Heterochrony, Maternal Effects, and Phenotypic Variation Among Sympatric Pupfishes

Abstract

Variation in ontogeny can produce phenotypic variation both within and among species. I investigated whether changes in timing and rate of growth were a source of phenotypic variation in a putative incipient species group of pupfish (Cyprinodon spp.). On San Salvador Island, Bahamas, sympatric forms of pupfish differ in morphology but show only partial reproductive isolation in the laboratory. Offspring from two forms and two geographical areas and their hybrids were bred in the laboratory, and ontogenetic trajectories of their feeding morphology were followed until maturity. In the Bahamian pupfish the two forms grow along similar size but not shape trajectories. Two heterochronic parameters, onset and rate of growth, alter shape trajectories in the Bahamian pupfish. Similar forms from different geographical areas (Florida and the Bahamas) grow along parallel shape trajectories, differing only in one heterochronic parameter, the onset shape. Hybrids within and between the pupfish forms produced intermediate feeding morphologies that were influenced by their maternal phenotype, suggesting that maternal effects may be a source of phenotypic variation in shape that can persist to maturity. In Cyprinodon, small changes in multiple heterochronic parameters translate into large phenotypic differences in feeding morphology.

Historical Biogeography of the New-World Pupfish Genus Cyprinodon (Teleostei: Cyprinodontidae)

“…comm. ), C. laciniatus and an undescribed species flock (Holtmeier, 2001) from the Bahamas, and C. higuey and C. nichollsi from Hispaniola. Surveys of mtDNA variation in pupfish from the Bahamas, Hispaniola, other sites in the West Indies, and the Atlantic and Gulf of Mexico coasts (Bunt, 2001;L.…”

Size correction in biology: how reliable are approaches based on (common) principal component analysis?

“…When dealing with a single population, this size-independent (co)variation is often analyzed directly using as new variables PC2-PCn (where n is the total number of traits) (e.g., Lande and Arnold 1983;Jockusch 1997;Merilä and Björklund 1999;Badyaev and Hill 2000;Holtmeier 2001;McGuigan et al 2003;Bolnick and Lau 2008). Alternatively, the original traits are regressed on their PC1 scores and the residuals treated as size-corrected morphological variables (e.g., Schluter and McPhail 1992;Schluter 1996;Berner et al 2008).…”

Reproductive isolation among endemic pupfishes (Cyprinodon) on San Salvador Island, Bahamas: microsatellite evidence

“…The San Salvador pupfishes are little known (Holtmeier, 2000, 2001) and undescribed. The three morphotypes (Fig.…”

“…The three morphotypes (Fig. 1) are normal, bulldog, and bozo (Holtmeier, 2000, 2001). Like most pupfishes, normal is a substrate‐browsing omnivore, consuming detritus, algae and other plant material, benthic macroplankton, and fish eggs (Holtmeier, 2000).…”