2.1.2 Sympatric populations
During fieldwork in the years 2014-2018 in north-central and north-west
Spain, we conducted a revision of the distribution data of both species
along the Iberian Peninsula from 2011 (reviewed in Boudot et al., 2009).
From two hybrid regions,
north-central Spain (Arreo, Cañas,
Mateo, Perdiguero, Valbornedo, Valpierre, and Villar) and north-west
Spain (Doniños, Laxe, Louro and Xuño) we included populations in which:
1) I. elegans was the dominant species; 2) I. graellsiiwas the dominant species, and 3) both species were present at different
proportions. Additionally, available information of presence/absence
from previous years (1987-2003) was also included. Populations were
visited between June and July during sunny days, and sampling was done
with entomological nets. Immature and mature males were included when
estimating the number of individuals in each species (species
proportion). Additionally, we included one population from north-east
Spain (Menorca, in the Balearic Islands) to test the replacement ofI. graellsii by I. elegans in the Balearic Islands
(results are given in supplementary Figure S4).
For the genomic work, a minimum of 20 adult males were collected during
the flight season between 2008-2015 using hand nets and stored in 100%
ethanol until DNA extraction. Because phenotypic hybrid assignment is
only possible through detailed morphological analyses of male caudal
appendages and prothoracic tubercle (see Monetti et al., 2002), all
individuals in this study (of which a majority were females) werea priori morphologically assigned to either I. elegans orI. graellsii based on their thorax colour and prothoracic
tubercle morphology. For
populations with both species (I. elegans and I.
graellsii ), we included samples of both species and aimed to keep the
species proportion observed in the field at each site (Table 1).
Previous data and our results allow us to discuss the present results in
a time- and space-frame context.