Evolution Of Correlations Research Articles

Late Cretaceous astrochronology, organic carbon evolution, and paleoclimate inferences for the subtropical western South Atlantic, Espírito Santo Basin

Cyclostratigraphy has revealed the quasi-periodic nature that globally distributed sedimentary successions present through the Phanerozoic. This is mainly the case of the strong eccentricity-related greenhouse climate of the Cretaceous period, a time interval in which the long-eccentricity 405-kyr cycle has been routinely used to constrain high-resolution astronomical time scales. Despite the importance of the South Atlantic opening to the evolution of the Cretaceous climate and carbon cycle, few investigations have applied the modern cyclostratigraphic analysis to explore the eventual orbital pacing of the Cretaceous South Atlantic successions. We use geophysical and geochemical data analysis from the Petrobras well ES-1 (offshore Espírito Santo Basin to develop a floating and anchored astronomical time scale (ATS) and infer the relation between sedimentation rate and TOC accumulation. Additionally, we estimate the net primary productivity (NPP) during intervals of high TOC accumulation. Our results show a pervasive orbitally-driven forcing imprint according to the Milankovitch spectral peak ratio as predicted to Cretaceous times, with a prominent occurrence of a 405-kyr long-eccentricity cycle, being used to constrain the elapsed time. An abrupt shift in the GR data likely associated with the Cretaceous – Paleogene boundary was used to anchor our floating ATS. The evolutionary Average Spectral Misfit (eASM) and Correlation Coefficient (COCO/eCOCO) tests demonstrate that the sedimentation rate can have contrasting effects over the organic matter burial, which is likely related to the large-scale paleogeographic configuration. Our study exemplifies that orbitally-driven sedimentation can be used to build high-resolution chronology for Brazilian marginal basins.

Novel ACE2 protein interactions relevant to COVID-19 predicted by evolutionary rate correlations.

Angiotensin-converting enzyme 2 (ACE2) is the cell receptor that the coronavirus SARS-CoV-2 binds to and uses to enter and infect human cells. COVID-19, the pandemic disease caused by the coronavirus, involves diverse pathologies beyond those of a respiratory disease, including micro-thrombosis (micro-clotting), cytokine storms, and inflammatory responses affecting many organ systems. Longer-term chronic illness can persist for many months, often well after the pathogen is no longer detected. A better understanding of the proteins that ACE2 interacts with can reveal information relevant to these disease manifestations and possible avenues for treatment. We have undertaken an approach to predict candidate ACE2 interacting proteins which uses evolutionary inference to identify a set of mammalian proteins that “coevolve” with ACE2. The approach, called evolutionary rate correlation (ERC), detects proteins that show highly correlated evolutionary rates during mammalian evolution. Such proteins are candidates for biological interactions with the ACE2 receptor. The approach has uncovered a number of key ACE2 protein interactions of potential relevance to COVID-19 pathologies. Some proteins have previously been reported to be associated with severe COVID-19, but are not currently known to interact with ACE2, while additional predicted novel ACE2 interactors are of potential relevance to the disease. Using reciprocal rankings of protein ERCs, we have identified strongly interconnected ACE2 associated protein networks relevant to COVID-19 pathologies. ACE2 has clear connections to coagulation pathway proteins, such as Coagulation Factor V and fibrinogen components FGA, FGB, and FGG, the latter possibly mediated through ACE2 connections to Clusterin (which clears misfolded extracellular proteins) and GPR141 (whose functions are relatively unknown). ACE2 also connects to proteins involved in cytokine signaling and immune response (e.g. XCR1, IFNAR2 and TLR8), and to Androgen Receptor (AR). The ERC prescreening approach has elucidated possible functions for relatively uncharacterized proteins and possible new functions for well-characterized ones. Suggestions are made for the validation of ERC-predicted ACE2 protein interactions. We propose that ACE2 has novel protein interactions that are disrupted during SARS-CoV-2 infection, contributing to the spectrum of COVID-19 pathologies.

