A Re-Examination of Body Size Reduction in Plethodon Yonahlossee Populations Due to Climate Change
Climate change is rapidly altering the earth’s natural systems. Some organisms, such as amphibians, are particularly vulnerable to the detrimental effects of climate change. One documented response by certain taxa is a reduction in body size. Recent evidence has suggested a reduction in body size of several salamander species from the genus Plethodon, including one of the largest species, Plethodon yonahlossee. However, the sample size for P. yonahlossee was small (n = 36) relative to the other Plethodon species examined. Therefore, we re-examined the possibility of body size reductions in P. yonahlossee populations from North Carolina over time. We measured the snout-vent length and head morphology of 221 specimens collected from 1979–2020 in North Carolina. We were also able to account for museum shrinkage when data were available. Contrary to previous research, we did not find evidence for declines in SVL over time. We also found original SVL measurements made at or near the time of preservation were significantly larger than measurements made in 2019, indicating that museum shrinkage had taken place. Local climate data from the same collection period indicate no significant change in mean daily temperature or annual precipitation from this period. Overall, these results suggest a lack of environmental pressure to elicit shifts in body size for these populations.ABSTRACT
Adult Yonahlossee salamander (Plethodon yonahlossee) from Watauga County, North Carolina (photographed by ZTV, 2020).
SVL of P. yonahlossee by collection year (A, B) and elevation (C, D) including (A, C) and not including (B, D) live measurements. Datapoints represent individual SVL measurements (mm) of specimens (nA,C = 221; nB,D = 177). Museum specimens were collected from sites in northwestern North Carolina from 1979–2004, whereas live specimens were measured in 2020. Elevation of collection sites ranged from 427–1097 m. Results indicate no significant change in SVL over this time period, however, SVL is significantly larger in lower elevations than higher elevations.
HL (A, B) and HW (C, D) of P. yonahlossee by collection year including (A, C) and not including (B, D) live measurements. Datapoints represent individual HL or HW measurements (mm) of specimens (nA,C = 221; nB,D = 177). Museum specimens were collected from sites in northwestern North Carolina form 1979–2004, whereas live specimens were measured in 2020. Results indicate a significant decrease in HL and HW from 1979–2020 (A, C), but a significant increase in HL when live measurements were not included (B, D).
Mean SVL (mm) with standard error bars by collection site including (A) and not including (B) live measurements. P. yonahlossee specimens were collected from sites in northwestern North Carolina from 1979–2004. Results indicate a significant difference in SVL between the Powder Horn Mountain (n = 64) and Rainbow Trail (n = 50) sites.
(A) Present SVL (mm) versus original SVL measurements when original measurements were available. (B) Differences between present SVL and original SVL when original measurements were available. Points are jittered for easier viewing. Blue represents individuals with a difference (present SVL – original SVL) < 0, while orange represents individuals with a difference ≥ 0. Original SVL indicates SVL measurements taken by collectors either in life or soon after preservation (n = 87). Present SVL indicates SVL measurements taken by the authors in 2019. Individuals were collected from sites in northwestern North Carolina from 1979–2004. Results of paired t-tests indicate a significant difference between original SVL and present SVL, indicating museum shrinkage has taken place.
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