Alexandre Reis Percequillo

Supplemental material for 'Phylogenetics and species boundaries in Akodon (Rodentia, Cricetidae) : implications for taxonomic revision (American Museum novitates no. 4053)' - https://hdl.handle.net/2246/7545

Akodon is one of the most diverse genera of Neotropical rodents, currently comprising 42 species with diploid numbers ranging from 2n = 10 to 44. Previous phylogenetic studies have divided the genus into five species groups, with additional species treated as incertae sedis or representing unique lineages. However, the monophyly of some species groups has been questioned, relationships among several clades remain unresolved, new species continue to be described, and the taxonomic status of various nominal taxa awaits evaluation. To investigate phylogenetic relationships within Akodon, we analyzed cytochrome b gene sequences from 341 specimens representing 40 species, and we applied four single-locus species delimitation methods to assess species boundaries. Our analyses recovered two major clades: Clade A, comprising the topology ((A. budini + A. siberiae) + (Aerosus Group + (A. albiventer + Varius Group))), was recovered with low support. By contrast, Clade B, comprising the topology ((Dolores Group) + (A. azarae + (Boliviensis Group + Cursor Group))), was strongly supported. Our study places A. kadiweu and A. philipmyersi as part of the Boliviensis Group, and A. lindberghi and A. mystax within the Cursor Group, although the latter hypothesis requires further support. Species delimitation methods showed varying results, identifying between 54 and 81 Molecular Operational Taxonomic Units (putative species) within Akodon. Considering molecular species boundaries, genetic divergence, clade monophyly, karyotypic data, and geographic distribution, we propose that Akodon might include as many as 53 valid species. These findings highlight the importance of integrating multiple methods for species delimitation, particularly for genera that exhibits broad geographic distribution and rapid, complex diversification at morphological, karyologic and molecular levels.

Rodents are the most diverse group of mammals, yet the natural history of many species remains poorly understood due to their elusive behavior. In this study, we examined the population structure, home range, space use, and food selection of two sympatric sigmodontine rodents, Euryoryzomys russatus and Sooretamys angouya, in the Morro Grande Forest Reserve, Brazil. E. russatus was more abundant than S. angouya, with its capture rates influenced by temperature. In contrast, the population variation of S. angouya showed no clear relationship with the assessed biotic (fruits and arthropods) or abiotic factors (temperature and precipitation), suggesting different primary regulatory factors for its population or a more generalist ecological strategy. The two species exhibited vertical stratification in space use: S. angouya displayed scansorial and arboreal locomotion, while E. russatus remained strictly terrestrial. Home range size, space use, and mobility were primarily influenced by resource availability, reproductive cycles, and individual body size. Our findings provide insights into the life strategies of these species, specifically regarding their vertical stratification in space use and their distinct responses to environmental resource fluctuations, enhancing our understanding of how sympatric rodents navigate shared spatial and temporal environments.

Natural history collections serve as crucial infrastructure for both basic and applied scientific research, providing temporal and spatial specimen data needed to understand biodiversity, environmental change, and emerging pathogens. This study surveyed mammal collections across South America to assess the scope and quality of this infrastructure. A detailed questionnaire was distributed to curators and collection managers from May 2021 to February 2022, gathering information on institutional characteristics, collection size, taxonomic and geographical scope, preservation methods, genetic resource availability, percentage digitization, financial support, and challenges such as funding limitations. Our survey identified 141 collections; more than twice the number reported by the American Society of Mammalogists in 2018. South American collections house ∼746 000 catalogued specimens, including 452 primary type specimens, representing only a modest proportion of the vast mammalian diversity of South America. Collections are geographically concentrated in Argentina, Brazil, Colombia, and Peru, with a significant gap in the Guianas region and a decline in responses from Venezuela. The survey highlights four major challenges facing South American collections: staffing shortages, minimal cryogenic infrastructure, incomplete digitization, and sustainability issues. This initiative aims to raise awareness of collections in South America, plan for strategic growth, and strengthen research capacity to address pressing global issues, such as climate change, zoonotic disease transmission, and long-term conservation strategies.

Systematics and taxonomy serve as fundamental pillars of biological research. Natural history collections (NHCs) play a crucial role in preserving type specimens and biodiversity data that underpin research in ecology, climate science, and conservation. Historically rooted in colonial-era exploration, major NHCs are concentrated in the Global North, creating persistent dependencies for Neotropical biodiversity studies. However, recent trends show increased species descriptions using Global South NHCs. We analyse 18th–21st century taxonomic patterns in Neotropical small mammals to assess whether Global South institutions and researchers are gaining prominence in describing their native biodiversity, examining holotype deposition trends and authorship affiliations to evaluate shifting practices in mammalogy. Our findings reveal that 78.6% of historical descriptions were led by Global North researchers, with holotypes predominantly deposited in northern institutions, with an increase in use of local NHCs in recent decades. We identified three distinct peaks in taxonomic activity: 1811–1850, 1891–1930, and 1991–present, coinciding with regional and global political and economic changes. These trends highlight the complex interplay between scientific progress and sociopolitical contexts, while underscoring the need for continued support of local research capacity to achieve equitable biodiversity documentation.