VARANASI, June 25 -- The Allee effect led to a decline of house sparrows, a study by a team of researchers from Manipal University, Jaipur, Banaras Hindu University, Varanasi, the Zoological Survey of India, Kolkata, and other leading institutions has revealed. The Allee effect describes a phenomenon where the per capita growth rate of a population decreases as population density decreases. A significant finding of the study is the identification of the Allee effect in sparrows, marking a novel contribution to our understanding of their population dynamics. The Allee effect, which indicates that low population density can negatively affect individual fitness, was revealed through an analysis of genomic data, said prof Gyaneshwar Chaubey, one of the researchers at department of Zoology, the co-author of the study. "This discovery is particularly pertinent given the concerning decline in sparrow populations worldwide, with urban areas like Paris experiencing an 89% reduction and Indian cities such as Mumbai and Bengaluru facing declines exceeding 70%. Major factors contributing to this trend include rapid urbanisation, habitat loss, and environmental changes. The genomic insights related to the Allee effect showed how diminished population sizes can further exacerbate declines by restricting reproductive success and genetic diversity, thereby providing a new perspective for conservation strategies, said Chaubey. The research, supported by the department of forestry, governments of Rajasthan and India, and the Birla Institute of Scientific Research, is a collaborative effort involving equal contributions from Vikas Kumar, Gopesh Sharma, Sankalp Sharma, Samvrutha Prasad, Shailesh Desai, and others. This high-quality genome assembly identified 24152 genes and offers a vital resource for understanding the evolutionary biology, adaptation, and population dynamics of passerines, a diverse group of birds that includes the house sparrow. This study was published today in the Giga Byte, Giga Science journal. Co-led by Prof. Prashanth Suravajhala and Prof. Gyaneshwer Chaubey of BHU, the study utilised sequencing technologies and a robust genomic workflow to produce a 922 MB reference genome. The assembly, comprising 268,193 contig bases, revealed genetic similarities to the genomes of the chicken (Gallus gallus) and zebra finch (Taeniopygia guttata)....