GENOTYPE-ENVIRONMENT INTERACTION FOR CLIMATE AND COMPETITION IN A NATURAL POPULATION OF FLOUR BEETLES,TRIBOLIUM CASTANEUM

The norm of reaction, the set of average phenotypes produced by a genotype in different environments, can be affected by spatial variation in natural selection especially when there exists genotype-environment interaction. In subdivided populations, the greater the genotype-environment interaction variance and the lower the migration rate, the more independent are the possible evolutionary trajectories for local adaptation. I examined genotype-environment interaction in the rate of population increase for lineages randomly derived from a wild population of Tribolium castaneum across a series of ecologically important environments. The lineages were derived from an outbred, wild-caught population by 14 generations of random genetic drift, during which the effective size of each lineage was approximately 22 breeding adults. The environments studied were the classic temperate-wet and cold-dry climates of Park (1954) in factorial combination with two genetic strains of a congeneric competitor, T. confusum. Much among-lineage genetic variation for rate of population increase was found for each of these ecologically important environments of climate and competition. Genotype-environment interaction accounted for 40.5% of the total among-lineage variance in rate of population increase signifying that the performance of a lineage in one environment is not necessarily a good predictor of its performance in another. Changing the genetic identity of the competitor changed the rate of increase of some lineages as much or more than changing the climatic conditions of temperature and humidity. This is the first empirical study to characterize the genotype-environment interaction variance associated with genetic variation in a competing congeneric species. This competitor-specific genetic variation in competitive ability may play an important role in coevolution in subdivided populations.     

SYMPATRIC CONVERGENCE AND ENVIRONMENTAL CORRELATION BETWEEN TWO LAND-SNAIL SPECIES

In the southern Appalachian region of North America, the phylogenetically convergent shells of the polygyrid snails Triodopsinae Neohelix major (Binney) and Polygyrinae Mesodon normalis (Pilsbry) are even more convergent in size and shape in sympatry (7 sites) than in allopatry (23 and 10 sites). Environmental correlations account for 34% and 30% of size and shape variations in N. major (larger, taller, and more loosely coiled at northern, high-altitude, sheltered sites), but for only 14% and 9% in M. normalis (larger, flatter, and more loosely coiled at south-facing, exposed sites). The statistical significance of the sympatric convergence dropped out when these correlations were removed. This phenomenon helps account for the many cases in eastern North America of nearly identical land-snail shells in sympatry and questions the importance of competitive character displacement in the evolution of land-snail shell morphology. This apparently nonmimetic case of sympatric convergence provides an unusually precise and well-delimited, naturally replicated experiment in evolutionary morphology, which is analyzed for controlling factors in a follow-up paper.     

Interaction of meropenem with ‘N’ and ‘B’ isoforms of human serum albumin: a spectroscopic and molecular docking study

Carbapenems are used to control the outbreak of β-lactamases expressing bacteria. The effectiveness of drugs is influenced by its interaction with human serum albumin (HSA). Strong binding of carbapenems to HSA may lead to decreased bioavailability of the drug. The non-optimal drug dosage will provide a positive selection pressure on bacteria to develop resistance. Here, we investigated the interaction between meropenem and HSA at physiological pH 7.5 (N-isoform HSA) and non-physiological pH 9.2 (B-isoform HSA). Results showed that meropenem quenches the fluorescence of both ‘N’ and ‘B’ isoforms of HSA (ΔG < 0 and binding constant ~10⁴ M^?1). Electrostatic interactions and van der Waal interactions along with H-bonds stabilized the complex of meropenem with ‘N’ and ‘B’ isoforms of HSA, respectively. Molecular docking results revealed that meropenem binds to HSA near Sudlow’s site II (subdomain IIIA) close to Trp-214 with a contribution of a few residues of subdomain IIA. CD spectroscopy showed a change in the conformation of both the isoforms of HSA upon meropenem binding. The catalytic efficiency of HSA (only N-isoform) on p-nitrophenyl acetate was increased primarily due to a decrease in K_m and an increase in k_cat values. This study provides an insight into the molecular basis of interaction between meropenem and HSA.     

