Trabajo Semestral

El trabajo semestral consistirá en un trabajo de revisión o de análisis de datos relacionados a los temas del programa, original y creativo, en formato de un artículo de revista científica. La extensión máxima del escrito son 15 páginas incluyendo figuras y bibliografía.

La fecha de entrega del trabajo final  será el Viernes 22 de Mayo 2015. Los trabajos los estaré recibiendo en el Insituto de  Investigaciones Biomédicas, Nueva sede, edificio C, laboratorio 110.

Lectura 13 Mayo 2015

Complex Ecological Interactions in the Coffee Agroecosystem
Ivette Perfecto, John Vandermeer and Stacy M. Philpott

Coffee agroecosystems have become iconic in the study of how agriculture can contribute to the conservation of biodiversity and how biodiversity can deliver ecosystem services to agriculture. However, coffee farms are also excellent model systems for ecological research. Throughout the tropics coffee farms are cultivated using varying numbers and diversity of shade trees, representing a gradient of diversity and complexity, ranging from forest-like “shade coffee” to intensified shadeless “sun coffee.” Here we synthesize ecological research in the coffee agroecosystem focusing on four topics that have received considerable recent attention: (a) trophic interactions (especially vertebrates and ants as predators), (b) trait-mediated indirect interactions, (c) competition and community assembly (mainly birds and ants), and (d ) spatial constraints on interactions.

Lectura 2 - 11 Mayo 2015

Mutualistic Interactions and Biological Invasions
Anna Traveset and David M. Richardson

Mutualisms structure ecosystems and mediate their functioning. They also enhance invasions of many alien species. Invasions disrupt native mutualisms, often leading to population declines, reduced biodiversity, and altered ecosystem functioning. Focusing on three main types of mutualisms (pollination, seed dispersal, and plant-microbial symbioses) and drawing on examples from different ecosystems and from species- and community-level studies, we review the key mechanisms whereby such positive interactions mediate invasions and are in turn influenced by invasions. High interaction generalization is “the norm” in most systems, allowing alien species to infiltrate recipient communities. We identify traits that influence invasiveness (e.g., selfing capacity in plants, animal behavioral traits) or invasibility (e.g., partner choice in mycorrhizas/rhizobia) through mutualistic interactions. Mutualistic disruptions due to invasions are pervasive, and subsequent cascading effects are also widespread. Ecological networks provide a useful framework for predicting tipping points for community collapse in response to invasions and other synergistic drivers of global change.

Lectura 1 - 11 Mayo 2015

Solar-Powered Sea Slugs. Mollusc/Algal Chloroplast Symbiosis
Mary E. Rumpho, Elizabeth J. Summer, and James R. Manhart

Solar-powered “leaves that crawl”? This description of photosynthetic sea slugs (adapted from Bill Rudman [www.austmus.gov.au/seaslugs/solarpow. htm] and Robert Trench [1975]) aptly describes the symbiotic association that occurs between certain molluscan sea slugs and algal chloroplasts. Faced with life without a protective shell in a predatory environment, some sea slugs evolved a protective mechanism dependent largely upon camouflage provided by symbiont plastids (Fig. 1). Sea slugs in the opisthobranch order of Gastropods, Ascoglossa (! Sacoglossa), have taken this one step further. They feed by slicing or puncturing siphonaceous algal cells and sucking out the cell contents. All of the contents, including the algal nucleus, are discarded except for the chloroplasts, which are engulfed phagocytotically into the digestive cells (see micrographs in Fig. 2, A and B). By distributing the “photosynthetic factories” throughout their extensively branched digestive system just one cell layer beneath the epidermis, the sea slugs not only blend into the green algal bed (Fig. 1C), but also capture light energy to fuel photoautotrophic CO2 fixation.

Lectura 06 Mayo 2015

Geographic isolation trumps coevolution as a driver of yucca and yucca moth diversification
David M. Althoff, Kari A. Segraves, Christopher I. Smith, James Leebens-Mack and Olle Pellmyr

Coevolution is thought to be especially important in diversification of obligate mutualistic interactions such as the one between yuccas and pollinating yucca moths. We took a three-step approach to examine if plant and pollinator speciation events were likely driven by coevolution. First, we tested whether there has been co-speciation between yuccas and pollinator yucca moths in the genus Tegeticula (Prodoxidae). Second, we tested whether co-speciation also occurred between yuccas and commensalistic yucca moths in the genus Prodoxus (Prodoxidae) in which reciprocal evolutionary change is unlikely. Finally, we examined the current range distributions of yuccas in relationship to pollinator speciation events to determine if plant and moth speciation events likely occurred in sympatry or allopatry. Co-speciation analyses of yuccas with their coexisting Tegeticula pollinator and commensalistic Prodoxus lineages demonstratedphylogenetic congruence between both groups of moths and yuccas, even though moth lineages differ in the type of interaction with yuccas. Furthermore, Yucca species within a lineage occur primarily in allopatry rather than sympatry. We conclude that biogeographic factors are the overriding force in plant and pollinator moth speciation and significant phylogenetic congruence between the moth and plant lineages is likely due to shared biogeography rather than coevolution.