Environmental Niche Divergence In The Kalmia Lineage: Integrating Phylogeny, Community Composition And Ecology To Understand Patterns Of Regional Plant Diversity

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Tesa Madsen-McQueen (Creator)
Appalachian State University (ASU )
Web Site: https://library.appstate.edu/
Zack Murrell

Abstract: The ongoing synthesis of the formerly disparate fields of ecology and evolution is resulting in a proliferation of insights, highlighting the interdependence and feedback between ecological and evolutionary processes. There is increasing evidence that evolutionary processes can influence community dynamics through geographic patterns of speciation, mutualist interactions, and other processes governing community phylogenetic patterns (Weber et al., 2017; Weeks et al., 2016). Here we adopt a clade-focused perspective to understand patterns of niche evolution in a single lineage, and subsequently address the regional community context of habitats which have facilitated the persistence and diversification of members of the genus. Hypothesized to have originated in eastern North America, the genus Kalmia contains ten species exhibiting widely varying and disjunct distributions while occupying a large spectrum of habitats- from alpine bogs to xeric sandhill scrub (Gillespie & Kron, 2013; Weakley, 2015). Given the extent of ecological and geographic divergence, we asked the following questions: what potential processes or factors underlie the patterns of lineage bifurcation and habitat differentiation in Kalmia, and what has been the role of phylogenetic niche conservatism in these lineage divergences? We constructed ecological niche models for seven of ten species of Kalmia using available climatic and topographic variables, and identified the variables contributing most to the observed distributions. We calculated niche overlap among all species, and subsequently used these metrics to assess the potential geographic pattern of divergence using a recent molecular phylogeny for the genus. We then subjected these results to an age-range correlation (ARC) test. We assessed the extent of niche conservatism in both morphological as well as abiotic traits that we could further use to infer processes underlying niche evolution. We suggest that the long evolutionary history of the Kalmia lineage in eastern North America coinciding with climatic and/or topographic changes has resulted in considerable niche lability, subsequently allowing Kalmia species to track suitable oligotrophic habitats while diverging in larger-scale climatic and topographic niche characteristics as well as less ecologically important morphological traits.To understand speciation and niche evolution in a community context, we investigated the habitat use among three of these closely related taxa that exhibit overlapping disjunct ranges. We assessed the taxonomic and phylogenetic patterns of local communities along an elevation gradient among three distinct floristic regions of the southeastern US that all contain at least one Kalmia species. We asked if there were differences in abiotic and biotic attributes among coastal plain, piedmont and mountain habitats, given that they all support the same focal taxa. Using community data from both field collection and an open-source vegetation database, we find that differences in edaphic and phylogenetic patterns among regions were minimal with only soil pH exhibiting differences. Our results of taxonomic and phylogenetic beta diversity support the prevalence of allopatric speciation patterns from closely related lineages establishing in similar habitats. This research highlights the importance of considering habitat-specific lineage pools when interpreting patterns of regional diversity and local community assembly, as well as consideration for lineage-specific history when evaluating regional diversity patterns.

Additional Information

Madsen-McQueen, T. (2018). "Environmental Niche Divergence In The Kalmia Lineage: Integrating Phylogeny, Community Composition And Ecology To Understand Patterns Of Regional Plant Diversity."
Language: English
Date: 2018
Plant community ecology, Community phylogenetics, Ecological niche modelling, Niche evolution, Niche conservatism

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