Cyclostratigraphy of the Cryogenian Fiq Formation, Oman and its implications for the age of the Marinoan glaciation

Cyclostratigraphy is a powerful tool in chronostratigraphic studies, and has shown its potential in Precambrian time. The Cryogenian Period is one of the most dynamic and intriguing intervals in Earth history and it is a witness to the most extreme climate changes on the planet, known as two Snowball Earth events. However, a robust chronostratigraphic framework is still lacking especially for the younger Marinoan Snowball Earth event, hampering the stratigraphic correlation and comparison among geographically separated records, as well as the understanding of the initiation and termination of this global-scale glaciation. The Cryogenian Fiq Formation in Oman is thought to be Marinoan-equivalent. The duration of the nonglacial units in the Fiq Formation could provide a conservative age constraint on the previously not well-determined onset age of the Marinoan glaciation. In this work, a cyclostratigraphic study has been conducted on three drill cores of the Fiq Formation. The multi-taper method (MTM) spectral analysis, the correlation coefficient (COCO), and the evolutionary correlation coefficient (eCOCO) analyses were performed on the high-resolution gamma-ray (GR) data from the three cores. A hierarchy of Milankovitch cycles (eccentricities, obliquities, and precessions) has been identified, which was used to estimate the optimal sedimentary accumulate rates and the duration of the Fiq Formation in each core. Based on the cyclostratigraphic results, the time scale of the Fiq Formation is at least ~6 Myr. Integrating the radiometric ages and the cyclostratigraphic data from other continents, the onset age of the Marinoan glaciation is suggested to be 650–641 Ma. This new result helps improve the chronostratigraphic framework for the Cryogenian Period and also provides critical temporal constraints for the geological and numerical models that explore the possible mechanisms for the Snowball Earth events.

Phytochemistry reflects different evolutionary history in traditional classes versus specialized structural motifs

Foundational hypotheses addressing plant–insect codiversification and plant defense theory typically assume a macroevolutionary pattern whereby closely related plants have similar chemical profiles. However, numerous studies have documented variation in the degree of phytochemical trait lability, raising the possibility that phytochemical evolution is more nuanced than initially assumed. We utilize proton nuclear magnetic resonance (1H NMR) data, chemical classification, and double digest restriction-site associated DNA sequencing (ddRADseq) to resolve evolutionary relationships and characterize the evolution of secondary chemistry in the Neotropical plant clade Radula (Piper; Piperaceae). Sequencing data substantially improved phylogenetic resolution relative to past studies, and spectroscopic characterization revealed the presence of 35 metabolite classes. Metabolite classes displayed phylogenetic signal, whereas the crude 1H NMR spectra featured little evidence of phylogenetic signal in multivariate tests of chemical resonances. Evolutionary correlations were detected in two pairs of compound classes (flavonoids with chalcones; p-alkenyl phenols with kavalactones), where the gain or loss of a class was dependent on the other’s state. Overall, the evolution of secondary chemistry in Radula is characterized by strong phylogenetic signal of traditional compound classes and weak phylogenetic signal of specialized chemical motifs, consistent with both classic evolutionary hypotheses and recent examinations of phytochemical evolution in young lineages.

Allometry of Egg Size as a Factor Influencing Egg Shape in Birds

Despite a huge diversity of egg shapes among birds, similar egg shapes occur in species that differ in habitats and are not phylogenetically closely related; this indicates the presence of factors limiting the egg shape variability. We assume that one of these factors is a general pattern of egg shape change across all birds. We tested a hypothesis of allometric patterns of egg morphometric traits (radii of blunt end (infundibular zone, ri), pointed end (cloacal zone, rc), lateral zone (rl) and maximum diameter (D)) scaling against egg length (L). Phylogenetic allometric analysis was applied. We also studied hierarchical distribution of variation in egg traits at different taxonomic levels in order to determine the degree of egg shape variability on each of them. We revealed allometric patterns in the scaling of egg traits: D and ri scaled against L with negative allometry, while rc and rl were positively allometric. A high degree of covariation was observed between the length and diameter, radii of the lateral and infundibular zones, i.e. traits that are associated with the overall size of an egg, the degree of its elongation, and the shape of infundibular zone. Evolutionary correlation between L and rc was rather low. The greatest variation of egg traits resided at the level of orders. The identified general trends in egg shape variation are realized on the basis of various groups of birds in phylogenetic and ecological sense that assume the influence of these factors on the bird's egg shape.

The coordination of major events in C4 photosynthesis evolution in the genus Flaveria

C4 photosynthesis is a remarkable complex trait, elucidations of the evolutionary trajectory of C4 photosynthesis from its ancestral C3 pathway can help us better understand the generic principles of the evolution of complex traits and guide the engineering of C3 crops for higher yields. Here, we used the genus Flaveria that contains C3, C3–C4, C4-like and C4 species as a system to study the evolution of C4 photosynthesis. We first mapped transcript abundance, protein sequence and morphological features onto the phylogenetic tree of the genus Flaveria, and calculated the evolutionary correlation of different features; we then predicted the relative changes of ancestral nodes of those features to illustrate the major events during the evolution of C4 photosynthesis. We found that gene expression and protein sequence showed consistent modification patterns in the phylogenetic tree. High correlation coefficients ranging from 0.46 to 0.9 among gene expression, protein sequence and morphology were observed. The greatest modification of those different features consistently occurred at the transition between C3-C4 species and C4-like species. Our results show highly coordinated changes in gene expression, protein sequence and morphological features, which support evolutionary major events during the evolution of C4 metabolism.

