@article {793,
	title = {Malaria{\textquoteright}s Eve: evidence of a recent population bottleneck throughout the world populations of Plasmodium falciparum.},
	journal = {Proc Natl Acad Sci U S A},
	volume = {95},
	year = {1998},
	month = {1998 Apr 14},
	pages = {4425-30},
	abstract = {We have analyzed DNA sequences from world-wide geographic strains of Plasmodium falciparum and found a complete absence of synonymous DNA polymorphism at 10 gene loci. We hypothesize that all extant world populations of the parasite have recently derived (within several thousand years) from a single ancestral strain. The upper limit of the 95\% confidence interval for the time when this most recent common ancestor lived is between 24,500 and 57,500 years ago (depending on different estimates of the nucleotide substitution rate); the actual time is likely to be much more recent. The recent origin of the P. falciparum populations could have resulted from either a demographic sweep (P. falciparum has only recently spread throughout the world from a small geographically confined population) or a selective sweep (one strain favored by natural selection has recently replaced all others). The selective sweep hypothesis requires that populations of P. falciparum be effectively clonal, despite the obligate sexual stage of the parasite life cycle. A demographic sweep that started several thousand years ago is consistent with worldwide climatic changes ensuing the last glaciation, increased anthropophilia of the mosquito vectors, and the spread of agriculture. P. falciparum may have rapidly spread from its African tropical origins to the tropical and subtropical regions of the world only within the last 6,000 years. The recent origin of the world-wide P. falciparum populations may account for its virulence, as the most malignant of human malarial parasites.},
	keywords = {Africa, Animals, Asia, Climate, Demography, DNA, Protozoan, Evolution, Molecular, Genes, Protozoan, Humans, Life Cycle Stages, Malaria, Malaria, Falciparum, Netherlands, Phylogeny, Plasmodium, Plasmodium falciparum, Polymorphism, Genetic, South America, Tetrahydrofolate Dehydrogenase, Time},
	issn = {0027-8424},
	author = {Rich, S M and Licht, M C and Hudson, R R and Ayala, F J}
}
@article {799,
	title = {Distribution of the Ixodes ricinus-like ticks of eastern North America.},
	journal = {Proc Natl Acad Sci U S A},
	volume = {92},
	year = {1995},
	month = {1995 Jul 3},
	pages = {6284-8},
	abstract = {We analyzed the geographic distribution of the Ixodes ricinus-like ticks in eastern North America by comparing the mitochondrial 16S rDNA sequences of specimens sampled directly from the field during the 1990s. Two distinct lineages are evident. The southern clade includes ticks from the southeastern and middle-eastern regions of the United States. The range of the northern clade, which appears to have been restricted to the northeastern region until the mid-1900s, now extends throughout the northeastern and middle-eastern regions. These phyletic units correspond to northern and southern taxa that have previously been assigned specific status as Ixodes dammini and Ixodes scapularis, respectively. The expanding range of I. dammini appears to drive the present outbreaks of zoonotic disease in eastern North America that include Lyme disease and human babesiosis.},
	keywords = {Animals, Base Sequence, Demography, DNA Primers, DNA, Mitochondrial, DNA, Ribosomal, Geography, Mitochondria, Molecular Sequence Data, Phylogeny, Polymerase Chain Reaction, Population, RNA, Ribosomal, 16S, Ticks, United States},
	issn = {0027-8424},
	author = {Rich, S M and Caporale, D A and Telford, S R and Kocher, T D and Hartl, D L and Spielman, A}
}
