The expansion of Africanized honeybees from South America to the southwestern United States in <50 years is considered one of the most spectacular biological invasions yet documented. In the American tropics, it has been shown that during their expansion Africanized honeybees have low levels of introgressed alleles from resident European populations. In the United States, it has been speculated, but not shown, that Africanized honeybees would hybridize extensively with European honeybees. Here we report a continuous 11-year study investigating temporal changes in the genetic structure of a feral population from the southern United States undergoing Africanization. Our microsatellite data showed that (1) the process of Africanization involved both maternal and paternal bidirectional gene flow between European and Africanized honeybees and (2) the panmitic European population was replaced by panmitic mixtures of A. m. scutellata and European genes within 5 years after Africanization. The post-Africanization gene pool (1998–2001) was composed of a diverse array of recombinant classes with a substantial European genetic contribution (mean 25–37%). Therefore, the resulting feral honeybee population of south Texas was best viewed as a hybrid swarm.
The expansion of Africanized honeybees from South America to the southwestern United States in 50 years is considered one of the most spectacular biological invasions yet documented. In the American tropics, it has been shown that during their expansion Africanized honeybees have low levels of introgressed alleles from resident European populations. In the United States, it has been speculated, but not shown, that Africanized honeybees would hybridize extensively with European honeybees. Here we report a continuous 11-year study investigating temporal changes in the genetic structure of a feral population from the southern United States undergoing Africanization. Our microsatellite data showed that (1) the process of Africanization involved both maternal and paternal bidirectional gene flow between European and Africanized honeybees and (2) the panmitic European population was replaced by panmitic mixtures of A. m. scutellata and European genes within 5 years after Africanization. The post-Africanization gene pool (1998–2001) was composed of a diverse array of recombinant classes with a substantial European genetic contribution (mean 25–37%). Therefore, the resulting feral honeybee population of south Texas was best viewed as a hybrid swarm. ; PRODEP II - Medida 5/Acção 5.3
Intraspecific variation maintained in natural populations has long intrigued scientists and naturalists. One form of this variation, color polymorphisms, provide a rich opportunity to connect genotypic and phenotypic diversity within an ecological and evolutionary context. The existence of color polymorphisms in Panamanian populations of the Neotropical tortoise beetle, Chelymorpha alternans, has been suspected but never systematically explored. To characterize geographic distribution and underlying genetics we sampled a total of 3819 beetles from 28 sites across Panama, quantifying five distinct phenotypes. Two phenotypes, the "metallic" and "rufipennis" are the most widely distributed phenotypes, occurring in nearly all collecting sites. The "veraguensis" phenotype was found to be restricted to the Western end of the Isthmus and the "militaris" phenotypes restricted to sites east of the canal. Controlled matings between phenotypes and reared offspring revealed no indications of reproductive barriers, even among phenotypes which do not co-occur in nature. Color pattern phenotype is largely controlled by Mendelian assortment of four alleles competing at a single locus. A clear dominance hierarchy exists among alleles, with two being co-dominant. Genomic scans from 32 individuals revealed low levels of genetic differentiation, with a small fraction of the genome showing a high degree of divergence. The easily observed variation among populations, simple genetic architecture, and rearing capabilities, make this a promising system for investigating proximate and ultimate factors of phenotypic variation.
The arrival to the United States of the Africanized honey bee, a hybrid between European subspecies and the African subspecies Apis mellifera scutellata, is a remarkable model for the study of biological invasions. This immigration has created an opportunity to study the dynamics of secondary contact of honey bee subspecies from African and European lineages in a feral population in South Texas. An 11-year survey of this population (1991-2001) showed that mitochondrial haplotype frequencies changed drastically over time from a resident population of eastern and western European maternal ancestry, to a population dominated by the African haplotype. A subsequent study of the nuclear genome showed that the Africanization process included bidirectional gene flow between European and Africanized honey bees, giving rise to a new panmictic mixture of A. m. scutellata- and European-derived genes. In this study, we examined gene flow patterns in the same population 23 years after the first hybridization event occurred. We found 28 active colonies inhabiting 92 tree cavities surveyed in a 5.14 km(2) area, resulting in a colony density of 5.4 colonies/km(2). Of these 28 colonies, 25 were of A. m. scutellata maternal ancestry, and three were of western European maternal ancestry. No colonies of eastern European maternal ancestry were detected, although they were present in the earlier samples. Nuclear DNA revealed little change in the introgression of A. m. scutellata-derived genes into the population compared to previous surveys. Our results suggest this feral population remains an admixed swarm with continued low levels of European ancestry and a greater presence of African-derived mitochondrial genetic composition.
