic structure of reservoir populations is a key characteristic in understanding the persistence of infectious diseases in natural systems. In the Highlands of Madagascar, where plague has persisted since 1920, the black rat, Rattus rattus (L., 1758), is the sole species acting as a reservoir of the disease. Ecological surveys have shown a clear correlation between the locations of the plague-persistence area in Madagascar (above 800 m elevation) and the distribution area of one endemic plague vector, the flea Synopsyllus fonquerniei , which is found exclusively on rats living outdoors. This clear habitat segregation has led to the suggestion that R. rattus populations in the central highlands are divided into indoor- and outdoor-dwelling populations. Using eight microsatellite markers, we analysed the genetic structure of R. rattus populations living within a human plague focus in relation to habitat and geographic distance. We found that habitat by itself was not a structuring factor, unlike geographic distance. Nevertheless, the significant genotypic differentiation of R. rattus populations that was found at a fine spatial scale might relate to differences in population dynamics between rats in indoor and outdoor habitats.

Strong habitat preference of a tropical rain forest tree does not imply large differences in population dynamics across habitats

Summary Many tropical forest tree species show habitat preference, commonly revealed by differences in abundance among habitats. Very little is known about differences in individual performance and population dynamics across habitats. We analysed habitat‐specific performance and demography of Scaphium borneense, a tropical rain forest tree with strong habitat preference in a 52‐ha plot at Lambir Hills, Malaysia. This species occurs at high densities on ridges with sandy soils (‘preferred habitat’), at low densities in valleys on loamy soils (‘non‐preferred habitat’) and at intermediate densities on slopes. We used 10‐year demographic data to compare tree performance across habitats and constructed population matrix models to analyse population dynamics. Tree performance was rather similar across habitats. Some vital rates (mortality) did not differ among habitats, while others were modestly (juvenile tree growth) to substantially higher (recruitment) in the non‐preferred valley habitat, probably due to higher canopy openness. Matrix models projected population sizes to remain stable in all habitats, thus maintaining abundance differences across habitats. This suggests that habitat preference of Scaphium is generated by (a)biotic differences among habitats and not by chance processes or disturbance history. Population dynamics were also very similar among habitats. The distribution of elasticity values over categories and vital rates was almost equal for the three habitats. Life table response experiment (LTRE) analysis showed that habitat differences in vital rates had little effect on λ. Thus, Scaphium populations in the three habitats are maintained in a very similar way, despite differences in (a)biotic conditions and abundance. We hypothesize that habitat preference of Scaphium is maintained because of a better performance in its preferred habitat relative to other species in that habitat, while the reverse may be true in non‐preferred habitats. We suggest that such differences in performance may become apparent during periods of drought, creating windows of opportunity for maintaining density differences. Strong habitat preference of rain forest tree species does not necessarily imply strong differences in tree performance, demography or population growth across habitats. The mechanisms that generate density differences across habitats remain to be unravelled.

Little evidence for climate effects on local‐scale structure and dynamics of California kelp forest communities

AbstractClimatic variables such as temperature and precipitation play an important role in controlling local and regional scale differences in population dynamics and species distributions, and large‐scale climatic events such as El Niño southern oscillation (ENSO) have been shown to affect population dynamics of key species in many ecosystems, particularly in kelp forests. Few studies have been able to evaluate the consequences of climate variables on the structure and dynamics of biological communities, in large part because the lack of data at appropriate spatial and temporal scales has made it difficult to adequately address local‐scale responses of species and communities to such events over relevant time scales. Here, we combined an unprecedented dataset of kelp forest species' abundances from the Channel Islands, California with data for several local, regional, and global scale climatic variables to evaluate the temporal and spatial scale at which one can detect community‐wide effects of climate variables, in particular ENSO events. We found large and significant local‐scale differences in community structure, but these differences were not related to differences in climatic variables. Moreover, giant kelp abundance, which has been shown to be highly sensitive to water temperature and storm disturbance, was a poor predictor of community differences, and all communities tended to decline in abundance over the 20‐year sampling period, suggesting a press perturbation to the system such as PDO cycles or sustained fishing pressure. Although ENSO events can have dramatic impacts on the abundance and distribution of giant kelp itself across the range of the species, such events appear to have little effect on local‐scale kelp forest community structure or dynamics.

