Recruitment Dynamics of the Relict Palm, Jubaea chilensis: Intricate and Pervasive Effects of Invasive Herbivores and Nurse Shrubs in Central Chile.

Shrubs can have a net positive effect on the recruitment of other species, especially relict species in dry-stressful conditions. We tested the effects of nurse shrubs and herbivory defoliation on performance (survival and growth) of nursery-grown seedlings of the largest living palm, the relict wine palm Jubaea chilensis. During an 18-month period, a total of more than 300 seedlings were exposed to of four possible scenarios produced by independently weakening the effects of nurse shrubs and browsers. The experiment followed a two-way fully factorial design. We found consistent differences in survival between protected and unprotected seedlings (27.5% and 0.7%, respectively), and herbivory had a dramatic and overwhelmingly negative effect on seedling survival. The invasive rabbit (Oryctolagus cuniculus) is clearly creating a critical bottleneck in the regeneration process and might, therefore, partially explain the general lack of natural regeneration of wine palms under natural conditions. Apparently biotic filters mediated by ecological interactions are more relevant in the early stages of recruitment than abiotic, at least in invaded sites of central Chile. Our data reveal that plant-plant facilitation relationship may be modulated by plant-animal interactions, specifically by herbivory, a common and widespread ecological interaction in arid and semi-arid environments whose role has been frequently neglected. Treatments that protect young wine palm seedlings are mandatory to enable the seedlings to attain a height at which shoots are no longer vulnerable to browsing. Such protection is an essential first step toward the conservation and reintroduction of this emblematic and threatened species

Average wine palm seedling mortality caused by ‘desiccation’ (when it was dried) or ‘herbivory’ (when damaged, broken, or chewed stems or leaves).

<p>Death and survival (‘alive’) rates were scored after 18-month study period to (A) protected and (B) non-protected seedlings to browsers. Error bars indicate the standard error (SE) of the mean.</p

Herbivore-nurse shrub factorial experiments used to quantify seedling performance.

<p>Where (A) browsers excluded but seedlings under shrub cover; (B) exposed to browsers but under shrub cover; (C) browsers excluded but seedlings without the protection of a shrub canopy; and (D) fully exposed plants.</p

The functions were calculated for an 18-month study period to compare wine palm seedling survival among treatments.

<p>The functions were calculated for an 18-month study period to compare wine palm seedling survival among treatments.</p

Palm forests in La Campana National Park, central Chile.

<p>Palm forests in La Campana National Park, central Chile.</p

Undergraduate teaching of evolution in Chile: more than natural selection [Enseñanza de la evolución en Chile: más que selección natural]

In a recent commentary, Nespolo (2003) makes reference to his personal experience as exattendant to the course of evolution imparted by Dr. Humberto Maturana and Dr. Jorge Mpodozis at the Facultad de Ciencias of the Universidad de Chile to construct a negative criticism of Chilean undergraduate teaching of evolution. As ex-attendants of the mentioned course of evolution we have had an experience that is directly comparable to that of Dr. Nespolo. Here we wish to point out our opinion regarding this course, which is markedly different. First, it is a caricature to state that in this course natural selection is taught as being wrong. A serious and critical revision of natural selection, the synthetic theory, and evolutionary ecology is a fundamental part of the course. These and other topics are presented by researchers from those fields, such as Drs. Germán Manríquez and Rodrigo Medel. The scientific contributions of both researchers receive positive comments in Nespolo (2003)

Undergraduate teaching of evolution in Chile: more than natural selection [Enseñanza de la evolución en Chile: más que selección natural]

In a recent commentary, Nespolo (2003) makes reference to his personal experience as exattendant to the course of evolution imparted by Dr. Humberto Maturana and Dr. Jorge Mpodozis at the Facultad de Ciencias of the Universidad de Chile to construct a negative criticism of Chilean undergraduate teaching of evolution. As ex-attendants of the mentioned course of evolution we have had an experience that is directly comparable to that of Dr. Nespolo. Here we wish to point out our opinion regarding this course, which is markedly different. First, it is a caricature to state that in this course natural selection is taught as being wrong. A serious and critical revision of natural selection, the synthetic theory, and evolutionary ecology is a fundamental part of the course. These and other topics are presented by researchers from those fields, such as Drs. Germán Manríquez and Rodrigo Medel. The scientific contributions of both researchers receive positive comments in Nespolo (2003)

Avaliação do efeito da colostomia proximal na cicatrização de anastomoses colocólicas em ratos com obstrução intestinal

OBJETIVO: Avaliar o efeito da colostomia proximal na cicatrização de anastomoses colocólicas em ratos com obstrução intestinal. MÉTODO: 72 ratos foram divididos em três grupos: grupo controle (C), submetido à anastomose colocólica e à colostomia proximal na ausência de oclusão intestinal; grupo sem colostomia (SC), submetido à oclusão intestinal de 72 horas e à anastomose colocólica primária; grupo com colostomia (CC) submetido à oclusão intestinal de 72 horas, à anastomose colocólica primária e à colostomia proximal. A cicatrização anastomótica foi avaliada em dois períodos, nos 2º e 7º dias de pós-operatório, em relação à deiscência anastomótica, aderências, epitelização mucosa, pressão de ruptura e a variáveis histológicas por estudo convencional e informatizado. RESULTADOS: verificou-se maior tendência a deiscência anastomótica no grupo SC (12,5%), e elevada incidência de complicações da colostomia no grupo CC (13%), entretanto tais resultados não apresentaram diferença estatística significante. No que se refere às demais variáveis analisadas para verificação da cicatrização anastomótica deve-se considerar que houve equivalência entre os três grupos nos dois períodos analisados. CONCLUSÃO: Não há diferença entre a cicatrização de anastomoses colocólicas associadas ou não à colostomia proximal, em ratos com obstrução intestinal