PHENOTYPIC PLASTICITY IN POLYGONUM PERSICARIA. I. DIVERSITY AND UNIFORMITY IN GENOTYPIC NORMS OF REACTION TO LIGHT

Several aspects of genotype-environment interaction may act to modulate natural selection in populations that encounter variable environments. In this study the norms of reaction (phenotypic responses) of 20 cloned genotypes from two natural populations of the annual plant Polygonum persicaria were determined over a broad range of controlled light environments (8%-100% full sun). These data reveal both the extent of functionally adaptive phenotypic plasticity expressed by individual genotypes, and the patterns of diversity among genotypes for characters relevant to fitness, in response to an environmental factor that is both highly variable within populations and critical to growth and reproduction.     

Climate‐related genetic variation in drought‐resistance of Douglas‐fir (Pseudotsuga menziesii)

There is a general assumption that intraspecific populations originating from relatively arid climates will be better adapted to cope with the expected increase in drought from climate change. For ecologically and economically important species, more comprehensive, genecological studies that utilize large distributions of populations and direct measures of traits associated with drought‐resistance are needed to empirically support this assumption because of the implications for the natural or assisted regeneration of species. We conducted a space‐for‐time substitution, common garden experiment with 35 populations of coast Douglas‐fir (Pseudotsuga menziesii var. menziesii) growing at three test sites with distinct summer temperature and precipitation (referred to as ‘cool/moist’, ‘moderate’, or ‘warm/dry’) to test the hypotheses that (i) there is large genetic variation among populations and regions in traits associated with drought‐resistance, (ii) the patterns of genetic variation are related to the native source‐climate of each population, in particular with summer temperature and precipitation, (iii) the differences among populations and relationships with climate are stronger at the warm/dry test site owing to greater expression of drought‐resistance traits (i.e., a genotype × environment interaction). During midsummer 2012, we measured the rate of water loss after stomatal closure (transpiration_min), water deficit (% below turgid saturation), and specific leaf area (SLA, cm² g^?1) on new growth of sapling branches. There was significant genetic variation in all plant traits, with populations originating from warmer and drier climates having greater drought‐resistance (i.e., lower transpiration_min, water deficit and SLA), but these trends were most clearly expressed only at the warm/dry test site. Contrary to expectations, populations from cooler climates also had greater drought‐resistance across all test sites. Multiple regression analysis indicated that Douglas‐fir populations from regions with relatively cool winters and arid summers may be most adapted to cope with drought conditions that are expected in the future.     

Otolith morphology varies between populations,sexes and male alternative reproductive tactics in a vocal toadfish Porichthys notatus

In this study, the morphology of sagittal otoliths of the plainfin midshipman fish Porichthys notatus was compared between populations, sexes and male alternative reproductive phenotypes (known as ‘type I males or guarders’ and ‘type II males or sneakers’). Sagitta size increased with P. notatus size and changes in shape were also detected with increasing body size. Porichthys notatus sagittae begin as simple rounded structures, but then elongate as they grow and take on a more triangular and complex shape with several prominent notches and indentations along the dorsal and caudal edges. Moreover, the sagittae of the two geographically and genetically distinct populations of P. notatus (northern and southern) differed in shape. Porichthys notatus from the north possessed taller sagittae with deeper caudal indentations compared to P. notatus from the south. Sagitta shape also differed between females and males of the conventional guarder tactic. Furthermore, guarder males had smaller sagittae for their body size than did sneaker males or females. These differences in sagittal otolith morphology are discussed in relation to ecological and life history differences between the sexes and male tactics of this species. This is the first study to investigate teleost otolith morphology from the perspective of alternative reproductive tactics.     

Effects of genotype-environment interactions on genetic correlations

The objective of the work presented here was to investigate the influence of genotype-environment interaction on genetic correlations. In our theoretical models we have considered plant populations consisting of random samples of lines from chromosome-doubled haploids produced from F ₁ gametes, highly inbred SSD-lines, and clones of randomly breeding populations grown in two and multiple environments. The results of our theoretical considerations are that if genotype-environment interaction exists, great differences are expected to occur in the estimates of genetic correlation coefficients obtained in different environments. Based on the variance and covariance components for genotype-environment interaction we suggest a new type of correlation coefficient, called genotype-environment correlation, r _ge . Our theory has been applied to several series of experiments. Estimates are presented from two series, both of which demonstrate clearly the consequences of genotype-environment interaction on the genetic correlations.     

