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Over the last decade, new types of massive and complex chromosomal rearrangements based on the chaotic shattering and restructuring of chromosomes have been identified in cancer cells as well as in patients with congenital diseases and healthy individuals. These unanticipated phenomena are named chromothripsis, chromoanasynthesis and chromoplexy, and are grouped under the term of chromoanagenesis. As mechanisms for rapid and profound genome modifications in germlines and early development, these processes can be regarded as credible pathways for genomic evolution and speciation process. Their discovery confirms the importance of genome-centric investigations to fully understand organismal evolution. Because they oppose the model of progressive acquisition of driver mutations or rearrangements, these phenomena conceptually give support to the concept of macroevolution, known through the models of "Hopeful Monsters" and the "Punctuated Equilibrium". In this review, we summarize mechanisms underlying chromoanagenesis processes and we show that numerous cases of chromosomal speciation and short-term adaptation could be correlated to chromoanagenesis-related mechanisms. In the frame of a modern and integrative analysis of eukaryote evolutionary processes, it seems important to consider the unexpected chromoanagenesis phenomena.

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Podostemaceae, the river-weeds, are characterized by remarkable differences between species and genera, which resulted from saltational evolution. This paper presents additional cases of such two genera, which are described here from the Phou Khao Khouay National Protected Area in northern Central Laos. Molecular phylogenetic data show that Ctenobryum mangkonense (gen. & sp. nov.) is sister to Hydrodiscus koyamae, while Laosia ramosa (gen. & sp. nov.) is isolated from all Asian genera of subfamily Podostemoideae. Ctenobryum mangkonense is distinct from Hydrodiscus koyamae in the crustose roots (versus rootless in the latter), scattered flowers on the root (versus alternate on the shoot), and pectinate bracts (versus simple, sheath-like). Laosia ramosa is distinct from all the genera in the columnar, endogenously branched axes and single style-stigma complex. The axis is an enigmatic organ with combined characteristics of root, stem and leaf, pending further study. Laos, together with Thailand, is a center of diversity of the Southeast and East Asian Podostemoideae. The three monotypic genera, i.e., Ctenobryum, Hydrodiscus and Laosia, occur in neighboring and closely similar aquatic habitats within the Area. The new taxa are formally described.

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How do stunning functional innovations evolve from unspecialized progenitors? This puzzle is particularly acute for ultrafast movements of appendages in arthropods as diverse as shrimps [1], stomatopods [2], insects [3-6], and spiders [7]. For example, the spectacular snapping claws of alpheid shrimps close so fast (∼0.5 ms) that jetted water creates a cavitation bubble and an immensely powerful snap upon bubble collapse [1]. Such extreme movements depend on (1) an energy-storage mechanism (e.g., some kind of spring) and (2) a latching mechanism to release stored energy quickly [8]. Clearly, rapid claw closure must have evolved before the ability to snap, but its evolutionary origins are unknown. Unearthing the functional mechanics of transitional stages is therefore essential to understand how such radical novel abilities arise [9-11]. We reconstructed the evolutionary history of shrimp claw form and function by sampling 114 species from 19 families, including two unrelated families within which snapping evolved independently (Alpheidae and Palaemonidae) [12, 13]. Our comparative analyses, using micro-computed tomography (microCT) and confocal imaging, high-speed video, and kinematic experiments with select 3D-printed scale models, revealed a previously unrecognized "slip joint" in non-snapping shrimp claws. This slip joint facilitated the parallel evolution of a novel energy-storage and cocking mechanism-a torque-reversal joint-an apparent precondition for snapping. Remarkably, these key functional transitions between ancestral (simple pinching) and derived (snapping) claws were achieved by minute differences in joint structure. Therefore, subtle changes in form appear to have facilitated wholly novel functional change in a saltational manner. VIDEO ABSTRACT.

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Cuticular hydrocarbons (CHCs) are ubiquitous and highly diverse in insects, serving as communication signal and waterproofing agent. Despite their vital function, the causes, mechanisms and constraints on CHC diversification are still poorly understood. Here, we investigated phylogenetic constraints on the evolution of CHC profiles, using a global data set of the species-rich and chemically diverse ant genus Crematogaster. We decomposed CHC profiles into quantitative (relative abundances, chain length) and qualitative traits (presence/absence of CHC classes). A species-level phylogeny was estimated using newly generated and previously published sequences from five nuclear markers. Moreover, we reconstructed a phylogeny for the chemically diverse Crematogaster levior species group using cytochrome oxidase I. Phylogenetic signal was measured for these traits on genus and clade level and within the chemically diverse C. levior group. For most quantitative CHC traits, phylogenetic signal was low and did not differ from random expectation. This was true on the level of genus, clade and species group, indicating that CHC traits are evolutionary labile. In contrast, the presence or absence of alkenes and alkadienes was highly conserved within the C. levior group. Hence, the presence or absence of biosynthetic pathways may be phylogenetically constrained, especially at lower taxonomic levels. Our study shows that CHC composition can evolve rapidly, allowing insects to quickly adapt their chemical profiles to external selection pressures, whereas the presence of biosynthetic pathways appears more constrained. However, our results stress the importance to consider the taxonomic level when investigating phylogenetic constraints.

