Mitochondrial haplogroup H1 is protective for ischemic stroke in Portuguese patients

<p>Abstract</p> <p>Background</p> <p>The genetic contribution to stroke is well established but it has proven difficult to identify the genes and the disease-associated alleles mediating this effect, possibly because only nuclear genes have been intensely investigated so far. Mitochondrial DNA (mtDNA) has been implicated in several disorders having stroke as one of its clinical manifestations. The aim of this case-control study was to assess the contribution of mtDNA polymorphisms and haplogroups to ischemic stroke risk.</p> <p>Methods</p> <p>We genotyped 19 mtDNA single nucleotide polymorphisms (SNPs) defining the major European haplogroups in 534 ischemic stroke patients and 499 controls collected in Portugal, and tested their allelic and haplogroup association with ischemic stroke risk.</p> <p>Results</p> <p>Haplogroup H1 was found to be significantly less frequent in stroke patients than in controls (OR = 0.61, 95% CI = 0.45–0.83, p = 0.001), when comparing each clade against all other haplogroups pooled together. Conversely, the pre-HV/HV and U mtDNA lineages emerge as potential genetic factors conferring risk for stroke (OR = 3.14, 95% CI = 1.41–7.01, p = 0.003, and OR = 2.87, 95% CI = 1.13–7.28, p = 0.021, respectively). SNPs m.3010G>A, m.7028C>T and m.11719G>A strongly influence ischemic stroke risk, their allelic state in haplogroup H1 corroborating its protective effect.</p> <p>Conclusion</p> <p>Our data suggests that mitochondrial haplogroup H1 has an impact on ischemic stroke risk in a Portuguese sample.</p

Adaptive individual variation in phenological responses to perceived predation levels

The adaptive evolution of timing of breeding (a component of phenology) in response to environmental change requires individual variation in phenotypic plasticity for selection to act upon. A major question is what processes generate this variation. Here we apply multi-year manipulations of perceived predation levels (PPL) in an avian predator-prey system, identifying phenotypic plasticity in phenology as a key component of alternative behavioral strategies with equal fitness payoffs. We show that under low-PPL, faster (versus slower) exploring birds breed late (versus early);the pattern is reversed under high-PPL, with breeding synchrony decreasing in conjunction. Timing of breeding affects reproductive success, yet behavioral types have equal fitness. The existence of alternative behavioral strategies thus explains variation in phenology and plasticity in reproductive behavior, which has implications for evolution in response to anthropogenic change

A multi-level approach to quantify speed-accuracy trade-offs in great tits (Parus major)

Animals often face a conflict between the speed and accuracy by which a decision is made. Decisions taken quickly might be relativelyinaccurate, whereas decisions taken more slowly might be more accurate. Such “speed-accuracy trade-offs” receive increasingattention in behavioral and cognitive sciences. Importantly, life-history theory predicts that trade-offs typically exist only at certainhierarchical levels, such as within rather than among individuals. We therefore examined within- and among-individual correlationsin the speed and accuracy by which decisions are taken, using a foraging context in wild-caught great tits (Parus major) as a workedexample. We find that great tits exhibit among-individual variation in speed-accuracy trade-offs: some individuals predictably maderelatively slow but accurate decisions, whereas others were predictably faster but less accurate. We did not, however, find evidencefor the trade-off at the within-individual level. These level-specific relationships imply that different mechanisms acted across levels.These findings highlight the need for future work on the integration of individual behavior and cognition across hierarchical levels