Crucibles of creativity: the geographic origins of tropical molluscan innovations

Extralimital traits—evolutionary innovations that represent unprecedented departures from the phenotypic norm in the clade in which they arise—are often thought preferentially to evolve in island-like settings, but accumulating evidence indicates that they also arise in highly diverse, competitively rigorous ecosystems. In order to evaluate the origins of extralimital traits, I reconstructed the history of all ecological and shell-morphological innovations in Miocene to Recent shallow-water molluscs from the two great modern tropical marine realms, the Indo-West Pacific (IWP) and Atlantic-eastern Pacific (AEP), with the expectation that the more diverse IWP would show a higher incidence of innovation. Of the 66 innovations I identified, 53 (80%) are IWP and 13 (20%) are AEP in origin. Data on the numbers of living species in 26 molluscan clades in the two tropical realms indicate that the species ratio (AEP to total number of species 0.32 ± 0.115) exceeds the innovation ratio (AEP to total innovations 0.21). The per-species frequency of innovation is therefore significantly higher in the IWP. None of the innovations is unique to endemic taxa on oceanic islands. I suggest that warm, large, highly productive environments are more conducive to the establishment of new ecological roles and phenotypic states than are smaller, less productive, more island-like settings; and that diversity need not be correlated with either high productivity or evolutionary opportunity for innovation.     

Correlates of diversification in the plant clade Dipsacales: geographic movement and evolutionary innovations

We explore patterns of diversification in the plant clades Adoxaceae and Valerianaceae (within Dipsacales), evaluating correlations between biogeographic change (i.e., movements into new areas), morphological change (e.g., the origin of putative key innovations associated with vegetative and reproductive characters), and shifts in rates of diversification. Our findings indicate that rates of diversification in these plants tend to be less tightly correlated with the evolution of morphological innovations but instead exhibit a pronounced correlation with movement into new geographic areas, particularly the dispersal of lineages into new mountainous regions. The interdependence among apparent novelties (arising from their nested phylogenetic distribution) and the correlation between morphological and biogeographic change suggests a complex history of diversification in Dipsacales. Overall, these findings highlight the importance of incorporating biogeographic history in studies of diversification rates and in the study of geographic gradients in species richness. Furthermore, these results argue against a simple deterministic relationship between dispersal and diversification: like other factors that may influence the probability of speciation and/or extinction, the impact of dispersal on diversification rates depends on being in the right place at the right time.     

An evaluation of the geographic method for recognizing innovations in nature,using zoo orangutans

Innovation and social learning are the raw materials for traditions and culture. Of these two, innovation has received far less scrutiny, largely because of difficulties assessing the innovation status of behaviors. A recent attempt proposes recognition of innovations in natural populations based on assessment of the behavior’s properties and its geographic and local prevalence. Here we examine the validity of this approach and the list of 43 potential innovations it generated for wild orangutans by extending the comparison to zoo orangutans. First, we created an inventory of the behavioral repertoire in the zoo population. Four of ten putative innovations recognized in the field and potentially present in captivity did not occur despite appropriate conditions, suggesting they are indeed innovations. Second, we experimentally produced relevant conditions to evaluate whether another five potential innovations could be elicited. Based on their continued absence or on their latencies relative to known behaviors, four of the potential innovations could be assessed as innovations and one as a modification. Because 53% of relevant innovations recognized in the field could be confirmed in this analysis, and another 27% assigned possible innovation status, we conclude that the geographic method for detecting innovation in the wild is valid. However, the experiments also yielded up to 13 additional innovations, suggesting that zoo orangutans are far more innovative than wild ones. We discuss the implications of this latter finding with regard to limiting factors for the expansion of cultural repertoires in wild orangutans.     

Female presence influences sperm velocity in the guppy

As sperm production is costly, males are expected to strategically allocate resources to sperm production according to mating opportunities. While sperm number adjustments have been reported in several taxa, only a few studies investigated whether sperm quality shows adaptive plasticity as well. We tested this prediction in the guppy, Poecilia reticulata. A total of 46 males were initially stripped of all retrievable sperm before being randomly allocated to one of two treatments simulating different levels of mating opportunities (visual contact with females or female deprived). After 3 days, males were stripped and sperm velocity was assayed using Computer Assisted Sperm Analysis. Males in the presence of females produced significantly faster sperm than their counterparts. Implications for the evolution of this ejaculate plasticity in the light of results of sperm competition studies are discussed.     

Consanguinity in Spain: socioeconomic,demographic, and geographic influences

Information on consanguinity in Spain was reanalyzed in order to obtain a more complete picture of consanguinity patterns by considering temporal, geographical, demographic, and economic factors. To obtain data on consanguineous marriages, we reviewed 106 published references. Only populations with homogeneous geographical characteristics, economic activities, transportation facilities, and the like, were considered. Two-way analysis of variance (ANOVA) provided highly significant differences (p < 0.001) for a both for time periods and for urban versus rural patterns, but there was no interaction between the latter two. A regression analysis shows that for rural areas the geographic characteristics, economy, communications, and index of demographic tendency were significant predictors of the inbreeding coefficient. The results obtained indicate that urban and rural patterns differ significantly and that the temporal factor needs to be taken into account before comparing inbreeding coefficients. In urban areas the census size and altitude are included in the regression equation as significant variables, but association was not found between alpha and the index of demographic tendency (population increase or decrease). Instead, the absolute number of inhabitants (census size) was significant. In rural areas geographic characteristics, communications, and index of demographic tendency were significant predictors of the inbreeding coefficient.     

