Morphological and genetic divergence in Swedish postglacial stickleback ( Pungitius pungitius ) populations

• Published in: BMC Evolutionary Biology
• Main Authors: Englund Göran, Johansson Frank, Lussetti Daniel, Mobley Kenyon B, Bokma Folmer
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2011
• Subjects: Evolution; QH359-425; Northern Sweden
• Online Access: https://doi.org/10.1186/1471-2148-11-287; https://doaj.org/article/bd4931c006fb4ea2aea08c9415a09b59

Abstract Background An important objective of evolutionary biology is to understand the processes that govern phenotypic variation in natural populations. We assessed patterns of morphological and genetic divergence among coastal and inland lake populations of nine-spined stickleback in northern Sweden. Coastal populations are either from the Baltic coast (n = 5) or from nearby coastal lakes (n = 3) that became isolated from the Baltic Sea (< 100 years before present, ybp). Inland populations are from freshwater lakes that became isolated from the Baltic approximately 10,000 ybp; either single species lakes without predators (n = 5), or lakes with a recent history of predation (n = 5) from stocking of salmonid predators (~50 ybp). Results Coastal populations showed little variation in 11 morphological traits and had longer spines per unit of body length than inland populations. Inland populations were larger, on average, and showed greater morphological variation than coastal populations. A principal component analysis (PCA) across all populations revealed two major morphological axes related to spine length (PC1, 47.7% variation) and body size (PC2, 32.9% variation). Analysis of PCA scores showed marked similarity in coastal (Baltic coast and coastal lake) populations. PCA scores indicate that inland populations with predators have higher within-group variance in spine length and lower within-group variance in body size than inland populations without predators. Estimates of within-group P ST (a proxy for Q ST ) from PCA scores are similar to estimates of F ST for coastal lake populations but P ST > F ST for Baltic coast populations. P ST > F ST for PC1 and PC2 for inland predator and inland no predator populations, with the exception that P ST < F ST for body size in inland populations lacking predators. Conclusions Baltic coast and coastal lake populations show little morphological and genetic variation within and between groups suggesting that these populations experience similar ecological ...