Abstract Detail

Biogeography

Smallwood, Patrick [1], Trapnell, Dorset [2].

Ecological niche modelling reveals significant shifts in optimal habitat for nine North American Cypripedium spp. (Orchidaceae) within recent decades.

Accelerating climate change is expected to cause range shifts of numerous taxa worldwide. While projections typically focus on the future (2050 or later), a measurable change in climatic conditions has occurred over recent decades, with species’ ranges already undergoing detectable change. We investigate whether recent climate change has caused measurable shifts in suitable habitat for nine North American species within the highly threatened genus Cypripedium (Orchidaceae). Using species occurrence records, 19 bioclimatic variables, land cover, and soil data, we constructed species distribution models using a maximum entropy (Maxent) approach for each species for two decadal time intervals (1980-1989 and 2010-2019). For each species, niche models are compared between time intervals to assess shifts in locality, elevation, and area of suitable habitat. The nine congeners did not reveal consistent directional shifts of suitable habitat between the two time intervals. However, these species occur in three regions of North American and within each region optimal habitat of co-occurring Cypripedium spp. showed similar directional and elevational shifts between time intervals. Consistent with our expectations, optimal habitat for C. californicum, C. fasciculatum, and C. montanum, which co-occur in the western U.S., shifted northwards. Surprisingly, suitable habitat for C. guttatum and C. passerinum, both of which occur in the northwest of North America, shifted southwards. In the third region, located in eastern North America, optimal habitat for C. acaule, C. arietinum, C. parviflorum, and C. reginae shifted in different directions, with the centroids all converging on the Great Lakes vicinity. Seven species experienced an increase in average elevation of suitable habitat. Interestingly, C. californicum and C. reginae revealed minor shifts to lower elevations. Change in area of suitable habitat ranged from -91.5 kha – 157.0 kha (mean 54.9 kha), with seven of the nine Cypripedium species experiencing gains in total area. Overlap of suitable habitat between the two time intervals ranged from 4.3% - 39.7% (mean = 20.5%). This work illustrates the somewhat idiosyncratic responses of species to changing climatic conditions and how the geographic area a species occupies is a better predictor of its response to climate change than is an understanding of how congeners respond, suggesting that biotic factors and the community in which a species exists may be more important in shaping species distributions.

1 - University of Georgia, Department of Plant Biology, 2502 Miller Plant Sciences, 120 Carlton St., Athens, GA, 30605, United States
2 - University Of Georgia, Plant Biology, 2502 Miller Plant Sci Bldg, Athens, GA, 30602, United States

Keywords:
climate change
species distribution
Orchidaceae
species distribution models.

Presentation Type: Oral Paper
Session: BIOGI, Biogeography I
Location: Virtual/Virtual
Date: Monday, July 19th, 2021
Time: 1:15 PM(EDT)
Number: BIOGI004
Abstract ID:368
Candidate for Awards:None