Search results for "Local adaptation"

Daphnia females adjust sex allocation in response to current sex ratio and density

2018

Cyclical parthenogenesis presents an interesting challenge for the study of sex allocation, as individuals’ allocation decisions involve both the choice between sexual and asexual reproduction, and the choice between sons and daughters. Male production is therefore expected to depend on ecological and evolutionary drivers of overall investment in sex, and those influencing male reproductive value during sexual periods. We manipulated experimental populations, and made repeated observations of natural populations over their growing season, to disentangle effects of population density and the timing of sex from effects of adult sex ratio on sex allocation in cyclically parthenogenetic Daphnia…

Molecular and ecological signs of mitochondrial adaptation: consequences for introgression?

2013

The evolution of the mitochondrial genome and its potential adaptive impact still generates vital debates. Even if mitochondria have a crucial functional role, as they are the main cellular energy suppliers, mitochondrial DNA (mtDNA) introgression is common in nature, introducing variation in populations upon which selection may act. Here we evaluated whether the evolution of mtDNA in a rodent species affected by mtDNA introgression is explained by neutral expectations alone. Variation in one mitochondrial and six nuclear markers in Myodes glareolus voles was examined, including populations that show mtDNA introgression from its close relative, Myodes rutilus. In addition, we modelled prote…

2019

High dispersal rates are known to homogenize host's population genetic structure in panmictic species and to disrupt host local adaptation to the environment. Long-distance dispersal might also spread micro-organisms across large geographical areas. However, so far, to which extent selection mechanisms that shape host's population genetics are mirrored in the population structure of the enteric microbiome remains unclear. High dispersal rates and horizontal parental transfer may homogenize bacterial communities between breeding sites (homogeneous hypothesis). Alternatively, strong selection from the local environment may differentiate bacterial communities between breeding sites (heterogene…

Parabiotic ants: the costs and benefits of symbiosis

2014

1. Mutualisms are important drivers of co-evolution and speciation. However, they typically imply costs for one or both partners. Each partner consequently tries to maximise benefits and minimise costs. Mutualisms can therefore develop towards commensalism or parasitism if one partner fails to provide sufficient benefits. This is particularly likely in diffuse interactions, where multiple species can associate with each other. If costs and benefits of a species vary with the identity of the partner species, this may result in a geographical mosaic of co-evolution. 2. In the present study, inter-specific interactions in two parabiotic associations of ants were studied (Hymenoptera: Formicida…

An improved version of the Atlantic cod genome and advancements in functional genomics: implications for the future of cod farming

2016

Abstract Recent advancements within state-of-the-art genomic tools and the generation of the first version of the Atlantic cod genome (Star et al., 2011) have proven to be valuable resources, improving our understanding of this species’ biology. In this chapter we describe some aspects and implications of using these resources to identify genes and molecular pathways involved in Atlantic cod growth and development, as well as responses to nutritional changes, pathogens and other immune stimuli, and environmental stressors (e.g., temperature, stress, or pollutants). Additionally, we highlight the immunological puzzle of the Atlantic cod that lacks components of the adaptive immune system pre…

Bet-hedging in diapausing egg hatching of temporary rotifer populations - A review of models and new insights

2014

Habitat unpredictability is a local adaptation factor shaping life-history traits in rotifer populations. It may select for the evolution of bet-hedging through risk-spreading strategies in diapausing egg hatching. This means that a fraction of diapausing eggs in wild populations do not hatch even when the conditions are favorable for population growth. Thus, there is a remaining fraction of viable diapausing eggs standing in the sediments for longer periods. According to theory, it is expected that the incidence of bet-hedging strategies for diapausing egg hatching will be higher in more uncertain habitats. Here, we review the major predictions derived from theoretical models applied to th…

Possible adverse impact of contaminants on Atlantic cod population dynamics in coastal ecosystems

2019

While many in-laboratory ecotoxicological studies have shown the adverse impact of pollutants to the fitness of an individual, direct evidence from the field on the population dynamics of wildlife animals has been lacking. Here, we provide empirical support for a negative effect of pollution on Atlantic cod ( Gadus morhua ) population dynamics in coastal waters of Norway by combining unique time series of juvenile cod abundance, body size, environmental concentration of toxic contaminants and a spatially structured population dynamics model. The study shows that mercury concentration might have decreased the reproductive potential of cod in the region despite the general decline in the env…

Is the host or the parasite the most locally adapted in an amphipod–acanthocephalan relationship? A case study in a biological invasion context

2007

8 pages; International audience; Manipulative endoparasites with complex life cycles can alter their intermediate host immunity and behaviour in ways that increase survival probability within the host body cavity and enhance successful transmission to the definitive host. These parasitic manipulations are variable among and within parasite species and may result from co-evolutionary processes, in which the parasite is constrained for adaptation to the local intermediate host. Hence, arrival of a new host species in a local host population may promote local parasite maladaptation. This study tested the occurrence of local adaptation in two distantly located populations of the acanthocephalan…

Signs of local adaptation by genetic selection and isolation promoted by extreme temperature and salinity in the Mediterranean seagrass Posidonia oce…

2023

Adaptation to local conditions is known to occur in seagrasses; however, knowledge of the genetic basis underlying this phenomenon remains scarce. Here, we analysed Posidonia oceanica from six sites within and around the Stagnone di Marsala, a semi-enclosed coastal lagoon where salinity and temperature exceed the generally described tolerance thresholds of the species. Sea surface temperatures (SSTs) were measured and plant samples were collected for the assessment of morphology, flowering rate and for screening genome-wide polymorphisms using double digest restriction-site-associated DNA sequencing. Results demonstrated more extreme SSTs and salinity levels inside the lagoon than the outer…

Widespread secondary contact and new glacial refugia in the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula.

2011

Small aquatic organisms harbour deep phylogeographic patterns and highly structured populations even at local scales. These patterns indicate restricted gene flow, despite these organisms' high dispersal abilities, and have been explained by a combination of (1) strong founder effects due to rapidly growing populations and very large population sizes, and (2) the development of diapausing egg banks and local adaptation, resulting in low effective gene flow, what is known as the Monopolization hypothesis. In this study, we build up on our understanding of the mitochondrial phylogeography of the halophilic rotifer Brachionus plicatilis in the Iberian Peninsula by both increasing the number of…