Related Species Research Articles

Robust discrimination between closely related species of salmon based on DNA fragments.

Closely related species of Salmonidae, including Pacific and Atlantic salmon, can be distinguished from one another based on nucleotide sequences from the cytochrome c oxidase sub-unit 1 mitochondrial gene (COI), using ensembles of fragments aligned to genetic barcodes that serve as digital proxies for the relevant species. This is accomplished by exploiting both the nucleotide sequences and their quality scores recorded in a FASTQ file obtained via Next Generation (NextGen) Sequencing of mitochondrial DNA extracted from Coho salmon caught with hook and line in the Gulf of Alaska. The alignment is done using MUSCLE (Muscle 5.2) (Edgar in Nat Commun 13:6968, 2022), applied to multiple versions of each fragment perturbed according to the nucleobase identification error probabilities underlying the quality scores. The Damerau-Levenshtein distance was used to determine the genetic barcode of the candidate species that is closest to each aligned, perturbed fragment. The "votes" that the sampled fragments cast for the different candidate species are then pooled and converted into identification probabilities, using weights determined by the entropy of the fragment-specific identification probability distributions. This novel approach to quantify the uncertainty associated with measurements made using NextGen Sequencing can be applied to discriminate closely related species, hence to value-assignment for reference materials supporting determinations of the authenticity of seafood, for example, NIST Reference Materials 8256 and 8257 (Coho salmon) (Ellisor et al., 2021).

Conserving saproxylic flagship species by complementing 150 years of natural history with citizen science data—the case of the stag beetles (Lucanidae, Coleoptera) of Portugal

Abstract The use of flagship species in conservation, such as the European Stag Beetle (Lucanus cervus), can positively affect the conservation of other taxonomic or functionally related species. This is especially true for taxonomic groups where the knowledge regarding their distribution and ecology is generally limited, as is the case of insects. This work represents the most accurate and up-to-date publication on the distribution, ecology and environmental niche of the four lucanids found in Portugal. Moreover, it unravels how citizen science initiatives can positively impact conservation planning for flagship species and their taxonomic and functionally related species. Compared to non-citizen science sources, citizen science data increased the known distribution area for all four species (1.6 to 7.2 fold) and confirmed most of the current known species distribution (50.0% to 95.5%). It also expanded the known environmental niche breadth for all species (1.1 to 4.2 fold) and the species suitable modelled habitat (1.1 to 2.1 fold) with very good model performances (AUC > 0.8 and TSS > 0.6). Our results suggest that to improve the conservation of these species, it is paramount to value native forests in Portugal. Management actions to accomplish this might include preserving current native forests and small natural features (such as large old trees) throughout the landscape while simultaneously increasing native forest development. In addition, climate change will affect the species' distribution since all are highly susceptible to specific (bio-)climatic conditions that are expected to change in the next decades. These findings not only enhance our understanding of these species' current distribution but also pave the way for targeted and integrative conservation efforts throughout the country, especially in areas where the (now assessed) ecological niche requirements and habitat availability (either in terms of landscape composition or structure) are met. Guidelines and priorities are discussed on how to implement conservation measures in Portugal following the recently approved European Nature Restoration Law.

Kineococcus halophytocola sp. nov., Isolated from Leaves of Halophyte Sesuvium portulacastrum L.

An aerobic, Gram-stain-positive, motile, coccus-shaped actinomycete, designated strain LSe6-4T, was isolated from leaves of sea purslane (Sesuvium portulacastrum L.) in Thailand and subjected to a polyphasic taxonomic studies. Growth of the strain occurred at temperatures between 15 and 38°C, and with NaCl concentrations 0-13%. The 16S rRNA gene sequences analysis indicated that the strain was most closely related to Kineococcus endophyticus KLBMP 1274T (99.2%), and Kineococcus mangrovi L2-1-L1T (99.0%). The genome of strain LSe6-4T was estimated to be 4.22 Mbp in size, with DNA G+C content of 74.57%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) relatedness values between strain LSe6-4T and the closely related species were less than the threshold values for identifying a novel species. Strain LSe6-4T showed morphological and chemotaxonomic characteristics of the genus Kineocoocus. The whole-cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, with arabinose, galactose, and ribose as whole-cell sugars. The predominant menaquinone was MK-9(H2). The polar lipid profile composed of phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid, three unidentified aminophospholipids, and an unidentified aminolipid. Major cellular fatty acids (> 10% of total fatty acids) were anteiso-C15:0 and iso-C14:0. It is evident from the combination of genotypic and phenotypic characteristics that strain LSe6-4T represents a novel species of the genus Kineococcus, for which the name Kineococcus halophytocola sp. nov. is proposed. The type strain is strain LSe6-4T (= TBRC 17798T = NBRC 116401T).

