Evaluation of the occurrence of multiple paternity in Squalus acanthias
in the South Atlantic region using nuclear markers
Abstract
Understanding shark reproductive modes is fundamental for their
conservation, as these K-strategist species are highly susceptible to
overexploitation. The spiny dogfish ( Squalus acanthias), a small
shark currently listed as ’vulnerable’ by the IUCN, exhibits a prolonged
gestation period of 22 months and a reproductive output ranging from 1
to 21 pups per litter. This study aimed to investigate the occurrence of
multiple paternity in S. acanthias using Single Nucleotide
Polymorphism (SNP) markers. Samples from six litters, comprising 40
individuals collected in Argentina, were analyzed using a ddRADSeq
library. SNP markers were screened through the STACKS pipeline, and
kinship and paternity analyses were conducted using COANCESTRY and
COLONY softwares. The results revealed between 1,021 and 1,620 SNPs per
litter, with multiple paternity detected in all litters. The number of
sires per litter ranged from 2 to 4. Notably, no correlation was found
between litter size and the occurrence of multiple paternity, suggesting
that this behavior may represent a reproductive strategy aimed at
enhancing genetic diversity. The species’ biological characteristics,
such as size and sex segregation, combined with the presence of females
in shallower waters, increase their susceptibility to capture. Moreover,
overfishing and bycatch in the Atlantic exacerbate the reduction in
sexually mature individuals, thereby threatening reproductive rates.
This study underscores the importance of preserving genetic variability
for species survival and highlights the need for urgent management
policies that incorporate these reproductive strategies, particularly
for species like S. acanthias that display complex life histories
and low population recovery rates.