Multiple traits and multifarious environments: integrated divergence of morphology and life history

• Published in: Oikos 2020-04, Vol.129 (4), p.480-492
• Main Authors: Riesch, Rüdiger, Martin, Ryan A., Langerhans, R. Brian
• Format: Article
• Language: English
• Subjects: adaptive radiation; Animal morphology; Body shape; convergent evolution; Demographics; Demography; Distension; Divergence; divergent natural selection; ecological speciation; Environment models; Fecundity; Freshwater fishes; Gambusia; Interspecific relationships; Least squares; Life history; Mathematical models; Morphology; Multivariate analysis; Multivariate statistical analysis; Poeciliidae; Predation; Resource availability
• ISSN: 0030-1299; 1600-0706
• DOI: 10.1111/oik.06344

Understanding complex responses of multiple character suites (e.g. behaviour, life history, morphology) across multifarious environments is a challenging task. Here we use a multivariate approach (partial least squares structural equation modelling) to disentangle environmental drivers (i.e. predation, resource availability and population demographics) of population divergence in life history and morphology. We further employ a two‐block partial least squares analysis in a novel approach to uncovering integrated and independent aspects of divergence in correlated character suites. Examining Bahamas mosquitofish Gambusia hubbsi inhabiting blue holes, we found phenotypic divergence mainly resulted from differences in predation regimes, but demography and resources also proved important in particular aspects of divergence. We uncovered significant covariation among life histories and morphologies, and revealed that phenotypic divergence between predation regimes involved both integrated and independent responses. For instance, female life histories strongly diverged independently of morphology, while some morphological shifts (abdominal distension) resulted from changes in fecundity; males showed strong morphological divergence independent of life history, but much of their life‐history shifts reflected joint morphological changes (lean weight and body shape). Our study illustrates the utility of gathering disparate data types from multiple populations/species to better understand the causes and nature of phenotypic divergence in the wild.