Orland, C. | bioRxiv Science

bioRxiv2024

Farming with Alternative Pollinators for Increased Biodiversity and Smallholder Incomes in Zimbabwe

1.Pollinator populations have dramatically declined over the past 50 years, with over 40% of invertebrate pollinator species at risk of extinction largely due to intensive agriculture, pesticide use, habitat loss and climate change. Pollinators provide an essential ecosystem service, with about 75% of global crops relying on pollination by animals. It is therefore essential to reconsider conventional farming practices, which are largely responsible for this decline. By cultivating flowering crops "Marketable Habitat Enhancement Plants", (MHEPs), alongside the edges of pesticide-free fields, the Farming with Alternative Pollinators (FAP) approach aims to enhance the presence of wild pollinators. In this study, we compared the performance of smallholder farmer plots using the FAP approach with plots following conventional approaches, for pollinator abundance and diversity, yield and income for 43 plots in Zimbabwe. We found significantly higher pollinator abundance and richness in FAP plots compared to control plots. There was significantly higher income and higher value of yields for all offtake in FAP plots for both crop cycles measured. Plots with higher pollinator abundance showed significantly higher income from all crops and significantly higher value of yields, showing a clear link between pollinator populations, crop production and income.

ecology↗

bioRxiv2024

Limited genomic signatures of population collapse in the critically endangered black abalone (Haliotis cracherodii)

The black abalone, Haliotis cracherodii, is a large, long-lived marine mollusc that inhabits rocky intertidal habitats along the coast of California and Mexico. In 1985, populations were impacted by a bacterial disease known as withering syndrome (WS) that wiped out >90% of individuals, leading to the species designation as critically endangered. Current conservation strategies include restoring diminished populations by translocating healthy individuals. However, population collapse on this scale may have dramatically lowered genetic diversity and strengthened geographic differentiation, making translocation-based recovery contentious. Additionally, the current prevalence of WS is unknown. To address these uncertainties, we sequenced and analyzed the genomes of 133 black abalone individuals from across their present range. We observed no spatial genetic structure among black abalone, with the exception of a single chromosomal inversion that increases in frequency with latitude. Genetic divergence between sites is minimal, and does not scale with either geographic distance or environmental dissimilarity. Genetic diversity appears uniformly high across the range. Despite this, however, demographic inference confirms a severe population bottleneck beginning around the time of WS onset, highlighting the temporal offset that may occur between a population collapse and its potential impact on genetic diversity. Finally, we find the bacterial agent of WS is equally present across the sampled range, but only in 10% of individuals. The lack of genetic structure, uniform diversity, and prevalence of WS bacteria indicates that translocation could be a valid and low-risk means of population restoration for black abalone species recovery.

evolutionary biology↗