Genome-wide investigation reveals high evolutionary rates in annual model plants

Background: ;Rates of molecular evolution vary widely among species. While significant deviations from molecular clock have been found in many taxa, effects of life histories on molecular evolution are not fully understood. In plants, annual/perennial life history traits have long been suspected to influence the evolutionary rates at the molecular level. To date, however, the number of genes investigated on this subject is limited and the conclusions are mixed. To evaluate the possible heterogeneity in evolutionary rates between annual and perennial plants at the genomic level, we investigated 85 nuclear housekeeping genes, 10 non-housekeeping families, and 34 chloroplast;genes using the genomic data from model plants including Arabidopsis thaliana and Medicago truncatula for annuals and grape (Vitis vinifera) and popular (Populus trichocarpa) for perennials.;Results: ;According to the cross-comparisons among the four species, 74-82% of the nuclear genes and 71-97% of the chloroplast genes suggested higher rates of molecular evolution in the two annuals than those in the two perennials. The significant heterogeneity in evolutionary rate between annuals and perennials was consistently found both in nonsynonymous sites and synonymous sites. While a linear correlation of evolutionary rates in orthologous genes between species was observed in nonsynonymous sites, the correlation was weak or invisible in synonymous sites. This tendency was clearer in nuclear genes than in chloroplast genes, in which the overall;evolutionary rate was small. The slope of the regression line was consistently lower than unity, further confirming the higher evolutionary rate in annuals at the genomic level.;Conclusions: ;The higher evolutionary rate in annuals than in perennials appears to be a universal phenomenon both in nuclear and chloroplast genomes in the four dicot model plants we investigated. Therefore, such heterogeneity in evolutionary rate should result from factors that have genome-wide influence, most likely those associated with annual/perennial life history. Although we acknowledge current limitations of this kind of study, mainly due to a small sample size available and a distant taxonomic relationship of the model organisms, our results indicate that the genome-wide survey is a promising approach toward further understanding of the;mechanism determining the molecular evolutionary rate at the genomic level.

Cascading climate effects and related ecological consequences during past centuries

The interface between climate and ecosystem structure and function is incompletely understood, partly because few ecological records start before the recent warming phase. Here, we analyse an exceptional 100-yr long record of the great tit (Parus major) population in Switzerland in relation to climate and habitat phenology. Using structural equation analysis, we demonstrate an uninterrupted cascade of significant influences of the large-scale atmospheric circulation (North-Atlantic Oscillation, NAO, and North-sea – Caspian Pattern, NCP) on habitat and breeding phenology, and further on fitness-relevant life history traits within great tit populations. We then apply the relationships of this analysis to reconstruct the circulation-driven component of fluctuations in great tit breeding phenology and productivity on the basis of new seasonal NAO and NCP indices back to 1500 AD. According to the structural equation model, the multi-decadal oscillation of the atmospheric circulation likely led to substantial variation in habitat phenology, productivity and consequently, tit population fluctuations with minima during the "Maunder Minimum" (∼ 1650–1720) and the Little Ice Age Type Event I (1810–1850). The warming since 1975 was not only related with a quick shift towards earlier breeding, but also with the highest productivity since 1500, and thus, the impact of the NAO and NCP has contributed to an unprecedented increase of the population. A verification of the structural equation model against two independent data series (1970–2000 and 1750–1900) corroborates that the retrospective model reliably depicts the major long-term NAO/NCP impact on ecosystem parameters. The results suggest a complex cascade of climate effects beginning at a global scale and ending at the level of individual life histories. This sheds light on how large-scale climate conditions substantially affect major life history parameters within a population, and thus influence key ecosystem parameters at the scale of centuries.

