TY - JOUR
T1 - Germination niche breadth varies inconsistently among three Asclepias congeners along a latitudinal gradient
AU - Finch, J.
AU - Walck, J. L.
AU - Hidayati, S. N.
AU - Kramer, Andrea L T
AU - Lason, V.
AU - Havens, Kayri
N1 - Funding Information:
We thank Rachel Kreb and Tia Chung-Swanson at Chicago Botanic Garden and the many undergraduate students at Middle Tennessee State University for lab assistance; Alexandra Seglias provided feedback on experimental design and analytical support; thanks to all site managers for their permission and logistic help in seed collection. We would also like to thank the members of the Kramer-Havens Lab at Chicago Botanic Garden for their comments on earlier versions of this manuscript. This work was supported in part by the Program in Plant Biology and Conservation at Northwestern University, the Chicago Botanic Garden’s College First and REU Site Programs (NSF DBI-1461007, 2016), the Botanical Society of America and the Illinois Association of Environmental Professionals.
Publisher Copyright:
© 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands
PY - 2019/5
Y1 - 2019/5
N2 - Species responses to climate change will be primarily driven by their environmental tolerance range, or niche breadth, with the expectation that broad niches will increase resilience. Niche breadth is expected to be larger in more heterogeneous environments and moderated by life history. Niche breadth also varies across life stages. Therefore, the life stage with the narrowest niche may serve as the best predictor of climatic vulnerability. To investigate the relationship between niche breadth, climate and life stage we identify germination niche breadth for dormant and non-dormant seeds in multiple populations of three milkweed (Asclepias) species. Complementary trials evaluated germination under conditions simulating historic and predicted future climate by varying cold–moist stratification temperature, length and incubation temperature. Germination niche breadth was derived from germination evenness across treatments (Levins B n ), with stratified seeds considered less dormant than non-stratified seeds. Germination response varies significantly among species, populations and treatments. Cold–moist stratification ≥4 weeks (1–3 °C) followed by incubation at 25/15 °C+ achieves peak germination for most populations. Germination niche breadth significantly expands following stratification and interacts significantly with latitude of origin. Interestingly, two species display a positive relationship between niche breadth and latitude, while the third presents a concave quadratic relationship. Germination niche breadth significantly varies by species, latitude and population, suggesting an interaction between source climate, life history and site-specific factors. Results contribute to our understanding of inter- and intraspecific variation in germination, underscore the role of dormancy in germination niche breadth, and have implications for prioritising and conserving species under climate change.
AB - Species responses to climate change will be primarily driven by their environmental tolerance range, or niche breadth, with the expectation that broad niches will increase resilience. Niche breadth is expected to be larger in more heterogeneous environments and moderated by life history. Niche breadth also varies across life stages. Therefore, the life stage with the narrowest niche may serve as the best predictor of climatic vulnerability. To investigate the relationship between niche breadth, climate and life stage we identify germination niche breadth for dormant and non-dormant seeds in multiple populations of three milkweed (Asclepias) species. Complementary trials evaluated germination under conditions simulating historic and predicted future climate by varying cold–moist stratification temperature, length and incubation temperature. Germination niche breadth was derived from germination evenness across treatments (Levins B n ), with stratified seeds considered less dormant than non-stratified seeds. Germination response varies significantly among species, populations and treatments. Cold–moist stratification ≥4 weeks (1–3 °C) followed by incubation at 25/15 °C+ achieves peak germination for most populations. Germination niche breadth significantly expands following stratification and interacts significantly with latitude of origin. Interestingly, two species display a positive relationship between niche breadth and latitude, while the third presents a concave quadratic relationship. Germination niche breadth significantly varies by species, latitude and population, suggesting an interaction between source climate, life history and site-specific factors. Results contribute to our understanding of inter- and intraspecific variation in germination, underscore the role of dormancy in germination niche breadth, and have implications for prioritising and conserving species under climate change.
KW - Environmental heterogeneity
KW - intraspecific variability
KW - latitude-niche breadth hypothesis
KW - milkweed
KW - physiological dormancy
KW - population variation
KW - seed germination
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U2 - 10.1111/plb.12843
DO - 10.1111/plb.12843
M3 - Article
C2 - 29779252
AN - SCOPUS:85052790280
VL - 21
SP - 425
EP - 438
JO - Plant Biology
JF - Plant Biology
SN - 1435-8603
IS - 3
ER -