Diet and trophic structure of fishes in the Barents Sea: between empty and full stomachs - large individual variability follows a common pattern.

More than 27,000 stomachs from 70 species of fish were collected from the Barents Sea in 2015. Quantitative stomach content expressed relative to the body weight of the predator fish (g g-1 as %) varied by four to five orders of magnitude for six species with the largest sample size (Atlantic cod Gadus morhua, haddock Melanogrammus aeglefinus, Greenland halibut Reinhardtius hippoglossoides, long rough dab Hippoglossoides platessoides, polar cod Boreogadus saida, and Atlantic capelin Mallotus villosus). The quantitative stomach contents of individual fish followed a common and strict statistical relationship for predator species or groups of species (by families), and for prey categories across predator species. The common pattern was log-normal-like and was modelled with good fit by different types of right-skewed distributions, that is, variants of the Box-Cox, generalized inverse Gaussian, inverse gamma, or gamma distributions. The long tail in the high end reflects high variation with no clear sign of a plateau, as could be expected from the concept of a "full stomach". This is interpreted to reflect that high stomach contents are rare events that are sampled at low frequencies. The maximum recorded stomach content varied from 1% to 34% of body weight for 55 species of fish, being positively correlated (R2 = 0.45) with sample size. About a third of the stomachs were empty, and the low tail of the log-normal-like distribution represents the transition to empty stomachs. The amount of food in the stomachs was overall low compared to maximum values, with mean and median of 2.0% and 1.1%, respectively, for the 17,873 stomachs containing food. Supported by bioenergetic considerations, this suggests relatively low feeding rates of the various fish predators but sufficient to meet their energy demands.

Scenarios for the emergence of new miRNA genes in the plant Arabidopsis halleri.

MicroRNAs (miRNAs) are central players of the regulation of gene expression in Eukaryotes. The repertoires of miRNA genes vary drastically even among closely related species, indicating that they are evolutionarily labile. However, the processes by which they originate over the course of evolution and the nature of their progenitors across the genome remain poorly understood. Here we analyzed miRNA genes in Arabidopsis halleri, a plant species where we recently documented a large number of species-specific miRNA genes, likely to represent recent events of emergence. Analysis of sequence homology across the genome indicates that a diversity of sources contributes to the emergence of new miRNA genes, including inverted duplications from protein-coding genes, rearrangements of transposable element sequences and duplications of preexisting miRNA genes. Our observations indicate that the origin from protein-coding genes was less common than was previously considered. In contrast, we estimate that almost half of the new miRNA genes likely emerged from transposable elements. Miniature inverted transposable elements (MITE) seem to be particularly important contributors to new miRNA genes, with the Harbinger and Mariner transposable element superfamilies representing disproportionate sources for their emergence. We further analyzed the recent expansion of a miRNA family derived from MuDR elements, and the duplication of miRNA genes formed by two hAT transposons. Overall, our results illustrate the rapid pace at which new regulatory elements can arise from the modification of preexisting sequences in a genome, and highlight the central role of certain categories of transposable elements in this process.

A taxonomic note on Chinese species of the Neolucanus fuscus group with the description of a new species (Coleoptera: Lucanidae: Lucaninae)

In this paper, we describe a new stag beetle species from Yunnan, China, i.e., Neolucanus horizontalis Xin, Zhong & Qi, new species which exhibits significant structural differences in mandible, labial vestiture, protibia and male genitalia compared to related species. We also provide redescription of the male of N. fuscus Didier, 1926 and N. brochieri Bomans & Miyashita, 1997. Neolucans fuscus zhongguo Schenk, 2012 is synonymized with N. fuscus fuscus Didier, 1926. We also present a distribution map and an identification key for the telodont males of the N. fuscus group. Finally, we discuss the species group affiliation of N. baongocae Nguyen, 2013.

