Neotropics as a Cradle for Adaptive Radiations.

Neotropical ecosystems are renowned for numerous examples of adaptive radiation in both plants and animals resulting in high levels of biodiversity and endemism. However, we still lack a comprehensive review of the abiotic and biotic factors that contribute to these adaptive radiations. To fill this gap, we delve into the geological history of the region, including the role of tectonic events such as the Andean uplift, the formation of the Isthmus of Panama, and the emergence of the Guiana and Brazilian Shields. We also explore the role of ecological opportunities created by the emergence of new habitats, as well as the role of key innovations, such as novel feeding strategies or reproductive mechanisms. We discuss different examples of adaptive radiation, including classic ones like Darwin's finches and Anolis lizards, and more recent ones like bromeliads and lupines. Finally, we propose new examples of adaptive radiations mediated by ecological interactions in their geological context. By doing so, we provide insights into the complex interplay of factors that contributed to the remarkable diversity of life in the Neotropics and highlight the importance of this region in understanding the origins of biodiversity.

Evolutionary drivers of the hump-shaped latitudinal gradient of benthic polychaete species richness along the Southeastern Pacific coast.

Latitudinal diversity gradients (LDG) and their explanatory factors are among the most challenging topics in macroecology and biogeography. Despite of its apparent generality, a growing body of evidence shows that 'anomalous' LDG (i.e., inverse or hump-shaped trends) are common among marine organisms along the Southeastern Pacific (SEP) coast. Here, we evaluate the shape of the LDG of marine benthic polychaetes and its underlying causes using a dataset of 643 species inhabiting the continental shelf (<200 m depth), using latitudinal bands with a spatial resolution of 0.5°, along the SEP (3-56° S). The explanatory value of six oceanographic (Sea Surface Temperature (SST), SST range, salinity, salinity range, primary productivity and shelf area), and one macroecological proxy (median latitudinal range of species) were assessed using a random forest model. The taxonomic structure was used to estimate the degree of niche conservatism of predictor variables and to estimate latitudinal trends in phylogenetic diversity, based on three indices (phylogenetic richness (PDSES), mean pairwise distance (MPDSES), and variation of pairwise distances (VPD)). The LDG exhibits a hump-shaped trend, with a maximum peak of species richness at ca. 42° S, declining towards northern and southern areas of SEP. The latitudinal pattern was also evident in local samples controlled by sampling effort. The random forest model had a high accuracy (pseudo-r2 = 0.95) and showed that the LDG could be explained by four variables (median latitudinal range, SST, salinity, and SST range), yet the functional relationship between species richness and these predictors was variable. A significant degree of phylogenetic conservatism was detected for the median latitudinal range and SST. PDSES increased toward the southern region, whereas VPD showed the opposite trend, both statistically significant. MPDSES has the same trend as PDSES, but it is not significant. Our results reinforce the idea that the south Chile fjord area, particularly the Chiloé region, was likely the evolutionary source of new species of marine polychaetes along SEP, creating a hotspot of diversity. Therefore, in the same way as the canonical LDG shows a decline in diversity while moving away from the tropics; on this case the decline occurs while moving away from Chiloé Island. These results, coupled with a strong phylogenetic signal of the main predictor variables suggest that processes operating mainly at evolutionary timescales govern the LDG.

Annotated list of island lady beetles from Chile (Coleoptera: Coccinellidae).

We provide a list of coccinellids (Coleoptera: Coccinellidae) species from the island territories of Chile. We report a total of 68 records, coming from ten islands, including 42 species corresponding to more than 35% of the species of the country. This paper presents the first Coccinellidae records for the Islas Desventuradas, Isla Mocha and Isla Tenglo. Contrary to what has been reported on other islands and other taxonomic groups in Chilean islands, the level of coccinellid endemism is low (8%), with only one and two species endemic to the Juan Fernández archipelago and Isla de Chiloé, respectively, and probably a fourth species from the Isla Grande de Tierra del Fuego. The presence of species with worldwide distribution and of agricultural relevance is strong in the Chilean oceanic islands, particularly in Rapa Nui. The fauna of the continental islands is very similar to the one in the nearby continental areas and composed of native species. Further surveys of Coccinellidae and other insects are required for the islands of Chile, especially for several of them in which there are no records.

