Guppy fish

Not all characteristics are subject to successful selection pressure. There must be natural variation, differences in reproduction, and inheritability of the trait in order for selection to produce results. Natural selection requires not only that there be genetic variation but also that the genes be expressed (Mulcahy and Mulcahy, 1987). Without the latter, the genetic code present in a BU is simply irrelevant. Those traits that are not genetically determined cannot be selected for. Predation can select for different traits than would otherwise be chosen. An example of this is the color of male guppy fish females breed preferentially with the most colorful ones, but predators can most easily locate and eat the most colorful ones. Thus, male guppies in upland streams where there are few predators are more colorful than guppies downstream where predators abound (Palumbi, 2001). 

AH of the propylene glycols are considered to be practically nontoxic to fish on an acute basis (LC q < 100 mg/L) and practically nontoxic to aquatic invertebrates, also on an acute basis. Acute marine toxicology testing (38) on propylene glycol showed that the 96-h LC q for fathead minnows was 54,900 mg/L and the 48-h LC q for Daphnia magna was 34,400 mg/L. A 24-h NOEL of 50,000 mg/L was also observed for fingerling trout. Similar results were observed for guppies and rainbow trout (39). 

The effects of EDCs on behavior in fish have been more extensively studied than in birds. Examples of the effects of EDCs seen in fish include profound alterations in courtship behavior in male guppies (Poecilia reticulate) exposed to vinclozolin and DDE, including at environmentally relevant concentrations (Baatrup and Junge 2001) and altered courtship behavior in three-spined stickleback exposed to environmentally relevant concentrations of EE2 (Bell 2001). In the stickleback studies, exposed males became less aggressive and had a reduced nesting activity, and this was linked with reduced concentrations of the male sex androgen 11-ketotestosterone. Recently,... 

It is assumed that in order to have vitamin A activity a molecule must have essentially one-half of its structure similar to that of (i-carotene with an added molecule of water at the end of the lateral polyene chain. Thus, P-carotene is a potent provitamin A to which 100% activity is assigned. An unsubstituted p ring with a Cii polyene chain is the minimum requirement for vitamin A activity. y-Car-otene, a-carotene, P-cryptoxanthin, a-cryptoxanthin, and P-carotene-5,6-epoxide aU have single unsubstimted rings. Recently it has been shown that astaxanthin can be converted to zeaxanthin in trout if the fish has sufficient vitamin A. Vitiated astaxanthin was converted to retinol in strips of duodenum or inverted sacks of trout intestines. Astaxanthin, canthaxanthin, and zeaxanthin can be converted to vitamin A and A2 in guppies. ... 

Pre-exposure to the organophosphate diazinon at exposures half the LC50 values increased the LC50 value by a factor of about five for guppy (Poecilia reticulata), but had no effect on the value for zebra fish (Brachydanio rerio). This was consistent with the observation that during pre-exposure of guppy there was a marked inhibition in the synthesis of the toxic metabolites diazoxon and pyrimidinol, whereas this did not occur with zebra fish in which the toxicity was mediated primarily by the parent compound (Keizer et al. 1993). 

Keizer J, G d Agostino, R Nagel, F Gramenzi, L Vittozzi (1993) Comparative diazinon toxicity in guppy and zebra fish different role of oxidative metabolism. Environ Toxicol Chem 12 1243-1250. 

Konemann, H., van Leeuewen, K. (1980) Toxicokinetics in fish accumulation of six chloro-benzenes by guppies. Chemosphere 9, 3-19. 

Pierson, K.B. 1981. Effects of chronic zinc exposure on the growth, sexual maturity, reproduction, and bioaccumulation of the guppy, Poecilia reticulata. Canad. Jour. Fish. Aquat. Sci. 38 23-31. 

Rongsriyam, Y., S. Prownebon, and S. Hirakoso. 1968. Effects of insecticides on the feeding activity of the guppy, a mosquito eating fish, in Thailand. Bull. World Health Org. 39 977-980. 

Keizer, J., G. D Agostino, and L. Vittozzi. 1991. The importance of biotransformation in the toxicity of xenobiotics to fish. I. Toxicity and bioaccumulation of diazinon in guppy (Poecilia reticulata) and zebra fish (Brachydanio rerio). Aquat. Toxicol. 21 239-254. 

Fed diets containing 6-150 mg PCB 133 or PCB 197/kg diet for 191-247 days, or 550-1400 mg/kg diet for 65 days At 6-150 mg/kg diet, uptake efficiency was near 50% at higher dietary loadings, uptake efficiency decreased to 25%. No deaths in controls or at low dietary dosages 13-25% mortality at 550-1400 mg/kg diet. Prior to death, guppies were sluggish, uncoordinated, and darkly colored fish that died during exposure contained >0.7 pmol PCB/g FW 7... 

LC50 (48-h) for guppies 0.16 to 0.3 mg/L (Hartley and Kidd, 1987), 14.8 and 47.6 pg/L for neonate and adult stage Hyalella azteca, respectively (Blockwell et al., 1998), Simocephalus serrulatus 520 pg/L, Daphnia pulex 460 pg/L (Sanders and Cope, 1966), zebra fish 120 pg/L (Slooff, 1979), Chironornus riparius second larval instar 55 pg/L (Taylor et al., 1991), three... 

Konemann, H. and van Leeuwen, K. Toxicokinetics in fish accumulation and elimination of six chlorobenzenes by guppies. Chemosphere, 9(1) 3-19, 1980. 

Clay may even benefit fish. Swain (1979) found that raising the levels of tannic acid in the water caused increasing discomfort and death to guppies (Fig. 11.29). The addition of clay to the water (52mg/ml water for a tannic acid concentration of 35 amol/l) extended the period the guppies survived over six times. Suspended clay particles in white rivers may adsorb phenolics and protect fish that cannot easily live in phenolic-rich black rivers (Swain, 1979). 

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