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. 2016 May;107(3):238-47.
doi: 10.1093/jhered/esw009. Epub 2016 Feb 10.

Regional Genetic Structure and Environmental Variables Influence our Conservation Approach for Feather Heads (Ptilotus macrocephalus)

Collin W Ahrens  1 , Elizabeth A James  1
Affiliations

Regional Genetic Structure and Environmental Variables Influence our Conservation Approach for Feather Heads (Ptilotus macrocephalus)

Collin W Ahrens et al. J Hered. 2016 May.

Abstract

Continued alterations to the Australian environment compromise the long-term viability of many plant species. We investigate the population genetics of Ptilotus macrocephalus, a perennial herb that occurs in 2 nationally endangered communities on the Victorian Volcanic Plain Bioregion (VVP), Australia, to answer key questions regarding regional differentiation and to guide conservation strategies. We evaluate genetic structure and diversity within and among 17 P. macrocephalus populations from 3 regions of southeastern Australia using 17 microsatellite markers developed de novo. Genetic structure was present in P. macrocephalus between the 3 regions but not at the population level. Environmental factors, namely temperature and precipitation, significantly explained differentiation between the North region and the other 2 regions indicating isolation by environment. Within regions, genetic structure currently shows a high level of gene flow and genetic variation. Our results suggest that within-region gene flow does not reflect current habitat fragmentation in southeastern Australia whereas temperature and precipitation are likely to be responsible for the differentiation detected among regions. Climate change may severely impact P. macrocephalus on the VVP and test its evolutionary resilience. We suggest taking a proactive conservation approach to improve long-term viability by sourcing material for restoration to assist gene flow to the VVP region to promote an increased adaptive capacity.

Keywords: Amaranthaceae; Australia; Victorian Volcanic Plain.; gene flow; microsatellites; population genetics; temperate grassland.

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Figures

Figure 1.
Figure 1.
Map of southeastern Australia showing the location of the 17 populations of P. macrocephalus. Populations are separated into their defined regions as indicated. Shading shows elevation changes and the most southern portion of the Great Dividing Range. Inset: map of Australia with the box outlining the research area.
Figure 2.
Figure 2.
Discriminate analysis of principal components (DAPC) calculated for all P. macrocephalus individuals (299) from 17 populations. Calculations are delineated based on prior assignment of (A) regions and (B) populations. Circles represent 95% confidence intervals of (A) regions and (B) populations, circle overlap denotes regions and populations that are not significantly different while nonoverlapping circles denote regions or populations that are significantly different.
Figure 3.
Figure 3.
Posterior probabilities of individual assignment from Bayesian clustering analysis of all P. macrocephalus individuals (299) (K = 2). (A) STRUCTURE K = 2, (B) STRUCTURE K = 3, and (C) TESS K = 2. Populations are geographically ordered by region as indicated.
Figure 4.
Figure 4.
RDA determining the relative contribution of 2 environmental variables (mean annual temperature and annual rainfall) on the genetic structure of P. macrocephalus. RD1 = 19% and RD2 = 8% for a total of 27% of the genetic variation explained.
See this image and copyright information in PMC

References

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