Aerial plankton from the Eastern Tropical Pacific / Plancton aéreo del Pacífico Tropical Oriental

Introduction: Small terrestrial invertebrates disperse in a passive manner through wind currents, forming what is known as aerial plankton, which has not been surveyed yet for the Eastern Tropical Pacific. Documenting the aerial plankton of Isla del Coco will allow to better understand the colonization process of this highly diverse island. Objective: Characterize the aerial plankton present on the transect Puntarenas - Isla del Coco. Methods: Specimens were collected using entomological nets on 2 roundtrip voyages during the months of July and August of 2017 and 2018, respectively. Results: A total of 10 morpho-species were collected corresponding to the orders: Diptera (Ceratopogonidae, Milichiidae, and Nematocera of a non-identified family), Hymenoptera (Chalcidoidea: Agaonidae), Hemiptera (Scutelleridae and Coreidae) and Lepidoptera (Sphingidae). Diptera and Hymenoptera were collected on the nets; while, Hemiptera and Lepidoptera were found on the deck of the boat. No spiders were collected. The Diptera and Hymenoptera families, as well as the family Coreidae (Hemiptera), have been previously recorded on this type of surveys across the tropical Pacific. Conclusions: Two of the taxa collected by nets, Ceratopogonidae (Diptera) and Chalcidoidea (Hymenoptera), have representatives on Isla del Coco, which could provide direct support for wind dispersal as a colonization mechanism for these groups. We also detected other insects (i.e. Lepidoptera and Scutelleridae-Hemiptera) which most likely reached the boat by their own means providing evidence of their dispersal abilities. This research provides data to further expand on questions about the mechanisms of island colonization.

Introducción: Los invertebrados terrestres pequeños se dispersan de manera pasiva en corrientes de viento, constituyendo lo que se conoce como plancton aéreo, el cual previamente no había sido evaluado en Pacífico Tropical Oriental (PTO). Documentar el plancton aéreo de la Isla del Coco permitiría entender mejor el proceso de colonización de esta diversa isla. Objetivos: Caracterizar el plancton aéreo del transecto Puntarenas - Isla del Coco. Métodos: Los especímenes fueron recolectados utilizando redes entomológicas en 2 viajes de ida y vuelta durante los meses de Julio y Agosto de 2017 y 2018, respectivamente. Resultados: Un total de 10 morfo-especies fueron recolectadas, correspondientes a los órdenes Diptera (Ceratopogonidae, Milichiidae, y Nematocera de familia no identificada), Hymenoptera (Chalcidoidea: Agaonidae), Hemiptera (Scutelleridae y Coreidae) y Lepidoptera (Sphingidae). Diptera e Hymenoptera fueron recolectados en las redes; mientras que Hemiptera y Lepidoptera fueron encontrados en la cubierta del barco. No se recolectaron arañas. Las familias de Diptera e Hymenoptera, al igual que la familia Coreidae (Hemiptera) han sido previamente registradas en este tipo de muestreos en el PTO. Conclusiones: Dos de los taxones recolectados en las redes, Ceratopogonidae (Diptera) y Chalcidoidea (Hymenoptera), están representados en la Isla del Coco, lo cual provee apoyo directo a la dispersión por viento como un mecanismo de colonización para estos grupos. Igualmente, encontramos otros insectos (Lepidoptera y Hemiptera: Scutelleridae), los cuales probablemente llegaron al barco por sus propios medios, evidenciando sus habilidades de dispersión. Esta investigación entrega datos para responder nuevas preguntas sobre los mecanismos de colonización de islas.

First endemic arachnid from Isla Sala y Gómez (Motu Motiro Hiva), Chile: a new species of tube-dwelling spider (Araneae: Segestriidae)

The Isla Sala y Gómez or Motu Motiro Hiva is located 415 km northeast of Rapa Nui (Easter Island) and 3420 km from the coast of northern Chile. It is a small oceanic island (2.5 km2) dominated by volcanic rock with very little vegetal cover. Here, we describe the first endemic arachnid for the island, Ariadna motumotirohiva sp. nov. Females are similar to those of Ariadna perkinsi Simon, 1900 from Hawaiʻi and Ariadna lebronneci Berland, 1933 from the Marquesas in the dorsal dark abdominal pattern, but they differentiate from the latter in the anterior receptaculum, promarginal cheliceral teeth and leg IV macrosetae. A recent survey of the arachnid fauna of Rapa Nui, which included Motu Nui and the rocky shores, did not record the presence of the family Segestriidae, neither has it been found during previous surveys. However, it is not possible to discard the possibility of a local extinction on Rapa Nui and survival on Sala y Gómez. This study suggests other endemic terrestrial arthropods could be present on this very small and remote island.