Recurrent origin of peripheral, coastal (sub)species in MediterraneanSenecio(Asteraceae)

Abstract

Background: It is argued that coastal endemic taxa may evolve in parallel at the periphery of the distributional range of a widespread species. Aims: We tested this hypothesis for the origins of three peripheral, coastal isolates of Senecio, S. glaucus ssp. glaucus (Israel), S. g. ssp. coronopifolius p.p. (Sicily), and S. hesperidium (Morocco), from widespread S. glaucus ssp. coronopifolius. We also determined the relative roles of selection vs. genetic drift in shaping phenotypic divergence in ssp. glaucus and S. hesperidium, using Lande's test of neutral morphological change. Methods: We surveyed morphological and/or allozyme variation in the three peripheral isolates and mainly inland populations of S. g. ssp. coronopifolius. Results: Genetic data supported independent origins of the coastal taxa from nearby populations of ssp. coronopifolius. These descendant and ancestral populations showed pronounced morphological but weak genetic differentiation. Phenotypic similarities between ssp. glaucus (Israel) and S. hesperidium (Morocco) in plant height and floral traits may have resulted from parallel divergent selection from ssp. coronopifolius, though drift remains an alternative cause in S. hesperidium. Conclusions: Our results indicate parallel ecotype formation and (sub)speciation in Senecio in which primarily selective vs. neutral determinants promoted the recurrent origin of coastal types in, respectively, Israel and Morocco.

Molecular signatures of parallel adaptive divergence causing reproductive isolation and speciation across two genera

“…Past reports of PERI in both animals and plants have focused on different populations of a single species or closely related species within a species complex. 5 , 11 , 37 , 38 , 39 , 40 , 41 , 42 , 43 To demonstrate PERI, it is necessary to distinguish multiple independent origins of RI caused by the same type of strong divergent natural selection, from RI owing to introgression and/or sorting of ancestral adaptive polymorphisms. 44 If introgression and sorting of ancestral polymorphisms can be ruled out, as should be the case when dealing with PERI across different reproductively isolated genera, it becomes easier to prove that natural selection is the driver of replicated divergence and RI.…”

Senecio as a model system for integrating studies of genotype, phenotype and fitness

“…). Among the numerous recorded radiations within Senecio there is evidence of local adaptation (Walter et al , ), parallel evolution (Roda et al , ; Comes et al , , ), polyploidy (Alexander, ; Chapman & Abbott, ), introgressive hybridization (Kim et al , ; Osborne et al , ), hybrid speciation (James & Abbott, ; Hegarty et al , ), and apparently stable hybrid zones (Brennan et al , ; Abbott et al , ).…”

“…Current research using S. lautus is exploring the molecular basis of auxin and gravity responses (Wilkinson et al , ). Within Senecio , the parallel evolution of traits across populations occurs in many other species; for example, nickel (Ni) accumulation in Senecio coronatus (Meier et al , ) and ecotype formation in Mediterranean Senecio (Comes et al , ). The existence of multiple adaptive radiations in Senecio , each involving adaptation to similar or contrasting environmental stresses, highlights the potential of the genus to understand the ecological genetics of adaptation and speciation.…”

Inter-primer binding site (iPBS) markers reveal the population genetic diversity and structure of tropical climbing Cissampelopsis (Asteraceae) in Thailand

“…The population genetic variation and structure estimation at the molecular level is available (Minn et al 2015;Grover and Sharma 2016;Allendorf 2017;Amom and Nongdam 2017;Comes et al 2017;Nadeem et al 2018), for several different markers, but only a few dominant markers are most regularly used, such as Randomly Amplified Polymorphic DNA (RAPD), Inter-Simple Sequence Repeats (ISSR), and Amplified Fragment Length Polymorphism (AFLP) (Suratman et al 2015;Grover and Sharma 2016;Al-Naggar et al 2017;Bidyaleima et al 2019;Amom et al 2020). Despite that, retrotransposon marker method is one of excellent sources of efficient genetic markers (Kalendar et al 2019;Ghonaim et al 2020).…”