Heterochrony and developmental timing mechanisms: Changing ontogenies in evolution

Keyte, Anna L.; Smith, Kathleen K.

doi:10.1016/j.semcdb.2014.06.015

Cited by 64 publications

(62 citation statements)

References 84 publications

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“…Sexual development consists of a series of events that take place in a highly regulated spatial and temporal context; changes in the timing of developmental events is termed heterochrony (Keyte and Smith ). In this study, we found that the pattern of gonadal and hemipenal development is similar to that described in other saurians.…”

Section: Discussionmentioning

confidence: 82%

Hemipenes in females of the mexican viviparous lizard Barisia imbricata (Squamata: Anguidae): an example of heterochrony in sexual development

Martı́nez-Torres

Rubio-Morales

Piña-Amado

et al. 2015

Evolution and Development

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The sexual development of saurians follows a similar pattern to that described for other amniotes. Changes in the timing or sequence of development events are known as heterochrony. We describe the pattern of sexual development in the viviparous Mexican lizard Barisia imbricata and report heterochrony in the regression of hemipenes in this lizard. We collected gestating females; some lizards were subjected to partial hysterectomy and the embryos were processed using routine histological technique to assess gonadal development; the remaining embryos were used to assess the development of hemipenes. Other pregnant females were kept in captivity in individual terraria until the time of delivery. All neonates were sexed by eversion of hemipenes and some of their body characteristics were recorded. Several neonates were sacrificed and processed to establish gonadal histology and the young of the remaining litters were maintained in captivity to observe the fate of the hemipenes in both sexes. Gonadal development began at embryonic stage 33 and the hemipenes were visible at the same stage. In the neonates, the ovary contained oogonias and ovarian follicles, whereas the testicles showed testicular cords. All neonates had hemipenes and sex could only be established through direct observation of the reproductive ducts and gonadal histology. The hemipenes regression in the females begins after approximately 7 months of postnatal development and concludes at about 15 months of age. We think that the delayed regression of the hemipenes reflects evolutionary differences among reptiles and may be an indication of a stage in the evolutionary process of this species.

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Section: Discussionmentioning

confidence: 82%

Hemipenes in females of the mexican viviparous lizard Barisia imbricata (Squamata: Anguidae): an example of heterochrony in sexual development

Martı́nez-Torres

Rubio-Morales

Piña-Amado

et al. 2015

Evolution and Development

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“…Strikingly, however, the forelimbs are functional with fully developed muscular and nervous systems, which are used to crawl from the birth canal to the teat. The onset of opossum Tbx5 expression is earlier than the mouse and its expression domain is bigger [73,74], suggesting that the accelerated forelimb development is achieved by heterochoronical and heterotopical regulation of the forelimb forming domain. The expanded domain of Tbx5 expression can be explained by shifted rostro-caudal Hox code [73], while the mechanism of its early expression is unclear.…”

Section: Specification Of the Limb Forming Domains And Heterochrony Imentioning

confidence: 99%

Subdivision of the lateral plate mesoderm and specification of the forelimb and hindlimb forming domains

Nishimoto

Logan

2016

Seminars in Cell & Developmental Biology

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The limbs are a significant evolutionary innovation that enabled vertebrates to diversify and colonise new environments. Tetrapods have two pairs of limbs, forelimbs in the upper body and hindlimbs in the lower body. The morphologies of the forelimbs and hindlimbs are distinct, reflecting their specific locomotory functions although they share many common signalling networks that regulate their development. The paired appendages in vertebrates form at fixed positions along the rostral-caudal axis and this occurs as a consequence of earlier subdivision of the lateral plate mesoderm (LPM) into regions with distinct limb forming potential. In this review, we discuss the molecular mechanisms that confer a broad region of the flank with limb-forming potential and its subsequent refinement into distinct forelimb-forming, hindlimb-forming and interlimb territories.

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“…Such malleability is incorporated in the concept of heterokairy, the change in developmental sequence of the onset of physiological regulatory mechanisms or supporting morphological structures within an individual or population (Spicer and Burggren, 2003;Spicer and Rundle, 2007;Spicer et al, 2011). This contrasts with heterochrony, which is a change in the development sequence between species over evolutionary time (Spicer and Burggren, 2003;Blom and Lilja, 2005;Spicer et al, 2011;Keyte and Smith, 2014;Mueller et al, 2015b). The relatively few experimental demonstrations of heterokairy have centered on either invertebrates or lower vertebrates.…”

Section: Studying Heterokairy With Avian Embryo Modelsmentioning

confidence: 99%

Cardio-respiratory development in bird embryos: new insights from a venerable animal model

2016

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-The avian embryo is a time-honored animal model for understanding vertebrate development. A key area of extensive study using bird embryos centers on developmental phenotypic plasticity of the cardio-respiratory system and how its normal development can be affected by abiotic factors such as temperature and oxygen availability. Through the investigation of the plasticity of development, we gain a better understanding of both the regulation of the developmental process and the embryo's capacity for self-repair. Additionally, experiments with abiotic and biotic stressors during development have helped delineate not just critical windows for avian cardio-respiratory development, but the general characteristics (e.g., timing and dose-dependence) of critical windows in all developing vertebrates. Avian embryos are useful in exploring fetal programming, in which early developmental experiences have implications (usually negative) later in life. The ability to experimentally manipulate the avian embryo without the interference of maternal behavior or physiology makes it particularly useful in future studies of fetal programming. The bird embryo is also a key participant in studies of transgenerational epigenetics, whether by egg provisioning or effects on the germline that are transmitted to the F1 generation (or beyond). Finally, the avian embryo is heavily exploited in toxicology, in which both toxicological testing of potential consumer products as well as the consequences of exposure to anthropogenic pollutants are routinely carried out in the avian embryo. The avian embryo thus proves useful on numerous experimental fronts as an animal model that is concurrently both of adequate complexity and sufficient simplicity for probing vertebrate cardio-respiratory development.

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Heterochrony and developmental timing mechanisms: Changing ontogenies in evolution

Cited by 64 publications

References 84 publications

Hemipenes in females of the mexican viviparous lizard Barisia imbricata (Squamata: Anguidae): an example of heterochrony in sexual development

Hemipenes in females of the mexican viviparous lizard Barisia imbricata (Squamata: Anguidae): an example of heterochrony in sexual development

Subdivision of the lateral plate mesoderm and specification of the forelimb and hindlimb forming domains

Cardio-respiratory development in bird embryos: new insights from a venerable animal model

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