Novelties on Vasivaea Baill. (Malvaceae, Grewioideae, Grewieae) for the Colombian flora

A new species of Vasivaea Baill. (Malvaceae, Grewioideae, Grewieae) from central and northwestern Colombia is described, illustrated, and their morphological relationships with related species are discussed. Vasivaea distopo is a tree up to 20 m tall, common in floodplain lowland forests (20–220 m elev.) located in the middle Magdalena, the lower Cauca, Nechí, and Atrato river basins. It is characterized by its tubular androgynophore with free lobes in staminate flowers and obcordate fruit shape. Vasivaea distopo represents the first species of this genus recorded from outside the Amazon, Essequibo, and Orinoco River basins. Geographical and phenological information, data about its conservation status, and an updated key to species are presented.

Comparative analysis of the WRKY gene family between Chimonanthus praecox and C. salicifolius.

Gene duplications provide evolutionary potentials for generating novel functions. Chimonanthus praecox and C. salicifolius are closely related species from Calycantaceae, Magnoliids. In this study, we compared the WRKY gene family from C. praecox and C. salicifolius, and predicted the potential gene function through gene expression patterns to explore the evolution of orthologous and paralogous gene pairs. A total of 73 and 85 WRKY genes were identified and analyzed from the whole genome sequencing of C. praecox and C. salicifolius. Based on the phylogenetic analysis, CpWRKY and CsWRKY genes were clustered into three groups (Group I、II、III) and 5 subgroups (Group IIa、IIb、IIc、IId、IIe). In C. praecox and C. salicifolius, we identified thirty-six and fifty-four pairs of WRKY segmental duplicated genes, respectively, along with two and three pairs of tandem duplicates, indicating that segmental duplication plays a crucial role in the evolution of Chimonanthus WRKY gene family. Most WRKY duplication gene pairs originated from segmental duplications before the first whole genome duplication (WGD), highlighting this period as a significant source of genetic diversity and functionality for the WRKY family. The analysis of WRKY gene expression levels suggests that CsWRKY18 and CsWRKY68 may promote the growth of the roots in C. salicifolius. Comparisons of expression profiles between species revealed that five orthologous gene pairs presented identical expression trends, indicating functional conservation and absence of neo-functionalization or sub-functionalization. However, most orthologous gene pairs exhibit differences in expression patterns, suggesting that they have undergone functional divergence. This functional differentiation may be due to the different selective pressures faced by C. praecox and C. salicifolius during their speciation processes. This study provided detailed information on the WRKY gene family from C. praecox and C. salicifolius, and a new insight for studying gene duplication and function evolution.

Integrative taxonomic study of Coccoloba gracilis (Polygonaceae) and C. ruiziana from Amotape–Huancabamba neotropical biodiversity hotspot

Abstract Accurate species delimitation is necessary to estimate species diversity. However, species delimitation remains challenging in the poorly studied Coccoloba genus in the northern Andes. Coccoloba gracilis and C. ruiziana are endemic related species inhabiting dry seasonal tropical forest of the Amotape–Huancabamba zone in Ecuador and Peru. The identity of C. ruiziana is widely recognized. However, some information about C. gracilis is missing and its identity has not been thoroughly checked by previous authors. We used morphological, phylogenetic, and ecological data in a robust methodological approach to investigate species boundaries. We studied 251 specimens from 17 herbaria, representing the entire distribution range of this species. Morphometric analysis suggested significant differentiation of multiple traits. Our phylogeny recovered Coccoloba gracilis related to C. ruiziana but with low statistical support. The results of ecological niche models showed a low levels of niche overlap between them. Our results support the recognition of two distinct species. Coccoloba gracilis Kunth emend. Arnelas mut. char., distributed in semi-deciduous, montane low forest and first rediscovered in Ecuador, and C. ruiziana, distributed at lower altitudes in lowland, dry seasonal tropical forest. Descriptions, photographs, and nomenclature notes are provided. One second-step lectotypification and one epitype for C. gracilis are provided.

Paraplaconeis dorofeyukae sp. nov. (Cymbellales, Bacillariophyceae)—a new species from Mongolia, described based on molecular and morphological investigations

An unknown species of the diatom genus Paraplaconeis was discovered during a field study of freshwater environments in Central Mongolia. In the course of further study, two monoclonal strains were acquired for the unknown species. The strains were utilized for molecular-genetic analysis on SSU rRNA and rbcL genes. As a result of the molecular investigation and careful morphological examination of valve structure with light and scanning electron microscopy, we propose the description of a new species—Paraplaconeis dorofeyukae sp. nov.—in this article. The new species is morphologically compared to similar taxa from the Paraplaconeis placentula group. Paraplaconeis dorofeyukae sp. nov. can be distinguished from related species by a combination of valve dimensions, morphology of apices and central area, and external valve ultrastructure.