Simulating the evolution of a clonal trait in plants with sexual and vegetative reproduction

Aims Phenotypic optimality models neglect genetics. However, especially when heterozygous genotypes ire fittest, evolving allele, genotype and phenotype frequencies may not correspond to predicted optima. This was not previously addressed for organisms with complex life histories. Methods Therefore, we modelled the evolution of a fitness-relevant trait of clonal plants, stolon internode length. We explored the likely case of air asymmetric unimodal fitness profile with three model types. In constant selection models (CSMs), which are gametic, but not spatially explicit, evolving allele frequencies in the one-locus and five-loci cases did not correspond to optimum stolon internode length predicted by the spatially explicit, but not gametic, phenotypic model. This deviation was due to the asymmetry of the fitness profile. Gametic, spatially explicit individual-based (SEIB) modeling allowed us relaxing the CSM assumptions of constant selection with exclusively sexual reproduction. Important findings For entirely vegetative or sexual reproduction, predictions. of the gametic SEIB model were close to the ones of spatially explicit CSMs gametic phenotypic models, hut for mixed modes of reproduction they appoximated those of gametic, not spatially explicit CSMs. Thus, in contrast to gametic SEIB models, phenotypic models and, especially for few loci, also CSMs can be very misleading. We conclude that the evolution of trails governed by few quantitative trait loci appears hardly predictable by simple models, that genetic algorithms aiming at technical optimization may actually, miss the optimum and that selection may lead to loci with smaller effects, in derived compared with ancestral lines.

Paternal inheritance of growth in fish pursuing alternative reproductive tactics

In species with indeterminate growth, age-related size variation of reproductive competitors within each sex is often high. This selects for divergence in reproductive tactics of same-sex competitors, particularly in males. Where alternative tactics are fixed for life, the causality of tactic choice is often unclear. In the African cichlid Lamprologus callipterus, large nest males collect and present empty snail shells to females that use these shells for egg deposition and brood care. Small dwarf males attempt to fertilize eggs by entering shells in which females are spawning. The bourgeois nest males exceed parasitic dwarf males in size by nearly two orders of magnitude, which is likely to result from greatly diverging growth patterns. Here, we ask whether growth patterns are heritable in this species, or whether and to which extent they are determined by environmental factors. Standardized breeding experiments using unrelated offspring and maternal half-sibs revealed highly divergent growth patterns of male young sired by nest or dwarf males, whereas the growth of female offspring of both male types did not differ. As expected, food had a significant modifying effect on growth, but neither the quantity of breeding substrate in the environment nor ambient temperature affected growth. None of the environmental factors tested influenced the choice of male life histories. We conclude that in L. callipterus growth rates of bourgeois and parasitic males are paternally inherited, and that male and female growth is phenotypically plastic to only a small degree.

Fixed and Flexible: Coexistence of Obligate and Facultative Migratory Strategies in a Freshwater Fish

Migration is an important event in many animal life histories, but the degree to which individual animals participate in seasonal migrations often varies within populations. The powerful ecological and evolutionary consequences of such partial migration are now well documented, but the underlying mechanisms are still heavily debated. One potential mechanism of partial migration is between-individual variation in body condition, where animals in poor condition cannot pay the costs of migration and hence adopt a resident strategy. However, underlying intrinsic traits may overrule such environmental influence, dictating individual consistency in migratory patterns. Unfortunately, field tests of individual consistency compared to the importance of individual condition on migratory propensity are rare. Here we analyse 6 years of field data on roach migration, gathered by tagging almost 3000 individual fish and monitoring their seasonal migrations over extended periods of time. Our aims were to provide a field test of the role of condition in wild fish for migratory decisions, and also to assess individual consistency in migratory tendency. Our analyses reveal that (1) migratory strategy, in terms of migration/residency, is highly consistent within individuals over time and (2) there is a positive relationship between condition and the probability of migration, but only in individuals that adopt a migratory strategy at some point during their lives. However, life-long residents do not differ in condition to migrants, hence body condition is only a good predictor of migratory tendency in fish with migratory phenotypes and not a more general determinant of migratory tendency for the population. As resident individuals can achieve very high body condition and still remain resident, we suggest that our data provides some of the first field evidence to show that both facultative and obligate strategies can co-exist within populations of migratory animals.

