A lizard with two tales: what diversification within Sceloporus occidentalis teaches us about species formation

In 1859, Charles Darwin proposed that species are not fundamentally different from subspecies or the varieties from which they evolve. A century later, Dobzhansky (1958) suggested that many such lineages are ephemeral and are likely to revert differentiation through introgression (Fig. 1A); only a few evolve complete reproductive isolation and persist in sympatry. In this issue of Molecular Ecology, Bouzid et al. (2021) show how new analytical methods, when applied to genome data, allow us to more precisely determine whether or not species formation follows the paths outlined by Darwin and Dobzhansky (Fig. 1B). The authors study the diversification of the lizard Sceloporus occidentalis, finding a continuum of genetic interactions between the preservation of genetic identity to genetic merger, analogous to what is exemplified by ring species. In doing so, they teach us two tales on species formation: that lineages are fractal byproducts of evolutionary processes such as genetic drift and selection, and that lineages are often ephemeral and do not always progress into species. Studying ephemeral lineages like those in S. occidentalis allows us to capture divergence at its earliest stages, and potentially to determine the factors that allow lineages to remain distinct despite pervasive gene flow. These lineages thus serve as a natural laboratory to address long standing hypotheses on species formation.

Temporal and vertical variations of polycyclic aromatic hydrocarbon at low elevations in an industrial city of southern Taiwan

Considered that human activities mostly occur below building heights, the objective of this study was to investigate the temporal variations of fine particular matter (PM2.5)-associated polycyclic aromatic hydrocarbons (PAHs) and benzo[a]pyrene-equivalent (BaPeq) concentrations at four different elevations (6.1, 12.4, 18.4, and 27.1 m) in Kaohsiung City, the largest industrial city of southern Taiwan. Temperature variation was critical for the PM2.5-associated PAH concentrations, which were dominated by benzo[g,h,i]perylene (0.27 ± 0.04 ng m−3 and 24.43% of the total concentration) and other high molecular weight (HMW) species. The PM2.5-associated BaPeq was dominated by 5-ring PAH (36.09%). The PM2.5-associated PAH and BaPeq concentrations at all elevations were significantly increased in winter. In the night, the correlations between the PM2.5-associated PAH concentrations and atmospheric temperatures became negatively stronger, notably at lower elevations (r = − 0.73 ~ − 0.86), whereas the BaPeq during daytime and nighttime were not changed significantly in most months. The PAHs analysis with different PM sizes demonstrated the importance of smaller particles such as PM2.5. The meteorological variation was more important than elevation to influence the low-elevation PM2.5-associated PAH and BaPeq concentrations in an urban area like Kaohsiung City, as the two concentrations were dominated by the PAHs with HMWs and those 5-ring species, respectively.

Geographic Patterns In Pollen Production In The Plant Ring Species Euphorbia tithymaloides In The Caribbean

Abstract—We examine investment in male function in the context of geography and floral morphology in the plant ring species Euphorbia tithymaloides, which colonized the Caribbean from Mexico/Guatemala along two fronts that roughly correspond to the Greater and the Lesser Antilles and that meet in the vicinity of the Anegada Passage. Our results on investment in pollen relative to ovule production are consistent with E. tithymaloides relying on pollinators for reproduction across its range in the Caribbean. We document a geographic pattern of reduction in anther number and pollen:ovule ratios in populations of E. tithymaloides towards the Anegada Passage, which is consistent with a possible geographic transition towards a mixed breeding system where selfing has increased importance in this area where its two expansion fronts meet. The reduction in pollen production is correlated with inflorescence morphology, which converges to relatively shorter cyathia towards the Anegada Passage along both fronts. We discuss alternative scenarios and potential drivers of the patterns we document.

Newer Developments in the Synthesis of P-Heterocycles

The P-heterocyclic field forms a special part of organophosphorus chemistry, and is a special discipline within heterocyclic chemistry. The relevant results accumulated in the group of the author of this minireview in last 5 years are summarized. After surveying the conformational situation of cyclic phosphinates, their Microwave (MW)-assisted direct esterification and the T3P®-promoted esterification are discussed. The next chapters describe newer results regarding the interpretation and modelling of the rate enhancing effect of MWs, and on an important, but somewhat neglected field, the hydrolysis of phosphinates. New results on the ring enlargement of 5-membered unsaturated P-heterocycles to 6-ring species, as well as on the synthesis of 7-phosphanorbornene derivatives, and their refunctionalization are also included. Novel findings on the preparation of cyclic amides and imides are also explored. Last but not least, the user-friendly deoxygenations of cyclic phosphine oxides elaborated by us are shown. The reader will be able to discover green chemical considerations and accomplishments throughout the series of organophosphorus transformations reviewed.

Synthesis, detailed geometric analysis and bond-valence method evaluation of the strength of π-arene bonding of two isotypic cationic prehnitene tin(II) complexes: [{1,2,3,4-(CH3)4C6H2}2Sn2Cl2][MCl4]2 (M = Al and Ga)

From solutions of prehnitene and the ternary halides (SnCl)[MCl4] (M = Al, Ga) in chlorobenzene, the new cationic SnII–π-arene complexes catena-poly[[chloridoaluminate(III)]-tri-μ-chlorido-4′:1κ2 Cl,1:2κ4 Cl-[(η6-1,2,3,4-tetramethylbenzene)tin(II)]-di-μ-chlorido-2:3κ4 Cl-[(η6-1,2,3,4-tetramethylbenzene)tin(II)]-di-μ-chlorido-3:4κ4 Cl-[chloridoaluminate(III)]-μ-chlorido-4:1′κ2 Cl], [Al2Sn2Cl10(C10H14)2] n , (1) and catena-poly[[chloridogallate(III)]-tri-μ-chlorido-4′:1κ2 Cl,1:2κ4 Cl-[(η6-1,2,3,4-tetramethylbenzene)tin(II)]-di-μ-chlorido-2:3κ4 Cl-[(η6-1,2,3,4-tetramethylbenzene)tin(II)]-di-μ-chlorido-3:4κ4 Cl-[chloridogallate(III)]-μ-chlorido-4:1′κ2 Cl], [Ga2Sn2Cl10(C10H14)2] n , (2), were isolated. In these first main-group metal–prehnitene complexes, the distorted η6 arene π-bonding to the tin atoms of the Sn2Cl2 2+ moieties in the centre of [{1,2,3,4-(CH3)4C6H2}2Sn2Cl2][MCl4]2 repeating units (site symmetry \overline{1}) is characterized by: (i) a significant ring slippage of ca 0.4 Å indicated by the dispersion of Sn—C distances [1: 2.881 (2)–3.216 (2) Å; 2: 2.891 (3)–3.214 (3) Å]; (ii) the non-methyl-substituted arene C atoms positioned closest to the SnII central atom; (iii) a pronounced tilt of the plane of the arene ligand against the plane of the central (Sn2Cl2)2+ four-membered ring species [1: 15.59 (11)°, 2: 15.69 (9)°]; (iv) metal–arene bonding of medium strength as illustrated by application of the bond-valence method in an indirect manner, defining the π-arene bonding interaction of the SnII central atoms as s(SnII—arene) = 2 − Σs(SnII—Cl), that gives s(SnII—arene) = 0.37 and 0.38 valence units for the aluminate and the gallate, respectively, indicating that comparatively strong main-group metal–arene bonding is present and in line with the expectation that [AlCl4]− is the slightly weaker coordinating anion as compared to [GaCl4]−.