Biomedical subjects

David K Yeates

Publications and source records attributed to David K Yeates.

3 recordsLinked to original sources

PubMed2005

Invasive phytophagous pests arising through a recent tropical evolutionary radiation: the Bactrocera dorsalis complex of fruit flies.

The Bactrocera dorsalis complex of tropical fruit flies (Diptera: Tephritidae: Dacinae) contains 75 described species, largely endemic to Southeast Asia. Within the complex are a small number of polyphagous pests of international significance, including B. dorsalis sensu stricto, B. papayae, B. carambolae, and B. philippinensis. Most species within the complex were described in 1994 and since then substantial research has been undertaken in developing morphological and molecular diagnostic techniques for their recognition. Such techniques can now resolve most taxa adequately. Genetic evidence suggests that the complex has evolved in only the last few million years, and development of a phylogeny of the group is considered a high priority to provide a framework for future evolutionary and ecological studies. As model systems, mating studies on B. dorsalis s.s. and B. cacuminata have substantially advanced our understanding of insect use of plant-derived chemicals for mating, but such studies have not been applied to help resolve the limits of biological species within the complex. Although they are commonly regarded as major pests, there is little published evidence documenting economic losses caused by flies of the B. dorsalis complex. Quantification of economic losses caused by B. dorsalis complex species is urgently needed to prioritize research for quarantine and management. Although they have been documented as invaders, relatively little work has been done on the invasion biology of the complex and this is an area warranting further work.

Animals↗

PubMed2004

Infrared video thermography: a technique for assessing cold adaptation in insects.

Insects can survive subzero temperatures by two main strategies: freeze tolerance and freeze avoidance. An array of techniques have been used to investigate the physiological limits of insects to low temperatures, such as differential scanning calorimetry, temperature-controlled cooling apparatus, thermocouples, and computer-controlled chart recording equipment. However, these techniques require animals to be stationary, precluding behavioral data. We used infrared video thermography to investigate cold adaptation in an alpine insect, expanding such investigations to include behavioral response as an indicator of physiological stress. This technique is noninvasive and provides a large amount of physiological information, such as supercooling points, lower lethal temperatures, and hemolymph melting points. Insect supercooling points in response to a constant cooling rate were variable; however, temperatures at the initiation of behavioral stress response were less variable. Assessments of supercooling points and lower lethal temperatures obtained in this way are more biologically meaningful because allowing unhindered movement of insects more closely resembles natural environments.

Adaptation, Physiological↗

PubMed2003

Time flies, a new molecular time-scale for brachyceran fly evolution without a clock.

The insect order Diptera, the true flies, contains one of the four largest Mesozoic insect radiations within its suborder Brachycera. Estimates of phylogenetic relationships and divergence dates among the major brachyceran lineages have been problematic or vague because of a lack of consistent evidence and the rarity of well-preserved fossils. Here, we combine new evidence from nucleotide sequence data, morphological reinterpretations, and fossils to improve estimates of brachyceran evolutionary relationships and ages. The 28S ribosomal DNA (rDNA) gene was sequenced for a broad diversity of taxa, and the data were combined with recently published morphological scorings for a parsimony-based phylogenetic analysis. The phylogenetic topology inferred from the combined 28S rDNA and morphology data set supports brachyceran monophyly and the monophyly of the four major brachyceran infraorders and suggests relationships largely consistent with previous classifications. Weak support was found for a basal brachyceran clade comprising the infraorders Stratiomyomorpha (soldier flies and relatives), Xylophagomorpha (xylophagid flies), and Tabanomorpha (horse flies, snipe flies, and relatives). This topology and similar alternative arrangements were used to obtain Bayesian estimates of divergence times, both with and without the assumption of a constant evolutionary rate. The estimated times were relatively robust to the choice of prior distributions. Divergence times based on the 28S rDNA and several fossil constraints indicate that the Brachycera originated in the late Triassic or earliest Mesozoic and that all major lower brachyceran fly lineages had near contemporaneous origins in the mid-Jurassic prior to the origin of flowering plants (angiosperms). This study provides increased resolution of brachyceran phylogeny, and our revised estimates of fly ages should improve the temporal context of evolutionary inferences and genomic comparisons between fly model organisms.

Animals↗