Estimating species relative abundances from museum records

Population abundance estimates in conservation and biodiversity research

Measuring and tracking biodiversity from local to global scales is challenging due to its multifaceted nature and the range of metrics used to describe spatial and temporal patterns. Abundance can be used to describe how a population changes across space and time, but it can be measured in different ways, with consequences for the interpretation and communication of spatiotemporal patterns. We differentiate between relative and absolute abundance, and discuss the advantages and disadvantages of each for biodiversity monitoring, conservation, and ecological research. We highlight when absolute abundance can be advantageous and should be prioritized in biodiversity monitoring and research, and conclude by providing avenues for future research directions to better assess the necessity of absolute abundance in biodiversity monitoring.

Unveiling global species abundance distributions

Whether most species are rare or have some intermediate abundance is a long-standing question in ecology. Here, we use more than one billion observations from the Global Biodiversity Information Facility to assess global species abundance distributions (gSADs) of 39 taxonomic classes of eukaryotic organisms from 1900 to 2019. We show that, as sampling effort increases through time, the shape of the gSAD is unveiled; that is, the shape of the sampled gSAD changes, revealing the underlying gSAD. The fraction of species unveiled for each class decreases with the total number of species in that class and increases with the number of individuals sampled, with some groups, such as birds, being fully unveiled. The best statistical fit for almost all classes was the Poisson log-normal distribution. This strong evidence for a universal pattern of gSADs across classes suggests that there may be general ecological or evolutionary mechanisms governing the commonness and rarity of life on Earth.

Six decades of museum collections reveal disruption of native ant assemblages by introduced species

There is a looming environmental crisis characterized by widespread declines in global biodiversity,^1,2,3,4,5,6 coupled with the establishment of introduced species at accelerated rates.^{7,8,9,10,11,12,13,14} We quantified how multi-species invasions affect litter ant communities in natural ecosystems by leveraging museum records and contemporary collections to assemble a large (18,990 occurrences, 6,483 sampled local communities, and 177 species) 54-year (1965-2019) dataset for the entire state of Florida, USA. Nine of ten species that decreased most strongly in relative abundance ("losers") were native, while nine of the top ten "winners" were introduced species. These changes led to shifts in the composition of rare and common species: in 1965, only two of the ten most common ants were introduced, whereas by 2019, six of ten were introduced species. Native losers included seed dispersers and specialist predators, suggesting a potential loss of ecosystem function through time, despite no obvious loss of phylogenetic diversity. We also examined the role of species-level traits as predictors of invasion success. Introduced species were more likely to be polygynous than native species. The tendency to form supercolonies, where workers from separate nests integrate, also differed between native and introduced species and was correlated with the degree to which species increased in their rank abundances over 50 years. In Florida, introduced ants now account for 30% of occurrence records, and up to 70% in southern Florida. If current trends continue, introduced species will account for over half of occurrence records in all Florida's litter ant communities within the next 50 years.

How to use natural history collections to resurrect information on historical parasite abundances

Many of the most contentious questions that concern the ecology of helminths could be resolved with data on helminth abundance over the past few decades or centuries, but unfortunately these data are rare. A new sub-discipline - the historical ecology of parasitism - is resurrecting long-term data on the abundance of parasites, an advancement facilitated by the use of biological natural history collections. Because the world's museums hold billions of suitable specimens collected over more than a century, these potential parasitological datasets are broad in scope and finely resolved in taxonomic, temporal and spatial dimensions. Here, we set out best practices for the extraction of parasitological information from natural history collections, including how to conceive of a project, how to select specimens, how to engage curators and receive permission for proposed projects, standard operating protocols for dissections and how to manage data. Our hope is that other helminthologists will use this paper as a reference to expand their own research programmes along the dimension of time.

The ornithological collection of the Zoological Museum of Babeș-Bolyai University, Cluj-Napoca, Romania - Part 1: the catalogue of bird skin specimens

This paper reviews the bird skin collection housed in the Zoological Museum of Babeș-Bolyai University, Cluj-Napoca, Romania. The collection includes 925 specimens, belonging to 193 species from 53 families and 20 orders, collected between 1859 and 2021. Due to its historical background and the presence of rare species, it is considered to be one of most important ornithological collections in Eastern Europe. Such a collection can serve as a basis for valuable ornithological studies. Furthermore, a map representation with new distribution data for bird species is provided, which represents a source of information for the status of the avifauna of the Carpathian basin in the 19^th and 20^th centuries.