Latest Projects
Project: Host Availability As A Determinant Of Seasonal Polyphenism In Life History Traits Of The Specialist Butterfly Battus polydamas
Recipient of a Postdoctoral Research Competition
Project number: 3120121
In highly seasonal environments some species have the ability to express two or more morphological forms to cope with seasonal environmental variability and persist across generations. Numerous studies have focused on the role of photoperiod and temperature as primary cues for the induction of seasonal phenotypic change. There is a large gap, however, in our understanding of how biotic factors, such as changes in host availability, affect seasonal polyphenism. Here, we use a multivoltine butterfly, Battus polydamas archidamas that depends entirely on Aristolochia plants for survival and development, to test whether seasonal polyphenism in life history traits across different generations is induced by changes in the availability and phenology of its host. Using a combination of field and common garden components, larvae from early and late generations were subject to different levels of leaf availability (low, medium and high) in a complete randomized block design to quantify life history trait variation. We also quantified field standing crop leaf availability and phenology across the season. Changes in host plant availability determine life-history trait variation. Larvae under low leaf availability grow and develop slow reaching lower final mass and increase development time compared to larvae under high and medium leaf availability. Patterns were more pronounced in the late generation, which is correlative with changes in leaf availability and phenology in the field. Therefore, seasonal changes in host availability induce seasonal changes in the life history of populations representing a major selective force that determines their sensitivity to current and future environmental change.
Project: Overgrazing effects by goats on native plant communities of threatened dryland ecosystems of Coquimbo, Chile
Recipient of a Rufford Small Grant, The Rufford Small Grants Foundation (“RSGF”)
Project number: 3120121
‘Ecology is confronted by a cruel dilemma: either communities have an order expressed in their species compositions, population abundances and diversities, or community ecology has been on the wrong track since its inception’ –McNaughton (1983).
Overgrazing by goats is one of the main threats to arid ecosystems worldwide, often leading to ecosystem degradation and biodiversity loss. In Chile, where 46% of the flora is endemic, the Coquimbo region has both the highest number of endemic plants (140), and the highest use of natural habitats for production of goats (37000 Km2, encompassing over 57% of all goats in Chile). Overgrazing by goats has increased the stressful nature of water-limited ecosystems and is considered the greatest threat to desert habitats in Coquimbo. Of 1.478 native plant species occurring in the region, 14% are vulnerable or endangered and two endemics have gone extinct. Moreover, overgrazing has placed 23 species in a vulnerable or endangered category. Ultimately, overgrazing by goats can alter plant community structure, but it is uncertain if it is by inducing changes in plant abundance, population structure and/or diversity. In an effort to restore their land, local human communities in Coquimbo fenced areas to exclude goats and ultimately design a management strategy for both conservation and livestock production. To design relevant management strategies, however, it is imperative to clearly understand the effects of overgrazing both on plant community structure and on species interactions.
This study examines the effect of overgrazing on community structure and species interactions in arid ecosystems of Coquimbo, Chile. Ongoing desertification thru grazing by goats threatens this region’s habitats. Using exclosures of 30-ha we will assess: 1) Changes in diversity, cover and composition of plant communities in areas with and without goats; 2) Quantify changes in species interactions key for community structure; and 3) Quantify grazing pressures to identify species vulnerable to overgrazing. This information will help evaluate the current status of plant communities, which is essential to elaborate long-term management strategies for both habitat conservation and livestock production.
Project: Estado de conservación de Porlieria chilensis: Evaluación a través de modelos poblacionales matriciales, ecología y patrones de distribución
Adjudicación del Tercer Concurso del Fondo de Investigación del Bosque Nativo
El Guayacán (Porleria chilensis Johnst.) (Zygophyllaceae) es un arbusto o árbol pequeño, siempreverde, endémico de Chile. Está distribuido desde la VI hasta la IV Región, en ambientes tanto costeros como de cordillera. Es una especie importante a nivel ecológico, ya que en ambientes xerofíticos hay evidencia de que P. chilensis puede actuar como un ingeniero ecosistémico. Además, el guayacán es importante también económicamente, ya que tiene un uso tradicional como forraje, combustible, medicina y madera. Actualmente el Guayacán está amenazado por factores como la tala indiscriminada y el sobrepastoreo por cabras. Hasta la fecha, no se conoce prácticamente nada acerca de la ecología, o de la biología poblacional del Guayacán, por lo tanto no se sabe cuál es el estado de conservación de la especie y, consecuentemente, ésta no ha sido podido ser clasificada en ninguna categoría de amenaza por la Comisión de Clasificación de Especies. En este estudio utilizaremos modelos matriciales poblacionales, patrones de distribución geográfica e identificación de amenazas a lo largo de su rango de distribución para evaluar el estado de conservación de P. chilensis. Específicamente determinaremos: 1) la presencia, distribución y área de ocupación de P. chilensis en Chile, 2) estimaremos el tamaño poblacional de distintas poblaciones a lo largo de su rango de distribución, utilizaremos modelos matriciales para 3) proyectar la dinámica poblacional en el tiempo y para 4) identificar los estadios que contribuyen más al crecimiento poblacional y en los cuales se puedan centrar los esfuerzos de gestión, manejo y conservación. Adicionalmente, 5) evaluaremos las amenazas actuales y futuras de distintas poblaciones de P. chilensis e 6) identificaremos sitios prioritarios para la conservación del Guayacán. Con la información generada en este estudio podremos determinar si P. chilensis presenta i) reducciones severas en el tamaño poblacional, ii) reducciones o fluctuaciones en el rango geográfico de distribución y/o numero de poblaciones, iii) poblaciones con tamaños poblacionales pequeños y iv) y una alta probabilidad de extinción en tiempos establecidos. Si el Guayacán cae en cualquiera de las cuatro tendencias deberá ser clasificada dentro de una de las tres categorías de en riesgo de extinción de la UICN.