scholarly journals Dramatic evolution of body length due to post-embryonic changes in cell size in a newly discovered close relative of C. elegans

2017 ◽  
Author(s):  
Gavin C. Woodruff ◽  
Patrick C. Phillips
Keyword(s):  
Body Size ◽  
Cell Size ◽  
Germ Line ◽  
Large Body ◽  
Developmental Genetics ◽  
Close Relative ◽  
Size Difference ◽  
C Elegans ◽  
Evolutionary Diversification ◽  
Ideal System

AbstractUnderstanding morphological diversity—and morphological constrainto—has been a central question in evolutionary biology since its inception. Nematodes of the genus Caenorhabditis, which contains the well-studied model system C. elegans, display remarkable morphological consistency in the face of extensive genetic divergence. Here, we provide a description of the broad developmental patterns of a recently discovered species, C. sp. 34, which was isolated from fresh figs in Okinawa and which is among the closest known relatives of C. elegans. C. sp. 34 displays an extremely large body size and can grow to be nearly twice as long as C. elegans and all other known members of the genus. Observations of the timing of developmental milestones reveal that C. sp. 34 develops about twice as slowly as C. elegans. Measurements of embryo and larval size show that the size difference between C. sp. 34 and C. elegans is largely due to post-embryonic events, particularly during the transition from larval to adult stages. This difference in size is not attributable to differences in germ line chromosome number or the number of somatic cells. The overall difference in body size is therefore largely attributable to changes in cell size via increased cytoplasmic volume. Because of its close relationship to C. elegans, the distinctness of C. sp. 34 provides an ideal system for the detailed analysis of evolutionary diversification. The context of over forty years of C. elegans developmental genetics also reveals clues into how natural selection and developmental constraint act jointly to promote patterns of morphological stasis and divergence in this group.

scholarly journals Recent Advances in the Genetic, Anatomical, and Environmental Regulation of the C. elegans Germ Line Progenitor Zone

2020 ◽  
Vol 8 (3) ◽  
pp. 14
Author(s):  
Kacy Gordon
Keyword(s):  
Stem Cell ◽  
Cell Population ◽  
Germ Line ◽  
Stem Cell Population ◽  
Developmental Genetics ◽  
C Elegans ◽  
Open Questions ◽  
Genetic Features ◽  
Adult Hermaphrodite ◽  
Cell Niche

The C. elegans germ line and its gonadal support cells are well studied from a developmental genetics standpoint and have revealed many foundational principles of stem cell niche biology. Among these are the observations that a niche-like cell supports a self-renewing stem cell population with multipotential, differentiating daughter cells. While genetic features that distinguish stem-like cells from their differentiating progeny have been defined, the mechanisms that structure these populations in the germ line have yet to be explained. The spatial restriction of Notch activation has emerged as an important genetic principle acting in the distal germ line. Synthesizing recent findings, I present a model in which the germ stem cell population of the C. elegans adult hermaphrodite can be recognized as two distinct anatomical and genetic populations. This review describes the recent progress that has been made in characterizing the undifferentiated germ cells and gonad anatomy, and presents open questions in the field and new directions for research to pursue.

scholarly journals Large body size variation is linked to low communication success in tandem running ants

2019 ◽  
Author(s):  
Wagner Thomas ◽  
Bachenberg Lena ◽  
Glaser Simone ◽  
Oikonomou Avgousta ◽  
Linn Melissa ◽  
...  
Keyword(s):  
Body Size ◽  
Group Performance ◽  
Large Body ◽  
Size Variation ◽  
Recruitment Strategy ◽  
Size Difference ◽  
Phenotypic Trait ◽  
Negative Effects ◽  
Tandem Running ◽  
Communication Processes

