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Absence of population structure across elevational gradients despite large phenotypic variation in mountain chickadees ( Poecile gambeli )

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ABSTRACT

Montane habitats are characterized by predictably rapid heterogeneity along elevational gradients and are useful for investigating the consequences of environmental heterogeneity for local adaptation and population genetic structure. Food-caching mountain chickadees inhabit a continuous elevation gradient in the Sierra Nevada, and birds living at harsher, high elevations have better spatial memory ability and exhibit differences in male song structure and female mate preference compared to birds inhabiting milder, low elevations. While high elevation birds breed, on average, two weeks later than low elevation birds, the extent of gene flow between elevations is unknown. Despite phenotypic variation and indirect evidence for local adaptation, population genetic analyses based on 18 073 single nucleotide polymorphisms across three transects of high and low elevation populations provided no evidence for genetic differentiation. Analyses based on individual genotypes revealed no patterns of clustering, pairwise estimates of genetic differentiation (FST, Nei's D) were very low, and AMOVA revealed no evidence for genetic variation structured by transect or by low and high elevation sites within transects. In addition, we found no consistent evidence for strong parallel allele frequency divergence between low and high elevation sites within the three transects. Large elevation-related phenotypic variation may be maintained by strong selection despite gene flow and future work should focus on the mechanisms underlying such variation.

No MeSH data available.


Map and elevation profiles of the six sites where mountain chickadees were sampled (created using R 3.3.0, R Core Team 2015). Inset shows region of California and Nevada where sites were sampled. Large blue shape in the middle of the inset represents Lake Tahoe. Panels show the elevation profiles found between the three pairs of elevational transects (points were sampled every 30 m as the duck flies between pairs of sites in ArcGIS). Triangles represent high elevation locations and circles represent low elevation locations.
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RSOS170057F1: Map and elevation profiles of the six sites where mountain chickadees were sampled (created using R 3.3.0, R Core Team 2015). Inset shows region of California and Nevada where sites were sampled. Large blue shape in the middle of the inset represents Lake Tahoe. Panels show the elevation profiles found between the three pairs of elevational transects (points were sampled every 30 m as the duck flies between pairs of sites in ArcGIS). Triangles represent high elevation locations and circles represent low elevation locations.

Mentions: In the autumn of 2013, we sampled 167 birds from three pairs of high (2535–2590 m) and low elevation sites (1891–2122 m) in the Sierra Nevada (table 1); Sagehen Experimental Forest, CA (exact same locations sampled as those used in all phenotypic variation studies [19,22,23,31,32,39]), Mount Rose, NV (exact same locations sampled as those used to show male song structure variation [23]), and Red Lake Peak, CA (no phenotypic variation data have been collected from these locations) (figure 1). Birds were captured using mistnets at established feeders at Sagehen Experimental Forest; the other locations do not have a feeder system in place. At Mount Rose and Red Lake Peak, a mistnet was set and mountain chickadee song was broadcast from the centre of the net using a FOXPRO Fury© playback speaker. Upon capture, approximately 100 µl of blood was collected from the basilic vein with a capillary tube and stored directly in Queen's lysis buffer (1 mM NaCl, 1 mM EDTA, 1 mM Tris).Figure 1.


Absence of population structure across elevational gradients despite large phenotypic variation in mountain chickadees ( Poecile gambeli )
Map and elevation profiles of the six sites where mountain chickadees were sampled (created using R 3.3.0, R Core Team 2015). Inset shows region of California and Nevada where sites were sampled. Large blue shape in the middle of the inset represents Lake Tahoe. Panels show the elevation profiles found between the three pairs of elevational transects (points were sampled every 30 m as the duck flies between pairs of sites in ArcGIS). Triangles represent high elevation locations and circles represent low elevation locations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383859&req=5

RSOS170057F1: Map and elevation profiles of the six sites where mountain chickadees were sampled (created using R 3.3.0, R Core Team 2015). Inset shows region of California and Nevada where sites were sampled. Large blue shape in the middle of the inset represents Lake Tahoe. Panels show the elevation profiles found between the three pairs of elevational transects (points were sampled every 30 m as the duck flies between pairs of sites in ArcGIS). Triangles represent high elevation locations and circles represent low elevation locations.
Mentions: In the autumn of 2013, we sampled 167 birds from three pairs of high (2535–2590 m) and low elevation sites (1891–2122 m) in the Sierra Nevada (table 1); Sagehen Experimental Forest, CA (exact same locations sampled as those used in all phenotypic variation studies [19,22,23,31,32,39]), Mount Rose, NV (exact same locations sampled as those used to show male song structure variation [23]), and Red Lake Peak, CA (no phenotypic variation data have been collected from these locations) (figure 1). Birds were captured using mistnets at established feeders at Sagehen Experimental Forest; the other locations do not have a feeder system in place. At Mount Rose and Red Lake Peak, a mistnet was set and mountain chickadee song was broadcast from the centre of the net using a FOXPRO Fury© playback speaker. Upon capture, approximately 100 µl of blood was collected from the basilic vein with a capillary tube and stored directly in Queen's lysis buffer (1 mM NaCl, 1 mM EDTA, 1 mM Tris).Figure 1.

View Article: PubMed Central - PubMed

ABSTRACT

Montane habitats are characterized by predictably rapid heterogeneity along elevational gradients and are useful for investigating the consequences of environmental heterogeneity for local adaptation and population genetic structure. Food-caching mountain chickadees inhabit a continuous elevation gradient in the Sierra Nevada, and birds living at harsher, high elevations have better spatial memory ability and exhibit differences in male song structure and female mate preference compared to birds inhabiting milder, low elevations. While high elevation birds breed, on average, two weeks later than low elevation birds, the extent of gene flow between elevations is unknown. Despite phenotypic variation and indirect evidence for local adaptation, population genetic analyses based on 18 073 single nucleotide polymorphisms across three transects of high and low elevation populations provided no evidence for genetic differentiation. Analyses based on individual genotypes revealed no patterns of clustering, pairwise estimates of genetic differentiation (FST, Nei's D) were very low, and AMOVA revealed no evidence for genetic variation structured by transect or by low and high elevation sites within transects. In addition, we found no consistent evidence for strong parallel allele frequency divergence between low and high elevation sites within the three transects. Large elevation-related phenotypic variation may be maintained by strong selection despite gene flow and future work should focus on the mechanisms underlying such variation.

No MeSH data available.