The new highest number of B chromosomes (Bs) in Leisler's bat Nyctalusleisleri (Kuhl, 1817)

Area of Science:

• * Genetics and Evolutionary Biology
• * Mammalian Cytogenetics

Background:

• * B chromosomes (Bs) are extra-chromosomal elements found in various organisms, known for their numerical instability.
• * Leisler's bat (Nyctalus leisleri) is one of only four known Chiroptera species with detected Bs, making it a rare subject for B chromosome research.

Purpose of the Study:

• * To investigate the presence and characteristics of B chromosomes in Leisler's bat populations in Serbia.
• * To document the interindividual variability in B chromosome number within this species.

Main Methods:

• * Cytogenetic analysis of four male Leisler's bats from two distinct localities in Serbia.
• * Microscopic examination to identify and quantify B chromosomes, noting their heterochromatic nature.

Main Results:

• * All analyzed Leisler's bats possessed B chromosomes, with numbers ranging from two to five per individual.
• * The detected B chromosomes were characterized as heterochromatic micro B chromosomes.
• * This study reports the highest number of B chromosomes observed to date in the species Nyctalus leisleri.

Conclusions:

• * B chromosomes are present and variable in Leisler's bats in Serbia, with a notable high count.
• * The findings contribute to understanding the prevalence and diversity of B chromosomes in Chiroptera, contrasting with their higher frequency in Rodentia.