Behavioral, Molecular, and Morphological Evidence for a Hybrid Zone between Chrysochus auratus and C. cobaltinus (Coleoptera: Chrysomelidae)

In this article, we describe a hybrid zone between the chrysomelid beetles, Chrysochus auratus (F.), andC. cobaltinus LeConte, which have historically been considered as having allopatric distributions. By combining field studies with surveys of museum specimens, we documented that in western North America there are two regions in which these beetles are sympatric, and four additional regions in which populations of the two species are Washington, we found an ≈25 km wide area of sympatry in which the two species freely interbreed. Morphological and allozyme differences between the species allowed us to demonstrate that individuals with intermediate coloration in this area are indeed hybrids; all 22 putative hybrids we assayed for allozyme variation were heterozygous at each of three species-specific loci. Museum specimens revealed that the two species have been hybridizing in this region at least since 1952. Within the hybrid zone, ≈10-15% of the beetles is apparently F1 hybrids. At one focal site, 22.9% of all matings involved heterospecific pairs and 20.8% of all matings involved at least one hybrid individual. Although we found no molecular evidence of introgression between the two species, morphometric results and preliminary ecological data suggest possible past introgression or weak ongoing introgression. We discuss the implications of our findings for the specific status of these two species. This system appears well suited to provide answers to long-standing questions concerning the evolution of premating barriers between hybridizing species. In addition, hybridization between these two beetle species with differing host ranges will allow us to test the hypothesis that ecologically significant traits such as diet breadth can be gained via introgression

Primary and Secondary Rewards Differentially Modulate Neural Activity Dynamics during Working Memory

Background: Cognitive control and working memory processes have been found to be influenced by changes in motivational state. Nevertheless, the impact of different motivational variables on behavior and brain activity remains unclear. Methodology/Principal Findings: The current study examined the impact of incentive category by varying on a withinsubjects basis whether performance during a working memory task was reinforced with either secondary (monetary) or primary (liquid) rewards. The temporal dynamics of motivation-cognition interactions were investigated by employing an experimental design that enabled isolation of sustained and transient effects. Performance was dramatically and equivalently enhanced in each incentive condition, whereas neural activity dynamics differed between incentive categories. The monetary reward condition was associated with a tonic activation increase in primarily right-lateralized cognitive control regions including anterior prefrontal cortex (PFC), dorsolateral PFC, and parietal cortex. In the liquid condition, the identical regions instead showed a shift in transient activation from a reactive control pattern (primary probe-based activation) during no-incentive trials to proactive control (primary cue-based activation) during rewarded trials. Additionally, liquid-specific tonic activation increases were found in subcortical regions (amygdala, dorsal striatum, nucleus accumbens), indicating an anatomical double dissociation in the locus of sustained activation

False claims about false memory research

Pezdek and Lam [Pezdek, K. & Lam, S. (2007). What research paradigms have cognitive psychologists used to study “False memory,” and what are the implications of these choices? Consciousness and Cognition] claim that the majority of research into false memories has been misguided. Specifically, they charge that false memory scientists have been (1) misusing the term “false memory,” (2) relying on the wrong methodologies to study false memories, and (3) misapplying false memory research to real world situations. We review each of these claims and highlight the problems with them. We conclude that several types of false memory research have advanced our knowledge of autobiographical and recovered memories, and that future research will continue to make significant contributions to how we understand memory and memory errors

Speech Communication

Contains table of contents for Part IV, table of contents for Section 1, an introduction, reports on seven research projects and a list of publications.C.J. Lebel FellowshipDennis Klatt Memorial FundNational Institutes of Health Grant T32-DC00005National Institutes of Health Grant R01-DC00075National Institutes of Health Grant F32-DC00015National Institutes of Health Grant R01-DC00266National Institutes of Health Grant P01-DC00361National Institutes of Health Grant R01-DC00776National Science Foundation Grant IRI 89-10561National Science Foundation Grant IRI 88-05680National Science Foundation Grant INT 90-2471

Cytonuclear Disequilibrium in Chrysochus Hybrids Is Not Due to Patterns of Mate Choice

We investigated patterns of cytonuclear disequilibrium between nuclear allozyme loci and partial mitochondrial COI and COII restriction fragment length polymorphism patterns within a population of hybridizing chrysomelid beetles and assessed to what degree the genotype frequencies of F1 hybrids were consistent with patterns of mate choice or endosymbiont infection. We document that in this population, ≥50% of the heterospecific pairs at a given time are composed of Chrysochus auratus females and Chrysochus cobaltinus males, suggesting that at least half of the F1 hybrids should possess the C. auratus mitochondrial genotype. However, we found that the majority (89%) of F1 hybrids possessed C. cobaltinus mtDNA (P \u3c 0.001). The lack of evidence for Wolbachia infection in these highly promiscuous beetles, coupled with the fact that F1 hybrids of both cross types do exist, indicates that endosymbionts are an unlikely explanation for the discrepancy between cytonuclear genotype frequencies and behavior. We argue that cytonuclear disequilibrium at this focal Chrysochus hybrid site is likely due to a strong directional bias in postmating prezygotic barriers in this system. The results presented here underscore the importance of combining both field and molecular data in studies of cytonuclear disequilibrium and point to the dangers inherent in attributing patterns of cytonuclear disequilibrium to assortative mating

Activation-performance relationship in the dorsal striatum.

<p>Correlation between sustained activation increase and performance improvement relative to baseline observed in the Liquid condition (A) within a region in the left dorsal striatum (−9, 12, 3; panel B). During the Money condition, no such correlation was present (C). Activation effect is percent change signal increase in incentive condition relative to Baseline. Performance effect is response time improvement (in msec) during incentive condition relative to Baseline.</p

Flexibility in activation dynamics of cognitive control regions related to incentive magnitude and category.

<p>A) Overlapping regions showing selective state effects in Money and selective item effects in Liquid. B) Overlapping regions showing a shift from sustained to transient activation across the Money and Liquid incentive conditions. Percent signal change average for all three overlapping regions, sustained effects showing averaged signal changes across the incentive block, and transient effects are averaged across frames 2 to 6 in high incentive trials. C) Time-courses for incentive trials and no-incentive trials within the Money and Liquid condition showing a shift in the peak of activation dynamics during the Liquid condition. On no-incentive trials, activation peaks late in the trial (around probe response), and on incentive trials, activation peaks earlier (during encoding). All are averaged for the three overlapping cognitive control regions. (MON_H: money high-incentive trials, MON_L: money low-incentive trials, MON_N: no-incentive trials during the Money block; LIQ_H: liquid high-incentive trials, LIQ_L: liquid low-incentive trials, LIQ_N: no-incentive trials during the Liquid block).</p

Regions showing selective state incentive effects in the money and selective item incentive effects in the liquid condition.

1<p>Regions of a cluster size smaller than 8 voxels are printed in italic.</p

Trial-specific incentive effects.

<p>Response times for no-incentive trials (NO), low incentive trials (LOW) and high incentive trials (HIGH) for the Money (MON) and Liquid (LIQ) blocks. Figure demonstrates main effect of incentive magnitude, reflected in faster response times on trials with higher incentive value.</p