Temporal stability in size distributions and growth rates of threeEsox luciusL. populations. A result of cannibalism?

The population total length (LT) structures and individual growth trajectories for three stream living pikeEsox luciuspopulations were studied for 7 years. All three populations exhibited small variation in both populationLTstructure and individual growth trajectories over time. These dynamics contrasted to the much more variable populationLTstructure of perchPerca fluviatilisstudied previously. The difference in population dynamics between the two species was related to differences in prey:predator size ratios. The pike populations in the more open and larger streams grew to larger sizes, but this difference in life history did not affect population dynamics of pike. It is concluded that (1) cannibalistic population dynamics may be predicted from individual life‐history characteristics such as minimum and maximum victim:cannibal size ratios and (2) the cannibal‐driven population dynamics observed in pike seems to be robust to variation in environmental conditions (system openness).

Population dynamics of insects associated with Rumex obtusifolius in different habitats

AbstractThe effect of different habitats on insect communities associated with Rumex obtusifolius was studied in detail. Study sites were selected for their variety of environmental characteristics (vegetation and habitat): shaded woodland, disturbed wasteland and pasture. The results of this study were that insect populations associated with R. obtusifolius responded differently to the different habitats. The observed differences in population dynamics among the insects showed quite clearly their responses to different habitats. There was also a pattern of time partitioning in the exploitation of the host‐plant among the insect species observed. Philaenus spumarius at nymphal stage had a peak density on approximately 20 June, Apion frumentarium and Apion spp. (Apion species other than A. frumentarium) had a peak density on approximately 30 June and Aphis rumicis had a peak density on approximately 28 July. This pattern of shift in time for peak population density (time‐shift) among the insects sharing a common host‐plant may guarantee each insect the opportunity to exploit the plant to a maximum.

Trade-off in investment between dispersal and ingestion capability in phytophagous insects and its ecological implications

In population ecology, dispersal plays a fundamental role, but is potentially costly. Traditionally, studies of phenotypic trade-offs involving dispersal focus on resource allocation differences between flight and reproduction. However, investments in dispersal may also result in reduced allocation to other "third-party traits" (e.g. compensatory feeding) that are not directly associated with reproduction. Such traits remain largely uninvestigated for any phytophagous insect despite their importance for performance and survival. Using two wing-dimorphic, phloem-feeding planthoppers, Prokelisia dolus and Prokelisia marginata that differ dramatically in dispersal abilities, we sought evidence for a trade-off between investments in dispersal (flight apparatus) and ingestion capability (allocation to the esophageal musculature governing ingestion). Dispersal allows species to meet nutrient demands by moving to higher-quality resources. In contrast, enhanced investment in esophageal musculature increases ingestion capacity and allows phloem feeders to compensate for deteriorating plant nutrition on site. Our objectives were to compare differences in flight and feeding investment between P. dolus and P. marginata and between the wing forms of both species, and to compare ingestion capacity between the two species and wing forms. Morphometric and gravimetric measures of investment in flight versus feeding indicate that the sedentary P. dolus allocates more muscle mass to feeding whereas P. marginata invests more heavily in flight. Likewise, brachypters invest more in feeding and less in flight than macropters. The greater esophageal investment in P. dolus is associated with enhanced ingestion capacity compared to P. marginata. As a consequence, P. dolus is better equipped to meet on-site nutrient demands when faced with deteriorating plant quality than P. marginata, which must migrate elsewhere to do so. Notably, such third-party trade-offs place constraints on how insect herbivores cope with changing resources and set the stage for fundamental differences in population dynamics.