Identification of Proteoforms Related to Nelumbo nucifera Flower Petaloid Through Proteogenomic Strategy

Nelumbo nucifera is an aquatic plant with a high ornamental value due to its flower. Despite the release of several versions of the lotus genome, its annotation remains inefficient, which makes it difficult to obtain a more comprehensive knowledge when –omic studies are applied to understand the different biological processes. Focusing on the petaloid of the lotus flower, we conducted a comparative proteomic analysis among five major floral organs. The proteogenomic strategy was applied to analyze the mass spectrometry data in order to dig out novel proteoforms that are involved in the petaloids of the lotus flower. The results revealed that a total of 4863 proteins corresponding to novel genes were identified, with 227 containing single amino acid variants (SAAVs), and 72 originating from alternative splicing (AS) genes. In addition, a range of post-translational modifications (PTMs) events were also identified in lotus. Through functional annotation and homology analysis with 24 closely related plant species, we identified five candidate proteins associated with floral organ development, which were not identified by ordinary proteomic analysis. This study not only provides new insights into understanding the mechanism of petaloids in lotus but is also helpful in identifying new proteoforms to improve the annotation of the lotus genome.

A Real-Time PCR Assay for Detecting Codling Moth Cydia pomonella on Material Intercepted at U.S. Ports of Entry—A Valuable Tool for Specimen Identification

Codling moth Cydia pomonella is well established nearly everywhere apples are grown. Due to this almost global distribution, larvae are often intercepted at U.S. ports of entry where immature specimens cannot be identified accurately to species leading to unnecessary quarantine actions. To assist with identifying intercepted C. pomonella from port inspections, we developed a probe-based real-time PCR assay to amplify the internal transcribed spacer (ITS) region 2 of C. pomonella. The assay was tested for inclusivity using 110 C. pomonella specimens from six continents. Analytical specificity was examined by testing related species intercepted at U.S. ports of entry, as well as non-targets with the same geographic distribution and host species as C. pomonella. The assay developed here identified all C. pomonella individuals correctly and produced appropriately negative results for all non-target species. These results ensure that the assay provides a rapid and accurate tool for unambiguously identifying C. pomonella among material intercepted at U.S. ports of entry. Since C. pomonella is not actionable, the ability to identify all life stages of C. pomonella conclusively will save time, effort, and money while also directing identification efforts towards species of current quarantine concern.

Functional genomics implicates ebony in the black pupae phenotype of tephritid fruit flies

The remarkable diversity of insect pigmentation offers a captivating avenue for studying evolution and genetics. In tephritids, understanding the molecular basis of mutant traits is also crucial for applied entomology, enabling the creation of genetic sexing strains through genome editing, thus facilitating sex-sorting before sterile insect releases. Here, we present evidence from classical and modern genetics showing that the black pupae (bp) phenotype in the GUA10 strain of Anastrepha ludens is caused by a large deletion at the ebony locus, removing the gene’s entire coding region. Targeted knockout of ebony induced analogous bp phenotypes across six major tephritid agricultural pests, demonstrating that disruption of Ebony alone is sufficient to produce the mutant trait in distantly related species. This functional characterization further allowed a deeper exploration of Ebony’s role in pigmentation and development across life stages in diverse species. Our findings offer key insights for molecular engineering of sexing strains based on the bp marker and for future evolutionary developmental biology studies in tephritids.

Complete chloroplast genome of the marine eelgrass Zostera pacifica (Zosteraceae, Plantae) from Monterey, California.

We present the complete chloroplast genome of the eelgrass Zostera pacifica from Monterey, California. The genome is circular and 144,675 bp in length. It consists of 82 protein-coding, 31 transfer RNA, and 8 ribosomal RNA genes and is 99.44%-99.42% similar in nucleotide pairwise identity to the closely related species Zostera marina.

Development of a qPCR assay for early detection and quantification of Phytopythium vexans in kiwifruit plant and soil affected by Vine Decline Syndrome.

