Immigrant reproductive dysfunction facilitates ecological speciation

The distributions of species are not only determined by where they can survive – they must also be able to reproduce. Although immigrant inviability is a well-established concept, the fact that immigrants also need to be able to effectively reproduce in foreign environments has not been fully appreciated in the study of adaptive divergence and speciation. Fertilization and reproduction are sensitive life-history stages that could be detrimentally affected for immigrants in non-native habitats. We propose that “immigrant reproductive dysfunction” is a hitherto overlooked aspect of reproductive isolation caused by natural selection on immigrants. This idea is supported by results from experiments on an externally fertilizing fish (sand goby, Pomatoschistus minutus). Growth and condition of adults were not affected by non-native salinity whereas males spawning as immigrants had lower sperm motility and hatching success than residents. We interpret these results as evidence for local adaptation or acclimation of sperm, and possibly also components of paternal care. The resulting loss in fitness, which we call “immigrant reproductive dysfunction,” has the potential to reduce gene flow between populations with locally adapted reproduction, and it may play a role in species distributions and speciation

Sperm adaptation in relation to salinity in three goby species

In externally fertilizing species, the gametes of both males and females are exposed to the influences of the environment into which they are released. Sperm are sensitive to abiotic factors such as salinity, but they are also affected by biotic factors such as sperm competition. In this study, the authors compared the performance of sperm of three goby species, the painted goby, Pomatoschistus pictus, the two-spotted goby, Pomatoschistus flavescens, and the sand goby, Pomatoschistus minutus. These species differ in their distributions, with painted goby having the narrowest salinity range and sand goby the widest. Moreover, data from paternity show that the two-spotted goby experiences the least sperm competition, whereas in the sand goby sperm competition is ubiquitous. The authors took sperm samples from dissected males and exposed them to high salinity water (31 PSU) representing the North Sea and low salinity water (6 PSU) representing the brackish Baltic Sea Proper. They then used computer-assisted sperm analysis to measure the proportion of motile sperm and sperm swimming speed 10 min and 20 h after sperm activation. The authors found that sperm performance depended on salinity, but there seemed to be no relationship to the species' geographical distribution in relation to salinity range. The species differed in the proportion of motile sperm, but there was no significant decrease in sperm motility during 20 h. The sand goby was the only species with motile sperm after 72 h

Molecular, behavioural and morphological comparisons of sperm adaptations in a fish with alternative reproductive tactics

In species with alternative reproductive tactics, there is much empirical support that parasitically spawning males have larger testes and greater sperm numbers as an evolved response to a higher degree of sperm competition, but support for higher sperm performance (motility, longevity and speed) by such males is inconsistent. We used the sand goby (Pomatoschistus minutus) to test whether sperm performance differed between breeding-coloured males (small testes, large mucus-filled sperm-duct glands; build nests lined with sperm-containing mucus, provide care) and parasitic sneaker-morph males (no breeding colouration, large testes, rudimentary sperm-duct glands; no nest, no care). We compared motility (per cent motile sperm), velocity, longevity of sperm, gene expression of testes and sperm morphometrics between the two morphs. We also tested if sperm-duct gland contents affected sperm performance. We found a clear difference in gene expression of testes between the male morphs with 109 transcripts differentially expressed between the morphs. Notably, several mucin genes were upregulated in breeding-coloured males and two ATP-related genes were upregulated in sneaker-morph males. There was a partial evidence of higher sperm velocity in sneaker-morph males, but no difference in sperm motility. Presence of sperm-duct gland contents significantly increased sperm velocity, and nonsignificantly tended to increase sperm motility, but equally so for the two morphs. The sand goby has remarkably long-lived sperm, with only small or no decline in motility and velocity over time (5 min vs. 22 h), but again, this was equally true for both morphs. Sperm length (head, flagella, total and flagella-to-head ratio) did not differ between morphs and did not correlate with sperm velocity for either morph. Thus, other than a clear difference in testes gene expression, we found only modest differences between the two male morphs, confirming previous findings that increased sperm performance as an adaptation to sperm competition is not a primary target of evolution.</p

Vad får användare att spara i Dreams?

