Genomic, Phenotypic and Environmental Correlates of Speciation in the Midwife Toads ( <i>Alytes</i> )
Speciation, i.e., the formation of new species, implies that diverging populations evolve genetic, phenotypic or ecological factors that promote reproductive isolation (RI), but the relative contributions of these factors remain elusive. Here we test which of genomic, bioacoustic, morphological, and environmental differences best predicts RI across a continuum of divergence in the midwife toads (genus Alytes), a group of Western Mediterranean amphibians, using a total evidence approach. We found that, without strong geographic barriers to dispersal, the extent of introgression across hybrid zones between phylogeographic lineages, which should reflect the strength of RI, predominantly covaries with genomic divergence. Overall phenotypic differentiation becomes substantial only between well established, fully isolated species. These results suggest that speciation in midwife toads initially involve cryptic lineages, which probably evolve RI through intrinsic (genetic) hybrid incompatibilities. As they continue to diverge, these nascent species eventually differentiate externally, which potentially enforces pre-mating barriers and facilitates sympatry. This speciation scenario has practical implications for species delimitation, notably when using hybrid zones and divergence thresholds as proxies for reproductive isolation.
Authors
- Pierre‐André Crochet (ORCID: https://orcid.org/0000-0002-0422-3960)
- Guillermo Velo‐Antón (ORCID: https://orcid.org/0000-0002-9483-5695)
- Spartak Nikolaevich Litvinchuk (ORCID: https://orcid.org/0000-0001-7447-6691)
- Johanna Ambu (ORCID: https://orcid.org/0000-0002-8072-7677)
- Helena Martínez‐Gil (ORCID: https://orcid.org/0000-0002-4868-8209)
- Helena Gonçalves (ORCID: https://orcid.org/0000-0001-5550-1361)
- Fernando Martínez‐Freiría (ORCID: https://orcid.org/0000-0003-2311-8960)
- Christophe Dufresnes (ORCID: https://orcid.org/0000-0002-8497-8908)
- Alfredo G. Nicieza (ORCID: https://orcid.org/0000-0003-4062-569X)
- Juan F. Beltrán (ORCID: https://orcid.org/0000-0002-0077-575X)
- Axel Hernández (ORCID: https://orcid.org/0000-0003-3720-2856)
- David Donaire‐Barroso
- Carlos Caballero‐Díaz (ORCID: https://orcid.org/0000-0002-5766-3206)
- Íñigo Martínez‐Solano (ORCID: https://orcid.org/0000-0002-2260-226X)
- Tomasz Suchan (ORCID: https://orcid.org/0000-0002-0811-8754)
Institutions
- Centre National de la Recherche Scientifique (FR)
- Université de Corse Pascal Paoli (FR)
- École Pratique des Hautes Études (FR)
- Universidad de Oviedo (ES)
- Nanjing Forestry University (CN)
- Universidade do Porto (PT)
- Université de Montpellier (FR)
- Université Paris Sciences et Lettres (FR)
- Sorbonne Université (FR)
- Centre d'Écologie Fonctionnelle et Évolutive (FR)
- Institut de Systématique, Évolution, Biodiversité (FR)
- Institute of Cytology (RU)
- Museo Nacional de Ciencias Naturales (ES)
- Asociación Herpetológica Española (ES)
- Asociación Española de Urología (ES)
- Institut de Biologia Evolutiva (ES)
- Władysław Szafer Institute of Botany (PL)
- Institut de Recherche pour le Développement (FR)
- Universidade de Vigo (ES)
- Universidad Autónoma de Madrid (ES)
- Universitat de Barcelona (ES)
- Universidad de Sevilla (ES)
- Polish Academy of Sciences (PL)
Publication Details
- Journal
- Molecular Ecology
- Published
- 2025-03-25
- DOI
- https://doi.org/10.1111/mec.17736
- Citations
- 5
- Primary Topic
- Genetic diversity and population structure
- Type
- article
- Field-Weighted Citation Impact
- 9.09
Funders
- Comunidad de Madrid
- Ministerio de Educación y Ciencias
- Deutsche Forschungsgemeinschaft
- National Natural Science Foundation of China
- Ministerio de Ciencia e Innovación
- Xunta de Galicia
- Région Occitanie Pyrénées-Méditerranée