Analysis of climatic and geographic factors affecting the presence of chytridiomycosis in Australia

Chytridiomycosis is an emerging fungal disease that has been implicated in the global decline of amphibian populations. Identifying climatic and geographic factors associated with its presence may be useful in control and prevention measures. Factors such as high altitude, cool temperature, and wet climate have been associated with chytridiomycosis outbreaks. Although some of these factors have been studied in a laboratory setting, there have been few studies in a natural setting. In this investigation, the relationship between altitude, average summer maximum temperature, or the amount of rainfall and the presence or absence of chytridiomycosis are statistically tested using data from 56 study sites in Australia. Currently, in Australia, 48 native species of wild amphibians have been found infected with chytridiomycosis. The 56 sites in the present study, extending along approximately 50% of the coastline of Australia, have been identified as either a chytrid site, where > or = 1 species are infected with chytridiomycosis, or a no-decline site, where none of the species present at the site are experiencing a decline or are known to be infected. The odds-ratio test and two-proportions test applied to this data indicate that the presence of chytridiomycosis in Australia is significantly related to temperature. In particular, the presence of chytridiomycosis is more likely at sites where the average summer maximum temperature is < 30 degrees C. The results of the analyses do not indicate a significant relationship between the presence of chytridiomycosis and altitude or rainfall.     

Modeling human fertility in the presence of measurement error

The probability of conception in a given menstrual cycle is closely related to the timing of intercourse relative to ovulation. Although commonly used markers of time of ovulation are known to be error prone, most fertility models assume the day of ovulation is measured without error. We develop a mixture model that allows the day to be misspecified. We assume that the measurement errors are i.i.d. across menstrual cycles. Heterogeneity among couples in the per cycle likelihood of conception is accounted for using a beta mixture model. Bayesian estimation is straightforward using Markov chain Monte Carlo techniques. The methods are applied to a prospective study of couples at risk of pregnancy. In the absence of validation data or multiple independent markers of ovulation, the identifiability of the measurement error distribution depends on the assumed model. Thus, the results of studies relating the timing of intercourse to the probability of conception should be interpreted cautiously.     

Il-4 influences apoptosis of mycobacterium-reactive lymphocytes in the presence of TNF-alpha

T cell apoptosis is associated with defective cell-mediated effector functions in several infectious diseases. In tuberculosis, there is evidence that T cell apoptosis may be cytokine mediated, but the mechanisms are not clearly understood. Type 2 cytokines have recently been associated with disease extent in human tuberculosis, but they have not previously been linked to apoptosis in mycobacterium-reactive T cells. This study presents evidence that PBLs from healthy donors respond to sonicated Mycobacterium tuberculosis Ags with increased IL-4 gene activation, CD30 expression, and apoptosis. The changes were significantly greater than those observed when cells were stimulated with Ags from nonpathogenic Mycobacterium vaccae. A hypothesis linking these observations was tested. CD30 expression and TNF-alpha-mediated lymphocyte apoptosis were both down-regulated by inhibiting IL-4 in this model. TNFR-associated factor 2 (TRAF2) expression was down-regulated in CD30(+) cells, and addition of anti-TNF-alpha Ab significantly reduced apoptosis in the CD30(+) but not the CD30(-) population. These observations support the hypothesis that increased IL-4 expression in M. tuberculosis-activated lymphocytes promotes CD30 expression, which sensitizes the lymphocytes to TNF-alpha-mediated apoptosis via TRAF2 depletion. This may be one mechanism by which IL-4 is associated with immunopathological consequences in human tuberculosis.     

Modeling cell concentration in complex media

A model that continuously predicts the concentration of microorganisms in complex medium fermentations is suggested. The model uses carbon dioxide evolution as its primary input and assumes that respiration activity can be differentiated into growth-related and maintenance-related functions. This model can be programmed on computer-coupled vessels and used to standardize on a physiological fermentation inoculum transfer time. The cell concentration estimate can also be used to calculate specific growth rate and can be combined with additional monitored information to calculate other important fermentation parameters such as specific oxygen uptake.     

Ester synthesis in aqueous media in the presence of various lipases

Summary The ability of seven lipase preparations to catalyse methyl ester synthesis in aqueous media was compared and the synthesis reaction (esterification or alcoholysis) determined. Three behaviours were observed: three enzymes catalysed ester synthesis by esterification of free fatty acids and one enzyme catalysed alcoholysis but the other three lipases did not catalyse a net ester synthesis under the conditions tested. The three groups also differed by the influence of methanol on the hydrolysis reaction. The first group was not significantly inhibited up to the highest methanol concentration tested (5 M). Hydrolysis in the presence of the enzyme of the second group was increasingly inhibited with increasing methanol concentrations. In the presence of the third group, hydrolysis was 40 to 50% inhibited for all the concentrations tested (0.2–5 M).     

