Quantitative genetic studies frequently utilize inbred strains of animals as tools for partitioning the direct and indirect effects of genes from environmental effects in generating an observed phenotype, however, this approach is rarely applied to behavioral studies.
Guppies, Poecilia reticulata, perform a set of anti-predator behaviors that may provide an ideal system to study how complex behavioral traits are generated. To assess the utility of ornamental guppies in quantitative genetics studies of behavior, we assayed five morphologically distinct strains of ornamental guppies for response to predator cues and for variation in response among strains. Despite individual variation, all five strains responded to predator cues and differences among strains were found for all assayed behaviors, including measures of boldness and predator avoidance.
KEY WORDS: Anti-predator behavior; inbred strain; Poecilia reticulata; quantitative genetics.

Background: Inbreeding can slow population growth and elevate extinction risk. A small number of unrelated immigrants to an inbred population can substantially reduce inbreeding and improve fitness, but little attention has been paid to the sex-specific effects of immigrants on such "genetic rescue". We conducted two subsequent experiments to investigate demographic consequences of inbreeding and genetic rescue in guppies.
Results: Populations established from pairs of full siblings that were descended either from two generations of full-sibling inbreeding or unrelated outbred guppies did not grow at different rates initially, but when the first generation offspring started breeding, outbred-founded populations grew more slowly than inbred-founded populations. In a second experiment, adding two outbred males to the inbred populations resulted in significantly faster population growth than in control populations where no immigrants were added. Adding females resulted in growth at a rate intermediate to the control and male-immigrant treatments.
Conclusion: The slower growth of the outbred-founded than inbred-founded populations is the opposite of what would be expected under inbreeding depression unless many deleterious recessive alleles had already been selectively purged in the inbreeding that preceded the start of the experiment, and that significant inbreeding depression occurred when the first generation offspring in outbred-founded populations started to inbreed. The second experiment revealed strong inbreeding depression in the inbred founded populations, despite the apparent lack thereof in these populations earlier on. Moreover, the fact that the addition of male immigrants resulted in the highest levels of population growth suggests that sex-specific genetic rescue may occur in promiscuous species, with male rescue resulting in higher levels of outbreeding than female rescue.

В обзоре рассмотрены работы, где в качестве модели для изучения биологической эволюции используются искусственно поддерживаемые популяции. Проанализированы данные об основных факторах эволюции генофонда — случайных процессах, межвидовой гибридизации, миграции, мутациях и отборе. Приводятся доказательства в пользу представления об отборе как о ведущем факторе эволюции, регулирующем действие других факторов напрямую или с помощью генетических систем.

he phenotype-linked fertility hypothesis suggests that a female can benefit directly from mate choice when the cues she uses indicate the quantity and/or quality of his spermatozoa. We tested the link between sperm quality and male body size and coloration in the resource-free mating system of the guppy, a tropical fish characterized by strong female choice. Larger males possessed larger testes and are therefore predicted to produce larger numbers of spermatozoa than smaller males. Larger male guppies also produced longer spermatozoa than smaller males. Degree of carotenoid coloration did not predict either the quantity or the quality of a male's spermatozoa. These results are consistent with a previous study that showed that female guppies in the study population prefer larger males to brightly colored males. The male-size directed increase in spermatozoon size may be the result of interplay between sperm competition and the coevolution of spermatozoon traits with the female reproductive tract.

Key words: male size, phenotype-linked fertility, Poecilia reticulata, sperm size, sperm velocity.

This paper deals with the inheritance and phenotypic expression of two new pairs of alleles controlling color patterns in the cyprinodont fish, Lebistes reticulatus, commonly known as the guppy. Especial attention is given to the structures and arrangements of chromatophores as affected by the various gene combinations.
Grateful acknowledgment is made for financial aid from the Denison fund for research in biology a t WESLEYAUNN IVERSITY.
The hereditary characters of Lebistes that have previously been analyzed are chiefly color characters, and most of these show X or Y chromosome inheritance or both-that is, crossing over between X and Y. For accounts of these see WINGE( 1927), BLACHER (1927, 1928), GOODRICH (1929) (a summary) WINGEa nd DITLEVSEN (1938). Autosomal characters hitherto described include a color character Zebrinus ( WINGE 1927), Abnomis (KIRPITCHNIKOFF 1935) (publication not accessible to us), Hunchback, which was studied by R. W. HARRISONan d reported in abstract by GOODRICeHt al. (1943). A character Fredlini, briefly described by HASKINSa nd DRUZBA(1 938) has by personal conference been shown to be identical with our Golden and will be discussed below.