Variation in population dynamics and movement patterns between two geographically isolated populations of the dusky hopping mouse (Notomys fuscus)

The ecology of the dusky hopping mouse (Notomys fuscus) was studied at Pelican Waterhole in south-west Queensland and Montecollina Bore in north-east South Australia over an eight-year period. Population parameters of N. fuscus differed markedly between the two study sites. Whilst the population at Montecollina Bore exhibited large fluctuations in size, captures at Pelican Waterhole were lower but more consistent. Recaptures between sessions at Montecollina Bore peaked at 60% but no individuals were recaptured at Pelican Waterhole. No evidence of seasonal breeding was recorded at either site. Male N. fuscus captured at Montecollina Bore were significantly heavier (average 31.4 g) than Pelican Waterhole animals (average 26.6 g). Over a 1–4-night period, the maximum linear distance moved by radio-collared individuals was 1.5 km (average 481 m) at Pelican Waterhole and 400 m (average 199 m) at Montecollina Bore. Differences in population dynamics between the two sites are ascribed to food availability and habitat quality. Whilst Pelican Waterhole may constitute a more stable, less degraded environment, Montecollina Bore appears to be defined by periods of either very high or very low resource availability depending on rainfall. The abundance of dingoes and low cat and fox activity may contribute to the persistence of N. fuscus at the two study sites.

The effect of sub-lethal increases in temperature on the growth and population trajectories of three scleractinian corals on the southern Great Barrier Reef

To date, coral death has been the most conspicuous outcome of warming tropical seas, but as temperatures stabilize at higher values, the consequences for the corals remaining will be mediated by their demographic responses to the sub-lethal effects of temperature. To gain insight into the nature of these responses, here I develop a model to test the effect of increased temperature on populations of three pocilloporid corals at One Tree Island, near the southern extreme of the Great Barrier Reef (GBR). Using Seriatopora hystrix, S. caliendrum and Pocillopora damicornis as study species, the effects of temperature on growth were determined empirically, and the dynamics of their populations determined under natural temperatures over a 6-month period between 1999 and 2000 [defined as the study year (SY)]. The two data sets were combined in a demographic test of the possibility that the thermal regime projected for the southern GBR in the next 55-83 years--warmer by 3 degrees C than the study year (the SY+3 regime), which is equivalent to 1.4 degrees C warmer than the recent warm year of 1998--would alter coral population trajectories through the effects on coral growth alone; the analyses first were completed by species, then by family after pooling among species. Laboratory experiments showed that growth rates (i.e., calcification) varied significantly among species and temperatures, and displayed curvilinear thermal responses with growth maxima at approximately 27.1 degrees C. Based on these temperature-growth responses, the SY+3 regime is projected to: (1) increase annualized growth rates of all taxa by 24-39%, and defer the timing of peak growth from the summer to the autumn and spring, (2) alter the intrinsic rate of population growth (lambda) for S. hystrix (lambda decreases 26%) and S. caliendrum (lambda increases 5%), but not for P. damicornis, and (3) have a minor effect on lambda (a 0.3% increase) for the Pocilloporidae, largely because lambda varies more among species than it does between temperatures. Ten-year population projections suggest that the effects of a sub-lethal increase in temperature (i.e., the SY+3 regime) are relatively small compared to the interspecific differences in population dynamics, but nevertheless will alter the population size and increase the relative abundance of large colonies at the expense of smaller colonies for all three species, as well as the Pocilloporidae. These effects may play an important role in determining the nuances of coral population structure as seawater warms, and their significance may intensity if the coral species pool is depleted of thermally sensitive species by bleaching.

Diverse Evolutionary Trajectories Characterize a Community of RNA-Cleaving Deoxyribozymes: A Case Study into the Population Dynamics of In Vitro Selection