Spatial patterns and species performances in experimental plant communities

Amongst the various hypotheses that challenged to explain the coexistence of species with similar life histories, theoretical, and empirical studies suggest that spatial processes may slow down competitive exclusion and hence promote coexistence even in the absence of evident trade-offs and frequent disturbances. We investigated the effects of spatial pattern and density on the relative importance of intra- and interspecific competition in a field experiment. We hypothesized that weak competitors increased biomass and seed production within neighborhoods of conspecifics, while stronger competitors would show increased biomass and seed production within neighborhoods of heterospecifics. Seeds of four annual plant species (Capsella bursa-pastoris, Stachys annua, Stellaria media, Poa annua) were sown in two spatial patterns (aggregated vs. random) and at two densities (low vs. high) in three different species combinations (monocultures, three and four species mixtures). There was a hierarchy in biomass production among the four species and C. bursa-pastoris and S. media were among the weak competitors. Capsella and Stellaria showed increased biomass production and had more individuals in the aggregated compared to the random pattern, especially when both superior competitors (S. annua, P. annua) were present. For P. annua we observed considerable differences among species combinations and unexpected pattern effects. Our findings support the hypothesis that weak competitors increase their fitness when grown in the neighborhood of conspecifics, and suggested that for the weakest competitors the species identity is not important and all other species are best avoided through intraspecific aggregation. In addition, our data suggest that the importance of spatial pattern for the other competitors might not only depend on the position within the hierarchy but also on the identity of neighbor species, species characteristics, below ground interactions, and other nonspatial factors.

The Nile perch invasion in Lake Victoria: cause or consequence of the haplochromine decline?

We review alternative hypotheses and associated mechanisms to explain Lake Victoria’s Nile perch takeover and concurrent reduction in haplochromines through a (re)analysis of long term climate, limnological and stock observations in comparison with size-spectrum model predictions of co-existence, extinction and demographic change. The empirical observations are in agreement with the outcomes of the model containing two interacting species with life-histories matching Nile perch and a generalized haplochromine. The dynamic interactions may have depended on size related differences in early juvenile mortality: mouth-brooding haplochromines escape predation mortality in early life stages, unlike Nile perch that have miniscule planktonic eggs and larvae. In our model predation on the latter by planktivorous haplochromine fry act as a stabilizing factor for co-existence, but external mortality on the haplochromines would disrupt this balance in favor of Nile perch. To explain the observed switch, mortality on haplochromines would need to be much higher than the fishing mortality that can be realistically re-constructed from observations. Abrupt concomitant changes in algal and zooplankton composition, decreased water column transparency, and widespread hypoxia from increased eutrophication most likely caused haplochromine biomass decline. We hypothesize that the shift to Nile perch was a consequence of an externally caused, climate triggered, decrease in haplochromine biomass and associated recruitment failure rather than a direct cause of the introduction.

Construyendo la memoria del barrio San Francisquito

Resumen: La constitución del barrio San Francisquito como barrio precarizado invita a desplegar múltiples estrategias de abordaje, en este caso, mediante un estudio intensivo que recupera las historias de vida de las familias que habitaron y aún hoy habitan el barrio posibilita una construcción subjetivo-colectiva de quienes viven y vivencian la vida cotidiana situaciones que nos habilitan a describir las condiciones de vida de los pobladores del Barrio San Francisquito.

Investigaciones sobre temas del desarrollo : Historización y desafíos de la parentalidad

Se historiza el recorrido teórico metodológico realizado en las actividades de investigación y el proceso de construcción de las diferentes líneas generadas. Se muestran los hallazgos de cada trabajo, desarrollando especialmente los de la investigación actual en familias con niños. Como hipótesis central, se considera que la crisis de las significaciones sociales, la declinación de valores, del sentido del deber y de la autoridad, diluye los marcos contenedores de las subjetividades, con efectos en el ser adolescente, hombre, mujer, madre, padre, abuelo, viejo. La metodología cualitativa utilizada, apunta a describir, analizar, interpretar y categorizar, los datos recogidos en base a: entrevistas en profundidad con madres, padres e informantes clave; entrevistas vinculares con parejas parentales, crónicas grupales, relatos de vida. Se concluye que las mutaciones sociohistóricas actuales, producen profundas transformaciones en la organización y funcionamiento familiar, que se evalúan como expresión de la diversidad propia de nuestra época y no como desviaciones del modelo. Se relevan tres modos predominantes de respuestas: 1) claudicación, confusión, incertidumbre y/o funcionamiento disociado; 2) refugio en la repetición de lo instituido , como así mismo, 3) construcción de estrategias innovadoras de habitar las situaciones, junto al ejercicio de una parentalidad compleja