Kiwifruit Vine Decline Syndrome (KVDS) is a soilborne disease affecting Actinidia fruit trees in perennial cropping systems. Since its emergence in 2012, studies have increasingly identified the oomycete Phytopythium vexans as a major causative agent of the disease. P. vexans is also implicated in complex soilborne disease systems of woody perennial crops, including replant disease in apple and pear. To date, most molecular assays for the detection of P. vexans target the nuclear ribosomal internal transcribed spacer (ITS), a region which is ill-suited for distinguishing between closely related oomycete species. The cytochrome oxidase subunit I (COI) mitochondrial gene was targeted for the design of new primers because it was previously identified as a better marker for differentiating oomycete species. The FOR2/REV4RCA primer pair gave the best results regarding PCR specificity and was selected for use in a SYBR Green-based qPCR assay. The specificity of the qPCR assay was evaluated using 29 P. vexans strains (including different phylogenetic groups) as well as a wide variety of closely related off-target species associated with pathogenic soil communities of fruit trees. P. vexans strains were successfully quantified down to 20 fg in water and in DNA extracted from kiwifruit roots. P. vexans was also detected in artificially inoculated Actinidia plant roots as well as in a variety of naturally infected field samples of both kiwi and apple trees. These results suggest that the qPCR assay developed in this study is highly sensitive and specific to target pathogen, regardless of sample matrix.

Utilization of oocytes from closely related domestic species for interspecies somatic cell nuclear transfer in gaur embryo production

Context The limited availability of recipient oocytes poses significant challenges in increasing the population of endangered species. Aims This study demonstrates the use of oocytes from closely related domestic species (cattle, buffalo, and goat) in the production of gaur embryos via interspecies somatic cell nuclear transfer (iSCNT). The developmental abilities of embryos from various combinations – gaur–bovine, gaur–buffalo, gaur–goat, and others – are analyzed. Previous achievements are retrospectively reviewed and summarized. Methods The methodologies for iSCNT and in vitro gaur embryo production are outlined. Key results Blastocyst rates among gaur–bovine, gaur–buffalo, and gaur–goat embryos showed no significant differences (P < 0.05). Gaur–bovine embryo development was comparable to intraspecies embryos (bovine–bovine), indicating successful developmental compatibility. Pregnancy rates after transferring gaur–bovine embryos were reported for the first time, with rates of 4.76%, 42.86%, 19.05% and 4.76% at Days 45, 60, 90 and 120, respectively. Conclusions Bovine, buffalo, and goat oocyte cytoplasm is effective for producing gaur iSCNT embryos, capable of initiating early pregnancies. Implications Laboratory techniques and methodologies can save costs and time, contributing to the conservation of endangered species.

Diploid Ancestor Tracing of Allopolyploid Cultivars in Camellia reticulata Based on ITS and RPB2 Sequences

Camellia reticulata is a well-known ornamental species with a type specimen that is an allohexaploid, possibly descended from diploid ancestors like C. saluenensis, C. pitardii, and diploid C. reticulata. With over 1500 years of cultivation, heritage C. reticulata cultivars show varied ploidy levels, including hexaploid, octoploid, and decaploid forms, though their diploid ancestors are still unidentified. This study aims to trace these diploid ancestors by cloning and sequencing ITS from 25 taxa and RPB2 from 21 taxa across various ploidy levels of C. reticulata and its traditional cultivars and related species, combined with their fruit morphology data. Analyses of the ITS and RPB2 sequences suggest that the diploid ancestors of C. reticulata and its traditional cultivars may include C. saluenensis, C. pitardii, and diploid C. reticulata, while excluding C. mairei and C. polyodonta. Morphological analysis showed that diploid C. reticulata has significantly larger fruit weight, diameter, and pericarp thickness compared to C. pitardii, C. saluenensis, and both tetraploid and hexaploid C. reticulata. Since diploid ancestors of allopolyploids are often classified as distinct taxa, we suggest that diploid C. reticulata be recognized as a new variety of C. pitardii, as its ITS sequences are closely aligned with C. pitardii. This study offers key insights into the origin, evolution, and breeding of C. reticulata.

