Biomedical subjects

H Dingle

Publications and source records attributed to H Dingle.

15 recordsLinked to original sources

PubMed2005

Altitudinal variation in behavioural thermoregulation: local adaptation vs. plasticity in California grasshoppers.

We investigated the adaptive significance of behavioural thermoregulation in univoltine populations of the grasshopper Melanoplus sanguinipes along an altitudinal gradient in California using laboratory tests of animals raised under different temperatures. Trials consisted of continuous body temperature measurements with semi-implanted microprobes in a test arena, and observation and simultaneous recording of behavioural responses. These responses included mobility, basking and orientation of the body axes (aspect angle) towards a radiation source. Mobility and basking are determined by the altitudinal origin of the parental generation and not by the temperature treatments. With increasing altitude, individuals tend increasingly to raise body temperatures via mobility and increased basking. In contrast, body orientation towards the radiation source is influenced by the temperature treatments but not by the altitude of origin. Individuals experiencing higher temperatures during rearing show a lower tendency to lateral flanking. We conclude that body orientation responses are not adapted locally. In contrast other components of the behavioural syndrome that increase body temperature, such as mobility and basking, are adaptive in response to local selection pressure. The thermoregulatory syndrome of these grasshoppers is an important contribution to life-history adaptations that appropriately match season lengths.

Adaptation, Physiological↗

PubMed2001

Patterns of recreational drug use at dance events in Edinburgh, Scotland.

AIMS: To describe the patterns of drug use at dance (rave) events in terms of prevalence, frequency, type of drugs used, patterns of use, access and risk-associated behaviours. DESIGN: Self-selecting participant-completed survey. SETTING: Three dance events in Edinburgh, Scotland, UK. PARTICIPANTS: One hundred and twenty-two drug users (57% males, 43% females), 90% of whom were in employment or education, with an age range of 16-47, 80% between 18 and 23 years. MEASUREMENTS: Participants who answered 'yes' to the question 'Have you used drugs for dance events in the past year' reported (i) the prevalence, types and frequency of drugs used; (ii) prevalence and contents of mixing drugs; (iii) accessing drugs; and (iv) engagement with drug-associated risk behaviours. FINDINGS: Over 80% of the participants had used ecstasy and amphetamine, over 30% cocaine and LSD; over 10% nitrites, psilocybin and ketamine and less than 5% had used crack or tranquillizers. Participants reported regular consumption of ecstasy and amphetamine (e.g. 35% used ecstasy and 25% amphetamine on a weekly basis) often taken in combination, with the occasional use of cocaine, LSD, ketamine and psilocybin. Poly- and mixing-drug behaviours were significantly more likely than monodrug usage. Drugs were accessed through friends than from any other source. Eighty-five per cent reported mixing drugs and/or alcohol, 35% driving on drugs, 36% having a bad experience on drugs; 30% unprotected sex; and 0.9% injecting drugs. Women in the sample reported higher consumption than men. CONCLUSIONS: Dance-drug use has a characteristic pattern that has implications for health promotion and criminal policy.

Adolescent↗

PubMed2001

Genetic architecture of adaptive differentiation in evolving host races of the soapberry bug, Jadera haematoloma.

To explore genetic architecture and adaptive evolution, we conducted environmental and genetic experiments with two recently (ca. 100 generations) diverged, geographically adjacent races of the soapberry bug. One race occurs on a native host plant species, the other on an introduced host. We focused on three traits: length of the mouthparts, body size and development time. The first experiment was an environmental manipulation, comparing individuals of each population reared on one or the other host species ('cross-rearing') and estimating three evolutionary rates for each trait. The first rate, 'evolutionary path' compares ancestral-derived populations when both were reared on the introduced host. The second, 'current ecological contrast' compares populations with each reared on its natal host. The third, 'evolved tradeoff' compares the two races when reared on the native host. Differences among these rates are striking and informative. For example, development time, which appears to be relatively undifferentiated phenotypically, has actually evolved very rapidly via countergradient selection. The pattern differs for each trait, and clear developmental tradeoffs have evolved as quickly as adaptation to the new host in each. The second experiment was a two-generation 'line cross' study. With joint-scaling analyses, we compared purebred, hybrid and backcrossed individuals to describe genetic architecture. Additive genetic variance for mouthpart length was consistently large (ca. 60%), but the interaction of dominance, maternal effects and epistasis was important in the other traits. Rearing host strongly affected genetic architecture. There was no clear relationship between genetic architecture and rate of evolution. Selection has produced both additive and nonadditive differentiation between the host races with surprising speed, consistent with theoretical predictions about evolution in fitness-associated traits.

Adaptation, Biological↗

PubMed2000

Enzyme profiles in two wing polymorphic soapberry bug populations (Jadera haematoloma: Rhopalidae).

Wing-polymorphic insects are excellent models for asking questions about trade-offs in physiology and life-history because of the existence of multiple morphs exhibiting numerous strategies living in one environment. We measured activities of select key enzymes in oxidative metabolism (citrate synthase), glycolysis (hexokinase, pyruvate kinase) and fatty acid oxidation (ß-hydroxyacyl CoA dehydrogenase, HOAD) in flying and non-flying long-winged bugs from two populations (ancestral and derived) of the wing-polymorphic soapberry bug (Jadera haematoloma). In the ancestral population, flyers had significantly greater activities of citrate synthase, hexokinase, pyruvate kinase, and HOAD than non-flyers. In contrast, in the derived population, flyers and non-flyers showed no significant differences in the activities of any of the enzymes tested. There were no significant differences in activities of citrate synthase as a function of adult age (3-20 d) for either population. Short-winged bugs in the derived population had significantly lower citrate synthase activities than either of the two derived, long-winged morphs, however, they were analogous to the ancestral long-winged non-flyer. These results suggest an evolution of alternative flight strategies between the two populations.

Journal Article↗

PubMed1974