Phytogeography of <i>Najas gracillima</i> (Hydrocharitaceae) in North America and its cryptic introduction to California

Les, Donald H.; Peredo, Elena L.; Benoit, Lori K.; Tippery, Nicholas P.; King, Ursula M.; Sheldon, Sallie P.

doi:10.3732/ajb.1300005

Cited by 8 publications

(4 citation statements)

References 35 publications

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“…2b) which is equivalent to the extent used in Soto-Centeno et al (2013). The Lambert conformal conic projection (central meridian 96°E, standard parallels 20°N and 60°N) was used to transform the environmental layers (see Appendix S6) because this has low spatial distortion for North America (Les et al, 2013). 3.…”

Section: Testing the Null Model Using Three Case Studiesmentioning

confidence: 99%

A null biogeographical test for assessing ecological niche evolution

Nunes

Pearson

2016

Journal of Biogeography

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Aims Quantification of the degree to which ecological niches change over evolutionary time‐scales is important for deepening our understanding of evolutionary and ecological processes. Phylogenetic niche conservatism (PNC) is when closely related species differ less ecologically than expected by chance, whereas Phylogenetic Niche Divergence (PND) is when closely related species differ more ecologically than expected by chance. We present a new null model to test for PNC and PND (the random translocation and rotation (RTR) significance test), which we combine with a novel metric for quantifying niche overlap. Location Europe, North America and Madagascar. Methods The RTR null model comprises many thousands of replicates generated by randomly translocating and rotating the set of occurrence records for two populations (e.g. sister species) while maintaining the spatial configuration between all occurrences within each replicate. For each replicate, we calculate niche overlap as the proportion of the combined niche breadth that is shared by the two species, averaged over n environmental dimensions. This approach enables us to test whether the observed niche overlap is more or less than expected by chance given the environmental conditions present in the study area. We test the performance of our approach in comparison to other methods using both simulated and real case scenarios, including crested newts in Europe, pocket gophers in North America, and lemurs in Madagascar. Results We find that our measure of niche overlap performs better than other metrics in an artificial simulation scenario, and we find evidence for both PNC and PND in our case studies for Europe, North America and Madagascar. Our results demonstrate that both the RTR significance test and the novel metric of niche overlap are consistent with evolutionary theory and are suitable methods to test for PNC and PND. Main conclusions We make available scripts to implement the RTR test and metric of niche overlap, and expect that the methods will prove useful for addressing a broad set of questions relating to ecological niche evolution and speciation, particularly for restricted‐range species for which few known occurrence records are available.

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Section: Testing the Null Model Using Three Case Studiesmentioning

confidence: 99%

A null biogeographical test for assessing ecological niche evolution

Nunes

Pearson

2016

Journal of Biogeography

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“…These studies on aquatic plants focused primarily on two groups: seagrasses (e.g., [ 20 – 22 ]) and emergent macrophytes in freshwater environments (e.g., [ 23 – 27 ]). Few studies have focused on freshwater submerged species (but see [ 28 , 29 ]), whose evolutionary processes are most likely distinct from those of emergent species due to their occurrence in exclusively aquatic habitats [ 2 , 30 ], and seagrasses due to their lower population connectivity in discrete and patchy habitats [ 31 ]. Therefore, phylogeographic studies on freshwater submerged macrophytes will provide new insights to increase our understanding of plant evolution.…”

Section: Introductionmentioning

confidence: 99%

The phylogeographic structure of Hydrilla verticillata (Hydrocharitaceae) in China and its implications for the biogeographic history of this worldwide-distributed submerged macrophyte

Jian

2015

BMC Evol Biol

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BackgroundAquatic vascular plants are a distinctive group, differing from terrestrial plants in their growth forms and habitats. Among the various aquatic plant life forms, the evolutionary processes of freshwater submerged species are most likely distinct due to their exclusive occurrence in the discrete and patchy aquatic habitats. Using the chloroplast trnL-F region sequence data, we investigated the phylogeographic structure of a submerged macrophyte, Hydrilla verticillata, the single species in the genus Hydrilla, throughout China, in addition to combined sample data from other countries to reveal the colonisation and diversification processes of this species throughout the world.ResultsWe sequenced 681 individuals from 123 sampling locations throughout China and identified a significant phylogeographic structure (NST > GST, p < 0.01), in which four distinct lineages occurred in different areas. A high level of genetic differentiation among populations (global FST = 0.820) was detected. The divergence of Hydrilla was estimated to have occurred in the late Miocene, and the diversification of various clades was dated to the Pleistocene epoch. Biogeographic analyses suggested an East Asian origin of Hydrilla and its subsequent dispersal throughout the world.ConclusionsThe presence of all four clades in China indicates that China is most likely the centre of Hydrilla genetic diversity. The worldwide distribution of Hydrilla is due to recent vicariance and dispersal events that occurred in different clades during the Pleistocene. Our findings also provide useful information for the management of invasive Hydrilla in North America.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0381-6) contains supplementary material, which is available to authorized users.

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“…Triest (1988) also cites a specimen from Turkey for the species. Further taxon sampling and the use of additional genetic markers, as done by Les & al. (2013) for N. gracillima, will determine whether this species is indigenous to Eurasia as a whole, or is introduced in Europe.…”

Section: Sect Americanaementioning

confidence: 99%

Phylogeny ofNajas(Hydrocharitaceae) revisited: Implications for systematics and evolution

Tanaka

Gale³

et al. 2017

TAXON

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Najas (Hydrocharitaceae) is a cosmopolitan genus of 30‐40 species of aquatic plants. While an infrageneric subdivision into two subgenera is generally accepted, various sectional classifications proposed in subg. Caulinia have been controversial. Earlier analyses identified tropical Asia, which harbors more than one‐third of all species, as the area of origin for the genus, but this inference requires re‐evaluation using worldwide taxon sampling. Polyploidy has been widely observed in the genus but its correlation with phylogeny has yet to be explored. Here we applied a molecular phylogenetic approach using balanced taxon sampling (1) to test infrageneric classifications, (2) to re‐assess biogeographic origin, and (3) to explore whether and how polyploidy characterizes evolutionary lineages. Our analyses of plastid and nuclear (ITS) DNA datasets produce largely congruent results that recover the two subgenera but find little support for most sectional classifications. To overcome this shortfall, we propose a new sectional classification of subg. Caulinia. The previously inferred tropical Asian origin of the genus is rejected and, instead, North America is discerned as the ancestral area, implicating dispersal of the most recent common ancestor of Najas and its sister genera in Hydrocharitaceae from tropical Asia. Based on chromosome counts confirmed in the present study and those compiled from literature, the role of polyploidization in the evolution of Najas is shown to be relatively limited, in contrast to the extreme infraspecific chromosome variation previously reported.

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Phytogeography of Najas gracillima (Hydrocharitaceae) in North America and its cryptic introduction to California

Cited by 8 publications

References 35 publications

A null biogeographical test for assessing ecological niche evolution

A null biogeographical test for assessing ecological niche evolution

The phylogeographic structure of Hydrilla verticillata (Hydrocharitaceae) in China and its implications for the biogeographic history of this worldwide-distributed submerged macrophyte

Phylogeny ofNajas(Hydrocharitaceae) revisited: Implications for systematics and evolution

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