With large wildfires becoming more frequent^1,2, we must rapidly learn how megafires impact biodiversity to prioritize mitigation and improve policy. A key challenge is to discover how interactions among fire-regime components, drought and land tenure shape wildfire impacts. The globally unprecedented^3,4 2019–2020 Australian megafires burnt more than 10 million hectares⁵, prompting major investment in biodiversity monitoring. Collated data include responses of more than 2,000 taxa, providing an unparalleled opportunity to quantify how megafires affect biodiversity. We reveal that the largest effects on plants and animals were in areas with frequent or recent past fires and within extensively burnt areas. Areas burnt at high severity, outside protected areas or under extreme drought also had larger effects. The effects included declines and increases after fire, with the largest responses in rainforests and by mammals. Our results implicate species interactions, dispersal and extent of in situ survival as mechanisms underlying fire responses. Building wildfire resilience into these ecosystems depends on reducing fire recurrence, including with rapid wildfire suppression in areas frequently burnt. Defending wet ecosystems, expanding protected areas and considering localized drought could also contribute. While these countermeasures can help mitigate the impacts of more frequent megafires, reversing anthropogenic climate change remains the urgent broad-scale solution.

An analysis of vicariant speciation ofGeotrupesandPhanaeus(Coleoptera, Geotrupidae, Scarabaeidae) from the mountains of Oaxaca, Mexico is undertaken. The new species of dung beetle (Coleoptera: Scarabaeidae) from Oaxaca, Mexico,Phanaeusdionysiussp. n.is described. Photos of the habitus and a distribution map are provided.PhanaeusmalyiArnaud is revalidated. An updated key for thePhanaeusendymionspecies group and new localities are also presented. An updated key for theGeotrupesof Oaxaca and new locality records are also submitted.

Insect diversity patterns of high mountain ecosystems remain poorly studied in the tropics. Sampling dung beetles of the subfamilies Aphodiinae, Scarabaeinae, and Geotrupinae was carried out at four volcanoes in the Trans-Mexican Volcanic Belt (TMVB) in the Mexican transition zone at 2,700 and 3,400 MASL, and on the windward and leeward sides. Sampling units represented a forest–shrubland–pasture (FSP) mosaic typical of this mountain region. A total of 3,430 individuals of 29 dung beetle species were collected. Diversity, abundance and compositional similarity (CS) displayed a high variability at all scales; elevation, cardinal direction, or FSP mosaics did not show any patterns of higher or lower values of those measures. The four mountains were different regarding dispersion patterns and taxonomic groups, both for species and individuals.Onthophagus chevrolatidominated all four mountains with an overall relative abundance of 63%. CS was not related to distance among mountains, but whenO. chevrolatiwas excluded from the analysis, CS values based on species abundance decreased with increasing distance. Speciation, dispersion, and environmental instability are suggested as the main drivers of high mountain diversity patterns, acting together at different spatial and temporal scales. Three species new to science were collected (>10% of all species sampled). These discoveries may indicate that speciation rate is high among these volcanoes—a hypothesis that is also supported by the elevated number of collected species with a restricted montane distribution. Dispersion is an important factor in driving species composition, although naturally limited between high mountains; horizontal colonization events at different time scales may best explain the observed species composition in the TMVB, complemented by vertical colonization events to a lesser extent. Environmental instability may be the main factor causing the high variability of diversity and abundance patterns found during sampling. Together, we interpret these results as indicating that species richness and composition in the high mountains of the TMVB may be driven by biogeographical history while variability in diversity is determined by ecological factors. We argue that current conservation strategies do not focus sufficiently on protecting high mountain fauna, and that there is a need for developing and applying new conservation concepts that take into account the high spatial and temporal variability of this system.

A new American Onthophagus of the chevrolati species-group is described (Onthophagus bolivari sp. nov.), providing also identification keys to the aztecus complex. Dorsal habitus and genital structures of the new species are illustrated. The relationships and geographical distribution of the aztecus complex are discussed, giving particular attention to the evolutionary history of O. bolivari.

In this study, we revise the taxonomy of the endemic Mexican genus Ceratotrupes Jekel, 1865. It comprises three species, distributed in the Sierra Madre Occidental and Trans-Mexican Volcanic Belt (Ceratotrupes fronticornis (Erichson, 1847) and Ceratotrupes bolivari Halffter & Martínez, 1962), and the Sierra Madre del Sur (Ceratotrupes sturmi (Jekel, 1865)). We confirm C. mniszechi (Jekel, 1865) as a junior subjective synonym of C. sturmi. The examination of the holotype of C. sturmi and specimens recently collected in the Sierra Sur de Oaxaca (Oaxaca) and Omiltemi (Guerrero) allowed us to identify and describe a new species, Ceratotrupes gonzaloi sp. nov. from Omiltemi, Guerrero. We redescribe the morphology of C. sturmi and provide a diagnostic key to the four members of the genus Ceratotrupes. Photographs of the habitus and male genitalia of the four species, a distribution map, and observations on their ecology and biogeography are provided.

Recent collecting and taxonomic studies of dung beetles of the genus Geotrupes Latreille (Coleoptera: Geotrupidae) in the mountains of Oaxaca have evidenced the existence of a vicariant speciation pattern, where one species occupies the northern mountain system and the other one the southern mountain range. A study of this possible vicariant speciation mechanism is presented using a paleobiogeographic mapping analysis of both Geotrupes species distribution during Late Quaternary glaciation events. Based on these paleomaps a possible speciation mechanism (vicariant speciation) is suggested, in which one common ancestor (mother species) lived at the bottom of the Valle de Oaxaca (Oaxaca Valley) during the last local glacial maximum (LLGM, 21-17.5 kyr) and whose possible continuous distribution was broken into two (or more) separated areas on mountaintops as the climate became warmer toward the present. We propose that the fragmentation and isolation of habitats may have promoted genetic differentiation of populations resulting in vicariant speciation, as suggested by a sky-island dynamic process. The example of a possible effect of the Little Ice Age in the mountains of Oaxaca is also discussed. Finally, a projection is made into the XXII century, based on climatic modeling predictions. These last results suggest the possible disappearance of the sky-island dynamic process through the accelerated speed of climatic change.