A genetic model of interpopulation variation and covariation of quantitative characters

Evolutionary consequences of natural selection, migration, genotype-environment interaction, and random genetic drift on interpopulation variation and covariation of quantitative characters are analysed in terms of a selection model that partitions natural selection into directional and stabilizing components. Without migration, interpopulation variation and covariation depend mainly on the pattern and intensities of selection among populations and the harmonic mean of effective population sizes. Both transient and equilibrium covariance structures are formulated with suitable approximations. Migration reduces the differentiation among populations, but its effect is less with genotype-environment interaction. In some special cases of genotype-environment interaction, the equilibrium interpopulation variation and covariation is independent of migration.     

QUANTITATIVE GENETICS OF BRYOZOAN PHENOTYPIC EVOLUTION. III. PHENOTYPIC PLASTICITY AND THE MAINTENANCE OF GENETIC VARIATION

Cheilostome bryozoan species show long-term morphologic stasis, implying stabilizing selection sustained for millions of years, but nevertheless retain significant heritable variation in traits of skeletal morphology. The possible role of within-genotype (within-colony) phenotypic variability in preserving genetic diversity was analyzed using breeding data for two species of Stylopoma from sites along 110 km of the Caribbean coast of Panama. Variation among zooids within colonies accounts for nearly two-thirds of the phenotypic variance on average, increases with environmental heterogeneity, and includes significant genotype-environment interaction. Thus, within-colony variability apparently represents phenotypic plasticity, at least some of which is heritable, rather than random “developmental noise.” Almost all of the among-colonies component of phenotypic variance is accounted for by additive genetic differences in trait means, suggesting that within-colony plasticity includes virtually all of the environmental component of phenotypic variance in these populations of Stylopoma. Thus, heritable within-colony plasticity could play a significant part in maintaining genetic diversity in cheilostomes, but it is also possible that rates of polygenic mutation alone are sufficient to balance the effects of selection.     

Within- and among-lake variation in shell morphology of the freshwater clam Elliptio complanata (Bivalvia: Unionidae) from south-central Ontario lakes

To compare the relative magnitude of variation in shell morphology within and among lakes, Elliptio complanata were collected from low and high exposure areas in each of four small lakes in south-central Ontario. Nested ANOVA's on shell length, height, width and weight revealed that shell morphology varied much more between sites of differing exposure within a lake than among lakes of differing alkalinity. Canonical variates analysis showed that clams from high exposure areas had larger and proportionately taller and heavier shells than those from low exposure areas. There was no relationship between alkalinity of lakes and shell morphology. These results suggest that the use of unionid shell morphology to predict long-term whole lake water chemistry (e.g. alkalinity) requires sampling designs which take into account within-lake variation in shell morphology.     

Intrapopulation variation in predator-avoidance performance of Galápagos lava lizards: The interaction of sexual and natural selection

Summary The interaction of sexual and natural selection in shaping variation in defensive behavior was explored via three steps. (1) Three predictions from the hypothesis that varying responses to predation account for intrapopulation variation in locomotory performance and wariness were tested. One measure of locomotory performance and two measures of wariness were compared between lava lizards (Tropidurus albemarlensis) inhabiting sparsely (1% cover) and heavily (33% cover) vegetated areas of Isla Plaza Sur in the Galapagos Archipelago. (2) Variation in morphology was examined to identify proximate mechanisms for differences seen in (1). (3) Levels of predation were compared between males and females to test a prediction from a model explaining the observed variation in defensive behavior. Male, but not female, lizards from sparsely vegetated areas were faster than those from heavily vegetated areas. Both male and female lizards from sparsely vegetated areas were significantly warier than those from heavily vegetated areas. Multiple regression, covariance, and residual analyses identify relatively longer hindlimbs of males as the proximate cause of their greater speed over that of females, rather than differences in body size, but neither body nor hindlimb size account for the microgeographic differences in speed of males. Significantly higher predation on males provided a positive test of the major prediction from our model of selective forces in which sexual selection for territory defense by males favors short approach distances (by minimizing time away from the territory caused by erroneous flight) and leads to natural selection for their increased hindlimb size and speed.     

