Explosions and hot spots in supertree methods.

In phylogenetic systematics a problem of great practical and theoretical interest is to construct one or more large phylogenies (evolutionary trees), i.e., supertrees, from a given set of small phylogenies with overlapping sets of leaf labels. Although the methods being used to solve this problem are usually given plausible biological or theoretical justifications, occasionally it is possible to see that the result of a supertree method (SM) is explosive, and therefore logically meaningless, in the sense that it has been inferred from logical propositions that are contradictory. This paper presents the basic ideas and issues of how explosions affect the inference of rooted trees by SMs. We define the relevant concepts, give examples, and show how sometimes it is possible to identify hot spots in the input from which an SM may make explosive inferences that cannot be logically justified.

Autonomy and children's reactions to being controlled: evidence that both compliance and defiance may be positive markers in early development.

This study examined reactions of 1-year-olds and young 2-year-olds to being controlled by mothers. Mothers' supportive behavior predicted children's willing compliance. However, contrary to research with older children, defiance was also associated with variables linked to maternal competence, specifically, mothers' supportive behavior, autonomy-granting controls, and low depressive symptoms. At this age high-defiant children initiated positive interaction with mothers more than did low-defiant children. With age, children displayed more willing compliance and more active resistance (defiance, low passivity). However, developmental increases in active resistance were absent when mothers were high in depressive symptoms. Findings are consistent with the proposal that in early development active resistance to parents often reflects children's motivation to control events, not poor parenting or strained parent-child relationships.

Parasitism of Lygus spp. nymphs by the parasitoid wasp, Peristenus howardi, in the alfalfa seed-growing region of the Pacific Northwest.

The parasitoid, Peristenus howardi Shaw (Hymenoptera: Braconidae) has been found to parasitize a large proportion of Lygus species in some Washington and Idaho alfalfa seed fields. During 2002-2003 a survey was conducted to estimate the proportion of Lygus spp. (Hemiptera: Miridae) parasitized and the amountof that parasitism attributable to P. howardi in crop and non-crop plants attacked by Lygus in the alfalfa seed growing region of southwestern Idaho and eastern Oregon. Percentage parasitism was estimated from dissection of field-collected Lygus nymphs. Polymerase chain reaction (PCR) was used to amplify DNA extracted from parasitoid larvae followed by restriction endonuclease digestion of PCR products to distinguish P. howardi from other potentially co-occurring Peristenus species. Peak parasitism of Lygus nymphs occurred between the first and third weeks of July for both years for all host plants sampled. Of the parasitoid larvae recovered from Lygus nymphs in our study, 75% to 80% tested positive as Peristenus spp. and 76% of these matched the endonuclease digestion banding pattern for P. howardi. The identity of the remaining 20% to 25% of the parasitoids is not known.