Viviparity stimulates diversification in an order of fish

Abstract

Species richness is distributed unevenly across the tree of life and this may be influenced by the evolution of novel phenotypes that promote diversification. Viviparity has originated ∼150 times in vertebrates and is considered to be an adaptation to highly variable environments. Likewise, possessing an annual life cycle is common in plants and insects, where it enables the colonization of seasonal environments, but rare in vertebrates. The extent to which these reproductive life-history traits have enhanced diversification and their relative importance in the process remains unknown. We show that convergent evolution of viviparity causes bursts of diversification in fish. We built a phylogenetic tree for Cyprinodontiformes, an order in which both annualism and viviparity have arisen, and reveal that while both traits have evolved multiple times, only viviparity played a major role in shaping the patterns of diversity. These results demonstrate that changes in reproductive life-history strategy can stimulate diversification.

Reversals in complex traits uncovered as reticulation events: Lessons from the evolution of parity‐mode, chromosome morphology, and maternal resource transfer

“…The topology of the Bayesian phylogenetic tree for Cyprinodontiformes (Figure a), was similar to that previously published by Helmstetter et al (). This tree revealed robust statistical evidence (Bayesian posterior probabilities ≥ 0.95; Figure ) for a potential reversal from viviparity to oviparity in the ancestor of Tomeurus gracilis and for reversals from lecithotrophy to placentotrophy in the ancestor of Pamphorichthys hollandi and the ancestor of Poeciliopsis elongate .…”

“…This tree revealed robust statistical evidence (Bayesian posterior probabilities ≥ 0.95; Figure ) for a potential reversal from viviparity to oviparity in the ancestor of Tomeurus gracilis and for reversals from lecithotrophy to placentotrophy in the ancestor of Pamphorichthys hollandi and the ancestor of Poeciliopsis elongate . The phylogenetic positions of Phalloceros caudimaculatus and Oxyzygonectes dovil were unresolved (no significant statistical support in Figure , and no reversal according to Helmstetter et al, ) and thus no statistical support existed for a reversal to placentothrophy and oviparity, respectively.…”

“…Discussion about reversals and Dollo's law centered around parity‐mode evolution (e.g., Blackburn, ; Griffith et al, ; Helmstetter et al, ; Pyron & Burbrink, ; Surget‐Groba et al, ) and it is suggested that the reappearance of oviparity by means of small evolutionary steps is difficult and highly unlikely (Griffith et al, ; Helmstetter et al, ; Pyron & Burbrink, ; Surget‐Groba et al, ) once viviparity has evolved, which is in line with Dollo's claim. The evolution of viviparity is complex because it requires changes in the timing of reproductive events (e.g., embryonic retention) and the evolution of structures that facilitate intrauterine gas exchange between the mother and her offspring.…”

Les règles de la biodiversité en temps profond

“…Dans les deux cas, les forces générées collectivement par le réseau entier apparaissent hors de proportion avec une prédiction naïve qui ignorerait le flambage, et notre théorie rend compte avec une bonne précision d'amplifications pouvant aller jusqu'à un facteur vingt. Au-delà de simples mesures de force, nos résultats sont en bon accord avec l'observation directe de la contraction de systèmes d'actomyosine reconstruits à partir de protéines purifiées, dans lesquels le flambage est prépondérant [8] Figure 1A). Les phylogénies molécu-laires datées ouvrent une fenêtre sur l'évolution de la diversité de la vie et sont nos guides les plus puissants pour comprendre comment les espèces ont évolué.…”

“…Ces questions sont presque aussi anciennes cation de tels modèles. Cela a révélé, par exemple, que la diversification chez les oiseaux a accéléré au cours des 50 derniers millions d'années [6], que les vitesses de spéciation des mammifères sont supérieures dans les régions tropicales que dans les régions tempé-rées [7], et que la viviparité entraîne des radiations 2 chez les poissons [8]. Notre compréhension actuelle de l'évo-lution est donc fondée à la fois sur les phénomènes microévolutionnaires de l'héritage génétique et sur l'étude de l'histoire phylogénétique des espèces.…”