Nonstationary response statistics of fractional oscillators to evolutionary stochastic excitation

While studying fractional oscillators to the excitation as an evolutionary stochastic process, this paper develops a novel pole-residue method to compute closed-form solutions for the nonstationary response statistics, including evolutionary power spectrum, correlation function and mean square value. The proposed method is not only suitable to the oscillators with an arbitrary fractional order, but also applies to oscillators with multiple fractional derivative terms. A necessary task of the proposed method is to obtain a pole-residue form of the oscillator’s transfer function (TF), which can be achieved through two steps: (1) obtaining a discrete impulse response function (IRF) from taking the inverse Fourier transform of the oscillator’s frequency response function (FRF), which is readily derived from its exact TF; (2) invoking the Prony-SS method to decompose this IRF signal for getting the poles and residues of the TF. Once the pole-residue TF is available, the remaining derivation can follow a similar pole-residue method that has been developed for ordinary linear oscillators. In the numerical studies, three fractional oscillators with one and two fractional derivative terms, respectively, are chosen to demonstrate the proposed method; considering the input to be a uniformly modulated random process modeled with either white noise or Kanai–Tajimi earthquake spectrum, the correctness of the proposed method is verified by Monte Carlo simulations.

Genomic phylogeography of the White-crowned Manakin Pseudopipra pipra (Aves: Pipridae) illuminates a continental-scale radiation out of the Andes

The complex landscape history of the Neotropics has generated opportunities for population isolation and diversification that place this region among the most species-rich in the world. Detailed phylogeographic studies are required to uncover the biogeographic histories of Neotropical taxa, to identify evolutionary correlates of diversity, and to reveal patterns of genetic connectivity, disjunction, and potential differentiation among lineages from different areas of endemism. The White-crowned Manakin (Pseudopipra pipra) is a small suboscine passerine bird that is broadly distributed through the subtropical rainforests of Central America, the lower montane cloud forests of the Andes from Colombia to central Peru, the lowlands of Amazonia and the Guianas, and the Atlantic forest of southeast Brazil. Pseudopipra is currently recognized as a single, polytypic biological species. We studied the effect of the Neotropical landscape on genetic and phenotypic differentiation within this species using genomic data derived from double digest restriction site associated DNA sequencing (ddRAD), and mitochondrial DNA. Most of the genetic breakpoints we identify among populations coincide with physical barriers to gene flow previously associated with avian areas of endemism. The phylogenetic relationships among these populations imply a novel pattern of Andean origination for this group, with subsequent diversification into the Amazonian lowlands. Our analysis of genomic admixture and gene flow reveals a complex history of introgression between some western Amazonian populations. These reticulate processes confound our application of standard concatenated and coalescent phylogenetic methods and raise the question of whether a lineage in the western Napo area of endemism should be considered a hybrid species. Lastly, analysis of variation in vocal and plumage phenotypes in the context of our phylogeny supports the hypothesis that Pseudopipra is a species-complex composed of at least 8, and perhaps up to 17 distinct species which have arisen in the last ~2.5 Ma.

Evolutionary genetic algorithm identifies IL2RB as a potential predictive biomarker for immune-checkpoint therapy in colorectal cancer.

Identifying robust predictive biomarkers to stratify colorectal cancer (CRC) patients based on their response to immune-checkpoint therapy is an area of unmet clinical need. Our evolutionary algorithm Atlas Correlation Explorer (ACE) represents a novel approach for mining The Cancer Genome Atlas (TCGA) data for clinically relevant associations. We deployed ACE to identify candidate predictive biomarkers of response to immune-checkpoint therapy in CRC. We interrogated the colon adenocarcinoma (COAD) gene expression data across nine immune-checkpoints (PDL1, PDCD1, CTLA4, LAG3, TIM3, TIGIT, ICOS, IDO1 and BTLA). IL2RB was identified as the most common gene associated with immune-checkpoint genes in CRC. Using human/murine single-cell RNA-seq data, we demonstrated that IL2RB was expressed predominantly in a subset of T-cells associated with increased immune-checkpoint expression (P < 0.0001). Confirmatory IL2RB immunohistochemistry (IHC) analysis in a large MSI-H colon cancer tissue microarray (TMA; n = 115) revealed sensitive, specific staining of a subset of lymphocytes and a strong association with FOXP3+ lymphocytes (P < 0.0001). IL2RB mRNA positively correlated with three previously-published gene signatures of response to immune-checkpoint therapy (P < 0.0001). Our evolutionary algorithm has identified IL2RB to be extensively linked to immune-checkpoints in CRC; its expression should be investigated for clinical utility as a potential predictive biomarker for CRC patients receiving immune-checkpoint blockade.

