The relationship between habitat complexity and species richness is well established but comparatively little is known about the evolution of morphological diversity in complex habitats. Reefs are structurally complex, highly productive shallow-water marine ecosystems found in tropical (coral reefs) and temperate zones (rocky reefs) which harbor exceptional levels of biodiversity. We investigated whether reef habitats promote the evolution of morphological diversity in the feeding and locomotion systems of grunts (Haemulidae), a group of predominantly nocturnal fishes that live on both temperate and tropical reefs. Using phylogenetic comparative methods and statistical analyses that take into account uncertainty in phylogeny and the evolutionary history of reef-living we demonstrate that rates of morphological evolution are faster in reef-dwelling haemulids. The magnitude of this effect depends on the type of trait; on average, traits involved in the functional systems for prey capture and processing evolve twice as fast on reefs as locomotor traits. This result, along with the observation that haemulids do not exploit unique feeding niches on reefs, suggests that fine-scale trophic niche partitioning and character displacement may be driving higher rates of morphological evolution. Whatever the cause, there is growing evidence that reef habitats stimulate morphological and functional diversification in teleost fishes.
500 Haemulidae phylogenies
These are the sample of 500 trees from the posterior distribution generated by BEAST that we used throughout the analyses. The nucleotide dataset was 2909 bp long and consisted of partial sequences of three mtDNA genes (16S rRNA, COI, and cytb) and two nuclear genes (RAG2 and S7 ribosomal protein intron 1). Relative divergence times of the sampled haemulid species were estimated using an uncorrelated lognormal (UCLN) model of molecular evolutionary rate heterogeneity implemented in the computer program BEAST v. 1.6.1 (Drummond et al. 2006; Drummond and Rambaut 2007). Each gene was treated as a separate data partition and for the protein coding genes (COI, cytb, and RAG1) we applied three partitions that corresponded to three codon positions.
Trees4dryad.txt
Haemulidae morphological data
Using 127 specimens from 50 haemulid species we measured 24 functional morphological traits related to feeding (11 traits) and locomotion (13 traits). These feeding traits included the mass of the jaw-closing adductor mandibulae muscle, (AM mass) the mechanical advantage of jaw closing (close ratio) and opening (open ratio), the length of the ascending process of the premaxilla bone which indicates the capacity for upper jaw protrusion, the length of longest gill raker on the ceratohyal of the first gill arch, and the diameter of the eye. In addition we calculated suction index, a morphologically-based estimate of the capacity to generate suction pressure during prey capture, by combining measures of buccal cavity length, buccal cavity with, head width, head height, and head length. The thirteen traits related to the body shape and locomotion included body fineness ratio, which for fish bodies is thought to be negatively correlated with drag exerted on the body. The size and shape of propulsive surfaces was measured by caudal fin aspect ratio and length of the base of the spiny and soft dorsal and anal fins, the average spine length of the spiny dorsal fin, and the perimeter and area of the caudal peduncle. In addition we measured maximum body width, maximum body depth, the body position of maximum body depth expressed as a fraction of fish standard length, and the horizontal and vertical position of the anterior-dorsal pectoral fin base expressed as fractions of standard length and maximum body depth.
Dataset4dryad.txt