Demographic history, genetic structure and gene flow in a steppe-associated raptor species

Abstract

BackgroundEnvironmental preferences and past climatic changes may determine the length of time during which a species range has contracted or expanded from refugia, thereby influencing levels of genetic diversification. Connectivity among populations of steppe-associated taxa might have been maximal during the long glacial periods, and interrupted only during the shorter interglacial phases, potentially resulting in low levels of genetic differentiation among populations. We investigated this hypothesis by exploring patterns of genetic diversity, past demography and gene flow in a raptor species characteristic of steppes, the Montagu's harrier (Circus pygargus), using mitochondrial DNA data from 13 breeding populations and two wintering populations.ResultsConsistent with our hypothesis, Montagu's harrier has relatively low genetic variation at the mitochondrial DNA. The highest levels of genetic diversity were found in coastal Spain, France and central Asia. These areas, which were open landscapes during the Holocene, may have acted as refugia when most of the European continent was covered by forests. We found significant genetic differentiation between two population groups, at the SW and NE parts of the species' range. Two events of past population growth were detected, and occurred ca. 7500-5500 and ca. 3500-1000 years BP in the SW and NE part of the range respectively. These events were likely associated with vegetation shifts caused by climate and human-induced changes during the Holocene.ConclusionsThe relative genetic homogeneity observed across populations of this steppe raptor may be explained by a short isolation time, relatively recent population expansions and a relaxed philopatry. We highlight the importance of considering the consequence of isolation and colonization processes in order to better understand the evolutionary history of steppe species.

A molecular phylogeny of the harriers (Circus, Accipitridae) indicate the role of long distance dispersal and migration in diversification

“…C. hudsonius) and 'young' species (C. aeruginosus), is likely not due to the age of origin or a selective sweep. Thus, taking the results from this study and previous harrier molecular studies into account (Garcia et al, 2011;Fuchs et al, 2014), continuous fluctuations in prey availability leading to recurrent variations in harrier population sizes may be the driver behind low genetic diversity observed within Circus species.…”

“…Previous phylogeographic studies on the Black Harrier (Fuchs et al, 2014) and the Montagu's Harrier (Garcia et al, 2011) have shown low (Garcia et al, 2011) to no (Fuchs et al, 2014) genetic variation among populations of both these species and very little to no geographic structure. Here, two harrier taxa were sampled from widespread localities of their 20 breeding distribution and they show similar trends.…”

Philopatry and natal dispersal of Montagu's harriers (Circus pygargus) breeding in Spain: a review of existing data

“…Hence, this result also suggests a high capacity for genetic exchange between populations, which would lead to relatively low genetic differentiation between populations of Western Europe. Such low degree of population genetic structuring has been recently described in this species (García et al 2011).…”

Mechanisms and reproductive consequences of breeding dispersal in a specialist predator under temporally varying food conditions

“…Dispersal is a major biological process influencing large‐scale population dynamics and evolutionary processes (Garant et al , Clobert et al , Garcia et al ). Theoretically, the evolution of dispersal is associated with a tradeoff between fitness‐related costs and benefits (Bowler and Benton , Clobert et al ).…”