Two parallel in vitro selections (denoted Selection A and Selection B) were conducted under different selection-pressure regimes, yielding a diverse community of RNA-cleaving deoxyribozymes. In Selection A, the reaction time was reduced four times (from 5 h to 5 s) over the course of 24 generations, while in Selection B the reaction time was maintained at 5 h for 30 rounds of selective amplification. Sequence alignment was conducted on more than 800 clones assembled from 18 generations that span both selections. Many prominent catalytic sequence classes, including some that extend across both selections, were identified and used to construct fitness landscapes depicting their rise and fall over time. The landscapes from both selections exhibit similar global trends despite differences in population dynamics. Some deoxyribozymes were predominant in the early rounds of selection but gave way to other species that dominated in the middle rounds. Ultimately, these middle classes disappeared from the landscape in favor of new and presumably more fit deoxyribozyme sequence classes. The shape of these landscapes alludes to the presence of many latent deoxyribozymes in the initial library, which can only be accessed by changes in the selection pressure and/or by adaptive mutations. Basic computer simulations provide theoretical corroboration of the experimentally observed pattern of staggered sequence-class transitions across the fitness landscapes. These simulations model the influence of one or more contributing factors, including catalytic rate, folding efficiency, PCR amplification efficiency, and random mutagenesis. This is the first study which thoroughly documents the topography of a deoxyribozyme fitness landscape over many generations of in vitro selection.

Benefits of closed area protection for a population of scallops

Despite the current interest in using closed areas for fisheries management, few studies have actually examined the benefits for invertebrate fisheries such as scallops. This study details the dynamics of a population of great scallops Pecten maximus (L.), within a closed area and an adjacent fished area off the Isle of Man, over a 14 yr period (1989 to 2003). Scallop densities were very low in both areas when the closed area was set up, but increased at an accelerated rate over time within the closed area. Scallop densities also increased on the adjacent fishing ground, but not to the same extent. Consequently, the density of scallops above the minimum legal landing size (110 mm SL) was more than 7 times higher in the closed area than in the fished area by 2003. There was also a shift towards much older and larger scallops in the closed area and, correspondingly, lower estimates of total mortality. Experimental dredging of 2 plots within the closed area confirmed that fishing drove these differences in population dynamics and structure. These patterns of scallop density, age and size structure resulted in the exploitable biomass (adductor muscle and gonad) of scallops being nearly 11 times higher in the closed area than in the fished area by 2003, and the reproductive biomass was 12.5 times higher. This is significant for fisheries management because the build up of high densities of large P. maximus individuals enhanced local reproductive potential and therefore the likelihood of export of larvae to the surrounding fishing grounds. Along with these direct benefits of closed area protection, juvenile scallops had higher survival and individual growth rates in the closed area, apparently in response to reduced fishing disturbance. Although juvenile scallops are not subject to direct removal by fishing, protection during this critical phase therefore appeared to assist the recovery of the closed area population. In summary, this study joins a growing number indicating that the use of closed areas offers a range of benefits over more traditional methods of managing fisheries. Fisheries for relatively sedentary and long-lived species such as P. maximus appear to be particularly suitable for this type of management.

Ecological studies toward the management of an Antarctic tourist landing site (Penguin Island, South Shetland Islands)

Increasing tourism in the Antarctic Peninsula region concerns scientists, policy-makers, and tourist companies with its potential negative effects on wildlife. Site-specific ecological studies have been initiated to examine differences in population dynamics and distribution of animals as well as their behavioural and physiological reactions to humans. Penguin Island (southeast of King George Island, South Shetland Islands, Antarctica) is frequently visited by tourists due to its high species diversity and aesthetic value. In two seasons, the authors conducted a bird census and studied behaviour and heart-rate changes of southern giant petrels and skuas relating to tourist visits on Penguin Island. Management recommendations are given, based on the study results. The protection of southern giant petrels should be increased by having a minimum distance of 50 m for all visitors. The eastern, southern, and western parts of the island should not be visited and should serve as refuge areas. The wildlife experience for tourists can still be enjoyed by concentrating visits to the northern and central part of Penguin Island. Use of a specific path to localise impacts in a prescribed area is recommended.

