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[
WormBook,
2006]
Although several Caenorhabditis species are now studied in laboratories in great detail, the knowledge of the ecology of most Caenorhabditis species is scarce. In this chapter we present data on the habitat, animal associations, and geographical distribution of the eighteen described and five undescribed Caenorhabditis species currently known to science. The habitats of these species are very diverse, ranging from rotting cactus tissue to inflamed auditory canals of zebu cattle. Some species, including C. elegans , have only been isolated from anthropogenic habitats. Consequently, their natural habitat is unknown. All Caenorhabditis species are colonizers of nutrient- and bacteria-rich substrates and none of them is a true soil nematode. Dauer juveniles of many Caenorhabditis species were shown to be associated with terrestrial arthropods or gastropods. An association with invertebrates is also likely for the remaining species. The type of association is either phoresy (for transport to a new habitat) or necromeny (to secure the body of the associated animal as a future food source). There are also some records of Caenorhabditis species associated with vertebrates. The Caenorhabditis stem species was probably a colonizer of nutrient-rich substrates and was phoretic on arthropods. Some evolutionary trends within the taxon are discussed.
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[
PLoS One,
2014]
The rapid pace of species discovery outstrips the rate of species description in many taxa. This problem is especially acute for Caenorhabditis nematodes, where the naming of distinct species would greatly improve their visibility and usage for biological research, given the thousands of scientists studying Caenorhabditis. Species description and naming has been hampered in Caenorhabditis, in part due to the presence of morphologically cryptic species despite complete biological reproductive isolation and often enormous molecular divergence. With the aim of expediting species designations, here we propose and apply a revised framework for species diagnosis and description in this group. Our solution prioritizes reproductive isolation over traditional morphological characters as the key feature in delineating and diagnosing new species, reflecting both practical considerations and conceptual justifications. DNA sequence divergence criteria help prioritize crosses for establishing patterns of reproductive isolation among the many species of Caenorhabditis known to science, such as with the ribosomal internal transcribed spacer-2 (ITS2) DNA barcode. By adopting this approach, we provide new species name designations for 15 distinct biological species, thus increasing the number of named Caenorhabditis species in laboratory culture by nearly 3-fold. We anticipate that the improved accessibility of these species to the research community will expand the opportunities for study and accelerate our understanding of diverse biological phenomena.
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[
J Nematol,
2019]
The genus <i>Pristionchus</i> (Kreis, 1932) consists of more than 30 soil nematode species that are often found in association with scarab beetles. Three major radiations have resulted in the "<i>maupasi</i> species group" in America, the "<i>pacificus</i> species group" in Asia, and the "<i>lheritieri</i> species group," which contains species from Europe and Asia. Phylogenetic analysis indicates that a group of three species, including the gonochorists <i>P. elegans</i> and <i>P. bucculentus</i> and the hermaphrodite <i>P. fissidentatus</i>, is basal to the above-mentioned radiations. Two novel species are described here: <i>Pristionchus paulseni</i> sp. n. from Taiwan and <i>P. yamagatae</i> sp. n. from Japan by means of morphology, morphometrics and genome-wide transcriptome sequence analysis. Previous phylotranscriptomic analysis of the complete <i>Pristionchus</i> genus recognized <i>P. paulseni</i> sp. n. as the sister species of <i>P. fissidentatus</i>, and thus its importance for macro-evolutionary studies. Specifically, the gonochorist <i>P. paulseni</i> sp. n. and the hermaphrodite <i>P. fissidentatus</i> form a species pair that is the sister group to all other described <i>Pristionchus</i> species. <i>P. paulseni</i> sp. n. has two distinct mouth forms, supporting the notion that the mouth dimorphism is ancestral in the genus <i>Pristionchus</i>.
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[
Curr Genomics,
2007]
Unbiased genome-wide studies of longevity in S. cerevisiae and C. elegans have led to the identification of more than one hundred genes that determine life span in one or both organisms. Key pathways have been uncovered linking nutrient and growth factor cues to longevity. Quantitative measures of the degree to which aging is evolutionary conserved are now possible. A major challenge for the future is determining which of these genes play a similar role in human aging and using that information to develop therapies toward age-associated diseases.
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[
Worm Breeder's Gazette,
1997]
Two years ago, I compiled a small database of nematode strains of species both closely and distantly related to C. elegans. I distributed a report from this database (Worm Systematics Resource Net) at the Systematics Workshop at the 1995 C. elegans meeting in Wisconsin. This report listed strains (with relevant information) both by lab and within a taxonomic hierarchy. To make the database, lists of strains were generously provided by various labs willing to make these stocks available to the general worm community (and in some cases to the general scientific or educational community). This year, I would like to distribute an updated version at the 1997 meeting and put out an Internet version as well. The main purpose of the database is to provide a quick way of locating living stocks of particular nematode species for use in such work as systematics (phylogenetics and hybridization tests) and comparative biological studies (e.g., comparative development or molecular comparisons). But there are several other benefits offered by such a database (e.g., it provides a rough survey of rhabditid diversity that could be adapted for use in undergraduate biology courses). If you are willing to share your non-elegans strains, please send me a strain list with the following information for each strain: Species binomen (as well as is known-see footnote) Strain designation (please see footnote!) From whom obtained (if not isolated by someone in your lab) By whom originally isolated (if known) Isolation date (if known) Isolation locality (as accurate as possible) Isolation habitat (as complete as possible, including notes about ecology, temperature, altitude, etc.) Culture conditions (also note cryophilicity and any special protocols required)
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[
Pflugers Arch,
2007]
The ability to detect changes in temperature is a fundamental sensory mechanism for every species and provides organisms with a detailed view of the environment. This review focuses on what is known of the neuronal and molecular substrates for thermosensation across species, focusing on the three robust model systems extensively used to study sensory signaling, the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the laboratory mouse. Nematodes migrate to thermal climes that are amenable to their survival, a behavior that is regulated primarily through a single sensory neuron. Additionally, nematodes "learn" to seek out this temperate zone based upon their prior experience, a robust model of learning and memory. Drosophila larvae also prefer select thermal zones that are optimal for growth and have also developed vigorous mechanisms to avoid unfavorable conditions. In mammals, the transduction mechanisms for thermosensation have been identified primarily due to the fact that naturally occurring plant products evoke distinct psychophysical sensation of temperature change. More remarkably, the elucidation of the molecular sensors in mammals, along with those in Drosophila, has demonstrated conservation in the molecular mediators of temperature sensation across diverse species.