Departamento de Oceanografia

Background and Aims 'Pollination syndromes' are suites of phenotypic traits hypothesized to reflect convergent adaptations of flowers for pollination by specific types of animals. They were first developed in the 1870s and honed during the mid 20th Century. In spite of this long history and their central role in organizing research on plant-pollinator interactions, the pollination syndromes have rarely been subjected to test. The syndromes were tested here by asking whether they successfully capture patterns of covariance of floral traits and predict the most common pollinators of flowers. † Methods Flowers in six communities from three continents were scored for expression of floral traits used in published descriptions of the pollination syndromes, and simultaneously the pollinators of as many species as possible were characterized. † Key Results Ordination of flowers in a multivariate 'phenotype space' defined by the syndromes showed that almost no plant species fall within the discrete syndrome clusters. Furthermore, in approximately two-thirds of plant species, the most common pollinator could not be successfully predicted by assuming that each plant species belongs to the syndrome closest to it in phenotype space. † Conclusions The pollination syndrome hypothesis as usually articulated does not successfully describe the diversity of floral phenotypes or predict the pollinators of most plant species. Caution is suggested when using pollination syndromes for organizing floral diversity, or for inferring agents of floral adaptation. A fresh look at how traits of flowers and pollinators relate to visitation and pollen transfer is recommended, in order to determine whether axes can be identified that describe floral functional diversity more successfully than the traditional syndromes.

Vigorous discussion of the degree of specialization in pollination interactions, combined with advances in the analysis of complex networks, has revitalized the study of entire plantÁpollinator communities. Noticeably rare, however, are attempts to quantify temporal variation in the structure of plantÁpollinator networks, and to determine whether the status of species as specialists or generalists is stable. Here we show that network structure varied through time in a montane meadow community from southern California, USA, in that pollinator species did not form the same links with plant species across years. Furthermore, composition of the generalized core group of species in the network varied among summers, as did the identity of those species involved in relationships that appeared to be reciprocally specialized within any one summer. These differences appear to be related to severe drought conditions experienced in the second summer of the 3 year study. In contrast to this variation, the pollinator community remained similarly highly nested in all three summers, even though species were packed into the nested matrix differently from year to year. These results suggest that plantÁpollinator networks vary in detail through time, while retaining some basic topological properties. This dynamic aspect of community-scale interactions has implications for both ecological and evolutionary inferences about pollination mutualisms.

In a recent letter to TREE [1], Alexandre Aebi and Peter Neumann propose a novel approach to researching the wide-scale losses of honey bee (Apis mellifera) colonies in the Northern hemisphere. We recognise the importance of understanding the causes of colony collapse for honey production and for a subset of the agricultural industry. However, we fundamentally question the authors' starting assertion that honey bees 'are essential pollinators for the maintenance of natural biodiversity and agriculture'[1]. This assertion ...

In a recent letter to TREE [1], Alexandre Aebi and Peter Neumann propose a novel approach to researching the wide-scale losses of honey bee (Apis mellifera) colonies in the Northern hemisphere. We recognise the importance of understanding the causes of colony collapse for honey production and for a subset of the agricultural industry. However, we fundamentally question the authors' starting assertion that honey bees 'are essential pollinators for the maintenance of natural biodiversity and agriculture'[1]. This assertion ...

Large-scale geographical patterns of biotic specialization and the underlying drivers are poorly understood, but it is widely believed that climate plays an important role in determining specialization. As climate-driven range dynamics should diminish local adaptations and favor generalization, one hypothesis is that contemporary biotic specialization is determined by the degree of past climatic instability, primarily Quaternary climate-change velocity. Other prominent hypotheses predict that either contemporary ...

