Bayesian Inference of Divergence Times and Feeding Evolution in Grey Mullets (Mugilidae)

Abstract

Grey mullets (Mugilidae, Ovalentariae) are coastal fishes found in near-shore environments of tropical, subtropical, and temperate regions within marine, brackish, and freshwater habitats throughout the world. This group is noteworthy both for the highly conserved morphology of its members-which complicates species identification and delimitation-and also for the uncommon herbivorous or detritivorous diet of most mullets. In this study, we first attempt to identify the number of mullet species, and then-for the resulting species-estimate a densely sampled time-calibrated phylogeny using three mitochondrial gene regions and three fossil calibrations. Our results identify two major subgroups of mullets that diverged in the Paleocene/Early Eocene, followed by an Eocene/Oligocene radiation across both tropical and subtropical habitats. We use this phylogeny to explore the evolution of feeding preference in mullets, which indicates multiple independent origins of both herbivorous and detritivorous diets within this group. We also explore correlations between feeding preference and other variables, including body size, habitat (marine, brackish, or freshwater), and geographic distribution (tropical, subtropical, or temperate). Our analyses reveal: (1) a positive correlation between trophic index and habitat (with herbivorous and/or detritivorous species predominantly occurring in marine habitats); (2) a negative correlation between trophic index and geographic distribution (with herbivorous species occurring predominantly in subtropical and temperate regions), and; (3) a negative correlation between body size and geographic distribution (with larger species occurring predominantly in subtropical and temperate regions). PLOS1/56 1 Grey mullets (Mugilidae, Ovalentariae) occur in coastal waters worldwide 2 and represent an important food source in several European and Pacific 3 countries. Mugilids are geographically widespread, with species ranging 4 from the tropics to northern Europe, and vary greatly in body size, with 5 species ranging from 10 − 120 cm in total length (TL). Despite this 6 variation, the morphology of mullets is extremely conservative; all species 7 share a torpedo-shaped body form with a similar overall appearance, 8 which makes accurate species identification exceptionally challenging [1]. 9 Most mullet species are euryhaline and may spend at least part of their 10 life cycle in brackish or freshwater habitats, even though the majority of 11 the adult life-stage and reproduction typically occur in marine habitats. 12 However, a few species (e.g., Liza abu, Agonostomus monticula and A. 13 catalai) are exclusively freshwater [1-4]. 14 The diet of grey mullets is unusual among marine fishes: most mullet 15 species feed predominantly on food items-such as detritus and 16 filamentous algae-with relatively low calories and/or protein per unit 17 mass (i.e., "low-quality food resources" [5]). Mullets have evolved a 18 number of morphological adaptations associated with this diet, including 19 a stomach with...

An overview of grey mullet (Mugilidae) global occurrence and species‐rich ecoregions, with indications of possible past dispersal routes within the family

“…Phylogenetic relationships, as well as divergence time among genera and species of the Mugilidae family shown in Figure 1, rely on the phylogenetic analyses provided by Santini et al . (2015). These authors mainly used the data set published by Durand, Shen, et al .…”

“…Phylogenetic relationships, as well as divergence time among genera and species of the Mugilidae family shown in Figure 1, rely on the phylogenetic analyses provided by Santini et al (2015). These authors mainly used the data set published by for phylogenetic reconstruction and were able to estimate absolute divergence times using fossil calibrations as prior probability densities relating to three internal nodes of mullet phylogeny (Santini et al, 2015).…”

“…There is considerable uncertainty about the exact number of species related to mullet phylogeny, which is also reflected by the uncertainty around diversification time scales. Nonetheless, a study by Santini et al (2015) identified two major lineages of grey mullet that diverged during the Palaeocene and Eocene, followed by a mainly Oligocene radiation across both tropical and subtropical coastal habitats. This radiation may have been facilitated by the abundant and widespread availability of food in the form of detritus and benthic microalgae, resources that are naturally concentrated in estuaries and shallow coastal shelf areas around the world.…”

Identificación molecular de especies crípticas de Mugil curema (Pisces: Mugilidae) en las costas de México

“…En este estudio se reporta por primera vez los tiempos de divergencia para linajes de M. curema. Actualmente solo se conoce el tiempo de divergencia con respecto a Mugil cephalus por Santini et al (2015) quienes emplearon el programa de reconstrucción filogenética bayesiana Beast (Drummond et al, 2012) útil solamente para el nivel interespecífico. En este estudio se utilizó "Isolation with migrate" diseñado para datos intraespecíficos.…”

“…En este sentido, en las costas de Veracruz durante la temporada de lluvias en la cual se lleva a cabo los procesos de dispersión larvaria favorable debido a que hay una mayor disponibilidad de alimento (Okolodkov et al, 2011), actualmente se reporta una de las mayores densidades de zooplancton e ictioplancton aunque es la zona costera de Campeche la que registra la mayor biomasa en todo el Golfo de México (Sanvicente-Añorve, 1990, Sánchez-Velasco et al, 1996. Uno de los principales alimentos de juveniles de M. curema es el zooplancton, la dieta de las especies del género Mugil de acuerdo con Santini et al, (2015) ha sido la misma desde el Paleógeno por lo que si una alta cantidad de haplotipos de Alvarado fuera explicada por la disponibilidad de alimento actualmente la localidad de Sabancuy, Campeche debería presentar también un alto número de haplotipos, pero el régimen de lluvias y vientos actual no se estableció sino hasta hace 11, 000 años por lo que la disponibilidad de alimento pudo haber sido diferente en el pasado aunque no se tienen referencias sobre la biomasa de zooplancton en el GM durante el Pleistoceno tardío podemos inferir que la laguna costera de Alvarado en el pasado presentaba una mayor biomasa de zooplancton e ictioplancton.…”