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1.
J Econ Entomol ; 105(3): 1051-6, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22812147

RESUMO

Tephritid fruit flies, an important pest of horticulture worldwide, are increasingly targeted for control or eradication by large-scale releases of sterile flies of the same species. For each species treated, strains must be domesticated for mass rearing to provide sufficiently large numbers of individuals for releases. Increases in productivity of domesticated tephritid strains are well documented, but there have been few systematic studies of the genetic consequences of domestication in tephritids. Here, we used nine DNA microsatellite markers to monitor changes in genetic diversity during the early generations of domestication in replicated lines of the fruit fly Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). The observed changes in heterozygosity and allelic richness were compared with the expected changes in heterozygosity generated by a stochastic simulation including genetic drift but not selection. The results showed that repeatable genetic bottlenecks occur in the early generations and that selection occurs in the later generations. Furthermore, using the same simulation, we show that there is inadvertent selection for increased productivity for the entire life on a mass-rearing colony, in addition to intentional selection for increased productivity. That additional selection results from the common practice of establishing the next generation of the breeding colony from a small proportion of one day's pupae collection (the pupal raffle). That selection occurs during all generations and acts only on fecundity variation. Practical methods to counter that unavoidable loss of genetic diversity during the domestication process in B. tryoni are discussed.


Assuntos
Técnicas de Cultura , Oviparidade/genética , Seleção Genética , Tephritidae/genética , Animais , Feminino , Fertilidade/genética , Masculino , Repetições de Microssatélites
2.
Heredity (Edinb) ; 105(2): 165-72, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19997126

RESUMO

Previous population genetic studies of the Queensland fruit fly, Bactrocera tryoni Froggatt (Diptera: Tephritidae), in its central range have shown barely detectable genetic differentiation across distances of almost 3000 km (F(st)=0.003). In this study, we investigated the genetic structuring of southern border populations of B. tryoni, in the region extending from the central population to the recently colonized southern range limit. The expectation was that marginal populations would be small, fragmented population sinks, with local adaptation limited by gene flow or drift. Unexpectedly, we found that the population at the southern extreme of the range was a source population, rather than a sink, for the surrounding region. This was shown by assignment testing of recent outbreaks in an adjoining quarantine area and by indirect migration estimates. Furthermore, populations in the region had formed a latitudinal cline in microsatellite allele frequencies, spanning the region between the central population and the southern range limit. The cline has formed within 250 generations of the initial invasion and appears stable between years. We show that there is restricted gene flow in the region and that effective population sizes are of the order of 10(2)-10(3). Although the cline may result from natural selection, neutral evolutionary processes may also explain our findings.


Assuntos
Migração Animal , Tephritidae/genética , Animais , Clima , Fluxo Gênico , Repetições de Microssatélites , Austrália do Sul , Tephritidae/fisiologia
3.
Bull Entomol Res ; 91(2): 139-47, 2001 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11260729

RESUMO

The population structure of a tephritid pest species, the Queensland fruit fly Bactrocera tryoni (Froggatt), has been analysed over a five year period (1994-1998), using six microsatellites. Adult fly samples were collected to cover most regions of eastern and central Australia where the flies are regularly found. Tests for heterogeneity indicated that flies within geographically defined regions were homogeneous. The samples were allocated into five regions, including one very large region, Queensland, which encompasses that portion of the fly's range where breeding can occur year-round. With one exception, the collections from different regions were homogeneous between years, showing a fairly static distribution of the species. However, differences between regions were highly significant. The one case of a change in frequency between years indicated a gradual replacement of flies in a marginal region by flies from the main part of the range. The finding of stability in the distribution of a highly mobile insect is of interest, potentially also for other species which have expanded beyond their native range. It is argued that a contributing reason for this stability may be adaptation to different climatic regimes, and that strategies for control based on this hypothesis afford a reasonable chance of success.


Assuntos
Dípteros/genética , Genes de Insetos , Repetições de Microssatélites , Animais , Austrália , Demografia , Masculino
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