Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies
Hemstrom WB, Freedman MG, Zalucki MP and others. Molecular ecology, July 2022.
Read the paper Free to read · doi:10.1111/mec.16592
What this paper is about
Monarchs have spread across the Pacific and established island populations that no longer migrate. The authors sequenced 275 butterflies from North America, twelve Pacific islands and elsewhere.
The interest is in what happens to a genome when migration is abandoned, and in dating the steps of the expansion.
Summarised here from the abstract below. Not the authors’ words.
Abstract
Range expansions-whether permanent or transient-strongly influence the distribution of genetic variation in space. Monarch butterflies are best known for long-distance seasonal migration within North America but are also established as nonmigratory populations around the world, including on Pacific Islands. Previous research has highlighted stepwise expansion across the Pacific, though questions remain about expansion timing and the population genetic consequences of migration loss. Here, we present reduced-representation sequencing data for 275 monarchs from North America (n = 85), 12 Pacific Islands (n = 136) and three locations in Australia (n = 54), with the goal of understanding (i) how the monarch's Pacific expansion has shaped patterns of population genetic variation and (ii) how loss of migration has influenced spatial patterns of differentiation. We find support for previously described stepwise dispersal across the Pacific and document an additional expansion from Hawaii into the Mariana Islands. Nonmigratory monarchs within the Mariana Islands show strong patterns of differentiation, despite their proximity; by contrast, migratory North American samples form a single genetically panmictic population across the continent. Estimates of Pacific establishment timing are highly uncertain (~100-1,000,000 years ago) but overlap with historical records that indicate a recent expansion. Our data support (i) a recent expansion across the Pacific whose timing overlaps with available historical records of establishment and (ii) a strong role for seasonal migration in determining patterns of spatial genetic variation. Our results are noteworthy because they demonstrate how the evolution of partial migration can drive population differentiation over contemporary timescales.
Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.
Key terms
Find the paper
Cite this page
This page is licensed CC BY 4.0. Quote it, adapt it and reuse it, including commercially, as long as you credit Milkweed USA and link back.
Milkweed USA. (2026). Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies (listing). Retrieved DATE, from https://milkweedusa.com/research/population-genetics-of-a-recent-range-expansion-and-subsequent-2022/
"Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/population-genetics-of-a-recent-range-expansion-and-subsequent-2022/. Accessed DATE.
Milkweed USA. "Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies (listing)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/research/population-genetics-of-a-recent-range-expansion-and-subsequent-2022/.
@misc{milkweedusa_researchpopulationgeneticsof,
title = {Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies (listing)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/research/population-genetics-of-a-recent-range-expansion-and-subsequent-2022/},
note = {Accessed DATE}
}