Abstract Detail

Biodiversity synthesis: Linking large phylogenies with species traits and ecologies.

Siniscalchi, Carolina [1], Kates, Heather [2], Soltis, Pamela [2], Soltis, Douglas [2], Guralnick, Robert [4], Folk, Ryan [5].

Testing the evolutionary success of nitrogen-fixing symbioses in challenging soil environments.

Nitrogen-fixing mutualistic relationships with bacteria borne in root nodules are tightly distributed in only ten angiosperm families among four orders, comprising the so-called nitrogen-fixing clade. Despite its status as one of the most globally successful symbioses, the evolutionary and ecological origins of the relationship between nitrogen-fixing bacteria and nodulating plants remain obscure. Basic questions such as the number of origins of nodulation, the drivers that led to its emergence, and its fine-scale distribution across today’s landscape remain unanswered. While poor phylogenetic resolution and limited distributional data have hampered robust quantitative approaches to these questions, evidence to date suggests nitrogen-fixing strategies are indeed primarily associated with environmental factors such as aridity and nitrogen-poor soils despite the ecological diversity of the clade. Although a causative role for the origins and maintenance of the relationship remains to be tested, this evidence is consistent with theoretical predictions that rich soil environments should be associated with decreased investment in expensive symbiotic structures and with a decreasingly mutualistic nature of the plant-bacterium relationship. Here, we make initial progress on these questions by testing hypotheses that (1) nodular nitrogen-fixing strategies are most prevalent in challenging soil environments, and that (2) diversification rates of nitrogen-fixing plants are higher in poor, arid soils, reflecting the specificity of their global success to these environments. To test these hypotheses, we assemble the largest phylogenetic estimate yet for the nitrogen-fixing clade, reconciling GenBank sequences with a backbone informed by densely sampled phylogenomic data and containing more than 19,000 taxa. We synthesize this tree together with global datasets of soil and environmental parameters, densely sampled distributional data, and parametric and non-parametric macroevolutionary methods. 

1 - Mississippi State University, Biological Sciences, Harned Hall, 295 Lee Blv, Mississippi State, MS, 39762, USA
2 - University Of Florida, Florida Museum Of Natural History, Dickinson Hall, Gainesville, FL, 32611, United States
3 - University Of Florida, Florida Museum Of Natural History, Dickinson Hall, Gainesville, FL, 32611, United States
4 - University Of Florida, Florida Museum Of Natural History, Dickinson Hall, Gainesville, FL, 32611, USA
5 - Mississippi State University, 295 E. Lee Blvd., P.O. Box GY, 295 E. Lee Blvd., P.O. Box GY, Mississippi State, MS, 39762, United States

Keywords:
nodulation
macroevolution
aridity
Diversification.

Presentation Type: Colloquium Presentations
Session: COL01, Biodiversity synthesis: Linking large phylogenies with species traits and ecologies
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 10:15 AM
Number: COL01002
Abstract ID:564
Candidate for Awards:None