Demography, genetic diversity and expansion load in the colonizing species Leontodon longirostris (Asteraceae) throughout its native range

Unravelling the evolutionary processes underlying range expansions is fundamental to understand the distribution of organisms, as well as to predict their future responses to environmental change. Predictions for range expansions include a loss of genetic diversity and an accumulation of deleterious...

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Published in:Molecular ecology Vol. 30; no. 5; pp. 1190 - 1205
Main Authors: Pedro, Manuel, Riba, Miquel, González‐Martínez, Santiago C., Seoane, Pedro, Bautista, Rocío, Claros, Manuel Gonzalo, Mayol, Maria
Format: Journal Article
Language:English
Published: England Blackwell Publishing Ltd 01-03-2021
Wiley
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Summary:Unravelling the evolutionary processes underlying range expansions is fundamental to understand the distribution of organisms, as well as to predict their future responses to environmental change. Predictions for range expansions include a loss of genetic diversity and an accumulation of deleterious alleles along the expansion axis, which can decrease fitness at the range‐front (expansion load). In plants, empirical studies supporting expansion load are scarce, and its effects remain to be tested outside a few model species. Leontodon longirostris is a colonizing Asteraceae with a widespread distribution in the Western Mediterranean, providing a particularly interesting system to gain insight into the factors that can enhance or mitigate expansion load. In this study, we produced a first genome draft for the species, covering 418 Mbp (~53% of the genome). Although incomplete, this draft was suitable to design a targeted sequencing of ~1.5 Mbp in 238 L. longirostris plants from 21 populations distributed along putative colonization routes in the Iberian Peninsula. Inferred demographic history supports a range expansion from southern Iberia around 40,000 years ago, reaching northern Iberia around 25,000 years ago. The expansion was accompanied by a loss of genetic diversity and a significant increase in the proportion of putatively deleterious mutations. However, levels of expansion load in L. longirostris were smaller than those found in other plant species, which can be explained, at least partially, by its high dispersal ability, the self‐incompatible mating system, and the fact that the expansion occurred along a strong environmental cline.
Bibliography:Funding information
This work was supported by the POREXPAN project (CGL2014‐53120‐P) from the Spanish Ministry of Economy and Competitiveness (MCIU) and the Catalan Government “Consolidated Research Group 2017SGR1006.” Funding from grants RTA2017‐00054‐C03‐03, TIN2017‐88728‐C2‐1‐R and AGL2017‐83370‐C3‐3‐R are also acknowledged. M.d.P. was supported by a PhD grant (BES‐2015‐074251) from the Spanish Ministry of Economy and Competitiveness.
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ISSN:0962-1083
1365-294X
DOI:10.1111/mec.15802