Desafíos actuales del envejecer

Presentamos hallazgos sobre el envejecer en la actualidad y su entrecruzamiento con la participación en grupos. Señalamos la importancia de la educación permanente en la producción de subjetividad. Se destaca la contribución de las investigaciones referidas a la: docencia, extensión universitaria y formación de investigadores. Partimos del marco teórico de la psicología, se revisan los aportes interdisciplinarios que enriquecen el campo gerontológico. A partir de la longevidad se busca identificar las transformaciones del envejecer, el proceso de revisión identificatoria y el trabajo psíquico de revisar, cuestionar y transformar las significaciones simbólicas, a la par que hacer lugar a lo nuevo en relación con sus funciones: hombre/mujer; esposo/esposa; abuelo/abuela. Se emplea metodología cualitativa: entrevistas en profundidad, historias de vida, crónicas del funcionamiento grupal. Surge la preocupación constante y conciente de los mayores, por preservar su capacidad de desear, crear, producir y gozar, la búsqueda de realización personal y la interrelación con el medio, con los otros y con sus pares. Se observan lógicas propias que promueven la horizontalidad de los vínculos y presentan representaciones, sentidos y conductas que modifican el concepto tradicional del viejo. Se destaca la riqueza del encuentro intersubjetivo entre investigadores y entrevistados, en la elaboración de los cambios.

Investigaciones sobre temas del desarrollo : Historización y desafíos de la parentalidad

Se historiza el recorrido teórico metodológico realizado en las actividades de investigación y el proceso de construcción de las diferentes líneas generadas. Se muestran los hallazgos de cada trabajo, desarrollando especialmente los de la investigación actual en familias con niños. Como hipótesis central, se considera que la crisis de las significaciones sociales, la declinación de valores, del sentido del deber y de la autoridad, diluye los marcos contenedores de las subjetividades, con efectos en el ser adolescente, hombre, mujer, madre, padre, abuelo, viejo. La metodología cualitativa utilizada, apunta a describir, analizar, interpretar y categorizar, los datos recogidos en base a: entrevistas en profundidad con madres, padres e informantes clave; entrevistas vinculares con parejas parentales, crónicas grupales, relatos de vida. Se concluye que las mutaciones sociohistóricas actuales, producen profundas transformaciones en la organización y funcionamiento familiar, que se evalúan como expresión de la diversidad propia de nuestra época y no como desviaciones del modelo. Se relevan tres modos predominantes de respuestas: 1) claudicación, confusión, incertidumbre y/o funcionamiento disociado; 2) refugio en la repetición de lo instituido , como así mismo, 3) construcción de estrategias innovadoras de habitar las situaciones, junto al ejercicio de una parentalidad compleja

Desafíos actuales del envejecer

Presentamos hallazgos sobre el envejecer en la actualidad y su entrecruzamiento con la participación en grupos. Señalamos la importancia de la educación permanente en la producción de subjetividad. Se destaca la contribución de las investigaciones referidas a la: docencia, extensión universitaria y formación de investigadores. Partimos del marco teórico de la psicología, se revisan los aportes interdisciplinarios que enriquecen el campo gerontológico. A partir de la longevidad se busca identificar las transformaciones del envejecer, el proceso de revisión identificatoria y el trabajo psíquico de revisar, cuestionar y transformar las significaciones simbólicas, a la par que hacer lugar a lo nuevo en relación con sus funciones: hombre/mujer; esposo/esposa; abuelo/abuela. Se emplea metodología cualitativa: entrevistas en profundidad, historias de vida, crónicas del funcionamiento grupal. Surge la preocupación constante y conciente de los mayores, por preservar su capacidad de desear, crear, producir y gozar, la búsqueda de realización personal y la interrelación con el medio, con los otros y con sus pares. Se observan lógicas propias que promueven la horizontalidad de los vínculos y presentan representaciones, sentidos y conductas que modifican el concepto tradicional del viejo. Se destaca la riqueza del encuentro intersubjetivo entre investigadores y entrevistados, en la elaboración de los cambios.

