Periodic Reporting for period 1 - MEGAN (Mega-evolutionary dynamics of anurans)
Reporting period: 2022-04-01 to 2024-03-31
Understanding the origin of biodiversity, how clades diversify, and how new phenotypes arise are major subjects in evolutionary biology. It is clear that phenotypic diversity is distributed unequally and non-randomly across the tree of life; however, how such contrasting patterns of morphological disparity among lineages emerged is still a challenging question.Unequal phenotypic diversity between closely related lineages can be the result of different ecological opportunities, and one mechanism that has been evoked to explain early high disparity is adaptive radiation. Adaptive radiation is marked by rapid phenotypic evolution, increase of morphospace occupation, and high rates of taxonomic diversification. Once niches are occupied, phenotypic disparities and diversification would reach lower rates and eventually stabilize. Thus, it would be expected that the early diversification of basal lineages would be marked by high phenotypic disparity, whereas less inclusive clades would be characterized by lower phenotypic variation. Due to this rapid expansion of morphospace in a short period of time, Gaylord Simpson called this early burst process mega-evolution. While mega-evolution explains the evolution of several groups, it has been challenged by empirical data in others. In MEGAN I tested this hypothesis regarding the evolution of anurans (frogs and toads) using larval morphology as evidence.
MEGAN comprised three working packages (WPs) that reflected the main research objectives. Besides those, I also had training and skill transfer objectives. The overall goals of the proposal were attained, although some deliverables and milestones had to be modified due to different circumstances.
1: To determine how larval characters are distributed in the anuran tree of life.
2: To reconstruct the phylomorphospace of anuran larvae.
3: To determine the rates of diversification of anurans based on larval characters.
MEGAN comprised three working packages (WPs) that reflected the main research objectives. Besides those, I also had training and skill transfer objectives. The overall goals of the proposal were attained, although some deliverables and milestones had to be modified due to different circumstances.
1: To determine how larval characters are distributed in the anuran tree of life.
2: To reconstruct the phylomorphospace of anuran larvae.
3: To determine the rates of diversification of anurans based on larval characters.
Tadpoles representatives of major lineages of frogs were obtained from scientific collections. After species confirmation, they were studied regarding their external and internal morphology; they were inspected under stereoscope microscope, manually dissected, cleared and stained, and/or submited to scaning electron microscope and micro-CT methods. Characters were individualized from oral apparatus, tail and body morphology, musculo-skeletal system, buccopharyngeal cavity, and visceral components.
A phenotypic matrix was compiled and 378 phenotypic characters proposed to explain the observed diversity. Data was obtained for over 400 species covering the phylogenetic, ecological, and morphological diveristy of frogs. Several new states were described for the first time. Character were optimized into a phylogeneticy hypothesis and several novel synapomorphies identified.
The phenotypic matrix was converted into a distance matrix and used to reconstruct the morphospace occupied by anurans, as well as for the analysis of phenotypic disparity. The available time-calibrate hypothesis was based on a dataset containing several errors, such as mislabelling of genes and contaminations with human DNA, which could affect the estimation of the rates of evolution. Thus, select a subset of terminals and corrected the molecular matrix. I ran a total evidence analysis and evaluated the unique, homplastic, and private phenotipic synapomorphies at major clades.
Phenotypic synapomorphies were recovered at all levels of inclusiviness. Apomorphic transformations were observed in all major clades of frogs. There were instances of convergent evolution across the anuran tree of life, particularly within neobatrachians. Anurans occupied different regions of the morphospace, with different regions occupied by different clades. Six major clustering can be observed: 1) Caudata; 2) Ascaphidae; 3) Costata; 4) Xenoanura; 5 Anomocoela; and 6) Neobatrachia. Those clusters are highly in accordance with the phylogeny of frogs. Anomocoela and Neobatrachians occupied similar regions of the morphospace. Xenoanura and Microhylids explored different regions of the morphospace, not occupied by representatives of other clades. Phenotypic disparity was quite similar in those clusters, with the highest value in Xenoanura. . Early evolution of anurans and more inclusive clades, such as Lalagobatrachia, is marked by the acquisition of unique and private synapomorphies. Evolution of less inclusive clades is marked mainly by homoplastic synapomorphies. The results shows that anuran had an early burst, marked by the acquisition of novel, unique character-states, with an occupation of different portions of the morphospace. Neobatrachians, the most diverse and speciose clades of frogs, is initially concentrated in a portion of the morphospace, with a secondary colonization of other regions by microhylids. Notwithstanding, apomorphic transformations occurred in similar proportion in that clade as in the most basal lineages, although many transformations are homoplastic. The results support the notion that anurans diversification have been continuous through time, although phenotypic innovations became less common and convergent evolution became an important player; this is highlighted by the fact the phenotypic disparity did not change drastically through time. Thus, the mega-evolutionary hypothesis is partially supported by tadpole morphology.