Reappraising the early evidence of durophagy and drilling predation in the fossil record: implications for escalation and the Cambrian Explosion

The Cambrian Explosion is arguably the most extreme example of a biological radiation preserved in the fossil record, and studies of Cambrian Lagerstätten have facilitated the exploration of many facets of this key evolutionary event. As predation was a major ecological driver behind the Explosion – particularly the radiation of biomineralising metazoans – the evidence for shell crushing (durophagy), drilling and puncturing predation in the Cambrian (and possibly the Ediacaran) is considered. Examples of durophagous predation on biomineralised taxa other than trilobites are apparently rare, reflecting predator preference, taphonomic and sampling biases, or simply lack of documentation. The oldest known example of durophagy is shell damage on the problematic taxon Mobergella holsti from the early Cambrian (possibly Terreneuvian) of Sweden. Using functional morphology to identify (or perhaps misidentify) durophagous predators is discussed, with emphasis on the toolkit used by Cambrian arthropods, specifically the radiodontan oral cone and the frontal and gnathobasic appendages of various taxa. Records of drill holes and possible puncture holes in Cambrian shells are mostly on brachiopods, but the lack of prey diversity may represent either a true biological signal or a result of various biases. The oldest drilled Cambrian shells occur in a variety of Terreneuvian‐aged taxa, but specimens of the ubiquitous Ediacaran shelly fossil Cloudina also show putative drilling traces. Knowledge on Cambrian shell drillers is sorely lacking and there is little evidence or consensus concerning the taxonomic groups that made the holes, which often leads to the suggestion of an unknown ‘soft bodied driller’. Useful methodologies for deciphering the identities and capabilities of shell drillers are outlined. Evidence for puncture holes in Cambrian shelly taxa is rare. Such holes are more jagged than drill holes and possibly made by a Cambrian ‘puncher’. The Cambrian arthropod Yohoia may have used its frontal appendages in a jack‐knifing manner, similar to Recent stomatopod crustaceans, to strike and puncture shells rapidly. Finally, Cambrian durophagous and shell‐drilling predation is considered in the context of escalation – an evolutionary process that, amongst other scenarios, involves predators (and other ‘enemies’) as the predominant agents of natural selection. The rapid increase in diversity and abundance of biomineralised shells during the early Cambrian is often attributed to escalation: enemies placed selective pressure on prey, forcing phenotypic responses in prey and, by extension, in predator groups over time. Unfortunately, few case studies illustrate long‐term patterns in shelly fossil morphologies that may reflect the influence of predation throughout the Cambrian. More studies on phenotypic change in hard‐shelled lineages are needed to convincingly illustrate escalation and the responses of prey during the Cambrian.     

A new mode of ammonite preservation – implications for dating of condensed phosphorite deposits

Unusual phosphatic casts of the ammonites Mortoniceras (Subschloenbachia) sp. and Stoliczkaia sp. from the upper Albian condensed phosphorite bed at Annopol, Poland, are discussed in terms of their taphonomic history. These specimens are interpreted as ‘secondary’ external casts of ammonite replicas preserved originally as attachment scars on oyster shells. The following genetic history is suggested for this previously undocumented mode of ammonite preservation: (1) settling of shells of dead ammonites on the seafloor; (2) colonization of these shells by oysters and formation of ammonite replicas on left valves of oysters; (3) dissolution of ammonite shells; (4) reworking and fragmentation of oyster shells; (5) casting of ammonite replicas by phosphatic material; and (6) separation of ammonite casts from oyster shells, either through mechanical disintegration or dissolution of the latter. The specimens studied were formed after dissolution of the ammonite conchs, not prior to this event as in the case of typical ammonite steinkerns (internal moulds). Therefore, they are here referred to as ‘pseudo‐steinkerns’. The time interval between loss of the original ammonite shells and the formation of oyster‐mediated pseudo‐steinkerns may be very extensive. Therefore, the pseudo‐steinkerns may potentially mislead in biostratigraphic dating of condensed phosphorite deposits.     

