Estimation of breeding population size using DNA‐based pedigree reconstruction in brown bears

Abstract

Robust estimates of demographic parameters are critical for effective wildlife conservation and management but are difficult to obtain for elusive species. We estimated the breeding and adult population sizes, as well as the minimum population size, in a high‐density brown bear population on the Shiretoko Peninsula, in Hokkaido, Japan, using DNA‐based pedigree reconstruction. A total of 1288 individuals, collected in and around the Shiretoko Peninsula between 1998 and 2020, were genotyped at 21 microsatellite loci. Among them, 499 individuals were identified by intensive genetic sampling conducted in two consecutive years (2019 and 2020) mainly by noninvasive methods (e.g., hair and fecal DNA). Among them, both parents were assigned for 330 bears, and either maternity or paternity was assigned to 47 and 76 individuals, respectively. The subsequent pedigree reconstruction indicated a range of breeding and adult (≥4 years old) population sizes: 128–173 for female breeders and 66–91 male breeders, and 155–200 for female adults and 84–109 male adults. The minimum population size was estimated to be 449 (252 females and 197 males) in 2019. Long‐term continuous genetic sampling prior to a short‐term intensive survey would enable parentage to be identified in a population with a high probability, thus enabling reliable estimates of breeding population size for elusive species.

Advances in wildlife abundance estimation using pedigree reconstruction

“…Additionally, sampling dispersing individuals aids in the inference of parents in populations inhabiting inaccessible areas, as noted by Shimozuru et al. 's ( 2022 ) study of brown bears. Alternatively, low‐density populations with restricted ranges would be suitable for pedigree reconstruction.…”

A novel method for fine-scale retrospective isotope analysis in mammals using eye lenses

“…For instance, direct observation is difficult for many mammals because they are often human-averse, highly mobile, and inhabit environments that are not easily visible (Cagnacci et al, 2010; Newsome et al, 2009). Repeatedly capturing individuals or collecting animal tissues for DNA analysis over a wide spatial area and extended periods involves high human and financial costs (Shimozuru et al, 2022). Bio-logging techniques potentially overcome these challenges, but are not easily applicable for a large number of individuals and/or a wide array of mammalian species, given the body-size limitations for equipped mammals, high financial cost, and substantial efforts required for non-lethal capturing and recapturing of individuals (Cagnacci et al, 2010).…”

Universal baleen whale microsatellite panel for individual identification and power to detect parentage

“…siblings or its own offspring) may incorrectly be assigned as a parent if the number of STR loci is insufficient given the sample size. Most parentage assessments in wild populations studies were aimed at terrestrial mammals, such as brown bears (Ursus arctos, Shimozuru et al 2022) or animals in captivity, such as the cultured giant groupers (Epinephelus lanceolatus, Weng et al 2021). In Mysticeti (baleen whales), a few parentage studies have been performed in humpback whales (Megaptera novaeangliae, Cerchio et al 2005;Cypriano-Souza et al 2010;Clapham and Palsbøll 1997;Nielsen et al 2001), minke whales (Balaenoptera acutorostrata, Skaug, Bérubé, and Palsbøll 2010), North Atlantic right whales (Eubalaena glacialis, Frasier et al 2007) and southern right whales (E. australis, Carroll et al 2012).…”