AbstractDiversity in animal groups is often assumed to increase group performance. In insect colonies, genetic, behavioral and morphological variation among workers can improve colony functioning and resilience. However, it has been hypothesized that during communication processes, differences between workers, e.g. in body size, could also have negative effects. Tandem running is a common recruitment strategy in ants and allows a leader to guide a nestmate follower to resources. A substantial proportion of tandem runs fail because leader and follower loose contact. Using the ant Temnothorax nylanderi as a model system, we tested the hypothesis that tandem running success is impaired if leader and follower differ in size. Indeed, we found that the success rate of tandem pairs drops considerably as size variation increases: only ~7% of tandem runs were successful when the leader-follower size difference exceeded 10%, whereas 80% of tandem runs were successful when ants differed less than 5% in body length. One possible explanation is that ant size is linked to the preferred walking speed. Ants did not choose partners of similar size, but extranidal workers were larger than intranidal workers, which could reduce recruitment mistakes because it reduced the chance that very large and very small ants perform tandem runs together. Our results suggest that phenotypic differences between interacting workers can have negative effects on the efficiency of communication processes. Whether phenotypic variation has positive or negative effects is likely to depend on the task and the phenotypic trait that shows variation.

scholarly journals Opposing directions of stage-specific body length change in a close relative of C. elegans

2020 ◽  
Author(s):  
Eric W. Hammerschmith ◽  
Gavin C. Woodruff ◽  
Patrick C. Phillips
Keyword(s):  
Body Size ◽  
Body Length ◽  
Developmental Stages ◽  
Parasitic Nematodes ◽  
Close Relative ◽  
Evolutionary Divergence ◽  
Fig Wasp ◽  
C Elegans ◽  
Dauer Larva ◽  
Dauer Larvae

AbstractBackgroundBody size is a fundamental organismal trait. However, as body size and ecological contexts change across developmental time, evolutionary divergence may cause unexpected patterns of body size diversity among developmental stages. This may be particularly evident in polyphenic developmental stages specialized for dispersal. The dauer larva is such a stage in nematodes, and Caenorhabditis species disperse by traveling on invertebrate carriers. Here, we describe the morphology of the dispersal dauer larva of the nematode Caenorhabditis inopinata, whose adults can grow to be nearly twice as long as its close relative, the model organism C. elegans.ResultsWe find that the C. inopinata dauer larva is shorter and fatter than those of its close relatives C. elegans, C. briggsae, and C. tropicalis, despite its much longer adult stage. Additionally, many C. inopinata dauer larvae were ensheathed, an apparent novelty in this lineage reminiscent of the infective juveniles of parasitic nematodes. We also found abundant variation in dauer formation frequency among twenty-four wild isolates of C. inopinata, with many strains unable to produce dauer larvae under laboratory conditions.ConclusionMost Caenorhabditis species thrive on rotting plants and disperse on snails, slugs, or isopods (among others) whereas C. inopinata is ecologically divergent and thrives in fresh Ficus septica figs and disperses on their pollinating wasps. These wasps are at least an order of magnitude smaller in length than the vectors of other Caenorhabditis species. While there is some unknown factor of the fig environment that promotes elongated body size in C. inopinata adults, the smaller size of its fig wasp carrier may be driving the reduced body length of its dauer larva. Thus ecological divergence across multiple developmental stages can promote unexpected and opposing changes in body size within a single species.

scholarly journals The ecological genetics of growth in Drosophila 4. The influence of larval nutrition on the manifestation of dominance

1961 ◽  
Vol 2 (3) ◽  
pp. 346-360 ◽  
Author(s):  
Forbes W. Robertson
Keyword(s):  
Body Size ◽  
Cell Size ◽  
Large Body ◽  
Ecological Genetics ◽  
Selected Lines ◽  
Pacific Population ◽  
Unselected Population ◽  
Selection For ◽  
Different Strains ◽  
Synthetic Media