Modeling the biocoenose of parasitic diseases using remote sensing and geographic information systems

Application of growing degree day-water budget analysis concepts to snail-borne diseases are reviewed to demonstrate use of the unique thermal-hydrological preferences and limits of tolerance of individual parasite-vector systems to define the environmental niche of disease agents in the landscape by modern geospatial analysis tools.     

Phenotypic plasticity influences the size, shape and dynamics of the geographic distribution of an invasive plant

Phenotypic plasticity has long been suspected to allow invasive species to expand their geographic range across large-scale environmental gradients. We tested this possibility in Australia using a continental scale survey of the invasive tree Parkinsonia aculeata (Fabaceae) in twenty-three sites distributed across four climate regions and three habitat types. Using tree-level responses, we detected a trade-off between seed mass and seed number across the moisture gradient. Individual trees plastically and reversibly produced many small seeds at dry sites or years, and few big seeds at wet sites and years. Bigger seeds were positively correlated with higher seed and seedling survival rates. The trade-off, the relation between seed mass, seed and seedling survival, and other fitness components of the plant life-cycle were integrated within a matrix population model. The model confirms that the plastic response resulted in average fitness benefits across the life-cycle. Plasticity resulted in average fitness being positively maintained at the wet and dry range margins where extinction risks would otherwise have been high ("Jack-of-all-Trades" strategy JT), and fitness being maximized at the species range centre where extinction risks were already low ("Master-of-Some" strategy MS). The resulting hybrid "Jack-and-Master" strategy (JM) broadened the geographic range and amplified average fitness in the range centre. Our study provides the first empirical evidence for a JM species. It also confirms mechanistically the importance of phenotypic plasticity in determining the size, the shape and the dynamic of a species distribution. The JM allows rapid and reversible phenotypic responses to new or changing moisture conditions at different scales, providing the species with definite advantages over genetic adaptation when invading diverse and variable environments. Furthermore, natural selection pressure acting on phenotypic plasticity is predicted to result in maintenance of the JT and strengthening of the MS, further enhancing the species invasiveness in its range centre.     

Modeling and analysis of prion dynamics in the presence of a chaperone

Prions are infectious agents and are polymers called PrP(Sc)-Prion protein scrapies, of a normal protein, a monomer called PrP(c)-Prion protein cellular. These PrP(Sc)s cause TSEs-transmissible spongiform encephalopathies such as bovine spongiform encephalopathy (BSE) in cattle, scrapies in sheep, Kuru and Creutzfeld-Jacob diseases in humans. Cellular molecular chaperones, which are ubiquitous, stress-induced proteins, and newly found chemical and pharmacological chaperones have been found to be effective in preventing misfolding of different disease-causing proteins, essentially reducing the severity of several neurodegenerative disorders and many other protein-misfolding diseases. In this work, we propose a model for the replication of prions by nucleated polymerization in the presence of a chaperone. According to this model, the biological processes of coagulation, splitting and the inhibitory effects of the chaperone can be described by a coupled system consisting of ordinary differential equations and a partial differential equation. The model is converted into a system of ordinary differential equations and the equilibrium points are computed and their stability is studied. We give a numerical simulation of the model and we find that a disease free state can be achieved in the presence of a chaperone. The duration of the disease free state is found to increase with the amount of chaperone and this amount of chaperone can be computed from the model.     

Modeling geographic risk of complex congenital heart defects in Eastern Wisconsin

BACKGROUND: Geographic variation may be an indicator of risk factors for birth defects. This study models the geographic distribution of three complex congenital heart defects (CHDs) in eastern Wisconsin, and evaluates effects of demographic census variables linked to geographic location. METHODS: Cases of Hypoplastic Left Heart Syndrome (HLHS), Tetralogy of Fallot (TOF) and d‐Transposition of the Great Arteries (d‐TGAs) born between1995 and 2004 were identified from three medical centers serving eastern Wisconsin. Case diagnoses were assigned by a pediatric cardiologist using echocardiographic records. Births by ZIP code were obtained from the State of Wisconsin. ZIP Code demographic variables were derived from 2000 census data. Numbers of cardiac defects by ZIP code were modeled using cluster analysis and Poisson generalized additive models (GAMs) for spatial coordinates including all and white only cases (excluding trisomies). GAM analyses were repeated adjusting for census variables. RESULTS: Four hundred forty‐eight cases were ascertained. A significant south‐to‐north spatial gradient for HLHS, TOF, and combined CHDs, but not d‐TGAs was identified. This gradient remained significant when census variables were included in the model for the full sample. In the analysis excluding non‐white cases, findings were the same for TOF, combined CHDs, and d‐TGAs. However, the geographic gradient for HLHS was not significant in the adjusted model. CONCLUSIONS: A south‐to‐north gradient was apparent for two of three complex CHDs in eastern Wisconsin. For white cases, demographic variation seems to explain some of this spatial gradient in HLHS. Further studies are needed to confirm demographic and other risk factors underlying this geographic gradient. Birth Defects Research (Part A) 2011. © 2011 Wiley‐Liss, Inc.