Incipient sympatric speciation in wild barley caused by geological-edaphic divergence

Abstract

Sympatric speciation (SS) has been contentious since the idea was suggested by Darwin. Here, we show in wild barley SS due to geologic and edaphic divergence in “Evolution Plateau,” Upper Galilee, Israel. Our whole genome resequencing data showed SS separating between the progenitor old Senonian chalk and abutting derivative young Pleistocene basalt wild barley populations. The basalt wild barley species unfolds larger effective population size, lower recombination rates, and larger genetic diversity. Both species populations show similar descending trend ∼200,000 yr ago associated with the last glacial maximum. Coalescent demography analysis indicates that SS was local, primary, in situ, and not due to a secondary contact from ex situ allopatric population. Adaptive divergent putatively selected genes were identified in both populations. Remarkably, disease resistant genes were selected in the wet basalt population, and genes related to flowering time, leading to temporal reproductive isolation, were selected in the chalk population. The evidence substantiates adaptive ecological SS in wild barley, highlighting the genome landscape during SS with gene flow, due to geologic-edaphic divergence.

Differential expressions of anthocyanin synthesis genes underlie flower color divergence in a sympatric Rhododendron sanguineum complex

“…This situation may initiate a shift in pollinator assembly and reproductive isolation consequently be reinforced over time. Our study may thus demonstrate an incipient sympatric speciation pattern induced by flower color differentiation, as has been observed for birds by behavioral isolation [65], and in plant species by geology-edaphic divergence [66], or geographic variation [67].…”

Sympatric speciation of the spiny mouse from Evolution Canyon in Israel substantiated genomically and methylomically

“…Sympatric speciation (SS) is still debated, although there are numerous theoretical and empirical studies supporting it ( 1 – 5 ). There are four criteria supporting SS traditionally, including 1) living entirely or largely sympatric; 2) substantial reproductive isolation between the sister species, preferentially based on genetic difference; 3) the species should be sister groups; and 4) they are diverging from the same ancestor without an allopatric history ( 6 ).…”

Incipient Sympatric Speciation and Evolution of Soil Bacteria Revealed by Metagenomic and Structured Non-Coding RNAs Analysis

“…Our previous studies identified numerous SS events in EC and EP. Several SS across life, from bacteria to mammals, have been identified at EC, including the soil bacterium Bacillus simplex [ 32 ], Hordeum spontaneum [ 37 ], wild emmer wheat [ 88 ], Triticum dicoccoides [ 89 ], crucifer Ricotia Lunaria [ 90 ], Oryzaphilus surinamensis [ 91 ], etc. Similarly, several SS cases were identified from the EP [ 24 , 25 , 39 , 40 ], which was suggested to be an SS hotspot [ 92 ].…”

“…Thus, basalt is generally acidic, while chalk is slightly alkaline [ 36 ]. Such contrasting ecologies without any physical barriers lead to population divergences with gene flow, including bacteria [ 32 ], wild barley [ 37 ], and blind mole rat [ 24 , 25 , 31 , 38 , 39 , 40 , 41 ]. This present study demonstrated that the bacterial community composition has significantly diverged between the chalk and basalt soil types.…”