Molecular and morphological consilience in the characterisation and delimitation of five nematode species from Florida belonging to the Xiphinema americanum-group

Abstract

Taxonomic keys and original descriptions were used to identify 26 Xiphinema americanum-group populations from Florida comprising X. georgianum (eight populations), X. citricolum (six), X. floridae (six), X. laevistriatum (five) and X. tarjanense (one). Principal component analysis of a subset of 19 morphometric characters accorded with the species designations; discriminant analysis of six characters assigned 93% (111 of 119) of the specimens to the correct putative species. A phylogeny of these populations estimated from analyses of rDNA sequences (ITS and D2D3) was also congruent with species designations from taxonomic keys and PCA. The D2D3 sequences revealed very little intraspecific variation whereas each population sampled produced a unique ITS sequence. Intraspecific variation in the suites of character code values from polytomous keys resulted mainly from minor discrepancies between population character means and reported character ranges for the species. We show that, for these taxa, species delimitation based on the requirement that sister taxa evolve autapomorphies distinguishes intraspecific variation from phylogeny and, as applied to molecular characters, delimits the same taxa as those predicted by morphological keys and PCA.

Molecular and Morphological Characterization of Xiphinema chambersi Population from Live Oak in Jekyll Island, Georgia, with Comments on Morphometric Variations

“…Sequence and phylogenetic analysis: Sequences of the D2-D3 of 28S rRNA, 18S rRNA, and coxI mtDNA genes obtained from several specimens of X. chambersi were aligned by ClustalX 1.83 (Thompson et al, 1997) using default parameters with corresponding published sequences of genes of X. chambersi (He et al, 2005;Gozel et al, 2006) and/or other Xiphinema species belonging to the Clade I of non-Xiphinema americanum group according to Gutierrez-Gutierrez et al (2013). Sequence of the ITS1 rRNA gene was aligned with those of other X. chambersi (Ye et al, 2004;Yu et al, 2010;Zeng et al, 2015) and two species outgroup species.…”

Distribution, morphological description, and molecular characterization of Xiphinema and Longidorous spp. associated with plants (Miscanthus spp. and Panicum virgatum) used for biofuels

“…The D3A/B region has been used to identify nematode species, including species of Longidorids (Rubtsova et al, 2001;He et al, 2005;Gozel et al, 2006;Sirca et al, 2007). In our study, a cluster analysis of D3A/B X. rivesi (NCBI AY210845.1) Fig.…”

Nematod taksonomisinde kullanılan moleküler markörler

“…Bu nedenle özellikle birbirine yakın nematod türleri ve tür içi varyasyonların düzeylerinin ortaya çıkarılabilmesi için tercih edilmektedir. Xiphinema americanum popülasyonları arasındaki farklılıklar mtDNA ile belirlenebilmiştir (Lazarova et al, 2006, Gözel et al, 2006a. M. arenaria, M. incognita, M. javanica (Devran et al, 2002), M. hispanica, M. hapla, M. chitwoodi ve M. mayaguensis (Blok et al, 2002 popülasyonlarının mtDNA haplotipleri sekans analizi ile tespit edilmiştir (Stanton et al, 1997).…”

“…ITS bölgelerinin dizileri kullanılarak birçok bitki paraziti nematod türünün tanımlanması yapılmıştır (Subbotin et al, 2001;Floyd et al, 2002;Reid et al, 2003;Gözel et al, 2006a;Inserra et al, 2007). 18S rRNA geninin dizi analizleri (Floyd et al, 2002) ve 28S rDNA'nın D2-D3 bölgeleri Tylenchidae (Subbotin et al, 2006) ve Longidoridae He et al, 2005) familyalarına ait türlerin tespitinde kullanılmıştır.…”