The cost of reproduction hypothesis suggests that current reproduction has inherent tradeoffs with future reproduction. These tradeoffs can be both in the form of energy allocated to current offspring as opposed to somatic maintenance and future reproduction (allocation costs), or as an increase in mortality as a result of morphological or physiological changes related to reproduction (viabilit...

The dynamics of mitochondrial and multilocus nuclear genotypic frequencies were monitored for 2 yr in experimental populations established with equal numbers of two poeciliid fishes (Gambusia affinis and Gambusia holbrooki) that hybridize naturally in the southeastern United States. In replicated "small-pool" populations (experiment I), 1018 sampled individuals at six time periods revealed an i...

The mosquito control potential of the mosquitofish and Bacillus thuringiensis var. israelensis (Bti) were evaluated in experimental wild rice fields in Lake County, California. Fields were assigned one of six treatment: control, 1.1 kg/ha G. affinis, 3.4 kg/ha G. affinis, Bti only (6 kg/ha Vectobac granules), 1.1 kg/ha G. affinis plus Bti and 3.4 kg/ha G. affinis plus Bti. Gambusia affinis, at ...

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. Figures 1. Standard curve demonstrating verification of a flow cytometric membrane integri...

Mosquitofish (Gambusia affinis) is an example of a freshwater fish species whose remarkable diffusion outside its native range has led to it being placed on the list of the world's hundred worst invasive alien species (International Union for Conservation of Nature). Here, we investigate mosquitofish shoaling tendency using a dichotomous choice test in which computer-animated images of their co...

The mosquitofish, Gambusia affinis, and the inland silverside, Menidia beryllina, were evaluated in experimental, one-tenth hectare wild rice plots in Lake County, California, for their impact on densities of Culex tarsalis, Anopheles freeborni and Anopheles franciscanus. Gambusia affinis were tested at 0.6 and 1.7 kg/ha and the silversides at ca. 0.9 kg/ha. The silversides did not survive well...

A population of western mosquitofish (Gambusia affinis) living below a wastewater treatment plant in the vicinity of Birmingham (AL, USA) was studied for evidence of exposure to estrogens. Mosquitofish are sexually dimorphic live-bearing fish. Males have an elongated and modified anal fin, called a gonopodium, used in mating. It has been hypothesized that exposure to estrogens and/or anti-andro...

in this study, cadmium (cd) accumulation was studied in an experimental aquatic exposure. mosquitofish (gambusia affinis) were acutely exposed for 96 h to a high concentration of cd (12 mg/l) and were chronically exposed to a low concentration of cd(0.4 mg/l) for 30 days. cd accumulation profiles differed between the two cd exposures. the cd concentation in g. affinis tissues increased linearly...

Invertebrates were collected and identified from the stomach contents of eight mosquitofish (Gambusia affinis) populations in the northern Waikato region of New Zealand at 3-month intervals from December 1994 to September 1995. To investigate temporal and spatial patterns in dietary composition a novel analysis programme was created that used Gower's similarity coefficient. The analysis found d...

During routine inspection of a colony of albino western mosquitofish Gambusia affinis, approximately 10 females were discovered to have distended abdominal cavities. Cause for the distention was investigated by examination of tissue sections from four sacrificed individuals, all of which suffered severe ascites. Hermaphroditic gonads were seen in two of the fish.