Abstract. Srisuwan S, Sungkaew S, Wachrinrat C, Asanok L, Kamyo T, Thinkampheang S, Kachina P, Hermhuk S, Phumphuang W, Yarnvudhi A, Marod D. 2024. Diversity and spatial distribution of Lauraceae tree species in Lower Montane Forest at Doi Suthep-Pui National Park, Northern Thailand. Biodiversitas 25: 3510-3520. Montane forests are characterized by high plant diversity, including a notable representation by the Lauraceae family, which offers a variety of ecological and economic benefits. This study aimed to assess the species diversity, spatial distribution, and habitat suitability of the Lauraceae family in the Doi Suthep-Pui National Park, Northern Thailand. A Generalized Linear Model (GLM) was employed to determine the spatial distribution of the dominant Lauraceae species, whereas the Maximum Entropy (MaxEnt) model was used to assess habitat suitability for key species. A total of 24 species across 10 genera were found. The most species-rich genera were Cinnamomum and Litsea, followed by Cryptocarya, Machilus and Phoebe, and Actinodaphne, Persea, Beilschmiedia, and Neocinnamomum. Habitat suitability for important Lauraceae species was categorized into low-, medium-, and high-potential areas. The elevation and soil organic matter were the most significant factors influencing species abundance. Additionally, soil properties also played a role in species distribution. The spatial distribution of Lauraceae species was primarily influenced by elevation. However, this distribution is also influenced by the interplay between elevation, soil properties, climate, and human activity. Thus, a comprehensive knowledge of these determinants can inform conservation strategies and ensure the long-term viability of Lauraceae populations in montane forests.
Abstract Genome size evolution and its relationship with pollen grain size has been investigated in sweet potato ( Ipomoea batatas ), an economically important crop which is closely related to diploid and tetraploid species, assessing the nuclear DNA content of 22 accessions from five Ipomoea species, ten sweet potato varieties and two outgroup taxa. Nuclear DNA amounts were determined using flow cytometry. Pollen grains were studied using scanning and transmission electron microscopy. 2C DNA content of hexaploid I. batatas ranged between 3.12–3.29 pg; the mean monoploid genome size being 0.539 pg (527 Mbp), similar to the related diploid accessions. In tetraploid species I. trifida and I. tabascana , 2C DNA content was, respectively, 2.07 and 2.03 pg. In the diploid species closely related to sweet potato e.g. I. × leucantha , I. tiliacea , I. trifida and I. triloba , 2C DNA content was 1.01–1.12 pg. However, two diploid outgroup species, I. setosa and I. purpurea , were clearly different from the other diploid species, with 2C of 1.47–1.49 pg; they also have larger chromosomes. The I. batatas genome presents 60.0% AT bases. DNA content and ploidy level were positively correlated within this complex. In I. batatas and the more closely related species I. trifida , the genome size and ploidy levels were correlated with pollen size. Our results allow us to propose alternative or complementary hypotheses to that currently proposed for the formation of hexaploid Ipomoea batatas .
