Biology subjects

Richard-Hansen, C.

Publications and source records attributed to Richard-Hansen, C..

2 recordsLinked to original sources

bioRxiv2025

Rainwash eDNA to monitor tropical rainforest biodiversity

Tropical rainforest canopies shelter an under-explored reservoir of biodiversity. In recent years, the amplification and sequencing of taxonomically informative DNA fragments from environmental samples (i.e. eDNA) has revolutionized biomonitoring. Here, we explore the potential of DNA contained in canopy throughfall water to sample the biological diversity of rainforest canopies. By sampling rainwash eDNA in two 1ha-plots, one mature Amazonian forest and a nearby tree plantation, we were able to detect 170 plant taxa, 72 vertebrate taxa including mammals, birds, and amphibians, and 313 insect taxa including e.g. mosquitoes, ants, beetles. The taxonomic composition retrieved in these two plots reflected their different disturbance status, and the plantation exhibited a much lower diversity. We also found that rainwash eDNA persists over ten days in passive eDNA collectors while providing a local picture of the diversity. This suggests that this method can be scaled up for a cost-effective environmental management of rainforest, and more generally of all forests canopies. TeaserRainwash DNA reveals the identity of plants, animals, and insects diversity, offering a practical tool for monitoring canopy biodiversity.

ecology↗

bioRxiv2020

Mysterious disappearances of a large mammal in Neotropical forests

The drivers of periodic population cycling by some animal species in northern systems remain unresolved1. Mysterious disappearances of populations of the Neotropical, herdforming white-lipped peccary (Tayassu pecari, henceforth "WLP") have been anecdotally documented and explained as local events resulting from migratory movements or overhunting2,3,4, or as disease outbreaks5,6, and have not been considered in the context of large-scale species-specific population dynamics. Here we present evidence that WLP disappearances represent troughs in population cycles that occur with regular periodicity and are synchronized at regional and perhaps continent-wide spatial scales. Analysis of 43 disappearance events and 88 years of commercial and subsistence harvesting data reveals boom - bust population cycles lasting from 20 to 30 years, in which a rapid population crash occurring over 1 to 5 years is followed by a period of absence of 7 to12 years and then a slow growth phase. Overhunting alone cannot explain the crashes, but as in northern systems dispersal during the growth phase appears to play a key role. This is the first documentation of population cycling in a tropical vertebrate.

ecology↗