Hourglass Model for Developmental Evolution of Ant Castes

2020 ◽  
Author(s):  
Waring Trible ◽  
Daniel J.C. Kronauer
Keyword(s):  
Developmental Evolution ◽  
Hourglass Model

scholarly journals Gene Expression Does Not Support the Developmental Hourglass Model in Three Animals with Spiralian Development

2019 ◽  
Vol 36 (7) ◽  
pp. 1373-1383 ◽  
Author(s):  
Longjun Wu ◽  
Kailey E Ferger ◽  
J David Lambert
Keyword(s):  
Gene Expression ◽  
Large Fraction ◽  
Molecular Data ◽  
Development Stage ◽  
Data Sets ◽  
Rna Seq ◽  
Developmental Evolution ◽  
Phylotypic Stage ◽  
Hourglass Model ◽  
Almost All

Abstract It has been proposed that animals have a pattern of developmental evolution resembling an hourglass because the most conserved development stage—often called the phylotypic stage—is always in midembryonic development. Although the topic has been debated for decades, recent studies using molecular data such as RNA-seq gene expression data sets have largely supported the existence of periods of relative evolutionary conservation in middevelopment, consistent with the phylotypic stage and the hourglass concepts. However, so far this approach has only been applied to a limited number of taxa across the tree of life. Here, using established phylotranscriptomic approaches, we found a surprising reverse hourglass pattern in two molluscs and a polychaete annelid, representatives of the Spiralia, an understudied group that contains a large fraction of metazoan body plan diversity. These results suggest that spiralians have a divergent midembryonic stage, with more conserved early and late development, which is the inverse of the pattern seen in almost all other organisms where these phylotranscriptomic approaches have been reported. We discuss our findings in light of proposed reasons for the phylotypic stage and hourglass model in other systems.

scholarly journals An irregular hourglass pattern describes the tempo of phenotypic development in placental mammal evolution

2020 ◽  
Vol 16 (5) ◽  
pp. 20200087
Author(s):  
Gerardo A. Cordero ◽  
Marcelo R. Sánchez-Villagra ◽  
Ingmar Werneburg
Keyword(s):  
Interspecific Variation ◽  
Published Data ◽  
Fetal Life ◽  
Phenotypic Differences ◽  
Developmental Evolution ◽  
Highly Active ◽  
Prenatal Ontogeny ◽  
Hourglass Model ◽  
Organismal Development ◽  
Conservation Model

Organismal development is defined by progressive transformations that ultimately give rise to distinct tissues and organs. Thus, temporal shifts in ontogeny often reflect key phenotypic differences in phylogeny. Classical theory predicts that interspecific morphological divergence originates towards the end of embryonic or fetal life stages, i.e. the early conservation model. By contrast, the hourglass model predicts interspecific variation early and late in prenatal ontogeny, though with a phylogenetically similar mid-developmental period. This phylotypic period, however, remains challenging to define within large clades such as mammals. Thus, molecular and morphological tests on a mammalian hourglass have not been entirely congruent. Here, we report an hourglass-like pattern for mammalian developmental evolution. By comparing published data on the timing of 74 homologous characters across 51 placental species, we demonstrated that variation in the timing of development decreased late in embryogenesis––when organ formation is highly active. Evolutionary rates of characters related to this timeframe were lowest, coinciding with a phylotypic period that persisted well beyond the pharyngula ‘stage’. The trajectory culminated with elevated variation in a handful of fetal and perinatal characters, yielding an irregular hourglass pattern. Our study invites further quantification of ontogeny across diverse amniotes and thus challenges current ideas on the universality of developmental patterns.

scholarly journals Quantitative system drift compensates for altered maternal inputs to the gap gene network of the scuttle fly Megaselia abdita

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Karl R Wotton ◽  
Eva Jiménez-Guri ◽  
Anton Crombach ◽  
Hilde Janssens ◽  
Anna Alcaine-Colet ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Network ◽  
Mechanistic Explanation ◽  
Developmental Evolution ◽  
Gap Gene ◽  
Spatio Temporal ◽  
Mechanistic Basis ◽  
Hourglass Model ◽  
Network Rewiring ◽  
Megaselia Abdita

The segmentation gene network in insects can produce equivalent phenotypic outputs despite differences in upstream regulatory inputs between species. We investigate the mechanistic basis of this phenomenon through a systems-level analysis of the gap gene network in the scuttle fly Megaselia abdita (Phoridae). It combines quantification of gene expression at high spatio-temporal resolution with systematic knock-downs by RNA interference (RNAi). Initiation and dynamics of gap gene expression differ markedly between M. abdita and Drosophila melanogaster, while the output of the system converges to equivalent patterns at the end of the blastoderm stage. Although the qualitative structure of the gap gene network is conserved, there are differences in the strength of regulatory interactions between species. We term such network rewiring ‘quantitative system drift’. It provides a mechanistic explanation for the developmental hourglass model in the dipteran lineage. Quantitative system drift is likely to be a widespread mechanism for developmental evolution.

Developmental Evolution

2013 ◽  
pp. 375-382 ◽  
Author(s):  
Manfred D. Laubichler ◽  
Jane Maienschein
Keyword(s):  
Developmental Evolution

scholarly journals Selection against expression noise explains the origin of the hourglass pattern of Evo-Devo

2019 ◽  
Author(s):  
Jialin Liu ◽  
Michael Frochaux ◽  
Vincent Gardeux ◽  
Bart Deplancke ◽  
Marc Robinson-Rechavi
Keyword(s):  
Regulatory Elements ◽  
Mutational Robustness ◽  
Expression Variability ◽  
Expression Noise ◽  
Environmental Perturbations ◽  
Phylotypic Stage ◽  
Robustness To Noise ◽  
Selection For ◽  
Hourglass Model ◽  
Evo Devo

The evolution of embryological development has long been characterized by deep conservation. Both morphological and transcriptomic surveys have proposed a “hourglass” model of Evo-Devo1,2. A stage in mid-embryonic development, the phylotypic stage, is highly conserved among species within the same phylum3–7. However, the reason for this phylotypic stage is still elusive. Here we hypothesize that the phylotypic stage might be characterized by selection for robustness to noise and environmental perturbations. This could lead to mutational robustness, thus evolutionary conservation of expression and the hourglass pattern. To test this, we quantified expression variability of single embryo transcriptomes throughout fly Drosophila melanogaster embryogenesis. We found that indeed expression variability is lower at extended germband, the phylotypic stage. We explain this pattern by stronger histone modification mediated transcriptional noise control at this stage. In addition, we find evidence that histone modifications can also contribute to mutational robustness in regulatory elements. Thus, the robustness to noise does indeed contributes to robustness of gene expression to genetic variations, and to the conserved phylotypic stage.

Test–retest reliability and developmental evolution of the 6-min walk test in Caucasian boys aged 5–12years

2013 ◽  
Vol 23 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Nathalie Goemans ◽  
Katrijn Klingels ◽  
Marleen van den Hauwe ◽  
Anneleen Van Orshoven ◽  
Sofie Vanpraet ◽  
...  
Keyword(s):  
Walk Test ◽  
Retest Reliability ◽  
Developmental Evolution ◽  
Test Retest Reliability
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