Founders,ancestors, and enemies: memory,family, time,and space in the Pernambuco sertão

This article concerns the use of narrative and genealogical frameworks among sertanejos, the inhabitants of the hinterlands (sertão) of Pernambuco in the Northeast of Brazil, in the process of grouping and differentiating families. It explores how accounts produced by different people are linked by shared memories of past conflicts – such as cangaço and questões de família (lit. ‘family issues’). Through conceived and lived relationships among relatives and the correlated concepts of ‘blood’ and ‘race’ current in this social formation, I look to identify the different meanings attributed to time and space, inscribed in the collective memory, and implicated in the moving configurations of ‘family’ in a cognatic universe.     

Evolutionary drivers of seasonal plumage colours: colour change by moult correlates with sexual selection,predation risk and seasonality across passerines

Some birds undergo seasonal colour change by moulting twice each year, typically alternating between a cryptic, non‐breeding plumage and a conspicuous, breeding plumage (‘seasonal plumage colours’). We test for potential drivers of the evolution of seasonal plumage colours in all passerines (N = 5901 species, c. 60% of all birds). Seasonal plumage colours are uncommon, having appeared on multiple occasions but more frequently lost during evolution. The trait is more common in small, ground‐foraging species with polygynous mating systems, no paternal care and strong sexual dichromatism, suggesting it evolved under strong sexual selection and high predation risk. Seasonal plumage colours are also more common in species predicted to have seasonal breeding schedules, such as migratory birds and those living in seasonal climates. We propose that seasonal plumage colours have evolved to resolve a trade‐off between the effects of natural and sexual selection on colouration, especially in seasonal environments.     

Age-states,population structure,and seedling regeneration of Chionochloa pallens in Canterbury alpine grasslands,New Zealand

Abstract. Age-states, population structure, and seedling regeneration of the grass Chionochloa pallens were investigated in eight alpine grassland stands representing the range of canopy cover (ca. 5–75 %) and basal area (112 - 3889 m²/ha^-1) in the headwaters of the Avoca catchment, Canterbury, New Zealand. In open-canopy stands (< 50 % canopy cover, < 2000 m²/ha^-1 basal area) C. pallens individuals were clearly distinguishable. Rela-tionshipsbetweenbasal diameter, number of tillers, height, and % crown death suggested four putative age-states: ‘seedlings‘, ‘juvenile tussocks’, ‘mature tussocks’ and ‘senescent tussocks’. Four types of population structure were identified depending onthe proportions of seedlings and juvenile and mature tussocks. C. pallens seedlings were present in seven stands at densities ranging from 0.6 to 123.4 / m². They were most frequent on microsites protected from frost-heave by short herbaceous vegetation or litter, but with little competition from taller vegetation. Differences in seedling densities between stands partly reflected the proximity and abundance of seed sources and degree of protection from frost-heave. C. pallens population structures appear to be influenced by the frequency and magnitude of geomorphic disturbances and browsing by introduced animals.     

Contrasting forms of competition set elevational range limits of species

How abiotic and biotic factors constrain distribution limits at the harsh and benign edges of species ranges is hotly debated, partly because macroecological experiments testing the proximate causes of distribution limits are scarce. It has long been recognized – at least since Darwin’s On the Origin of Species – that a harsh climate strengthens competition and thus sets species range limits. Using thorough field manipulations along a large elevation gradient, we show the mechanisms by which temperature determines competition type, resulting in a transition from interference to exploitative competition from the lower to the upper elevation limits in burying beetles (Nicrophorus nepalensis). This transition is an example of Darwin’s classic hypothesis that benign climates favor direct competition for highly accessible resources while harsh climates result in competition through resources of high rivalry. We propose that identifying the properties of these key resources will provide a more predictive framework to understand the interplay between biotic and abiotic factors in determining geographic range limits.     

