Affiliation:
1. Departamento de Biologia Animal, Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB) Instituto de Biologia, Unicamp Campinas São Paulo Brazil
2. Pós‐Graduação em Biologia Animal, Unicamp Campinas São Paulo Brasil
3. Departamento de Biologia Universidade Federal de São Carlos Sorocaba São Paulo Brazil
4. Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas Universidade de Brasília Brasília Federal District Brazil
5. Instituto de Ciências Biológicas e da Saúde Universidade Federal Rural do Rio de Janeiro Seropédica Rio de Janeiro Brazil
Abstract
AbstractAnurans of the genus Brachycephalus are among the smallest vertebrates in the world, due to an extreme process of miniaturization. As an example of this process, Brachycephalus species show loss of fingers, loss of the eardrum and middle ear, bone fusions, and the presence of paravertebral plates and parotic plaque. However, no studies addressing the consequences of miniaturization on internal organs, such as the lungs and heart, are currently available. Thus, this study aimed to investigate if overall small body size has affected the cardiorespiratory system. We investigated, via dissections, individuals of four Brachycephaloidea species: Brachycephalus rotenbergae, B. pitanga, Eleutherodactylus johnstonei, and Ischnocnema parva. We observed that B. rotenbergae and B. pitanga present a reduction of the atrial septum and absence of the carotid body. On the other hand, despite being a member of the sister genus to Brachycephalus (both genera belong to the Brachycephalidae), individuals of Ischnocnema present a heart with a complete septum and carotid body; this is also observed in E. johnstonei (Eleutherodactylidae). We observed that B. rotenbergae and B. pitanga have thin skin with a one to two cell thick germ layer, and their lungs likely exhibit lower blood supply when compared to individuals of the E. johnstonei and I. parva species. Based on the observed structures, we suggest that in species of Brachycephalus, respiration is performed mainly through the skin, and their lungs may have a reduced respiratory function.
Funder
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Fundação de Amparo à Pesquisa do Estado de São Paulo
Subject
Cell Biology,Developmental Biology,Molecular Biology,Ecology, Evolution, Behavior and Systematics,Histology,Anatomy