Results of MEGAN have been presented in national and international conferences. They have also been disclosed in social media. Additionally, I organised multiple scientific events, including the, II International Symposium Tadpole Evolution, that had almost 400 attendants from different regions of the World; this online and free of charge event, was the most comprehensive event about tadpole biology ever and reached people from different culture, academic levels, and social backgrounds.
A phenotypic matrix was compiled and 378 phenotypic characters proposed to explain the observed diversity. Data was obtained for over 400 species covering the phylogenetic, ecological, and morphological diveristy of frogs. Several new states were described for the first time. Character were optimized into a phylogeneticy hypothesis and several novel synapomorphies identified.
The phenotypic matrix was converted into a distance matrix and used to reconstruct the morphospace occupied by anurans, as well as for the analysis of phenotypic disparity. The available time-calibrate hypothesis was based on a dataset containing several errors, such as mislabelling of genes and contaminations with human DNA, which could affect the estimation of the rates of evolution. Thus, select a subset of terminals and corrected the molecular matrix. I ran a total evidence analysis and evaluated the unique, homplastic, and private phenotipic synapomorphies at major clades.
Phenotypic synapomorphies were recovered at all levels of inclusiviness. Apomorphic transformations were observed in all major clades of frogs. There were instances of convergent evolution across the anuran tree of life, particularly within neobatrachians. Anurans occupied different regions of the morphospace, with different regions occupied by different clades. Six major clustering can be observed: 1) Caudata; 2) Ascaphidae; 3) Costata; 4) Xenoanura; 5 Anomocoela; and 6) Neobatrachia. Those clusters are highly in accordance with the phylogeny of frogs. Anomocoela and Neobatrachians occupied similar regions of the morphospace. Xenoanura and Microhylids explored different regions of the morphospace, not occupied by representatives of other clades. Phenotypic disparity was quite similar in those clusters, with the highest value in Xenoanura. . Early evolution of anurans and more inclusive clades, such as Lalagobatrachia, is marked by the acquisition of unique and private synapomorphies. Evolution of less inclusive clades is marked mainly by homoplastic synapomorphies. The results shows that anuran had an early burst, marked by the acquisition of novel, unique character-states, with an occupation of different portions of the morphospace. Neobatrachians, the most diverse and speciose clades of frogs, is initially concentrated in a portion of the morphospace, with a secondary colonization of other regions by microhylids. Notwithstanding, apomorphic transformations occurred in similar proportion in that clade as in the most basal lineages, although many transformations are homoplastic. The results support the notion that anurans diversification have been continuous through time, although phenotypic innovations became less common and convergent evolution became an important player; this is highlighted by the fact the phenotypic disparity did not change drastically through time. Thus, the mega-evolutionary hypothesis is partially supported by tadpole morphology.
Results of MEGAN have been presented in national and international conferences. They have also been disclosed in social media. Additionally, I organised multiple scientific events, including the, II International Symposium Tadpole Evolution, that had almost 400 attendants from different regions of the World; this online and free of charge event, was the most comprehensive event about tadpole biology ever and reached people from different culture, academic levels, and social backgrounds.
The results of MEGAN improved our understanding of the evolutionary and diversification processes of anurans. As expected, early evolution of the group was marked by the acquisition of novel phenotypes, but phenotypic diversifciation did not decreased in less inclusive clades, although convergent evolution has played a major role in those clades.
I believe that my strategies of communication and dissemination had a positive impact on society. The organization of events, such as the International Symposium on Tadpole Evolution and the public lectures were very influential. I believe that dissemination and communication, as well as the training and development of new students, are part of the activities of a scientist. I always wanted to promote the study of tadpoles because they are amazing model organisms to test major evolutionary theories (as in MEGAN). The symposium was a success, with almost 400 attendants from all continents and several nationality and education level. The event was completely online and free of charging; thus, it was highly inclusive and allowed people to have access to high quality lectures, perform network activities, and be updated on the novelties in the field of tadpole biology. Also, we organized an event to respect gender balance (50-50) and to bring researchers with different socioeconomical backgrounds together. After the event I received on my personal email several positive feedback from young scientists thanking for the event and saying that they were highly inspired in study tadpoles.
I believe that my strategies of communication and dissemination had a positive impact on society. The organization of events, such as the International Symposium on Tadpole Evolution and the public lectures were very influential. I believe that dissemination and communication, as well as the training and development of new students, are part of the activities of a scientist. I always wanted to promote the study of tadpoles because they are amazing model organisms to test major evolutionary theories (as in MEGAN). The symposium was a success, with almost 400 attendants from all continents and several nationality and education level. The event was completely online and free of charging; thus, it was highly inclusive and allowed people to have access to high quality lectures, perform network activities, and be updated on the novelties in the field of tadpole biology. Also, we organized an event to respect gender balance (50-50) and to bring researchers with different socioeconomical backgrounds together. After the event I received on my personal email several positive feedback from young scientists thanking for the event and saying that they were highly inspired in study tadpoles.