Control of Liriomyza langei on chrysanthemum by Diglyphus isaea produced with a standard or modified parasitoid rearing technique

Abstract: Overproduction of male parasitoids during mass rearing will increase costs for biological control because wasp shipments contain fewer females and only females kill hosts directly. We have developed a rearing technique capable of significantly reducing male‐biased sex ratios in Diglyphus isaea (Walker) (Hym., Eulophidae), a commercially reared parasitoid of agromyzid leafminers. In this study, we examined the effect of rearing technique on the efficacy of D. isaea for biological control of Liriomyza langei Frick (Dip., Agromyzidae) on chrysanthemum, Dendranthema grandiflora Tzvelev var. ‘Miramar’. We produced D. isaea on mixtures of small and large hosts (our modified technique) or on only large hosts (simulating commercial mass‐rearing) and compared: (1) control of L. langei with D. isaea produced by the two rearing techniques, and (2) damage and yield of unprotected and protected plants. The two rearing techniques produced similar numbers of waSPS per rearing cohort, but the ‘modified’ technique reduced the proportion of males by approximately 13%. The two techniques also produced females of similar size, but the ‘modified’ technique produced smaller males. In greenhouse trials simulating leafminer infestations of potted chrysanthemums during commercial production, we found no significant differences between the levels of control obtained by releasing identical numbers and sex ratios of adult waSPS produced by either rearing technique. Mine counts on plants protected by waSPS of either rearing history were similar and around 30–70% less than unprotected plants during most of the 11‐week crop cycle. At crop harvest, more than half of the foliage on protected plants was undamaged compared with <10% on unprotected crops. Damage to the flower stems of protected plants was relatively light in the top half of the canopy compared with the bottom half. Protected plants were around 10–15% taller and produced twice as many flower buds compared with unprotected plants. Our ‘modified’ rearing technique can reduce overproduction of males in D. isaea with no compromise in biological control efficacy. Adoption of our rearing technique by commercial insectaries could reduce implementation costs for not only D. isaea but also other parasitoids that show host‐size‐dependent sex allocation.     

Nonrandom variation of morphological traits across environmental gradients in a land snail

Morphological variation is often attributed to differential adaptations to diverse habitats, but adaptations to a similar environment do not necessarily result in similar phenotypes. Adaptations for water and heat budget are crucial for organisms living in arid habitats, and in snails, variation in shell morphology has been frequently attributed to selection by stressful environmental factors. However, their phenotypic divergence often is not accompanied by a relevant niche differentiation and consistent relationships with environmental correlates are lacking. In the pulmonate genus Albinaria, there is great size and shape variation between and within species, and there are two major shell sculpture morphotypes, ribbed and smooth. We used 62 populations of 28 Albinaria species, taking into account their phylogeny, to examine the variation of shell traits (sculpture, size, shape), their effect on water and heat budget, and their association with geographical and climatic gradients. We found unambiguous size and shape discrimination between the two morphotypes. Ribbed shells are lighter, taller, and slimmer and have a smaller aperture than the smooth ones. Moreover, significant correlations between shell traits and heat/moisture budget and climate/geography were revealed. Ribbed and taller shells retain more water on their shell surface, and on the other hand, smooth shells exhibit lower water permeability. Therefore, two strategies are being used to prevent water loss, active retention or resistance to loss. Consequently, different alternative solutions evolved and were retained as responses to the same stressful factor by the two distinct shell morphotypes. Larger shells occur in southern latitudes, mostly on islands, and at sites where there is a shortage of rainfall. Therefore, the variation of the examined traits is nonrandom with respect to location and to climate and their evolution can be attributed to selection by environmental factors, with water availability being the key driving agent of body-size variation.     

Allozyme genotype-environment relationships in natural populations of Drosophila buzzatii

Allozyme frequency data from natural populations of Drosophila buzzatii were analyzed for genotype-environment relationships. Allele frequency and heterozygosity at six loci polymorphic throughout eastern Australia and a number of environmental factors (both means and variabilities) were examined by a variety of multivariate techniques. Significant genotype-environment associations were found for five of the six loci, and after correcting for geographic location significant associations remained for Est-2 and Adh-1 gene frequencies and heterozygosities and for Pgm gene frequencies. The results are discussed in relation to selection and gene flow and provide the basis for laboratory studies to disentangle confounded effects of (1) environmental means and environmental variabilities and (2) allele frequency and heterozygosity, and thus to further test for and determine the nature of any natural selection at particular allozyme loci.This work was supported by a grant from the Australian Research Grants Committee to J. S. F. B.