Biology subjects

Nuerk, N. M.

Publications and source records attributed to Nuerk, N. M..

3 recordsLinked to original sources

bioRxiv2024

Different resource partitioning explains plant species richness patterns in tropical alpine ecosystems

Species co-existence based on resource partitioning modulates biodiversity patterns across latitudes and altitudes. Resource partitioning can occur via specialisation or separation in the geographic range or niche. Here, we compare two tropical alpine ecosystems with similar climates to test for geographic range and climatic niche partitioning strategies in explaining species richness difference. We compare the species-rich tropical alpine ecosystem in the South American Andes with the more species-poor one in the eastern African mountains. We combine phylogenomic data for three locally diversified plant lineages in each region with occurrence records and estimate climatic niche and geographic range metrics (size and overlap). We found that the Andean species have overall larger niches than the African species, thus smaller niches indicating specialisation is not the explanation for the higher species richness in the Andes. Instead, for species with overlapping geographic ranges, we found that the Andean species tend to show less niche overlap than the African species, indicating more effective niche separation. Taken together, we propose that different degrees of niche separation in geographically overlapping species, and hence, a different pattern of resource partitioning, explain the differences in species richness between the two tropical alpine ecosystems.

ecology↗

bioRxiv2019

Phylogenetic relationships in the southern African genus Drosanthemum (Ruschioideae, Aizoaceae)

BackgroundDrosanthemum, the only genus of the tribe Drosanthemeae, is widespread over the Greater Cape Floristic Region in southern Africa. With 114 recognized species, Drosanthemum together with the highly succulent and species-rich tribe Ruschieae constitute the core ruschioids in Aizoaceae. Within Drosanthemum, nine subgenera have been described based on flower and fruit morphology. Their phylogenetic relationships, however, have not yet been investigated, hampering understanding of monophyletic entities and patterns of geographic distribution.\n\nMethodsUsing chloroplast and nuclear DNA sequence data, we performed network- and tree-based phylogenetic analyses of 73 species represented by multiple accessions of Drosanthemum. A well-curated, geo-referenced occurrence data set comprising the phylogenetically studied and 867 further accessions was used to describe the distributional ranges of intrageneric lineages and the genus as a whole.\n\nResultsPhylogenetic inference supports nine clades within Drosanthemum, seven of them group in two major clades, while the remaining two show ambiguous affinities. The nine clades are generally congruent to previously described subgenera within Drosanthemum, with exceptions such as (pseudo-) cryptic species. In-depth analyses of sequence patterns in each gene region revealed phylogenetic affinities not obvious in the phylogenetic tree. We observe a complex distribution pattern including widespread, species-rich clades expanding into arid habitats of the interior (subgenera Drosanthemum p.p., Vespertina, Xamera) that are molecular and morphologically diverse. In contrast, less species-rich, molecularly less divergent, and morphologically unique lineages are restricted to the central Cape region and more mesic conditions (Decidua, Necopina, Ossicula, Quastea, Quadrata, Speciosa). Our results suggest initial rapid radiation generating the main lineages, with some clades showing subsequent diversification.

evolutionary biology↗

bioRxiv2018

Leaps and bounds: geographical and ecological distance constrained the colonisation of the Afrotemperate by Erica

AO_SCPCAPBSTRACTC_SCPCAPThe coincidence of long distance dispersal and biome shift is assumed to be the result of a multifaceted interplay between geographical distance and ecological suitability of source and sink areas. Here, we test the influence of these factors on the dispersal history of the flowering plant genus Erica (Ericaceae) across the Afrotemperate. We quantify similarity of Erica climate niches per biogeographic area using direct observations of species, and test various colonisation scenarios while estimating ancestral areas for the Erica clade using parametric biogeographic model testing. We infer that the overall dispersal history of Erica across the Afrotemperate is the result of infrequent colonisation limited by geographic proximity and niche similarity. However, the Drakensberg Mountains represent a colonisation sink, rather than acting as a \"stepping stone\" between more distant and ecologically dissimilar Cape and Tropical African regions. Strikingly, the most dramatic examples of species radiations in Erica were the result of single unique dispersals over longer distances between ecologically dissimilar areas, contradicting the rule of phylogenetic biome conservatism. These results highlight the importance of rare biome shifts, in which a unique dispersal event fuels evolutionary radiation.\n\nThis article has been peer-reviewed and recommended by: Peer Community in Evolutionary Biology (DOI: 10.24072/pci.evolbiol.100065)

evolutionary biology↗