The younger generation shows a different consumption behavior compared to previousgenerations where the attitude towards debt and loans is more relaxed. In addition, manypeople also experience difficulties with saving money and the human brain is a major factorin the connection between money and consumption behavior. Dreams is an application whereyou can save money and they argue that they increase the user’s wellbeing, feeling of safetyand motivation towards saving money. Dreams is designed for the users to be able to savemoney in an easy, fun and innovative way. The black background with white text bothclarifies and creates contrast for the user. This qualitative study that is based on semistructured interviews will analyze how Dreams persuade their users to save money. The studyis based on Fogg’s behavior model for persuasive design and Persuasive system designmodel. Both models explain persuasive design that influences behavior. The results show thatthere are design factors that contribute to users saving in Dreams as well as design factorsthat would make Dreams more persuasive. Den yngre generationen visar ett annorlunda konsumtionsbeteende jämfört med tidigaregenerationer, där inställningen till skulder och lån är mer avslappnad. Dessutom upplevermånga svårigheter med att spara pengar och den mänskliga hjärnan är en stor faktor ikopplingen mellan pengar och konsumtionsbeteende. Dreams är en app där man kan sparapengar och de argumenterar att de ökar användarens välmående, trygghet och motivation attspara pengar. Dreams är designad för att användarna ska kunna spara pengar på ett enkelt,roligt och innovativt sätt. Den svarta bakgrunden och vita texten som tydliggör och skaparkontraster för användaren. Den här kvalitativ studien som är baserad på semistruktureradeintervjuer kommer analysera hur Dreams övertygar sina användare att spara pengar. Studienutgår från Foggs beteendemodell och Persuasive system design model. Båda modellernaförklarar övertygande design som påverkar beteende. Resultatet visar att det finnsdesignfaktorer som bidrar till att användare sparar i Dreams samt designfaktorer som skullegöra Dreams mer övertygande.

Elevinflytande för ökad motivation : hur väl påverkar ökat elevinflytande elevers motivation till lärande?

Validerat; 20101217 (root

Post-glacial establishment of locally adapted sand goby populations over a steep salinity gradient

Studies of colonization of new habitats that appear from rapidly changing environments are interesting and highly relevant to our understanding of divergence and speciation. Here, we analyse phenotypic and genetic variation involved in the successful establishment of a marine fish (sand goby, Pomatoschistus minutus) over a steep salinity drop from 35 PSU in the North Sea (NE Atlantic) to two PSU in the inner parts of the post-glacial Baltic Sea. We first show that populations are adapted to local salinity in a key reproductive trait, the proportion of motile sperm, which in itself may result in reproductive isolation caused by natural selection on immigrants. Thereafter, we show that genome variation at 22,190 single nucleotide polymorphisms (SNPs) shows strong differentiation among populations along the gradient. Sequences containing outlier SNPs and transcriptome sequences, mapped to a draft genome, reveal associations with genes with relevant functions for adaptation in this environment

Behavioural and genomic analyses of locally adapted sand goby populations over a steep salinity gradient

Studies of colonization of new habitats appearing from rapidly changing environments increase our understanding of populations’ potential to cope with environmental changes. Here, we analyse behavioural, phenotypic and genetic variation involved in the successful establishment of the sand goby, Pomatoschistus minutus, over a steep salinity drop from 35 PSU in the North Sea (NE Atlantic) to two PSU in the inner parts of the post-glacial Baltic Sea. We show e.g. that populations are adapted to local salinity in a key reproductive trait, the proportion of motile sperm, which in itself may result in reproductive isolation caused by natural selection on immigrants. Genome variation shows strong differentiation among populations along the gradient. Sand gobies in the current Baltic Sea lineage is adapted to the low salinity in traits related to osmoregulation and reproduction, but also to both abiotic and biotic environmental factors correlated to salinity evident in traits such as vision and immune function. The salinity-biotic factors correlation is omnipresent in behavioral studies. Many loci also appear to be involved in these traits, but the specific functional mechanism (e.g., coding sequence, regulatory loci) remains to be clarified. We conclude that the first steps on the speciation continuum trajectory have been taken