Morphological Heritability in a Hybrid Bunting Complex: Nesospiza at Inaccessible Island
Abstract Juvenile Nesospiza buntings measured 7–11 weeks after hatching were compared with the sizes of their parents to estimate the heritability (h2) of six external morphological characters. There was no evidence of size selection before juveniles were seven weeks old, but some additional growth...
| Published in: | The Condor |
|---|---|
| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Oxford University Press (OUP)
2001
|
| Subjects: | |
| Online Access: | http://dx.doi.org/10.1093/condor/103.3.429 http://academic.oup.com/condor/article-pdf/103/3/429/29710740/condor0429.pdf |
| Summary: | Abstract Juvenile Nesospiza buntings measured 7–11 weeks after hatching were compared with the sizes of their parents to estimate the heritability (h2) of six external morphological characters. There was no evidence of size selection before juveniles were seven weeks old, but some additional growth in bill size probably occurred after this age. All characters had significant heritabilities among Tristan Buntings (N. acunhae; h2 = 0.66–0.95) and hybrids with Wilkins' Buntings (N. wilkinsi; h2 = 0.62–0.93). Positive heritabilities also were found within color morphs of the Tristan Bunting, although not all regressions were significant. Hybrid offspring generally were intermediate in size between their parents' phenotypes, but one hybrid pair had an unusually small offspring, possibly the result of an extra-pair fertilization. Differences between h2 estimates from sib-sib and parent-offspring regressions suggest that environmental factors contribute to morphological variability, but the large heritable component confirms the potential for rapid morphological evolution among the small Nesospiza populations. Calculation of the relative importance of genetic and environmental effects requires controlled breeding experiments, but cross-fostering between broods in the field should not be performed, to avoid disrupting the natural population structure. Heredabilidad Morfológica en un Complejo Híbrido: Nesospiza en Isla Inaccessible Resumen. Las dimensiones de juveniles de Nesospiza medidos 7–11 semanas después de eclosionar fueron comparadas con las de sus padres para estimar la heredabilidad (h2) de seis caracteres morfológicos externos. No hubo evidencia de selección por tamaño antes de que los juveniles tuvieran siete semanas de edad, pero probablemente ocurrió un crecimiento adicional en el tamaño del pico luego de esta edad. Todos los caracteres tuvieron heredabilidades significativas entre N. acunhae (h2 = 0.66–0.95) y entre híbridos con N. wilkinsi (h2 = 0.62–0.93). También se encontraron heredabilidades positivas ... |
|---|