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The moss-like river-weeds or Podostemaceae offer a special opportunity to study the diversity and evolution of plants that are adapted to extreme environments. This paper reviews multidisciplinary studies on this subject. Based on field work in the four continents, we discovered many species and several genera that are new components of biodiversity, and revealed the Podostemaceae floras of East Asia, Southeast Asia, and Australia. The historical biogeography of the family, i.e., the change in distribution in space and time, is characterized by a few dispersals between continents, followed by diversification within each continent. Local species may be derived from parts of separated populations of parental species, which consequently are paraphyletic. The remarkable morphological adaptations of Podostemaceae include the development of the horizontal axis in plant body, with which the plants adhere to rock surfaces under violent current. The vertical axis is reduced or lost and the horizontal axis develops in the embryo and seedling. We also found saltational organ-level variation, such as presence or absence of shoot, shoot apical meristem, root, and root cap; the form of shoot and root; the mode of root branching and leaf production; and the number of cotyledons. Morphological evolution may not be always adaptive to the habitats, which are rocks periodically submerged across the distribution range. Analyses of shoot regulatory gene expression found that, in contrast to the expression pattern in primitive species with ordinary shoots, which is comparable with Arabidopsis, the unique pattern in derived species may result in 'fuzzy' morphology of the shoot and leaf. Finally, problems for future study are pointed out.

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BACKGROUND: Various groups of flowering plants reveal profound ('saltational') changes of their bauplans (architectural rules) as compared with related taxa. These plants are known as morphological misfits that appear as rather large morphological deviations from the norm. Some of them emerged as morphological key innovations (perhaps 'hopeful monsters') that gave rise to new evolutionary lines of organisms, based on (major) genetic changes. SCOPE: This pictorial report places emphasis on released bauplans as typical for bladderworts (Utricularia, approx. 230 secies, Lentibulariaceae) and river-weeds (Podostemaceae, three subfamilies, approx. 54 genera, approx. 310 species). Bladderworts (Utricularia) are carnivorous, possessing sucking traps. They live as submerged aquatics (except for their flowers), as humid terrestrials or as epiphytes. Most Podostemaceae are restricted to rocks in tropical river-rapids and waterfalls. They survive as submerged haptophytes in these extreme habitats during the rainy season, emerging with their flowers afterwards. The recent scientific progress in developmental biology and evolutionary history of both Lentibulariaceae and Podostemaceae is summarized. CONCLUSIONS: Lentibulariaceae and Podostemaceae follow structural rules that are different from but related to those of more typical flowering plants. The roots, stems and leaves - as still distinguishable in related flowering plants - are blurred ('fuzzy'). However, both families have stable floral bauplans. The developmental switches to unusual vegetative morphologies facilitated rather than prevented the evolution of species diversity in both families. The lack of one-to-one correspondence between structural categories and gene expression may have arisen from the re-use of existing genetic resources in novel contexts. Understanding what developmental patterns are followed in Lentibulariaceae and Podostemaceae is a necessary prerequisite to discover the genetic alterations that led to the evolution of these atypical plants. Future molecular genetic work on morphological misfits such as bladderworts and river-weeds will provide insight into developmental and evolutionary aspects of more typical vascular plants.

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The parthenogenetic all-female marbled crayfish is a novel research model and potent invader of freshwater ecosystems. It is a triploid descendant of the sexually reproducing slough crayfish, Procambarus fallax, but its taxonomic status has remained unsettled. By cross-breeding experiments and parentage analysis we show here that marbled crayfish and P. fallax are reproductively separated. Both crayfish copulate readily, suggesting that the reproductive barrier is set at the cytogenetic rather than the behavioural level. Analysis of complete mitochondrial genomes of marbled crayfish from laboratory lineages and wild populations demonstrates genetic identity and indicates a single origin. Flow cytometric comparison of DNA contents of haemocytes and analysis of nuclear microsatellite loci confirm triploidy and suggest autopolyploidisation as its cause. Global DNA methylation is significantly reduced in marbled crayfish implying the involvement of molecular epigenetic mechanisms in its origination. Morphologically, both crayfish are very similar but growth and fecundity are considerably larger in marbled crayfish, making it a different animal with superior fitness. These data and the high probability of a divergent future evolution of the marbled crayfish and P. fallax clusters suggest that marbled crayfish should be considered as an independent asexual species. Our findings also establish the P. fallax-marbled crayfish pair as a novel paradigm for rare chromosomal speciation by autopolyploidy and parthenogenesis in animals and for saltational evolution in general.