Patterns of ferns community assemblages in some Malaysian and Nigerian tropical forests

Research on fern ecology has gained attention in the last decade, yet
there is a paucity of information on the comparison of ferns communities
across continents. This study focused on comparing the ferns community
assemblages in some tropical forests of Malaysia and Nigeria, thereby
assessing the patterns of species richness (SR) and phylogenetic
diversity(PD) in relation to the bioclimatic drivers across the
continents. The diversity and taxonomic compositions of ferns were
assessed using 180 plots of 10 m x 10 m in each country. The species
richness and other diversity indices were determined using the combined
forests data for each country and for the individual forests. Also, the
phylogenetic diversity of the ferns was assessed using the genus-based
molecular sequences downloaded from the GeneBank. The patterns of the
ferns SR and PD in the two countries as driven by some bioclimatic factors
were evaluated using the regression analysis. The observed and
rarefied–extrapolated fern species richness is significantly higher in
Malaysian forests than in Nigerian forests. Also, the other diversity
indices are significantly higher in Malaysian forests except for the
Shannon index which showed no significant difference between the two
biogeographic regions. There is a very low similarity (7.41%) in the
taxonomic composition of ferns between the two biogeographic areas,
although the similarity in composition increased with increasing taxonomic
levels (species: 7.41%, genus: 12.77%, family: 70.96%). Terrestrial and
epiphytic ferns are more dominant than the other life forms in the two
countries. The precipitation variables drive the phylogenetic structure of
ferns in Nigeria whereas both precipitation and temperature variables
drive the phylogenetic structure of ferns in Malaysia. This indicates that
ferns assemblages in Nigeria and Malaysia are driven by both climatic
variables. Besides, we also hypothesize that these observed differences
could be due to other historical and evolutionary processes.

近十年来，蕨类生态学研究逐渐受到学界关注，但目前针对跨大陆蕨类群落的对比研究仍存在信息匮乏的问题。
本研究聚焦对比马来西亚与尼日利亚部分热带森林中的蕨类群落组成，借此评估两大洲间物种丰富度（SR）与系统发育多样性（PD）随生物气候驱动因子的变化格局。
研究通过在两国各布设180块10 m × 10 m的样地，对蕨类的多样性与分类学组成开展调查。基于两国及各单一森林的联合样地数据，计算得到物种丰富度及其他多样性指数；同时依托从基因银行（GenBank）下载的属级分子序列，评估蕨类的系统发育多样性。
本研究采用回归分析，探究两国蕨类的物种丰富度与系统发育多样性受部分生物气候因子的驱动格局。结果显示，马来西亚森林中观测到的及经稀化-外推法校正的蕨类物种丰富度，均显著高于尼日利亚森林。除香农指数（Shannon index）在两大生物地理区域间无显著差异外，马来西亚森林的其余多样性指数均显著更高。
两大生物地理区域的蕨类分类学组成相似度极低（7.41%），但随着分类层级提升，组成相似度逐渐升高：物种水平为7.41%，属水平为12.77%，科水平为70.96%。两国的陆生与附生蕨类均为优势生活型，占比高于其他蕨类生活型。
在尼日利亚，降水变量主导蕨类的系统发育结构；而在马来西亚，降水与温度变量共同驱动蕨类的系统发育结构。这表明尼日利亚与马来西亚的蕨类群落组成均受气候变量调控。
此外，本研究还提出假说：观测到的群落差异可能还与其他历史与进化过程相关。