Conspicuous Animals Remain Alert When Under Cover but Do Not Differ in the Temporal Course of Vigilance from Less Conspicuous Species

Conspicuousness increases the risk of predation. One strategy to reduce this risk is to increase vigilance. We investigated the frequency of head movements as a measure of vigilance at waterholes in two related songbird species that differed in their conspicuousness: the Gouldian finch and the long-tailed finch. While both species showed a high frequency of head movements (high vigilance) when sitting in an open tree, the more colourful Gouldian finch remained more vigilant than the less conspicuous long-tailed finch when sitting under cover. Moreover, juvenile Gouldian finches had similar vigilance levels than adults; whereas, juveniles of the long-tailed finch were less vigilant, possibly because of staying in the family group. Furthermore, both species showed a similar temporal course of vigilance with a fast decrease in vigilance after landing in the tree, which was affected by group size. Single individuals had much higher vigilance than groups of birds. Finally, vigilance was higher at small waterholes. The results show that conspicuousness, uncertainty when arriving at waterholes, and higher perceived risk at small waterholes increased vigilance.

Integrative supporting techniques for the taxonomy of Schistorchis carneus Lühe, 1906 (Digenea: Megaperidae) with perspective for the existence of species complexes

The morphology and host-parasite data of Schistorchis carneus Lühe, 1906 indicate low host specificity and geographical range variation, accompanied by a large scale of intraspecific variability and ambiguous molecular phylogeny, confusing in determining biodiversity extent and specificity to a particular host and/or locality. To address the challenging circumstances of records of S. carneus, a detailed morphological description, molecular characterization and species delimitation analyses were conducted using a combination of comparative morphology, molecular phylogeny, multivariate analyses, and host-parasite data. Several morphological features exhibited an extensive intra-variation, as well as a wide morphometric range in many measurements within and across records. Phylogenetic analyses showed that the classification of schistorchiines is highly correlated with the morphology/nature of the oral sucker and highlighted the limitations of ribosomal 28S rDNA and ITS2 rDNA in distinguishing morphologically close/related taxa. Species delimitation analyses reflected the critical importance of host distinction in schistorchiines recognition/differentiation, even those that are indistinct morphologically. The clustering of schistorchiines into certain groups was driven by host differences. Additionally, host variation typically corresponds to a distinct schistorchiine species, even if it is morphologically identical to another. Cluster analysis associated with host-parasite data revealed high morphometric convergence and significant diversity among Egyptian and Sri-Lankan records of S. carneus. It also confirmed the distinction between Indian records from the Bay of Bengal and those from the Gulf of Mannar (previously mentioned as Manaar), each in their own distant group. In conclusion, the records of S. carneus represent a repository for a group of closely related cryptic species. The restricted concept of S. carneus should include only records from the white-spotted puffer, Arothron hispidus (Linnaeus) and the stellate puffer, Arothron stellatus (Anonymous). The Australian specimens from the narrow-lined puffer, Arothron manilensis (Marion de Procé) and the Indian record from the lunartail puffer, Lagocephalus lunaris (Bloch & Schneider) likely represent a free-standing cryptic species with limited distribution, requiring further characterization.

A computational study on the effect of structural isomerism on the excited state lifetime and redox energetics of archetype iridium photoredox catalyst platforms [Ir(ppy)2(bpy)]+ and Ir(ppy)3.

This study investigates the impact of structural isomerism on the excited state lifetime and redox energetics of heteroleptic [Ir(ppy)2(bpy)]+ and homoleptic Ir(ppy)3 photoredox catalysts using ground-state and time-dependent density functional theory methods. While the ground- and excited-state reduction potentials differ only slightly among the isomers of these complexes, our findings reveal significant variations in the radiative and non-radiative decay rates of the reactivity-controlling triplet 3MLCT states of these closely related species. The observed differences in radiative decay rates could be traced back to variations in the transition dipole moment, vertical energy gaps, and spin-orbit coupling of the isomers. In [Ir(ppy)2(bpy)]+, transition dipole moment differences play a significant role in controlling the relative lifetime of the triplet states, which we rationalized by a vectorial analysis of permanent dipole moments of the ground and excited states. Regarding the two isomers of Ir(ppy)3, changes in radiative decay rates were primarily attributed to variations in vertical energy gaps and intensity borrowing from other singlet-singlet transitions driven by spin-orbit coupling. Non-radiative decay variations were assessed in terms of differences in reorganization energies, adiabatic energy gap, and spin-orbit coupling. For both complexes, reorganization energies associated with low-energy molecular vibrations and metal-ligand bond length changes following the de-excitation process were major contributors. These insights provide a deeper understanding of how molecular design can be leveraged to optimize the performance of iridium-based photoredox catalysts, potentially guiding the development of more efficient catalytic systems for future applications.