AN INVASIVE PLANT PROMOTES UNSTABLE HOST–PARASITOID PATCH DYNAMICS

In theory, the rate of interpatch dispersal significantly influences the population dynamics of predators and their prey, yet there are relatively few field experiments that provide a strong link between these two processes. In tallgrass prairies of North America, the planthopper, Prokelisia crocea, and its specialist parasitoid, Anagrus columbi, exist among discrete host-plant patches (prairie cordgrass, Spartina pectinata). In many areas, the matrix, or habitat between patches, has become dominated by the invasive exotic grass, smooth brome (Bromus inermis). We performed a landscape-level field study in which replicate cordgrass networks (identical in number, size, quality, and distribution of cordgrass patches) were embedded in a matrix composed of either mudflat (a native matrix habitat) or smooth brome. Mark–recapture experiments with the planthopper and parasitoid revealed that the rate of movement among cordgrass patches for both species was 3–11 times higher in smooth brome than in mudflat. Within three generations, planthopper and parasitoid densities per patch were on average ∼50% lower and spatially 50–87% more variable for patches embedded in a brome as compared to a mudflat matrix. A brome-dominated landscape also promoted extinction rates per patch that were 4–5 times higher than the rates per patch in native mudflat habitat. The effect was more acute for the parasitoid. We suggest that the differences in population dynamics between networks of patches in brome and those in mudflat were driven by underlying differences in interpatch dispersal (i.e., patch connectivity). To our knowledge, this is the first experimental study to reveal that matrix composition, in particular, the presence of an invasive plant species, affects the spatial and temporal dynamics of an herbivore and its natural enemy.

The Role of Pigmentation, Ultraviolet Radiation Tolerance, and Leaf Colonization Strategies in the Epiphytic Survival of Phyllosphere Bacteria

Phenotypic mechanisms that enhance bacterial UVR survival typically include pigmentation and DNA repair mechanisms which provide protection from UVA and UVB wavelengths, respectively. In this study, we examined the contribution of pigmentation to field survival in Clavibacter michiganensis and evaluated differences in population dynamics and leaf colonization strategies. Two C. michiganensis pigment-deficient mutants were significantly reduced in UVA radiation survival in vitro; one of these mutants also exhibited reduced field populations on peanut when compared to the wild-type strain over the course of replicate 25-day experiments. The UVR-tolerant C. michiganensis strains G7.1 and G11.1 maintained larger epiphytic field populations on peanut compared to the UVR-sensitive C. michiganensis T5.1. Epiphytic field populations of C. michiganensis utilized the strategy of solar UVR avoidance during leaf colonization resulting in increased strain survival on leaves after UVC irradiation. These results further demonstrate the importance of UVR tolerance in the ability of bacterial strains to maintain population size in the phyllosphere. However, an examination of several bacterial species from the peanut phyllosphere and a collection of environmental Pseudomonas spp. revealed that sensitivity to UVA and UVC radiation was correlated in some but not all of these bacteria. These results underscore a need to further understand the biological effects of different solar wavelength groups on microbial ecology.

Food-plant effects on larval performance do not translate into differences in fitness between populations of Panolis flammea (Lepidoptera: Noctuidae).

In the UK, Panolis flammea (Denis & Schiffermüller) is a pest of monocultures of non-native lodgepole pine Pinus contorta Douglas, but not of the indigenous host Scots pine P. sylvestrisL. This difference in population dynamics may be due to the adaptation of P. flammea populations to the phenology, chemical composition and natural enemy complement of lodgepole pine. To ascertain if there was local adaptation of P. flammea populations to lodgepole pine, this study tested for improved performance of both larvae and adults on the host plant species from which they were sourced, compared with their performance on the alternative host plant species. No difference was found in the relative mean performance of populations sourced from Scots pine or lodgepole pine plantations, when fed on Scots or lodgepole pine foliage. Larvae grew faster on Scots pine but this difference did not translate into differences in pupal weight, female body weight or fecundity. Indeed, those insects that had fed on lodgepole pine had a longer lifespan than those that had fed on Scots pine, which, if translated into greater probability of mating or higher fecundity, could contribute to the observed outbreak dynamics in the field. The prediction that the observed outbreak dynamics of P. flammea can be explained by the existence of populations locally adapted to lodgepole pine was not supported. These results cast doubt on the use of larval growth parameters as surrogates of fitness in Lepidoptera.