Evolutionary importance of the relationship between cytogeography and climate: New insights on creosote Bushes from North and South America

ROMINA VIDAL-RUSSEL; M. TADEY.; URFUSOVÁ, ROMANA; URFUS, TOMÁ; SOUTO C. P.

Plant Diversity

Elsevier

Año: 2022

2096-2703

Relationships between genome size and environmental variables suggest that DNAcontent might be adaptive and of evolutionary importance in plants. The genus Larreaprovides an interesting system to test this hypothesis, since it shows both intra- andinterspecific variation in genome size. Larrea has an amphitropical distribution inNorth and South American deserts, where it is most speciose. Larrea tridentata inNorth America shows a gradient of increasing auto polyploidy; while three of the fourstudied South American species are diploids, L. divaricata , L. nitida , L. ameghinoi, and the fourth is an allopolyploid, L. cuneifolia . We downloaded available focalspecies? georeferenced records from seven data reservoirs. We used these records toextract biologically relevant environmental variables from WorldClim at 30 arcsecondsscale, to have a broad characterization of the variable climatic conditions of bothregions, and a climatic envelope for each species. We estimated relative DNA contentindex and relative monoploid genome values, by flow cytometry, of four most abundantLarrea species throughout their respective ranges. Then we winnow the bioclimaticdataset down to uncorrelated variables and sampled locales, to analyse the degree ofassociation between both intra- and interspecific relative DNA content and climaticvariables that are functionally relevant in arid environments using Pearson correlations,general linear and mixed effects models. Within the genus Larrea , relative DNAcontent increases with rising temperature and decreases with rising precipitation. Atthe intraspecific level, all four species show relative DNA content variation acrossclimatic conditions. Larrea is a genus that shows genome size variation correlatedwith climate. Our results are also consistent with the hypothesis that extremeenvironmental pressures may have facilitated repeated whole genome duplicationevents in North America, while in South America, reticulate evolution, asallopolyploidization, and speciation might have been climate-dependent since theOligocene.