4000 years of phenotypic change in an island bird: heterogeneity of selection over three microevolutionary timescales.
Evolution
; 62(9): 2393-410, 2008 Sep.
Article
em En
| MEDLINE
| ID: mdl-18540948
ABSTRACT
Pronounced phenotypic shifts in island populations are typically attributed to natural selection, but reconstructing heterogeneity in long-term selective regimes remains a challenge. We examined a scenario of divergence proposed for species colonizing a new environment, involving directional selection with a rapid shift to a new optimum and subsequent stabilization. We provide some of the first empirical evidence for this model of evolution using morphological data from three timescales in an island bird, Zosterops lateralis chlorocephalus. In less than four millennia since separation from its mainland counterpart, a substantial increase in body size has occurred and was probably achieved in fewer than 500 generations after colonization. Over four recent decades, morphological traits have fluctuated in size but showed no significant directional trends, suggesting maintenance of a relatively stable phenotype. Finally, estimates of contemporary selection gradients indicated generally weak directional selection. These results provide a rare description of heterogeneity in long-term natural regimes, and caution that observations of current selection may be of limited value in inferring mechanisms of past adaptation due to a lack of constancy even over short time-frames.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fenótipo
/
Seleção Genética
/
Aves Canoras
/
Evolução Biológica
Tipo de estudo:
Prognostic_studies
Limite:
Animals
País/Região como assunto:
Oceania
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article