The existence of a continuous array of sympatric biotypes - from polymorphisms, through ecological or host races with increasing reproductive isolation, to good species - can provide strong evidence for a continuous route to sympatric speciation via natural selection. Host races in plant-feeding insects, in particular, have often been used as evidence for the probability of sympatric speciation...

ABSTRACT Strains of the carnation wilt pathogen, Fusarium oxysporum f. sp. dianthi, can be distinguished by DNA fingerprint patterns, using the fungal transposable elements Fot1 and impala as probes for Southern hybridization. The DNA fingerprints correspond to three groups of F. oxysporum f. sp. dianthi strains: the first group includes isolates of races 1 and 8; the second group includes isol...

ABSTRACT Plant pathogens often exhibit variation in virulence, the ability to cause disease on host plants with specific resistance, evident from the diversity of races observed within pathogen species. The evolution of races in asexual fungal pathogens has been hypothesized to occur in a stepwise fashion, in which mutations to virulence accumulate sequentially in clonal lineages, resulting in ...

There’s nothing quite like a day at the races . . . . The quickening of the pulse as the starter’s pistol sounds, the thrill when your favorite contestant speeds out into the lead (or the distress if another contestant dashes out ahead of yours), and the accompanying fear (or hope) that the leader might change. And what if the race is a marathon? Maybe one of the contestants will be far stronge...

Data races are a common problem in concurrent programming. Experience shows that the notion of data race is not powerful enough to capture certain types of inconsistencies occurring in practice. In this paper we investigate data races on a higher abstraction layer. This enables us to detect inconsistent uses of shared variables, even if no classical race condition occurs. For example, a data st...

Data races in multi-threaded programs may occur when multiple accesses on different threads access a shared location without proper synchronization, and one of them is a store. It is difficult to develop data race free programs and to manually fix existing data races in the programs, because they may lead to unpredictable results to the programmer. This paper presents a technique that heals dat...

Coevolutionary arms races between species can favor exaggeration of traits for attack and defense, but relentless escalation of these arms races does not necessarily occur in all populations.

Introduction Forty years ago, Robert Gagne published the first edition of his book The Conditions of Learning (1965) in which he proposed nine events of instruction that provide a sequence for organizing a lesson. These events remain the foundation of current instructional design practice (Reiser, 2002; Richey, 2000). They represent desirable conditions in an instructional program and increase ...

Progeny from single females of four known races of Heterodera glycines Ichinohe were used to establish relatively uniform populations. Single females from these populations were mated with males of other races in all possible combinations to study compatibility and inheritance patterns. When race 1 or 3 was crossed with either race 2 or 4, there was a significant reduction in number of females ...