Analysing the Floral Elements of the Lost Tree of Easter Island: A Morphometric Comparison between the Remaining Ex-Situ Lines of the Endemic Extinct Species Sophora toromiro

Abstract

Sophora toromiro (Phil) Skottsb. is a species that has been extinct in its natural habitat Easter Island (Rapa Nui) for over 50 years. However, seed collections carried out before its extinction have allowed its persistence ex-situ in different botanical gardens and private collections around the world. The progenies of these diverse collections have been classified in different lines, most of them exhibiting high similarity as corroborated by molecular markers. In spite of this resemblance observed between the different lines, one of them (Titze) has dissimilar floral elements, thus generating doubts regarding its species classification. The floral elements (wing, standard and keel) belonging to three different S. toromiro lines and two related species were analyzed using geometric morphometrics. This method was applied in order to quantify the floral shape variation of the standard, wing, and keel between the different lines and control species. Geometric morphometrics analyses were able to distinguish the floral elements at both intra (lines) and inter-specific levels. The present results are on line with the cumulative evidence that supports the Titze line as not being a proper member of the S. toromiro species, but probably a hybridization product or even another species of the Edwardsia section. The reintroduction programs of S. toromiro should consider this information when assessing the authenticity and origin of the lines that will be used to repopulate the island.

Generation of Chloroplast Molecular Markers to Differentiate Sophora toromiro and Its Hybrids as a First Approach to Its Reintroduction in Rapa Nui (Easter Island)

“…The main issue that arises to begin the reintegration of the species into the island is the existence of several hybrid lines of Sophora, being the Titze line (S. toromiro × S. microphylla) [8,12] the most common of the hybrids. S. microphylla, introduced from New Zealand into cultivation, and S. toromiro are genetically very similar and readily hybridise [13,14].…”

Explaining Intricate Morphometric Variability with Environmental Predictors: The Case of Globularia cordifolia Species Complex

“…We used generalized procrustes analysis (GPA) as a superimposition method, considering the objects as symmetric [82]. GPA is an established procedure for analysis of 2D and 3D shapes, which has been widely applied to plants in the last years [83][84][85][86][87][88]. Although objects such as leaves can be analyzed also by means of elliptical Fourier analysis [89], we decided that a landmark approach was more suited to detect possible subtle changes with potential diagnostic value, such as those considering the morphology of leaf apex.…”

Quantifying the Geometric Shell Shape between Populations of True Limpets Lottia Mesoleuca (Mollusca: Lottidae) in Colombia

“…To establish if there were differences between the means of the population shapes, the Procrustes distances between groups were used extracted from a canonical variate analysis [45] performed in the software MorphoJ 1.06d [46]. The significance of pairwise comparisons is established by means of Bonferroni's adjustment, which is calculated with the likelihood of getting a significant result equivalent to 95%, in the number of possible combinations [47].…”