Evolution and development of evolutionary novelties during anuran ontogenesis

• Applicant: Dr. Paul Lukas
• Subject Area: Evolution, Anthropology ; Developmental Biology
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 418528051

• Final Report Year: 2024

Final Report Abstract

Evolutionary novelties are morphological structures that allow organisms to perform new or specialized functions. The origin and mechanisms of these innovations are central to developmental biology research. An interesting example is the cartilaginous skeleton of anurang tadpoles, which is unique compared to other vertebrate groups. The tadpoles of anurans have two unique cartilages: the suprarostral cartilage at the front edge of the upper jaw and the infrarostral cartilage in the front area of the lower jaw. The infrarostral cartilage is connected to Meckel's cartilage via the equally unique intramandibular joint. In addition to cartilage structures, certain tadpoles possess unique cartilages, such as submeckelian, admandibular, or adrostral cartilages, depending on their location. The evolution and development of these structures requires genetic signals during individual development to allow the organism to develop in a specific way. This project presents various scientific works in the field of amphibian research that explore the evolution and development of these evolutionary novelties in different ways. A study analysing the zax gene in Xenopus laevis demonstrates that knockdown of this gene results in changes in the head skeleton, indicating its potential role in evolution and development. Subsequent research provides comprehensive insights into the cartilage development of various Anura species, such as Bombina orientalis, Discoglossus scovazzi, Bufo bufo, and Hymenochirus boettgeri, illustrating the diversity of head skeleton development in amphibians. Additionally, this text describes characteristics that distinguish Gnathostomata from other organisms. Other studies provide detailed descriptions of the head skeleton and musculature of tadpoles from various species, including Alytes muletensis, Heleophryne orientalis, Pelobates fuscus, and Ranitomeya variabilis. These studies identified additional cartilages in the mandibular region and analyzed their origin and function. All studies identify relevant features systematically, thus reinforcing the systematic positions of the corresponding species. Further research is dedicated to the morphology of the feeding apparatus of sirenid salamanders, and on the historical development from Ernst Haeckel's basic biogenetic law and the gastraea theory to the modern application of molecular data.

Publications

• Knockdown of zax in Xenopus laevis leads to craniofacial malformations and the absence of the intramandibular joint. Vertebrate Zoology, 70, 9-22.
  Lukas, P., Schmidt, J. & Olsson, L.
  
• Larval cranial anatomy of the Eastern Ghost Frog (Heleophryne orientalis). Acta Zoologica, 102(4), 452-466.
  Lukas, Paul
  
• Sequence of chondrocranial development in the oriental fire bellied toad Bombina orientalis . Journal of Morphology, 281(6), 688-701.
  Lukas, Paul & Olsson, Lennart
  
• Form and function of the feeding apparatus of sirenid salamanders (Caudata: Sirenidae): Three-dimensional chewing and herbivory?. Zoologischer Anzeiger, 295, 99-116.
  Schwarz, Daniel; Fedler, Matthew T.; Lukas, Paul & Kupfer, Alexander
  
• Hidden but not lost: the larval cranial anatomy of the Majorcan midwife toad (Alytes muletensis). Salamandra, 57 (3), 378-388.
  Lukas, P.
  
• The biogenetic law and the Gastraea theory: From Ernst Haeckel's discoveries to contemporary views. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 338(1-2), 13-27.
  Levit, Georgy S.; Hoßfeld, Uwe; Naumann, Benjamin; Lukas, Paul & Olsson, Lennart
  
• A decharming metamorphosis: The larval and adult morphology of the common spadefoot toad, Pelobates fuscus. Zoologischer Anzeiger, 296, 37-49.
  Jandausch, Kenny; Schwarz, Daniel; Bock, Bernhard Leopold & Lukas, Paul
  
• Sequence of chondrocranial development in basal anurans—Let’s make a cranium. Frontiers in Zoology, 19(1).
  Lukas, Paul & Ziermann, Janine M.
  
• Embryonic pattern of cartilaginous head development in the European toad, Bufo bufo. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 340(7), 437-454.
  Lukas, Paul
  
• Tadpole morphological characterization of Ranitomeya variabilis (Zimmermann & Zimmermann, 1988) (Anura: Dendrobatidae), with skeleton, muscle system and inner organs. Zoomorphology, 142(4), 477-486.
  Regnet, Ruth A.; Lukas, Paul; Rödder, Dennis; Wipfler, Benjamin & Solé, Mirco
  
• The chondrocranium of the tadpole of Hymenochirus boettgeri (Anura: Pipidae) and the sequence and timing of its development. Zoologischer Anzeiger, 310, 53-66.
  Lukas, Paul; Araújo, Olívia G.S. & Hernández-Nieto, Sebastián