Thursday, February 25, 2016

Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

Next week's paper selection: 

Global warming is increasing the overheating risk for many organisms, though the potential for plasticity in thermal tolerance to mitigate this risk is largely unknown. In part, this shortcoming stems from a lack of knowledge about global and taxonomic patterns of variation in tolerance plasticity. To address this critical issue, we test leading hypotheses for broad-scale variation in ectotherm tolerance plasticity using a dataset that includes vertebrate and invertebrate taxa from terrestrial, freshwater and marine habitats. Contrary to expectation, plasticity in heat tolerance was unrelated to latitude or thermal seasonality. However, plasticity in cold tolerance is associated with thermal seasonality in some habitat types. In addition, aquatic taxa have approximately twice the plasticity of terrestrial taxa. Based on the observed patterns of variation in tolerance plasticity, we propose that limited potential for behavioural plasticity (i.e. behavioural thermoregulation) favours the evolution of greater plasticity in physiological traits, consistent with the ‘Bogert effect’. Finally, we find that all ectotherms have relatively low acclimation in thermal tolerance and demonstrate that overheating risk will be minimally reduced by acclimation in even the most plastic groups. Our analysis indicates that behavioural and evolutionary mechanisms will be critical in allowing ectotherms to buffer themselves from extreme temperatures.

Thursday, February 18, 2016

Mate choice learning in D. melanogaster

Posted by Anna Nordén, on behalf of Katrine Lund-Hansen

Since I haven’t seen a fly in weeks, I thought it would be nice to read about one instead. This paper from former EXEB member, Machteld Verzijden, explores the importance of visual cues in mate choice learning in male D. melanogaster. These are novel findings in D. melanogaster and interesting results for mate choice learning.

And I’ll bring fika!

Link to the paper is here

When: Tuesday, February 23th, 10 am
Where: Argumentet

Title: Male Drosophila melanogaster learn to prefer an arbitrary trait associated with female mating status

Abstract: Although males are generally less discriminating than females when it comes to choosing a mate, they still benefit from distinguishing between mates that are receptive to courtship and those that are not, in order to avoid wasting time and energy. It is known that males of Drosophila melanogaster are able to learn to associate olfactory and gustatory cues with female receptivity, but the role of more arbitrary, visual cues in mate choice learning has been overlooked to date in this species. We therefore carried out a series of experiments to determine: 1) whether males had a baseline preference for female eye color (red versus brown), 2) if males could learn to associate an eye color cue with female receptivity, and 3) whether this association disappeared when the males were unable to use this visual cue in the dark. We found that naive males had no baseline preference for females of either eye color, but that males which were trained with sexually receptive females of a given eye color showed a preference for that color during a standard binary choice experiment. The learned cue was indeed likely to be truly visual, since the preference disappeared when the binary choice phase of the experiment was carried out in darkness. This is, to our knowledge 1) the first evidence that male D. melanogaster can use more arbitrary cues and 2) the first evidence that males use visual cues during mate choice learning. Our findings suggest that that D. melanogaster has untapped potential as a model system for mate choice learning.

Friday, February 12, 2016

Is Plasticity facilitating or impeding Adaptive Evolution?

Again. I know that we discussed this topic not too long ago, but I feel that the issue is not satisfyingly resolved and I got a bit stuck with it... Therefore, I would like to discuss a paper by Dayan et al., 2015, Mol Ecol, that tackles this controversy. The authors are trying to assess the role of phenotypic plasticity in evolution by comparing gene expression patterns in killifish (Fundulus spp.). They are contrasting divergent populations and test to what extent their ability to acclimate to different temperatures varies. They address questions such as whether plasticity and genetic divergence operate in parallel on the same set of genes, or what the magnitude of the plastic response is compared to the evolved response. I think these are exciting questions and I hope you enjoy reading the paper and discussing their ideas (don't get scared by the stats!).

Link to the paper is here and there is also a little commentary on it here.

When: Tuesday, 16th of Feburuary 2016, 10 am
Where: Argumentet

Title: Phenotypic plasticity in gene expression contributes to divergence of locally adapted populations of Fundulus heteroclitus
Abstract: We examine the interaction between phenotypic plasticity and evolutionary adaptation using muscle gene expression levels among populations of the fish Fundulus heteroclitus acclimated to three temperatures. Our analysis reveals shared patterns of phenotypic plasticity due to thermal acclimation as well as non-neutral patterns of variation among populations adapted to different thermal environments. For the majority of significant differences in gene expression levels, phenotypic plasticity and adaptation operate on different suites of genes. The subset of genes that demonstrate both adaptive differences and phenotypic plasticity, however, exhibit countergradient variation of expression. Thus, expression differences among populations counteract environmental effects, reducing the phenotypic differentiation between populations. Finally, gene-by-environment interactions among genes with non-neutral patterns of expression suggest that the penetrance of adaptive variation depends on the environmental conditions experienced by the individual.

...and yes, there will be fika :-)

Friday, February 5, 2016

Lab Meeting on Ancient Microbiomes

Posted by Katie Duryea

This week for lab meeting I thought it might be fun to read this recent paper that explores the gut microbiome of the Iceman mummy to draw inference on the evolutionary history of human stomach ailments. I'll bring some fika that will hopefully sit well with your microbiome;)

When: Tues, February 9th, 10:00
Where: Argument

The 5300-year-old Helicobacter pylori genome of the Iceman

  • Frank Maixner 1 , * , , 
  • Ben Krause-Kyora 2 , , 
  • Dmitry Turaev 3 ,
  • Alexander Herbig 4 , 5 ,
  • Michael R. Hoop Mann 6 ,
  • Janice L. Hallow 6 , 
  • Ulrike Kusebauch 6
  • Eduard Egarter Vigl 7
  • Peter Malfertheiner 8
  • Francis Megraud 9 ,
  • Niall O'Sullivan 1
  • Giovanna Cipollini 1
  • Valentina Coia 1
  • Marco Samadelli 1
  • Lars Engstrand 10
  • Bodo Linz 11 ,
  • Robert L. Moritz 6
  • Rudolf Grimm 12
  • John Krause 4 , 5 ,
  • Almut Nebel 2 ,
  • Yoshan Moodley 13 , 14 ,
  • Thomas Rattei 3 ,
  • Albert Zink 1 , *

  • Abstract

    The stomach bacterium Helicobacter pylori is one of the most prevalent human pathogens. It has dispersed globally with its human host, resulting Thing thing into a distinct phylogeographic pattern That Can Be Used to Reconstruct bothering Recent and ancient human migrations. The extant European populations of H. pylori is known to be a hybrid between Asian and African bacteria, but there exist different Hypotheses about When and Where The hybridization took place, reflecting the complex demographic history of Europeans. Here, we present a 5300-year-old H. pylori genome from a European Copper Age glacier mummy. The "Iceman" H. pylori is a nearly pure representative of the bacterial population of Asian origin That existed in Europe before hybridization, suggesting That the African population arrived in Europe within the past few thousand years.