Investigaciones sobre temas del desarrollo : Historización y desafíos de la parentalidad

Se historiza el recorrido teórico metodológico realizado en las actividades de investigación y el proceso de construcción de las diferentes líneas generadas. Se muestran los hallazgos de cada trabajo, desarrollando especialmente los de la investigación actual en familias con niños. Como hipótesis central, se considera que la crisis de las significaciones sociales, la declinación de valores, del sentido del deber y de la autoridad, diluye los marcos contenedores de las subjetividades, con efectos en el ser adolescente, hombre, mujer, madre, padre, abuelo, viejo. La metodología cualitativa utilizada, apunta a describir, analizar, interpretar y categorizar, los datos recogidos en base a: entrevistas en profundidad con madres, padres e informantes clave; entrevistas vinculares con parejas parentales, crónicas grupales, relatos de vida. Se concluye que las mutaciones sociohistóricas actuales, producen profundas transformaciones en la organización y funcionamiento familiar, que se evalúan como expresión de la diversidad propia de nuestra época y no como desviaciones del modelo. Se relevan tres modos predominantes de respuestas: 1) claudicación, confusión, incertidumbre y/o funcionamiento disociado; 2) refugio en la repetición de lo instituido , como así mismo, 3) construcción de estrategias innovadoras de habitar las situaciones, junto al ejercicio de una parentalidad compleja

Desafíos actuales del envejecer

Presentamos hallazgos sobre el envejecer en la actualidad y su entrecruzamiento con la participación en grupos. Señalamos la importancia de la educación permanente en la producción de subjetividad. Se destaca la contribución de las investigaciones referidas a la: docencia, extensión universitaria y formación de investigadores. Partimos del marco teórico de la psicología, se revisan los aportes interdisciplinarios que enriquecen el campo gerontológico. A partir de la longevidad se busca identificar las transformaciones del envejecer, el proceso de revisión identificatoria y el trabajo psíquico de revisar, cuestionar y transformar las significaciones simbólicas, a la par que hacer lugar a lo nuevo en relación con sus funciones: hombre/mujer; esposo/esposa; abuelo/abuela. Se emplea metodología cualitativa: entrevistas en profundidad, historias de vida, crónicas del funcionamiento grupal. Surge la preocupación constante y conciente de los mayores, por preservar su capacidad de desear, crear, producir y gozar, la búsqueda de realización personal y la interrelación con el medio, con los otros y con sus pares. Se observan lógicas propias que promueven la horizontalidad de los vínculos y presentan representaciones, sentidos y conductas que modifican el concepto tradicional del viejo. Se destaca la riqueza del encuentro intersubjetivo entre investigadores y entrevistados, en la elaboración de los cambios.

Human-caused environmental change: Impacts on plant diversity and evolution

Human-caused environmental changes are creating regional combinations of environmental conditions that, within the next 50 to 100 years, may fall outside the envelope within which many of the terrestrial plants of a region evolved. These environmental modifications might become a greater cause of global species extinction than direct habitat destruction. The environmental constraints undergoing human modification include levels of soil nitrogen, phosphorus, calcium and pH, atmospheric CO2, herbivore, pathogen, and predator densities, disturbance regimes, and climate. Extinction would occur because the physiologies, morphologies, and life histories of plants limit each species to being a superior competitor for a particular combination of environmental constraints. Changes in these constraints would favor a few species that would competitively displace many other species from a region. In the long-term, the “weedy” taxa that became the dominants of the novel conditions imposed by global change should become the progenitors of a series of new species that are progressively less weedy and better adapted to the new conditions. The relative importance of evolutionary versus community ecology responses to global environmental change would depend on the extent of regional and local recruitment limitation, and on whether the suite of human-imposed constraints were novel just regionally or on continental or global scales.