RESUMEN. Se analiza la época reproductiva de Strangomera bentincki y Engraulis ringens y se estima la talla promedio de primera madurez sexual (Lm 50%) para el período 1993-1997. Los indicadores reproductivos utilizados para analizar la época reproductiva son el índice gonadosomático (IGS) y la frecuencia temporal de los estados de madurez sexual macroscópicos de las hembras maduras e hidratadas. La Lm 50% se determinó sobre la base del 50% de hembras maduras ajustando un modelo logístico. El mes en que ocurre el máximo IGS, en el período de mayor actividad reproductiva que se extiende entre julio y septiembre, presenta una baja variabilidad interanual, i.e. coeficientes de variación de 5,1% y 14,6% para S. bentincki y E. ringes, respectivamente. En tanto, la posición relativa del máximo estival del IGS presenta una variación de 45% para S. bentincki y de 35,3% para E. ringens. La Lm 50% se estimó en 10 cm para S. bentincki y en 11,5 cm para E. ringens, la que es alcanzada en julio al término del primer año de vida en S. bentincki y en diciembre, al año y medio en E. ringens. Se postula que la mayor actividad reproductiva poblacional de ambas especies, centrada en agosto, es una respuesta adaptativa de las poblaciones al sistema de surgencia costera estacional de la zona centro-sur de Chile. La mayor productividad asociada al período de surgencias que comienza a mediados de septiembre y que se extiende hasta fines de marzo, sería favorable tanto para la sobrevivencia y crecimiento de estados larvales y juveniles como para el almacenamiento de energía de los adultos para ser utilizada en la reproducción durante el período invernal. Palabras claves: época de desove, talla de primera madurez sexual, estrategia reproductiva, ecosistema de surgencia, peces pelágicos pequeños, Talcahuano (Chile). Reproductive period and mean size at first maturity for Strangomera bentincki and Engraulis ringens from 1993 to 1997 off central-southern Chile. ABSTRACT. The reproductive period of Strangomera bentincki and Engraulis ringens and the size at first maturity (Lm 50%) are analyzed for the period 1993-1997. The reproductive indicators used are the gonadosomatic index (GSI) and the temporal frequency of macroscopic sexual maturity stages for mature and hydrated females. Lm 50% was determined on the basis of 50% of mature females criteria using a logistic equation fitted to observed data. The month at maximum GSI, between July and September, has the lowest interannual variability, i.e. coefficients of variation of 5.1% y 14.6% for S. bentincki and E. ringens respectively. The month at secondary maximum GSI presented coefficients of variation of 45% for S. bentincki and of 35.3% for E. ringens. Lm 50% was estimated in 10 cm TL for S. bentincki and 11.5 cm for E. ringens. The Lm 50% of S. bentincki is achieved in July, at the end of the first year of life, while the Lm 50% of E. ringens is achieved in February, at about 1.5 year old. It is postulated that the populational reproductive period for both species, occurring in August during winter time, is a consequence of the adaptation to the seasonal coastal upwelling ecosystem off central-southern Chile. A higher productivity (e.g.food) in the coastal waters can be found as a consequence of the occurrence of upwelling events from middle September to late March. Under this hypothesis, larval stages and juveniles could find good conditions for growth and survival during spring and summer time, and adults could gain energy that could be used in gonad maturation for the reproduction during winter time, the less-productive season.

Jumbo squid ( Dosidicus gigas ) off central Chile (32 ˚00'S‐41 ˚30'S) was estimated using data collected from July to November during 2005 and 2006 on board the commercial bottom trawl fleet, where D. gigas is part of the bycatch. A geostatistical approach was ap plied to estimate the jumbo squid biomass in Chilean hake ( Merluccius gay i) fishing grounds, which reached almost 135,000 t in 2005 and 131,000 t in 2006. The consumption-biomass ratio and the diet composition from a jumbo squid predation study during 2005 and 2006 were used to estimate the consumption of Merluccius gayi by D. gigas between 2001 and 2006. Assuming a direct relationship between the biomass and the catch per unit effort, D. gigas biomass and its consumption were estimated for 2001 to 2004. We also consider that the predation of jumbo squid on Chilean hake played an important role in the biomass reduction of this species off central Chile.

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Crabs of the galatheid genus Munida have a worldwide distribution, and currently over 150 different species have been recorded (Macpherson, 1994). Studies on the composition of the megaepifauna in the Magellan Region have shown that Munida subrugosa, with a circumpolar distribution between 35°S and 58°S (Zeldis, 1985), is one of the most abundant decapods, and can constitute up to 50% of the benthic biomass south of the Beagle Channel (Arntz et al., 1999). For many predators at a higher trophic level, M. subrugosa represents a large part of the diet composition (Moreno and Jara, 1984). However, the state of knowledge about the autecology of M. subrugosa is low. Previous work SCIENTIA MARINA 71(1)

Pleuroncodes monodon es 1 de las 3 especies que sustentan las pesquerías demersales de crustáceos en Chile, con niveles de desembarque que han mostrado amplias variaciones y una muy lenta recuperación en la última década. La unidad de pesquería sur se encuentra en estado de recuperación desde 2017, después de una intensa sobrepesca, la que afectó tanto al potencial reproductivo como a la distribución geográfica del stock. En el presente estudio, se usó información de lances de pesca de 14 campañas de evaluación directa de P. monodon para estimar la densidad del potencial reproductivo del stock de hembras en el periodo 2005-2018 en la zona centro-sur (32.0° S a 37.0° S) de Chile mediante un análisis geoestadístico. El promedio anual de huevos potenciales se estimó en 78,055.0 millones de huevos potenciales, con una densidad promedio de 74.0 millones de huevos por kilómetro cuadrado. Se reconocieron 2 zonas de agregación del potencial reproductivo, una entre 33.5° S y 34.5° S (zona no...