Female Aedes aegypti mosquitoes infect more than 400 million people each year with dangerous viral pathogens including dengue, yellow fever, Zika and chikungunya. Progress in understanding the biology of mosquitoes and developing the tools to fight them has been slowed by the lack of a high-quality genome assembly. Here we combine diverse technologies to produce the markedly improved, fully re-annotated AaegL5 genome assembly, and demonstrate how it accelerates mosquito science. We anchored physical and cytogenetic maps, doubled the number of known chemosensory ionotropic receptors that guide mosquitoes to human hosts and egg-laying sites, provided further insight into the size and composition of the sex-determining M locus, and revealed copy-number variation among glutathione S-transferase genes that are important for insecticide resistance. Using high-resolution quantitative trait locus and population genomic analyses, we mapped new candidates for dengue vector competence and insecticide resistance. AaegL5 will catalyse new biological insights and intervention strategies to fight this deadly disease vector. ; National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services [U19AI110818]; USDA [2017-05741]; NIH Intramural Research Program; National Library of Medicine; National Human Genome Research Institute; NSF [PHY-1427654]; NIH [R01AI101112, R35GM118336, R21AI121853, R01AI123338, T32GM007739, NIH/NCATS UL1TR000043, DP2OD008540, U01AI088647, 1R01AI121211, D43TW001130-08, U01HL130010, UM1HG009375, 5K22AI113060, 1R21AI123937, R00DC012069]; Defence Advanced Research Project Agency [HR0011-17-2-0047]; Jane Coffin Childs Memorial Fund; Center for Theoretical Biological Physics postdoctoral fellowship; Robertson Foundation; McNair Foundation; Welch Foundation [Q-1866]; French Government's Investissement d'Avenir program, Laboratoire d'Excellence Integrative Biology of Emerging Infectious Diseases [ANR-10-LABX-62-IBEID]; Agence Nationale de la Recherche [ANR-17-ERC2-0016-01]; European Union [734584]; Pew and Searle Scholars Programs; Klingenstein-Simons Fellowship in the Neurosciences; Verily Life Sciences ; We thank R. Andino; S. Emrich and D. Lawson (Vectorbase); A. A. James, M. Kunitomi, C. Nusbaum, D. Severson, N. Whiteman; T. Dickinson, M. Hartley and B. Rice (Dovetail Genomics) for early participation in the AGWG; C. Bargmann, D. Botstein, E. Jarvis and E. Lander for encouragement and facilitation. N. Keivanfar, D. Jaffe and D. M. Church (10X Genomics) prepared DNA for structural-variant analysis. We thank A. Harmon of the New York Times and acknowledge generous pro bono data and analysis from our corporate collaborators. This research was supported in part by federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under grant number U19AI110818 to the Broad Institute (S.N.R. and D.E.N.); USDA 2017-05741 (E.L.A.); NSF PHY-1427654 Center for Theoretical Biological Physics (E.L.A.); NIH Intramural Research Program, National Library of Medicine and National Human Genome Research Institute (A.M.P. and S.K.) and the following extramural NIH grants: R01AI101112 (J.R.P.), R35GM118336 (R.S.M. and W.J.G.), R21AI121853 (M.V.S., I.V.S. and A. S.), R01AI123338 (Z.T.), T32GM007739 (M.H.), NIH/NCATS UL1TR000043 (Rockefeller University), DP2OD008540 (E.L.A.), U01AI088647, 1R01AI121211 (W.C.B. IV), Fogarty Training Grant D43TW001130-08, U01HL130010 (E.L.A.), UM1HG009375 (E.L.A), 5K22AI113060 (O.S.A.), 1R21AI123937 (O.S.A.), and R00DC012069 (C.S.M.); Defence Advanced Research Project Agency: HR0011-17-2-0047 (O.S.A.). Other support was provided by Jane Coffin Childs Memorial Fund (B.J.M.), Center for Theoretical Biological Physics postdoctoral fellowship (O.D.), Robertson Foundation (L.Z.), and McNair & Welch (Q-1866) Foundations (E.L.A.), French Government's Investissement d'Avenir program, Laboratoire d'Excellence Integrative Biology of Emerging Infectious Diseases (grant ANR-10-LABX-62-IBEID to L.L.), Agence Nationale de la Recherche grant ANR-17-ERC2-0016-01 (L.L.), European Union's Horizon 2020 research and innovation program under ZikaPLAN grant agreement no. 734584 (L.L.), Pew and Searle Scholars Programs (C.S.M.), Klingenstein-Simons Fellowship in the Neurosciences (C.S.M.). A.M.W., B.J.W., J.E.C. and S.N.M. were supported by Verily Life Sciences. L.B.V. is an investigator of the Howard Hughes Medical Institute.
