Abstract
AbstractWhen plants colonize new habitats altered by natural or anthropogenic disturbances, those individuals may encounter biotic and abiotic conditions novel to the species, which can cause plant functional trait divergence. Over time, site‐driven adaptation can give rise to population‐level genetic variation, with consequences for plant community dynamics and ecosystem processes. We used a series of 3000‐yr‐old, lava‐created forest fragments on the Island of Hawai`i to examine whether disturbance and subsequent colonization can lead to genetically differentiated populations, and where differentiation occurs, if there are ecosystem consequences of trait‐driven changes. These fragments are dominated by a single tree species, Metrosideros polymorpha (Myrtaceae) or ʻōhiʻa, which have been actively colonizing the surrounding lava flow created in 1858. To test our ideas about differentiation of genetically determined traits, we (1) created rooted cuttings of ʻōhiʻa individuals sampled from fragment interiors and open lava sites, raised these individuals in a greenhouse, and then used these cuttings to create a common garden where plant growth was monitored for three years; and (2) assessed genetic variation and made QST/FST comparisons using microsatellite repeat markers. Results from the greenhouse showed quantitative trait divergence in plant height and pubescence across plants sampled from fragment interior and matrix sites. Results from the subsequent common garden study confirmed that the matrix environment can select for individuals with 9.1% less shoot production and 17.3% higher leaf pubescence. We found no difference in molecular genetic variation indicating gene flow among the populations. The strongest QST level was greater than the FST estimate, indicating sympatric genetic divergence in growth traits. Tree height was correlated with ecosystem properties such as soil carbon and nitrogen storage, soil carbon turnover rates, and soil phosphatase activity, indicating that selection for growth traits will influence structure, function, and dynamics of developing ecosystems. These data show that divergence can occur on centennial timescales of early colonization.
Highlights
The movement of plant species into new habitats can have important evolutionary and ecological consequences
Shoot length, measured in the greenhouse, was consistent with field height observations, with shoot lengths in kıpuka-derived plants 53% greater than matrixderived plants (Fig. 1b). This pattern was maintained in the common garden where kıpuka trees were 9.2% taller in 2014 (Fig. 1c) and 9.3% taller than matrix trees in 2015 (Fig. 1d). These results highlight a consistent pattern of genetic divergence in plant height between the kıpuka and matrix individuals
In situ Specific leaf area (SLA) was observed to be 27.9% greater in kıpuka vs. matrix trees, there were no significant differences observed in the common garden after one year of growth, there appeared to be a trend in this direction
Summary
The movement of plant species into new habitats can have important evolutionary and ecological consequences. Invasive pine trees in Brazil had distinct phenotypes in colonized vs source portions of their range (Zenni et al 2014b), suggesting that selective pressures during colonization favored certain traits. Such effects clearly have important implications for managing invasive species, but beyond the study of invasive species (see reviews by Buswell et al 2011, FelkerQuinn et al 2013, Moran and Alexander 2014), surprisingly few studies have examined the evolutionary consequences of colonization by native species (Foster et al 2007, Schwarzer et al 2013, Hargreaves et al 2014). This knowledge gap is notable because such colonization events are extensive and arguably the most important process in primary and secondary succession, as well as recovery of the Earth’s degraded landscapes (Sarrazin and Lecomte 2016)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
