Gene flow and range expansion in a mountain-dwelling passerine with a fragmented distribution

Abstract

We studied gene flow and bottleneck events in the population history of locally isolated citril finches endemic to European mountains. For the present study, we used two genetic markers with different rates of evolution: a fast evolving mitochondrial marker (ATPase6/8) and a more slowly evolving nuclear marker (02401). Populations north of the Pyrenees showed in general fewer haplotypes and a considerable lower nucleotide and gene diversity than the Iberian populations. Unexpectedly, we found very little genetic variability in the fast evolving mitochondrial marker, arguing for a strong and relatively recent bottleneck event in the species population history. This pattern potentially reflects a sudden decrease of crucial resources during Mid-Holocene (mountain pine, Scots pine, and black pine) and a subsequent breakdown of the population. The bottleneck could also have been caused or coincide with a selective sweep in the mitochondrion. By contrast, the slowly evolving nuclear marker showed a much higher variability. This marker probably reflects major gene flow along a potential expansion pathway from the Eastern Pyrenees, northwards to the populations of Central Europe, and southwards to the more fragmented populations of central and southern Spain. The population of the Western Pyrenees (Navarra) appears to be cut-off from this major gene flow and our data indicate a certain degree of partial isolation, probably reflecting more ancient events (e.g. the separation in distinct refuge sites during the last glacial maximum).

Phylogeography of the Spanish Moon Moth Graellsia isabellae (Lepidoptera, Saturniidae)

“…A similar result was obtained for the Northern Pine Processionary Moth ( Thaumetopoea pinivora ) [ 79 ]. Secondly, a Holocene spatial migration of some ancestors of the EP cluster northwards following pine expansions is plausible from a biogeographic perspective: (i) suitable habitat ( P. nigra salzmannii ) for G. isabellae existed in Southeastern France even before the LGM [ 80 ], (ii) the first postglacial expansion of the so-called “light-green haplotype” of P. sylvestris was traced (based on macrofossils) from the easternmost part of the Pyrenees northwards [ 16 ] and (iii) other montane species dependent on pine forest likely spread from the Eastern Pyrenees northward following Holocene pine expansions [ 81 ].…”

“…Or maybe that connection occurred before the LGM, as in the case of the plant Ramonda myconi [ 76 ], and therefore was not reported in any of those works. The LGM-isolation hypothesis of cluster WP receives additional support from the phylogeography of Carduelis citrinella , a pine-associated bird, which shows remarkable coincidences with G. isabellae in terms of distribution area and genetic structure [ 81 ].…”

Familiarity adds to attractiveness in matters of siskin mate choice

“…The citril finch Serinus citrinella is a third example. Different subpopulations, known to adapt locally and to differ in morphometrics and genetic structure [76,77], are allopatric during the breeding season, but intermix in the shared Table 1. Results from the second experiment in which females had to choose between a poorly ornamented familiar male (small yellow wing patch) and an ornamented unfamiliar male (large yellow wing patch).…”

“…wintering areas where pairing takes place [78,79]. Citril finch subpopulations, however, remain differentiated [76,77]. Subpopulations remain differentiated in siskins, crossbills and citril finches, even though cohabitation of the different subpopulations during the pairing period would provide ample opportunities for intermixing, resulting in gene flow, and ultimately in homogenization [27,79].…”

Local Genetic Structure on Breeding Grounds of a Long-Distance Migrant Passerine: The Bluethroat (Luscinia svecica) in Spain

“…In this respect, it is necessary to bear in mind that in the Iberian Peninsula, there is no suitable habitat for the bluethroat further north of the Cantabrian Mountains. Consequently, under a global warming scenario, the northward expansion of the Spanish subspecies would be limited (Walther et al 2002;Förschler et al 2011). It remains unclear if the proposed site selection and philopatry is strong enough to hamper the adaptation of individuals from clusters K-NE and K-NW to a southern and more Mediterranean habitat under a global warming scenario.…”