Range dynamics driven by Quaternary climate oscillations explain the distribution of introgressed mtDNA of Lepus timidus origin in hares from the Iberian Peninsula

Abstract

Aim A striking case of mitochondrial DNA (mtDNA) introgression occurs in the Iberian Peninsula: the mtDNA of Lepus timidus, a species that inhabited this territory during the Last Glacial Maximum (LGM), is almost fixed in the Iberian range of Lepus europaeus, is very frequent in the northern half of Iberia within Lepus granatensis, and is fixed in Lepus castroviejoi. Here, we used a transdisciplinary approach to understand the ecological drivers of the distribution of this introgressed mtDNA in the Iberian hare species. Location Europe, with an emphasis on the Iberian Peninsula. Methods First, we modelled the climatic niche of L. timidus to predict the favourability for the species during the LGM. Second, we gathered data regarding L. timidus mtDNA introgression for 1137 individuals (139 populations) from the Iberian Peninsula. We tested whether the climatic favourability for L. timidus during the LGM reflects the frequency of the introgressed mtDNA in the carrier hare populations. Results The climatic favourability for the LGM is positively related to the presence of individuals with L. timidus mtDNA, and discriminates better than by chance between individuals with and without this lineage. At the population level, the favourability values relate to the observed frequencies of mtDNA introgression and discriminate between populations with and without L. timidus mtDNA. Main conclusions The results suggest that the geographical distribution of L. timidus mtDNA introgression is linked to L. timidus distribution in Iberia during the LGM. Our study helps to improve our understanding of the role of climate in the reticulated evolutionary history of hares, and is a first step towards understanding the ecological impact of mtDNA introgression on Iberian hares.

Range expansion underlies historical introgressive hybridization in the Iberian hare

“…However, the demographic history of L. granatensis , which could account for patterns of introgression, has not yet been inferred. Ecological niche modeling partially supports the northwards range expansion scenario, showing that areas where mtDNA introgression is found are those with highest habitat favorability for L. timidus at the last glacial maximum17. Still, the highest climatic favorability for L. granatensis in the same period is more dispersed across the Iberian Peninsula18.…”

Glacial cycles drive rapid divergence of cryptic field vole species

“…Then, the dataset with the localities selected after TSA was split and each model was parameterized on the training dataset (80%) and its predictive performance was evaluated on the validation dataset (20%). For each model, logistic regression was used to relate the predictors with species distribution range since it has proved to produce consistent results when models are hindcasted to past climatic scenarios (Acevedo et al, ). Their performance was assessed on the validation dataset both in terms of discrimination (AUC) and reliability (Hosmer and Lemeshow test, and calibration plots), the latter being more informative of their predictive capacity (see Jiménez‐Valverde, Acevedo, Barbosa, Lobo, & Real, ).…”

Alpine glacial relict species losing out to climate change: The case of the fragmented mountain hare population (Lepus timidus) in the Alps

“…Sum of daily solar radiation (h) between June and August Indicator for heat stress (Acevedo et al, 2015;Beever, Ray, Mote, & Wilkening, 2010;Wilkening et al, 2011;Yandow et al, 2015;Yang, 1990) Temperature during the reproductive season Average daily temperatures (°C) between April and August Indicator for heat stress or exposure of juveniles to cold temperatures (Jansson & Pehrson, 2007;Rehnus, 2013)…”

“…Total # of days with average temperature ≤5°C between April and August More cold days are an indicator of increased chances of fertility due to decreased parasite loads Summer warmth Total # of days with average temperature ≥10°C between June and August Indicator for heat stress (Acevedo et al, 2015;Beever et al, 2010;Wilkening et al, 2011;Yandow et al, 2015;Yang, 1990) Diurnal temperature range…”

“…Indicator for climatic temperature range (Acevedo et al, 2012(Acevedo et al, , 2015 Seasonality of precipitation Precipitation seasonality (coefficient of variation as a measure of climatic stability)…”