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, 63 (3), 341-348

Howl Variation Across Himalayan, North African, Indian, and Holarctic Wolf Clades: Tracing Divergence in the World's Oldest Wolf Lineages Using Acoustics


Howl Variation Across Himalayan, North African, Indian, and Holarctic Wolf Clades: Tracing Divergence in the World's Oldest Wolf Lineages Using Acoustics

Lauren Hennelly et al. Curr Zool.


Vocal divergence within species often corresponds to morphological, environmental, and genetic differences between populations. Wolf howls are long-range signals that encode individual, group, and subspecies differences, yet the factors that may drive this variation are poorly understood. Furthermore, the taxonomic division within the Canis genus remains contended and additional data are required to clarify the position of the Himalayan, North African, and Indian wolves within Canis lupus. We recorded 451 howls from the 3 most basal wolf lineages-Himalayan C. lupus chanco-Himalayan haplotype, North African C. lupus lupaster, and Indian C. lupus pallipes wolves-and present a howl acoustic description within each clade. With an additional 619 howls from 7 Holarctic subspecies, we used a random forest classifier and principal component analysis on 9 acoustic parameters to assess whether Himalayan, North African, and Indian wolf howls exhibit acoustic differences compared to each other and Holarctic wolf howls. Generally, both the North African and Indian wolf howls exhibited high mean fundamental frequency (F0) and short duration compared to the Holarctic clade. In contrast, the Himalayan wolf howls typically had lower mean F0, unmodulated frequencies, and short howls compared to Holarctic wolf howls. The Himalayan and North African wolves had the most acoustically distinct howls and differed significantly from each other and to the Holarctic wolves. Along with the influence of body size and environmental differences, these results suggest that genetic divergence and/or geographic distance may play an important role in understanding howl variation across subspecies.

Keywords: Canis lupus; acoustic variation; geographic variation; mammal communication..


Figure 1
Figure 1
Phylogenetic tree displaying the major relationships within C. lupus clade based on 726 bp of the Cyt b gene from Rueness et al. (2011).
Figure 2
Figure 2
PCA plot incorporating 1,070 howls across the Holarctic, Himalayan, Indian, and North African lineages of C. lupus. The Holarctic lineage represents Iberian, Italian, Israeli, European, Mexican, Mackenzie Valley, and Arctic wolf subspecies. The basal wolf lineages form distinct separate clusters with partial overlap within the Holartic clade.
Figure 3
Figure 3
Classical MDS plot from the random forest algorithm using 9 acoustic parameters across the 10 wolf subspecies. Himalayan and Iberian wolves form distinct highly variable clusters, whereas North African and Indian wolves form tight clusters in the upper right section of the axis.

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