Biology subjects

Lopez, D. N.

Publications and source records attributed to Lopez, D. N..

4 recordsLinked to original sources

bioRxiv2023

Rapid population recovery of a foundation species from experimental small-scale harvesting

Ecological stability is central to understand how disturbances challenge the persistence of populations and communities through time, particularly when species with strong effects on other species are disturbed. The bull kelp Durvillaea incurvata is a foundation habitat forming species that provides habitat, food, and shelter for various species, and supports the livelihoods of human communities along the southeast Pacific coast of Chile. Harvesting of D. incurvata has raised concerns about the long-term viability of its populations, but the stability responses of bull kelps to anthropogenic disturbances are still unclear. Here, we conducted a manipulative field experiment in which we removed once all individuals of the bull kelp from two sites in southern Chile. We simulated the loss of bull kelps to harvesting in 1-m2-plots interspersed in matrices of dense D. incurvata stands. Fronds cannot regrow from the holdfasts after harvesting. Holdfasts were therefore also removed, a practice not typically carried out by local gatherers. For 25 months we quantified bull kelp recruitment, holdfast densities, percent cover, mean frond size and density, biomass, and population size structure in two rocky intertidal sites. In both sites, all metrics completely recovered within five to seven months. The removal of D. incurvata did not have a significant impact on recruitment, which was constant during the experiment. The relatively small spatial scale of the disturbances, constant recruitment provided by the surrounding bull kelp matrix, and the removal of holdfasts that released settlement substratum may have allowed for the strong stability responses in these populations. Therefore, spatial heterogeneity, which allows for settles to colonize the disturbed plots, should be prioritized in management strategies of natural seaweeds stands.

ecology↗

bioRxiv2022

Disentangling the spread dynamics of insect invasions using spatial networks

Describing and understanding spatiotemporal spread patterns in invasive species remains a longstanding interdisciplinary research goal. Here we show how a network-based top-down approach allows the efficient description of the ongoing invasion by Drosophila suzukii in Chile. To do so, we apply theoretical graph methods to calculate the minimum cost arborescence graph (MCA) to reconstruct and understand the invasion dynamics of D. suzukii since the first detection in 2017. This method estimates a directed rooted weighted graph by minimizing the total length of the resulting graph. To describe the temporal pattern of spread, we estimate three metrics of spread: the median dispersal rate, the median coefficient of diffusion, and the median dispersal acceleration. The estimated MCA shows that over four years, D. suzukii colonized a ~1,000 km long strip in the central valley of Chile, with an initial phase with long paths and connections and no clear direction pattern, folowed by a clearer north-east propagation pattern. The median dispersal rate for the entire period was 8.8 [7.4 - 10.6,95% CI], while the median diffusion coefficient was 19.6 meters2/day [13.6 - 27.9, 95% CI]. The observed spread dynamics and the log-normal distribution of accelerations are consistent with longdistance dispersal events. The complexities of real landscapes cannot be summarized in any model, but this study shows how an alternative top-down approach based on graph theory can facilitate the ecological analysis of the spread of an invasive species in a new territory.

ecology↗

bioRxiv2022

Can suitability indices predict plant growth in the invaded range? The case of Acacias species

Forestry in many parts of the world depends on exotic species, making this industry a source of invasions in some countries. Among others, plantations of the genus Pinus, Eucalyptus, Acacia, Populus, and Pseudotsuga underpin the forestry industry and are a vital component of many countries economies. Among woody plants, the cosmopolitan genus Acacia includes some of the most commonly planted trees worldwide. In order to prevent, manage and control invasive plant species, one of the most used tools is species distribution models. The output of these models can also be used to obtain information about population characteristics, such as spatial abundance patterns or species performance. Although ecological theory suggests a direct link between fitness and suitability, this link is often absent. The reasons behind the lack of this relationship are multiple. Chile is one of the countries where Acacia species, in particular, A. dealbata and A. melanoxylon, have become invaders. Here, we used climatic and edaphic variables to predict the potentially suitable habitats for A. dealbata and A. melanoxylon in continental Chile and evaluate if the suitability indices obtained from these models are associated with the observed performance of the trees along the country. Our models show that variable importance showed significant similarities between the variables that characterize each species niche. However, despite the high accuracy of our models, we did not observe an association between suitability and tree growth. This disconnection between suitability and performance can result from multiple causes, from structural limitations, like the lack of biotic interactions in the models, to methodological issues, like the usefulness of the performance metric used. Whatever the scenario, our results suggest that plans to control invasive species should be cautious in assuming this relationship in their design and consider other indicators such as species establishment success.

plant biology↗

bioRxiv2022

A bug's tale: revealing the history, biogeography and ecological patterns of 500 years of insect introductions

The arrival of Europeans to the Americas triggered a massive exchange of organisms on a continental scale. This exchange was accelerated by the amazing increase in the movement of people and goods during the 20th century. In Chile, scientific and technical literature contains hundreds of records of exotic insect species in different parts of the territory, from the hyperarid Atacama Desert to the Magallanes Region. Here, we analyze the biological patterns obtained from the database of introductions of exotic insects to Chile from the European arrival to the present. Our task includes a review of old records in museums, libraries, collections, expedition records and catalogs. Almost 600 species of exotic insects have been reported in Chile. Introductions started at the very arrival of Europeans to the central valley of Chile and underwent a huge acceleration in the second half of the 20th century. The order Hemiptera was the most prevalent among introduced insects. Most species are linked to agriculture and forestry. Species are of Palearctic origin in more than 50% of the records. In terms of temporal trends, the rate of introduced species shows an abrupt increase at the beginning of the 1950s. This change may be associated with the strong development in agriculture and forestry in Chile after World War II and the increase in intercontinental air traffic. We believe that the understanding of past patterns of introductions is an important component in the design of current policies to minimize the impact of invasive insects.

ecology↗