Development and validation of a novel forensic STR multiplex assay for blue (Anthropoides paradiseus), wattled (Bugeranus carunculatus), and grey-crowned crane (Balearica regulorum)

Abstract

The blue crane (Anthropoides paradiseus), wattled crane (Bugeranus carunculatus), and grey-crowned crane (Balearica regulorum) are species of concern as their populations are declining and they face several threats including habitat loss, disturbance and illegal trade. In South Africa, these species are bred in captivity for trade purposes which is permitted and regulated globally under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Legal sustainable trade through captive breeding of endangered wildlife species such as cranes has been promoted to counteract the illegal trade of individuals from the wild. Captive breeding independent of wild populations may reduce the harvest pressures on wild bird populations which in turn benefit the recovery of exploited species. This approach is considered to be controversial by some individuals. Although captive breeding of endangered species, for both population sustainability and commercial purposes, is promoted to aid in conserving species, concerns have been raised with regards to breeding facilities being used for laundering of animals. To monitor the legal trade of cranes in South Africa a short tandem repeat (STR) assay following recommendations of the International Society for Forensic Genetics (ISFG) was developed and validated. An STR assay comprising of four multiplexes that include 16 STR markers and two gender determination markers was proven to be highly informative with average polymorphic information content (PIC) values of 0.806, 0.646 and 0.725 for A. paradiseus, B. regulorum and B. carunculatus respectively. In addition, the assay showed sufficient discriminatory power for parentage assignment of closely related individuals in all three species (A. paradiseus: PI = 1.7×10⁻²⁴, PIsibs = 4.7×10⁻⁰⁸, and B. carunculatus: PI = 1.4×10⁻¹⁹, PIsibs = 2.9×10⁻⁰⁷ and B. regulorum: PI = 1.7×10⁻¹², PIsibs = 5.0×10⁻⁰⁵). Analysis of 251 samples suggested that the validated multiplex assay ensures reliability, reproducibility, and repeatability for applications in forensic case work where illegal trade of offspring is suspected through verifying parentage of captive birds in breeding facilities.