Annual Lipid Cycle in Eastern Mosquitofish (Gambusia holbrooki: Poeciliidae) from South Carolina

Copeia ◽  
1993 ◽  
Vol 1993 (3) ◽  
pp. 596 ◽  
Author(s):  
Gary K. Meffe ◽  
Franklin F. Snelson
1991 ◽  
Vol 48 (1) ◽  
pp. 60-66 ◽  
Author(s):  
Gary K. Meffe

Much light can be shed on life history evolution through study of responses of organisms to chronic exposure to a novel or perturbed environment. To determine the influence of 28 yr of temporally unpredictable thermal elevation on their life history patterns, I sampled eastern mosquitofish (Gambusia holbrooki) from a thermally elevated (outflow from a nuclear reactor) and an ambient (farm pond) habitat in South Carolina every month for 2 yr. Fish from the artificially heated environment reproduced all year, had higher reproductive investments (higher clutch sizes and reproductive biomass), and smaller offspring than did fish from the ambient environment, which ceased reproduction from October through March, typical for natural populations of the region. Likely environmental factors responsible for these differences include unpredictable food resources, higher mortality from thermal death, and higher predation by fishes and birds in the heated waters. The extent to which these life history alterations are the result of adaptive genetic changes versus phenotypically plastic responses remains to be tested.


1995 ◽  
Vol 52 (12) ◽  
pp. 2704-2711 ◽  
Author(s):  
Gary K. Meffe ◽  
Stephen C. Weeks ◽  
Margaret Mulvey ◽  
K. L. Kandl

Two populations of eastern mosquitofish (Gambusia holbrooki; Poeciliidae) in South Carolina, one in an ambient temperature pond and the other in a pond heated to near-lethal temperatures by nuclear reactor effluents for 60–90 mosquitofish generations, offered an excellent opportunity to observe selection for increased thermal tolerance. We performed three experiments. First, we determined the critical thermal maximum of each population and, as predicted, found the thermal population to have a higher one. We then exposed fish from both populations to an acute thermal LD50 stress and compared genetic diversity of fish that died and fish that survived. Survivors had higher heterozygosities, indicating that genetic diversity may contribute to thermal tolerance. Finally, we used a half-sib – full-sib experimental design to estimate heritabilities for temperature tolerance in fish from the heated pond. We calculated a narrow-sense heritability for temperature at death of over 32%, indicating that selection has not depleted the population of genetic variation associated with thermal tolerance. Our results have implications for climate change because adaptations to higher thermal regimes must, in part, come from selection on genetic variation for temperature tolerance within populations.


1993 ◽  
Vol 50 (10) ◽  
pp. 2185-2191 ◽  
Author(s):  
Gary K. Meffe ◽  
Franklin F. Snelson Jr.

In animals, strategies of energy allocation among growth, maintenance and reproduction can be significantly altered by lipid storage. Poeciliid (livebearing) fishes store energy in late summer and fall for overwintering and first reproduction in spring, but details of energy use in reproduction are lacking. We conducted a laboratory experiment on the eastern mosquitofish (Gambusia holbrooki) and the sailfin molly (Poecilia latipinna) to document changes in lipid content in both the ovary and soma during development of a brood. In females of both species, ovarian lipid content was highest early in embryogeny and then declined; adult somatic lipids increased (were replenished) during embryonic development in mosquitofish, but declined in mollies. Larger clutches sequestered a larger share of body lipids in both species, possibly indicating energetic limits to reproduction. Finally, growth rate was positively correlated with somatic lipid content in both species, indicating among-individual differences in metabolic efficiency or feeding efficiency rather than a trade-off between growth and energy storage.


Limnetica ◽  
2011 ◽  
Vol 30 (1) ◽  
pp. 1-4
Author(s):  
Raquel Moreno-Valcárcel ◽  
Ana Ruiz-Navarro ◽  
Mar Torralva ◽  
Francisco José Oliva-Paterna

2012 ◽  
Vol 60 (4) ◽  
pp. 235 ◽  
Author(s):  
Kate D. L. Umbers ◽  
Michael D. Jennions ◽  
J. Scott Keogh

We isolated 25 new polymorphic microsatellite markers from the eastern mosquitofish, Gambusia holbrooki. Initially, 454 shotgun sequencing was used to identify 1187 loci for which primers could be designed. Of these 1187, we trialled 48 in the target species, 40 of which amplified a product of expected size. Subsequently, those 40 loci were screened for variation in 48 individuals from a single population in Canberra, Australia. Twenty loci were in Hardy–Weinberg equilibrium and polymorphic, with observed heterozygosity ranging from 0.04 to 0.72 (mean: 0.45 ± 0.18) and the number of alleles per locus ranged from 2 to 5 (mean: 3.20 ± 1.05). These loci will be useful in understanding genetic variation, paternity analysis and in managing this species across both its native and invasive range.


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