Developmental Processes, Evolvability, and Dental Diversification of New World Monkeys
BERNAL V.; GONZALEZ P.; PEREZ S.I.
Lugar: Berlin; Año: 2013 vol. 40 p. 532 - 541
The developmental processes that contribute tovariation of morphological traits are the subject of considerableinterest when attempting to understand phenotypicevolution. It is well demonstrated that most characteristicsof tooth pattern can be modified by tinkering conservedsignal pathways involved in dental development. This effectcan be evaluated by comparing developmental models withnaturally occurring variation within explicit phylogeneticcontexts. Here, we assess whether evolutionary changes inlower molar (M) ratios among platyrrhines were channelledby alterations in the balance of activators and inhibitors aspredicted by the inhibitory cascade (IC) model (Kavanaghet al. in Nature 449:427?432, 2007). Ordinary linearregression adjusted to M2/M1 versus M3/M1 ratios of 38species of platyrrhines indicated that the slope and interceptwere significantly different from the IC model. Conversely,when the phylogeny was incorporated into the regressionanalyses (PGLS), variation in molar ratios did not differfrom the developmental model. PGLS also showed thatchanges in molar proportions are not an allometric effectassociated with body size. Discrepancies between phylogeneticallycorrected and non-corrected analyses are mainlydue to the departure of Callitrichines from the predictedvalues. This subfamily displays agenesis of M3 with higherthan expected M2/M1 ratios, indicating that M3 fails todevelop even when the inhibition by M1 on the subsequentmolars is not increased. Our results show that evolution inmolar ratios is concordant with slight changes in the proportionof activators and inhibitors that regulate molardevelopment; however, other processes are required toaccount for variation in the number of teeth