A review of novel coronavirus disease (COVID-19): based on genomic structure, phylogeny, current shreds of evidence, candidate vaccines, and drug repurposing.

Coronavirus disease (COVID-19) pandemic is instigated by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of March 13, 2021, more than 118.9 million cases were infected with COVID-19 worldwide. SARS-CoV-2 is a positive-sense single-stranded RNA beta-CoV. Most COVID-19 infected individuals recover within 1–3 weeks. Nevertheless, approximately 5% of patients develop acute respiratory distress syndrome and other systemic complications, leading to death. Structural genetic analyses of SARS-CoV-2 have shown genomic resemblances but a low evolutionary correlation to SARS-CoV-1 responsible for the 2002–2004 outbreak. The S glycoprotein is critical for cell adhesion and the entrance of the virus into the host. The process of cell entry uses the cellular receptor named angiotensin-converting enzyme 2. Recent evidence proposed that the CD147 as a SARS-CoV-2′s potential receptor. The viral genome is mainly held by two non-structural proteins (NSPs), ORF1a and ORF1ab, along with structural proteins. Although NSPs are conserved among the βCoVs, mutations in NSP2 and NSP3 may play critical roles in transmitting the virus and cell tropism. To date, no specific/targeted anti-viral treatments exist. Notably, more than 50 COVID-19 candidate vaccines in clinical trials, and a few being administered. Preventive precautions are the primary strategy to limit the viral load transmission and spread, emphasizing the urgent need for developing significant drug targets and vaccines against COVID-19. This review provides a cumulative overview of the genomic structure, transmission, phylogeny of SARS-CoV-2 from Indian clusters, treatment options, updated discoveries, and future standpoints for COVID-19.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13205-021-02749-0.

Mechanical and optical property assessment of irradiated SiC with displaced atoms

Explicit method to emulate neutron radiation effects on key ceramic materials is lacking, with most literatures stressing direct comparison between radiation parameters while underestimating the defect-property correlation. Herein, the evolutionary correlation between defects of displaced atoms and properties in 6H-SiC was systematically investigated, aiming to found the basis for performance assessment of neutron irradiated material. The point defect accumulation, defect cluster growth, and homogeneous crystalline-amorphous (c-a) transition were recognized, with different stages of Young’s modulus reduction and optical absorption enhancement accordingly triggered. Specifically, the relaxation process accompanying the c-a transition was believed to induce the final reduction stage of Young’s modulus and account for the conflict between existing research results. Average lattice disorder, regarded as the average density of displaced atoms, was proved to be the success reference in the property assessment approach, paving the way for the extension into high temperature radiation where more defect types coexist.

Evolutionary Rates are Correlated Between Buchnera Endosymbionts andthe Mitochondrial Genomes of Their Aphid Hosts.

The evolution of bacterial endosymbiont genomes is strongly influenced by host-driven selection. Factors affecting host genome evolution will potentially affect endosymbiont genomes in similar ways. One potential outcome is correlations in molecular rates between the genomes of the symbiotic partners. Recently, we presented the first evidence of such correlations between the mitochondrial genomes of cockroaches and the genomes of their endosymbiont (Blattabacterium cuenoti). Here we investigate whether similar patterns are found in additional host-symbiont partners. We use partial genome data from multiple strains of the bacterial endosymbionts Buchnera aphidicola and Sulcia muelleri, and the mitochondrial genomes of their sap-feeding insect hosts. Both endosymbionts show phylogenetic congruence with the mitochondria of their hosts, a result that is expected due to their identical mode of inheritance. We compared root-to-tip distances and branch lengths of phylogenetically independent species pairs. Both analyses showed a highly significant correlation of molecular rates between thegenomes of Buchnera and themitochondrial genomes of their hosts. A similar correlation was detected between Sulcia and their hosts, but was not statistically significant. Our results indicate that evolutionary rate correlations between hosts and long-term symbionts may be a widespread phenomenon.

