Amphibian chytridiomycosis, due to infection with the fungus Batrachochytrium dendrobatidis (Bd), has been associated with the alarming decline and extinction crisis of amphibians worldwide. It is essential for conservation management to identify regions with high or low suitability for Bd. We use a species distribution model to estimate the environmental suitability of Bd in the Chilean Winter Rainfall–Valdivian Forest biodiversity hotspot. Fourteen environmental variables were used as predictors in the statistical modeling (Maxent, generalized linear models, random forest) which also included 56 independent Bd+ localities. High‐risk areas (i.e., suitability above a defined threshold) were validated through prospective field surveys conducted in 2017. As results from Maxent, which only uses presence data, were the only results retained, refugia (i.e., suitability below a defined threshold) were validated with the Bd absences (N = 12) used in the GLM and RF modeling. Our results showed that (1) suitability for Bd increased with human footprint and with shorter distances to urban centers and water bodies and decreased with elevation; (2) climate was not a major factor shaping the current distribution of Bd; and (3) the model predicted high‐risk and refugia areas fairly well. Surveys of 24 new localities in high‐risk areas confirmed that 23 were Bd+; hence, these areas warrant consideration for long‐term Bd surveillance, population monitoring, and disease mitigation. In addition, five localities with apparent Bd absence were found in the predicted high‐risk areas. Our models showed that refugia can exist near high‐risk areas and Bd+ sites. Four localities with apparent Bd absence were located within the refugia predicted by the model. Preventing Bd transmission to such refugia is of paramount importance for persistence of Bd‐susceptible amphibian populations. The identification and validation through prospective field surveys of high‐risk areas and refugia are imperative to develop strategies to prevent further arrival and establishment of Bd and also, by identifying amphibian species or populations of conservation concern in such areas, will help to guide specific actions to reduce the biodiversity loss caused by chytridiomycosis.

No abstract

Consumidores de frutos de ABSTRACTFrugivory is a common interaction mechanism between plants and animals in the temperate rainforest of southern South America. In this study, we examined primary dispersal and predation stages of Persea lingue (Ruiz et Pav.) Nees (Lauraceae), an endemic large-seeded tree of these forests. The main goal was to determine the identity of vertebrate seed dispersers of P. lingue, to distinguish legitimate seed dispersers, pulp consumers and seed predators, and their influence on seed germination. In order to know which birds and small mammals were feeding P. lingue seeds, we observed 20 P. lingue canopies, and live traps baited with P. lingue seeds were installed in fragment forests in south-central Chile.To determine whether birds could be legitimate dispersers of P. lingue, we collected regurgitated and fecal samples. We examined whether rodents removed the fruit pulp, the seeds, or the whole fruit. Additionally, we studied if seeds placed on the forest floor were removed by rodents. In a final experiment we conducted germination trials to establish whether pulp removal (by birds, rodents, or artificially-removed) influenced germination rates. We found six bird species feeding on P. lingue seeds. None of them defecated intact seeds, but, Turdus falcklandii Quoy & Gaimard (Turdinae) and Xolmis pyrope (Kittlitz) (Tyrannidae) regurgitated intact seeds. We captured five species of rodents in Sherman traps. Four of them left intact seeds. We did not find any effect of the seed handling types (pulp consumption vs. seed regurgitation) in seed germination rates. However, pulp removal was an important factor for germination success. We conclude that T. falcklandii and X. pyrope are legitimate seed dispersers of P. lingue, since they swallow the whole fruit and regurgitate the intact seed. Abrothrix olivaceus (Waterhouse) (Cricetidae) and probably Oligoryzomys longicaudatus (Bennett) (Cricetidae) are potential secondary dispersers of P. lingue seeds, as they prefer to eat the fruit pulp rather than the seeds. KEYWORDS:Frugivory, Austral thrush, seed germination, southern temperate rainforest. RESUMENLa dispersión de semillas por endozoocoría es uno de los principales mecanismos de interacción mutualista entre plantas y animales en el bosque templado de Sudamérica. En este estudio indagamos acerca de los mecanismos de dispersión primaria y estadios de depredación de semillas de Persea lingue (Ruiz et Pav.) Nees (Lauraceae), árbol endémico de estos bosques. El objetivo principal fue determinar la identidad de los vertebrados dispersores de semillas de P. lingue, distinguiendo dispersores legítimos, de consumidores de pulpa y predadores de semillas, y determinar su efecto en la germinación. Se realizaron observaciones focales de la copa de adultos de P. lingue; además, se instalaron trampas Sherman cebadas con frutos de P. lingue en fragmentos de bosque en el valle central del centro-sur de Chile. Se colectaron muestras de fecas y semillas regurgitadas, se determinó cuáles especies de roedores c...

Recolonization of wind-dispersed tree species in degraded areas may decline with distance from remnant forest fragments because seed rain frequently decreases with distance from the seed source. However, regeneration of these species may be even more limited to sites close to the seed source if dispersal distance is negatively affected by seed mass, and germination probability is positively affected by seed mass. We evaluated these hypotheses in a Mediterranean-type ecosystem of central Chile, using the wind-dispersed tree species Quillaja saponaria. We assessed the seed rain curve in a degraded open area adjacent to a remnant forest fragment of this species, and related seed mass with dispersal distance from the seed source. Then, we evaluated the relationship between seed mass, germination, and seedling growth, and if seeds that fall nearer the seed source have greater germination probability. We found a decreasing seed rain with the distance from the seed source. Seed mass was not related to dispersal distance, although seeds with higher wing area dispersed further. Germination probability was Communicated by Michelle Tedder.