Joao Botelho

Joao Botelho
Pontificia Universidad Católica de Chile | UC · Escuela de Medicina Veterinaria

PhD

About

23
Publications
13,136
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228
Citations
Additional affiliations
September 2014 - December 2015
University of Auckland
Position
  • PostDoc Position

Publications

Publications (23)
Article
Full-text available
Armoured dinosaurs are well known for their evolution of specialized tail weapons—paired tail spikes in stegosaurs and heavy tail clubs in advanced ankylosaurs1. Armoured dinosaurs from southern Gondwana are rare and enigmatic, but probably include the earliest branches of Ankylosauria2–4. Here we describe a mostly complete, semi-articulated skelet...
Article
Living beings are autopoietic systems with highly context-dependent structural dynamics and interactions, that determine whether a disturbance in the genotype or environment will lead or not to phenotypic change. The concept of epigenesis entails how a change in the phenotype may not correspond to a change in the structure of an earlier development...
Article
Full-text available
Radical transformation of the skull characterizes bird evolution. An increase in the relative size of the brain and eyes was presumably related to the loss of two bones surrounding the eye, the prefrontal and postorbital. We report that ossification centres of the prefrontal and postorbital are still formed in bird embryos, which then fuse seamless...
Article
Full-text available
In songbirds the learning and maintenance of song is dependent on auditory feedback, but little is known about the presence or role of other forms of sensory feedback. Here we studied the innervation of the avian vocal organ, the syrinx, in the zebra finch. Using a combination of immunohistochemistry, immunofluorescence and neural tracing with subu...
Article
In early theropod dinosaurs—the ancestors of birds—the hallux (digit 1) had an elevated position within the foot and had lost the proximal portion of its metatarsal. It no longer articulated with the ankle, but was attached at about mid-length of metatarsal 2 (mt2). In adult birds, the hallux is articulated closer to the distal end of mt2 at ground...
Article
Full-text available
Birds have a distally reduced, splinter-like fibula that is shorter than the tibia. In embryonic development, both skeletal elements start out with similar lengths. We examined molecular markers of cartilage differentiation in chicken embryos. We found that the distal end of the fibula expresses Indian Hedgehog (IHH), undergoing terminal cartilage...
Article
Full-text available
The song system of songbirds consists of an interconnected set of forebrain nuclei that has traditionally been regarded as dedicated to the learning and production of song. Here, however, we suggest that the song system could also influence muscles used in reproductive behaviour, such as the cloacal sphincter muscle. We showthat the samemedullary n...
Article
Full-text available
Endochondral ossification is a process essential for the formation of the vertebrate skeleton. Indian Hedgehog (IHH) is a key regulator of this process. So far, monitoring IHH expression in whole-mount developing skeletal structures has been hampered by the permeability and the opacity of the tissue. Whole-mount preparations require advanced techni...
Article
Full-text available
Specialized morphologies of bird feet have evolved several times independently as different groups have become zygodactyl, semi-zygodactyl, heterodactyl, pam-prodactyl or syndactyl. Birds have also convergently evolved similar modes of development, in a spectrum that goes from precocial to altricial. Using the new context provided by recent molecul...
Article
Full-text available
Owen's pre-evolutionary definition of a homolog as "the same organ in different animals under every variety of form and function" and its redefinition after Darwin as "the same trait in different lineages due to common ancestry" entail the same heuristic problem: how to establish "sameness."Although different criteria for homology often conflict, t...
Article
Full-text available
Most birds have an opposable digit 1 (hallux) allowing the foot to grasp, which evolved from the non-opposable hallux of early theropod dinosaurs. An important morphological difference with early theropods is the twisting of the long axis of its metatarsal. Here, we show how embryonic musculature and the onset of its activity are required for twist...
Article
Full-text available
From early dinosaurs with as many as nine wrist bones, modern birds evolved to develop only four ossifications. Their identity is uncertain, with different labels used in palaeontology and developmental biology. We examined embryos of several species and studied chicken embryos in detail through a new technique allowing whole-mount immunofluorescen...
Article
Full-text available
The zygodactyl orientation of toes (digits II and III pointing forwards, digits I and IV pointing backwards) evolved independently in different extant bird taxa. To understand the origin of this trait in modern birds, we investigated the development of the zygodactyl foot of the budgerigar (Psittaciformes). We compared its muscular development with...
Article
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The homology of the digits in the bird wing is a high-profile controversy in developmental and evolutionary biology. The embryonic position of the digits cartilages with respect to the primary axis (ulnare and ulna) corresponds to 2, 3, 4, but comparative-evolutionary morphology supports 1, 2, 3. A homeotic frameshift of digit identity in evolution...
Article
Full-text available
Background Sonic hedgehog (Shh)/Gli pathway plays an important regulatory role on the neuroepithelial cells (NEc) proliferation in the dorsal regions of the developing vertebrate Central Nervous System. The aim of this paper was to analyze the effect of the Shh/Gli signaling pathway activation on the proliferation dynamics and/or the spatial organi...
Article
Full-text available
The historiography of genetics usually recognizes its origin in the rediscovery of Mendel’s work and its fusion with cytology. This historiography neglects that genetics maintains ontological assumptions from former discussions about heredity. In this work I Intend to show how one of these ontological assumptions – the existence of a hereditary mat...
Thesis
Full-text available
There is a consensus in contemporary biology that genetics provided a conciliatory solution for the long-standing debate between preformacionists and epigenesists. Development, according to the genetic conciliation, is a hybrid process of preformation and epigenesis. Preformation persists as information, as a codified program of the development. Ep...

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