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Figure 1 | EvoDevo

Figure 1

From: Revisiting de Beer’s textbook example of heterochrony and jaw elongation in fish: calmodulin expression reflects heterochronic growth, and underlies morphological innovation in the jaws of belonoid fishes

Figure 1

Heterochrony has contributed significantly to craniofacial diversity in the Belonoidei. (A) Simplified phylogeny based on[27] showing the relationships between representative taxa of the Belonoidei including needlefish and halfbeak, and medaka, which belong to their sister group the Adrianichthyoidei. (B, C) Developmental heterochrony was assessed in the jaws of these three species by plotting shape, represented by the ratio of lower jaw (lj) to upper jaw (uj) length (lj:uj), against relative age. The term ‘onset age’ refers to the commencement of skeletal ossification, while ‘offset age’ refers to the completion of ossification. Medaka retained the ancestral condition, maintaining an lj:uj of 1.0. Conversely, needlefish and halfbeak display acceleration of lj growth relative to the uj (indicated by lj:uj > 1.0). This ratio is maintained to adulthood in halfbeak. Additionally, needlefish display a secondary acceleration of uj growth, resulting in a ratio of approximately 1.0, which is then maintained until adulthood. (D, E) In addition to the aforementioned heterochronic shifts, the uj and lj also display allometry in their growth, as indicated by plotting their ontogenetic trajectories. (C, E) 95% confidence intervals are indicated for both the heterochrony plot and ontogenetic trajectory respectively.

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