(1) Two lines have been selected for small wing cell size from the cage Pacific population. Body size was reduced by about 10% and 15% in the two lines which did not regress when selection was relaxed.(2) The effects of crossing each line to the unselected population has been determined in a number of repeated tests on the live yeast medium and also on various sub-optimal synthetic media.(3) The size of the F1, relative to the size of the parents, is greatly influenced by the composition of the larval diet. The F1 may coincide with the mid-parent value but generally significantly exceeds it and is often the same size as the unselected parent population.(4) In crosses to an unselected population on alternative media the F1 was either the same size as the unselected population or exceeded it.(5) Crosses between the selected lines produced an F1 which exceeded the larger parent but remained well below the level of the unselected population.(6) To test for interaction between genes at different loci, chromosomes from the unselected population were substituted in the genetic background of each of the selected lines to provide an array of genotypes in which one, two or three pairs of major chromosomes had homologues derived from different strains. Leastsquares analysis indicated differences between the lines in the distribution of effects among the chromosomes together with the presence of interaction between chromosomes and this was greater for the substitutions in the line which showed the greater consistency of recessive behaviour in crosses to the unselected population.(7) At the end of the selection experiment two lines were selected for large body size from the F2 of the cross between the two selected lines. Both responded to selection for three to four generations and then fluctuated at a level slightly below that of the unselected population.(8) The physiological changes which involve correlated changes in body and cell size differ from those which result from selection for smaller body size, at least in the early stages of such selection, and are associated with differences in genetic behaviour. The apparently recessive property, which involves extensive non-allelic interaction, is progressively established during the course of selection. Apparently selection for smaller cell size is particularly effective in disturbing the normal homeostasis of growth and is accompanied by relatively greater loss of heterozygosis than is likely with equivalent reduction in size due to selection for smaller body as opposed to cell size.

scholarly journals A large close relative of C. elegans is slow-developing but not long-lived

2018 ◽  
Author(s):  
Gavin C. Woodruff ◽  
Erik Johnson ◽  
Patrick C. Phillips
Keyword(s):  
Life History ◽  
Body Size ◽  
Reproductive Mode ◽  
Developmental Timing ◽  
Close Relative ◽  
Female Reproduction ◽  
Evolutionary Patterns ◽  
Adult Lifespan ◽  
C Elegans ◽  
Geographic Origins

AbstractBackgroundVariation in body size is thought to be a major driver of a wide variety of ecological and evolutionary patterns, including changes in development, reproduction, and longevity. Caenorhabditis inopinata is a recently-discovered fig-associated nematode that is unusually large relative to other members of the genus, including the closely related model system C. elegans. Here we test whether the dramatic increase in body size has led to correlated changes in key life history and developmental parameters within this species.ResultsUsing four developmental milestones, C. inopinata was found to have a slower rate of development than C. elegans across a range of temperatures. Despite this, C. inopinata did not reveal any differences in adult lifespan from C. elegans after accounting for differences in developmental timing and reproductive mode. C. inopinata fecundity was generally lower than that of C. elegans, but fitness improved under continuous-mating, consistent with sperm-limitation under gonochoristic (male/female) reproduction. C. inopinata also revealed greater fecundity and viability at higher temperatures.ConclusionConsistent with observations in other ectotherms, slower growth in C. inopinata indicates a potential trade-off between body size and developmental timing, whereas its unchanged lifespan suggests that longevity is largely uncoupled from its increase in body size. Additionally, temperature-dependent patterns of fitness in C. inopinata are consistent with its geographic origins in subtropical Okinawa. Overall, these results underscore the extent to which changes in ecological context and body size can shape life history traits.

A new species of the subgenus Scheloribates (Topobates) (Acari: Oribatida: Scheloribatidae) from Panama

2020 ◽  
Vol 29 (2) ◽  
pp. 278-283
Author(s):  
S.G. Ermilov
Keyword(s):  
New Species ◽  
Body Size ◽  
Leaf Litter ◽  
Related Species ◽  
Large Body ◽  
Oribatid Mite ◽  
Neotropical Region ◽  
Large Body Size ◽  
First Time ◽  
A New Species

The oribatid mite subgenus Scheloribates (Topobates) Grandjean, 1958, is recorded from the Neotropical region for the first time. A new species of this subgenus is described from the leaf litter collected in Cayo Agua Island, Panama. Scheloribates (Topobates) panamaensis sp. nov. differs from its related species by the very large body size and presence of a strong ventrodistal process on the leg femora II–IV.

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