Genomic and phenotypic consequences of range expansion and colonisation

Climate change and human activities are currently affecting species around us in a variety of ways. For instance, many species are expanding their range and settling further north in the northern hemisphere as the climate is warming. There is a lack of knowledge of how a range expansion affects the expanding species. Newly established populations may thrive or fail, and the ability to adapt to new conditions and prosper differs from species to species. In this thesis, I studied the reed warbler (Acrocephalus scirpaceus), a migratory bird which is expanding its range northwards in Europe into Fennoscandia, but has also recently colonised Malta in the south of Europa. I looked at changes in observable characteristics of the birds, and at their genetic material. To learn more about the reed warbler's genes, I assembled the entire genome of the reed warbler. I found that the different European populations are very similar genetically, but there is some novel variation in the newly established populations. I also found that the reed warblers are highly adaptable, and responsive to climatic conditions. The success of the reed warbler's range expansions is in contrast with many other species that are negatively affected by our changing world

Data from: Sperm morphology, sperm motility and paternity success in the bluethroat (Luscinia svecica)

Postcopulatory sexual selection may select for male primary sexual characteristics like sperm morphology and sperm motility, through sperm competition or cryptic female choice. However, how such characteristics influence male fertilization success remains poorly understood. In this study, we investigate possible correlations between sperm characteristics and paternity success in the socially monogamous bluethroat (Luscinia svecica svecica), predicting that sperm length and sperm swimming speed is positively correlated with paternity success. In total, 25 % (15/61) of broods contained extra-pair offspring and 10 % (33/315) of the offspring were sired by extra-pair males. Paternity success did not correlate significantly with sperm morphology or any aspects of sperm motility. Furthermore, sperm morphology and sperm motility did not correlate significantly with male morphological characters that previously have been shown to be associated with paternity success. Thus, the sperm characteristics investigated here do not appear to be strong predictors of paternity success in bluethroats

Rapid adaptive phenotypic change following colonization of a newly restored habitat

Real-time observation of adaptive evolution in the wild is rare and limited to cases of marked, often anthropogenic, environmental change. Here we present the case of a small population of reed warblers (Acrocephalus scirpaceus) over a period of 19 years (1996–2014) after colonizing a restored wetland habitat in Malta. Our data show a population decrease in body mass, following a trajectory consistent with a population ascending an adaptive peak, a so-called Ornstein–Uhlenbeck process. We corroborate these findings with genetic and ecological data, revealing that individual survival is correlated with body mass, and more than half of the variation in mean population fitness is explained by variation in body mass. Despite a small effective population size, an adaptive response has taken place within a decade. A founder event from a large, genetically variable source population to the southern range margin of the reed warbler distribution likely facilitated this process

Data from: Rapid adaptive phenotypic change following colonization of a newly restored habitat

Real-time observation of adaptive evolution in the wild is rare and limited to cases of marked, often anthropogenic, environmental change. Here we present the case of a small population of reed warblers (Acrocephalus scirpaceus) over a period of 19 years (1996–2014) after colonizing a restored wetland habitat in Malta. Our data show a population decrease in body mass, following a trajectory consistent with a population ascending an adaptive peak, a so-called Ornstein–Uhlenbeck process. We corroborate these findings with genetic and ecological data, revealing that individual survival is correlated with body mass, and more than half of the variation in mean population fitness is explained by variation in body mass. Despite a small effective population size, an adaptive response has taken place within a decade. A founder event from a large, genetically variable source population to the southern range margin of the reed warbler distribution likely facilitated this process

Sperm morphology, sperm motility and paternity success in the bluethroat (<i>Luscinia svecica</i>)

<div><p>Postcopulatory sexual selection may select for male primary sexual characteristics like sperm morphology and sperm motility, through sperm competition or cryptic female choice. However, how such characteristics influence male fertilization success remains poorly understood. In this study, we investigate possible correlations between sperm characteristics and paternity success in the socially monogamous bluethroat (<i>Luscinia svecica svecica</i>), predicting that sperm length and sperm swimming speed is positively correlated with paternity success. In total, 25% (15/61) of broods contained extra-pair offspring and 10% (33/315) of the offspring were sired by extra-pair males. Paternity success did not correlate significantly with sperm morphology or any aspects of sperm motility. Furthermore, sperm morphology and sperm motility did not correlate significantly with male morphological characters that previously have been shown to be associated with paternity success. Thus, the sperm characteristics investigated here do not appear to be strong predictors of paternity success in bluethroats.</p></div

Correlations between sperm characteristics and fertilization success in generalized linear mixed models.

<p>Fertilization success was measured as within-pair (WP) fertilization success (males that had not been cuckolded = 0; males that had been cuckolded = 1), extra-pair (EP) fertilization success (males that had not sired extra-pair offspring = 0; males that had sired extra-pair offspring = 1), and total fertilization success (total number of offspring sired). Red border width and age were added as covariates to the models, but their results are not shown here (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.s004" target="_blank">S4 Table</a>).</p

Paired comparisons of total sperm length (left) and sperm velocity (VCL; right) between within-pair (WP) males and the extra-pair (EP) males that cuckolded them.

<p>Paired comparisons of total sperm length (left) and sperm velocity (VCL; right) between within-pair (WP) males and the extra-pair (EP) males that cuckolded them.</p

Paired comparisons of within-pair (WP) males and the extra-pair (EP) male that cuckolded them, with mean values (± SE) of sperm traits and body morphology traits.

<p>Uncorrected <i>p</i> values are shown.</p

Within-season repeatability, comparing measurements of males that have been sampled twice in the same year^a.

<p><i>R</i>² is the repeatability, mean ± SE is shown for first and second measure, along with <i>F</i> value, number of males (<i>N</i>), and <i>p</i> value. All significant correlations (<i>p</i> < 0.05) were robust to correction for multiple testing using false discovery rate correction [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref059" target="_blank">59</a>], and are marked in bold.</p