Does fragmentation of wetlands affect gene flow in sympatric Acrocephalus warblers with different migration strategies?

Abstract

Wetlands are naturally patchy habitats, but patchiness has been accentuated by the extensive wetlands loss due to human activities. In such a fragmented habitat, dispersal ability is especially important to maintain gene flow between populations. Here we studied population structure, genetic diversity and demographic history of Iberian and North African populations of two wetland passerines, the Eurasian reed warbler Acrocephalus scirpaceus and the moustached warbler Acrocephalus melanopogon. These species are closely related and sympatric in our study sites, but the reed warbler is a long-distance migrant and widespread bird while the moustached warbler is resident or migrates over short distances, and breeds across a more discontinuous range. Using microsatellites and mtDNA data, we found higher population differentiation in moustached than in reed warbler, indicating higher dispersal capability of the latter species. Our results also suggest that the sea limits dispersal in the moustached warbler. For both species, we found evidence of gene flow between study sites, indicating the capability of compensating for habitat fragmentation.However, in most cases gene flow was restricted, possibly because of the large distances between study sites (from c. 290 to 960 km) or breeding site fidelity. Haplotype diversity was higher for the reed warbler, possibly because of a more important contribution of dispersal from different populations and the higher population size. Studying demographic history, we obtained signs of postglacial population growth for both species, and evidences of a recent colonization or recolonization of the Mallorca Island by the moustached warbler.2

Genetic structuring among populations of the great egret, Ardea alba egretta, in major Brazilian wetlands

“…Monitoring waterbirds with a genetic approach may also provide valuable information for the establishment of management policies and protective measures for wetlands (Lopes et al, 2007). Examples of genetic monitoring for wetland conservation include the assessment of genetic variation among threatened wetland plants (Godt et al, 1995;Edwards and Sharitz, 2000), the identification of evolutionary lineages of freshwater isopods (Gouws and Stewart, 2007), the use of molecular markers to examine the stock composition of the Chinook salmon (Teel et al, 2009) and, more recently, the investigation of population structure, genetic diversity and demographic history of populations of wetland passerines (Ceresa et al, 2015).…”

Between‐patch natal dispersal declines with increasing natal patch size and distance to other patches in the endangered Southern Dunlin Calidris alpina schinzii

“…, Ceresa et al . ), but fragmented habitats may represent barriers to breeding dispersal of migratory birds even though they do not constrain their movement during migration (Lindsay et al . ).…”

“…Thus, the effects may differ between taxa and life history strategies (Peacock & Smith 1997, Cushman 2006, Callens et al 2011, Garrard et al 2012. In birds, dispersal is less restricted in migratory than in resident species (Weatherhead & Forbes 1994, Paradis et al 1998, Ceresa et al 2015, but fragmented habitats may represent barriers to breeding dispersal of migratory birds even though they do not constrain their movement during migration (Lindsay et al 2008). Hence, the level of structural connectivity may explain why among conspecific populations, some show high natal philopatry whereas others do not (Weatherhead & Forbes 1994, Hansson et al 2002.…”

The Behavioural Ecology, Local Population Dynamics and Conservation of the Bearded Reedling <i>Panurus Biarmicus</i> in “El Hondo Natural Park” (SE Spain)

“…Bearded Reedlings population dissimilarities between South-east and Central-Spain and similarities with small isolated populations placed at similar latitude in Turkey [95] and Italy [96,97] indicates that distant study populations from the same species are exposed to similar regional climates and they may have different characteristics in social organisation due to the populations sizes involved in each site and that seasonal cycle of climatic regimes could exert a major importance on them [69,98]. Also, some populations may have a higher tendency to disperse than others [99] or different populations may vary in composition and behaviour, perhaps reflected in age-specific or sex-specific avoidance behaviour [7,8].…”