Differences in seed dormancy and germination in amphicarpic legumes: manifold bet-hedging in space and time

Abstract Aims Dispersal through space or time via dormancy is one of the primary processes whereby organisms can influence the environment they experience. In plants, strong evolutionary correlations are expected between the two kinds of dispersal because both are performed by the seeds and play comparable adaptive roles. In this paper, we investigated these evolutionary correlations using amphicarpic plants, which simultaneously produce aerial seeds with high spatial dispersal propensity and subterranean seeds that do not disperse. Methods We investigated the variation in dormancy and germination in aerial and subterranean seeds of two amphicarpic legumes (Vicia amphicarpa L. and Lathyrus amphicarpos L.) and two closely related homocarpic taxa (Vicia sativa L. and Lathyrus cicera L.) by estimating germination percentages following different combinations of dormancy breaking treatments (i.e. dry after-ripening, cold stratification and physical scarification). Important Findings Our results showed complex interactions between spatial and temporal dispersal. Right after dispersal, aerial seeds were more dormant than their subterranean counterparts, but this trend reversed with after-ripening, as seeds developed physical dormancy. Seeds of homocarpic plants germinated at higher percentages than those of their amphicarpic congeners and lost dormancy homogeneously with after-ripening. Conversely, amphicarpic seeds exhibited varied dormancy strategies modulated by both physiological and physical dormancy. These are expected to increase variation in emergence timing, providing multiple levels of diversifying bet-hedging. This strategy might be adaptive under highly unpredictable conditions by enabling plants to rely on historically favorable sites in good seasons without preventing spatial and temporal migration.

The evolution of siphonophore tentilla for specialized prey capture in the open ocean

Predator specialization has often been considered an evolutionary "dead end" due to the constraints associated with the evolution of morphological and functional optimizations throughout the organism. However, in some predators, these changes are localized in separate structures dedicated to prey capture. One of the most extreme cases of this modularity can be observed in siphonophores, a clade of pelagic colonial cnidarians that use tentilla (tentacle side branches armed with nematocysts) exclusively for prey capture. Here we study how siphonophore specialists and generalists evolve, and what morphological changes are associated with these transitions. To answer these questions, we: a) Measured 29 morphological characters of tentacles from 45 siphonophore species, b) mapped these data to a phylogenetic tree, and c) analyzed the evolutionary associations between morphological characters and prey-type data from the literature. Instead of a dead end, we found that siphonophore specialists can evolve into generalists, and that specialists on one prey type have directly evolved into specialists on other prey types. Our results show that siphonophore tentillum morphology has strong evolutionary associations with prey type, and suggest that shifts between prey types are linked to shifts in the morphology, mode of evolution, and evolutionary correlations of tentilla and their nematocysts. The evolutionary history of siphonophore specialization helps build a broader perspective on predatory niche diversification via morphological innovation and evolution. These findings contribute to understanding how specialization and morphological evolution have shaped present-day food webs.

Remarkable sexually dimorphic features ofConiceromyia(Diptera: Phoridae): evolution in the light of phylogeny and comparative evidence about their function

AbstractConiceromyia is a genus of 100 species of phorid flies mostly distributed in the Neotropical region. The genus is distinguishable based on several male-exclusive features in different parts of the body, many of which are unique among the Phoridae. In addition, many species of Coniceromyia have nearly identical morphology of their male copulatory apparatus (i.e. hypopygium). The co-occurrence of these unusual characteristics suggests an evolutionary correlation between them. To investigate this possible correlation and to understand other aspects of the evolution of these puzzling male-exclusive characters, we performed the first phylogenetic analysis of Coniceromyia, based on morphological and molecular data. Ancestral state reconstructions and comparative analyses then allowed us to infer the evolution of these characters and search for general evolutionary patterns and correlated histories. We demonstrate that these male-exclusive features varied from highly homoplastic to uniquely derived on the phylogenetic history of Coniceromyia. For some characters, we found evidence of a biased evolution favouring gains over losses of the feature, but no male characteristics were significantly correlated with hypopygium morphology. The evolutionary patterns of the male-exclusive features and comparative evidence with other better known groups suggest possible functions for these features related to sexual selection.

Wing Shape in Waterbirds: Morphometric Patterns Associated with Behavior, Habitat, Migration, and Phylogenetic Convergence.

