Holm, Sille
- Department of Ecology, Swedish University of Agricultural Sciences
Abstract
The evolutionary dynamics of diurnal Aletis moths (Lepidoptera: Geometridae: Sterrhinae) in the Afrotropics have been obscured by their allopatric distributions, significant inter- and intraspecific variation in adult and caterpillar phenotypes, and involvement in complex mimicry systems. Extensive phenotypic disparity, alongside conserved genital morphology and a lack of suitable material for genomic studies, has complicated species delineation. To elucidate species boundaries within Aletis, as well as explore their evolutionary history, divergence times, and patterns of population genetic structure, we collected fresh specimens of both caterpillars and adults across the Aletis distribution in South Africa and Uganda. We then conducted analyses using mitochondrial DNA and genome-wide SNP data from ddRAD sequencing. Our finding supports the hypothesis of five distinct species in the study areas: Aletis variabilis, A. helcita, A. erici, A. libyssa and A. concolor. The mtDNA divergences range from 4.2% to 11.5%, while genomic data indicating diversification began 0.9 million years ago (Mya), and more recent divergence events occurred between 0.35 and 0.27 Mya. In eastern South Africa, we identified distinct northern and southern genetic lineages, potentially shaped by Pleistocene isolation influenced by climate, whereas in Uganda, habitat and/or altitudinal variation appears to play a key role in their isolation. Notable genetic admixture was found within both northern and southern South African regions, along with gene flow from Uganda to northern South Africa, and extensive internal gene flow among southern populations. We conclude that habitat fragmentation, leading to the patchy occurrence of caterpillar host plants, has contributed to increased genetic isolation and allopatric speciation. We also emphasize the critical conservation needs for preserving genetic diversity, which is essential for resilience in the rapidly changing Afrotropical landscape.
Keywords
allopatry; caterpillar; ddRAD-sequencing; gene flow; Lepidoptera; mimicry; molecular phylogeny; radiation; speciation; species delimitation
Published in
Ecology and Evolution
2025, volume: 15, number: 12, article number: e72745
Publisher: WILEY
SLU Authors
UKÄ Subject classification
Evolutionary Biology
Zoology
Biological Systematics
Publication identifier
- DOI: https://doi.org/10.1002/ece3.72745
Permanent link to this page (URI)
https://res.slu.se/id/publ/145600