Conservation Genetic Analysis of Blanding’s Turtles across Ohio, Indiana, and Michigan

Round 1

Reviewer 1 Report

The manuscript "Conservation Genetic Analysis of Blanding’s Turtles Across Ohio, Indiana, and Michigan" by Guinto et al. presents an insightful investigation on the genetic diversity of Blanding's Turtle (Emydoidea blandingii) in 16 localities within the Great Lakes region. The study effectively utilizes 14 microsatellite loci to characterize the genetic diversity of the species and explore its population structure. This information is valuable for future research in conservation genetics and management of Blanding's Turtle populations.

The authors presented the methodology and results clearly. However, I suggest the manuscript includes supplementary material with the R code used for the analyses, even if it is only for the Mantel test. This would enhance the reproducibility of the study and provide a valuable resource for other researchers in the field.

In conclusion, the manuscript is a valuable contribution to the literature on the conservation genetics of Blanding's Turtles. The authors are congratulated for their work and are encouraged to continue research in this area. As a final remark, it is worth considering whether the data collected in this study could be used to create mechanical models for estimating the potential spatial abundance and distributions of the species under different climatic scenarios. Although this is not the focus of the current paper, it would be an interesting avenue for future research and a valuable addition to the conservation planning of Blanding's Turtles.

Author Response

R source coded for mantel test was included in supplemental material

 

Reviewer 2 Report

The manuscript aims to describe the genetic diversity and population structure of Blanding’s turtles in the region of Lake Eerie. The authors use microsatellites and a large sample size distributed across Michigan, Ohio and Indiana.

The authors describe diversity (Table 1) and bottleneck (Table 2) patterns by sampling site, however, their STRUCTURE/TESS3r analysis showed that there are 4 clusters. Given that the same patterns are expected within the same clusters, I suggest that the authors reassess their analysis from Table 1 and 2 considering the populations found. One possibility would be to keep both tables and add the results for each of the 4 populations.

Following the inclusion of these analysis, I suggest that the authors re-evaluate their section on Conservation Implications. While conceptually I don’t see any flaws in it, the 50/500 rule is usually applied to species or populations with unique genetic identity. In the case of this study, and also mentioned by the authors, differentiation within Blanding’s turtles is very low (also shown in table 4), thus given the genetic structure found species-wide recommendations should also be made.

-          The introduction is long and could be reduced. Much of the descriptions on genetic diversity could be incorporated in the discussion by comparing previous studies with your results.

-          Figure 1 – this figure is very hard to see. The map lines are too light. Readers that do not know much on the geography or Michigan and Ohio could benefit from an inset map with a larger perspective of the sampling site.

-          And great summary in Table 4!

 

-          Line 428 and 429: substitute “crossed” for “included”

Author Response

Tables S6 & S7 were added to the supplemental with summaries for the 4 Clusters derived from TESS3r.

Though the clusters can identify management units within which individuals can be translocated to maintain minimum viable population sizes while maintaining the genetic history, we chose to keep the site level summaries in the main text since gene flow between localities is currently unlikely and the lasting structure likely represents historic gene flow. The cluster-based analysis represents population genetic characteristics of historically connected populations. The site based approach is desired by property managers to inform them on their locality and provides guidance for management decisions with in the management units given the lack of geneflow. Though differentiation is low we feel the lack of connectivity between localities warrants treating them as separate populations.

The last paragraph of our conservation recommendations are meant to apply range wide: “Levels of genetic variation are currently robust within the species across the geographic range (Table 4). This provides an opportunity to strategically manage populations to avoid the expected future loss of genetic variation in small, isolated populations. First, it is necessary to identify large, relatively stable or growing populations that occur in large tracts of suitable habitat [93]. These populations can serve as a source of individuals for translocation to other localities that have habitat sufficient to support viable populations. Our results suggest that genetic structure should be a minor concern for translocation. If possible, source and recipient populations should share the same watershed at the level of HUC 4 (above and [93]). However, the minimal structure between watersheds and the overall history of recolonization following deglaciation suggests that movement of turtles between watersheds will carry little risk of outbreeding depression within phylogeographic regions [7,10]. In this case, we suggest that source and recipient populations are chosen to maximize geographic proximity (isolation by distance) and environmental similarity to avoid possible disruption of co-adapted gene complexes [99].”

Lines 80 and 81 were removed “Anthonysamy et al., [31] found no evidence of inbreeding in E. blandingii in northeast Illinois and even found potential evidence of outbreeding.“

Lines 89 to 94 were removed. “Davy et al. [33] discovered four genetic clusters utilizing 12 microsatellite loci in southern Ontario, and Anthonysamy et al. [5] found evidence of a hierarchical assortment of three clusters nested into two large broad clusters across six sites in northeast Illinois using 14 loci. Sethuraman et al. [29] found four to 6 hierarchical clusters across Illinois, Iowa, Minnesota and Nebraska.”

Lines 101 to 106 were removed  “Comparing historical migration with recent migration can be useful in determining where gene flow no longer exists between localities [31,33]. Understanding historic versus recent gene flow can be used to determine where corridors or translocation may be useful in promoting gene flow and maintaining genetic diversity by staving off genetic bottlenecks associated with the fragmentation of populations [31,33].”   

Lines 96 to 99 were removed. “Sethuraman et al., [29] indicated relatively small scale differentiation in some pairwise comparisons, but similarity across large distances in other comparisons. McCluskey et al., [30] observed high genetic diversity in most localities but also evidence of significant past declines in genetic variation in other localities.”

Comparison to Anthonysamy et al., was added at line 440.

Figure One edited to darken county boundaries and a small map of the US was included to indicate regional geography.

On lines 428 and 429 “crossed” was replaced by “included”

Round 2

Reviewer 1 Report

Really enjoyed reading the manuscript. Congratulations on your work!