Wing shape plays a critical role in flight function in birds and other powered fliers and has been shown to be correlated with flight performance, migratory distance, and the biomechanics of generating lift during flight. Avian wing shape and flight mechanics have also been shown to be associated with general foraging behavior and habitat choice. We aim to determine if wing shape in waterbirds, a functionally and ecologically diverse assemblage united by their coastal and aquatic habitats, is correlated with various functional and ecological traits. We applied geometric morphometric approaches to the spread wings of a selection of waterbirds to search for evolutionary patterns between wing shape and foraging behavior, habitat, and migratory patterns. We found strong evidence of convergent evolution of high and low aspect ratio wing shapes in multiple clades. Foraging behavior also consistently exhibits strong evolutionary correlations with wing shape. Habitat, migration, and flight style, in contrast, do not exhibit significant correlation with wing shape in waterbirds. Although wing shape is critical to aerial flight function, its relationship to habitat and periodic locomotor demands such as migration is complex.

Bios2cor: an R package integrating dynamic and evolutionary correlations to identify functionally important residues in proteins.

Both dynamic correlations in protein sidechain motions during molecular dynamics (MD) simulations and evolutionary correlations in multiple sequence alignments (MSAs) of homologous proteins may reveal functionally important residues. We developed the R package Bios2cor that provides a unique framework to investigate and, possibly, integrate both analyses. Bios2cor starts with an MSA or an MD trajectory and computes correlation/covariation scores between positions in the MSA or between sidechain dihedral angles or rotamers in the MD trajectory. In addition, Bios2cor provides a variety of tools for the analysis, the visualization and the interpretation of the data. The R package Bios2cor is available from the Comprehensive R Archive Network, at https://CRAN.R-project.org/package=Bios2cor.

Evolution of stamen dimetrism in Melastomataceae, a large radiation of pollen flowers

Changes in floral traits across evolutionary time are expected in response to selective pressures imposed by pollinators. Stamen dimetrism (here defined as size differences between stamens within the same flower) represents an important strategy to decrease pollen loss during bee-flower interactions in pollen flowers. However, the evolutionary history of stamen dimetrism, and the links between this and other reproductive traits across long periods of time are still poorly understood. Here we investigate the evolution of stamens dimetrism and the evolutionary correlation of this trait and other floral structures and reproductive strategies in Melastomataceae. Floral traits were scored from 336 species and reproductive biology data was gathered for 81 species. Stamen dimetrism is a labile trait, appeared several times throughout the evolutionary history of this clade and is evolutionarily correlated to floral size. Among the 81 species analyzed, we observed that the lineages that depend on pollinators to reproduce correspond to those that evolved the highest stamen dimetrism. The evolutionary lability of stamen dimetrism has probably contributed to the maintenance of the buzz pollination adaptive plateau in possibly the largest radiation of pollen flowers in angiosperms.

The Relationship between Functional and Evolutionary Correlations of Enzyme Reactions in Metabolic Network Evolution

HIGHLIGHTS A method of computing the correlation connection network is first proposed. A concept of the mean functional concentration ratios of the enzyme reactions is proposed. The functional concentration ratio and the evolutionary correlation are related.

A phylogenetic approach to understand the evolution of reproduction in coleoid cephalopods

A central question in the evolution of life-histories is whether organisms reproduce once or repeatedly. For cephalopods, the main differences between semelparous and iteroparous are based on ovulation pattern and spawning type. The different reproductive strategies in coleoid cephalopods could be related to the habitat in which the species dwell (coastal vs. oceanic) and/or to environmental forces, thus, both aspects should be quantitatively evaluated under an evolutionary perspective to reconstruct: (a) the ancestral ovulation type of coleoid cephalopods, and (b) the potential of correlated evolution between ovulation type versus habitat and environment. Ancestral states of ovulation type were estimated using stochastic mapping based on literature data (i.e. synchronous or asynchronous), and this information was combined with a new molecular phylogeny including 165 species. The evolutionary correlation between ovulation type, habitat, and environment was estimated by means of the Markov model comparing the rates of gain and loss. The estimates of ancestral states of ovulation type for coleoid cephalopods resulted in a high probability that Octopodiformes evolved from synchronous ovulation type, and Decapodiformes from asynchronous ovulation type. The three traits evaluated presented phylogenetic signal, although no correlation was found between habitat and ovulation type. Overall, species in stable environments showed a tendency towards synchronous ovulation type, while the asynchronous ovulation pattern was found more frequently in species that live in unstable environments, being this last trait also responsible for triggering the change of ovulation type in some species throughout evolution.