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Life History of Poecilia picta (Poeciliidae) from the Island of Trinidad
Abstract and Figures
We describe the life history of Poecilia picta from four collections made at three localities in Trinidad. Dependent variables include the number and size of offspring, the average size of mature males, the size distribution of reproducing females, and the mode of reproduction. Poecilia picta contain only one brood of developing young at a time (i.e., do not have superfetation). The young lose approximately 36% of their dry mass during development, implying that this species is lecithotrophic or that there is no maternal provisioning after the eggs are fertilized. We compared the life history with that of the closely related P. reticulata (guppies) from three types of communities in Trinidad and found that P. picta has a life history very similar to guppies which co-occur with Crenicichla alta (a predator on adult size classes of guppies) and other predators. This means that they give birth to relatively many, small young and have high reproductive allotments. This comparison is consistent with the similar assemblage of predators found at all three P. picta localities and suggests that predation may have played a role in the evolution of P. picta's life history. Variation in life-history patterns in P. picta from different localities was similar to the pattern of variation observed in guppies reared on different levels of food availability in the laboratory, suggesting that differences among localities' food availability may account for some of this variation. Specifically, high food availability is associated with increased body size, litter size, and reproductive allotment; this same pattern accounts for the significant differences in life histories seen among the four P. picta collections.
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... Hester (1964) demonstrated across three parturition periods that guppies (Poecilia reticulata, Poeciliidae) on the lowest rations had less than half the number of oocytes for future reproduction than those on the full ration. Several other experiments demonstrate that high food availability to guppies is associated with increased body size, litter size and reproductive allotment (Reznick 1983(Reznick , 1990Reznick et al. 1992Reznick et al. , 1996Reznick and Yang 1993). Some of these relationships were quite complex. ...
... In such cases, females with large reserves are the capital breeders, while conspecifics with smaller reserves adopt an income breeding strategy. Experimental demonstrations of the effects of food on the reproductive potential of the guppy were reviewed earlier, and similar effects are also evident in research on the congener, swamp guppy (Poecilia picta, Poeciliidae; Reznick et al. 1992). ...
Fish spawning frequency varies from daily to once in a lifetime. Some species spawn and feed in separate areas, during different seasons, by storing energy and drawing on it later for reproduction (i.e. capital breeding). Other species spawn using energy acquired locally, throughout a prolonged spawning season, allocating energy directly to reproduction (i.e. income breeding). Capital breeders tend to ovulate all at once and are more common at boreal latitudes where productivity varies seasonally. Income breeding allows small fish to overcome allometric constraints on egg production and respond to current conditions; ceasing egg production when food is in short supply and resuming quickly when conditions improve. Many species exhibit mixed capital- and income breeding patterns, suggesting that breeding patterns are a conditional reproductive strategy that allows females to prioritize their own condition over their propagules’ condition at any given spawning opportunity, thereby expending energy cautiously to maximize lifetime reproductive value. Poor-feeding environments can lead to delayed maturation, skipped spawning, fewer spawning events per season or fewer eggs produced per event. In a few cases, variations in feeding environments appear to affect recruitment variability. These findings have implications for temporal and spatial sampling designs, and for interpreting fishery and ecosystem assessments.
... Although the Y chromosome in P. reticulata and P. wingei contains only a small area of limited degeneration [25][26][27][28] , the entirety of the Y chromosome of P. picta is highly degenerate 25 . P. parae is a sister species of P. picta Extreme Y chromosome polymorphism corresponds to five male reproductive morphs of a freshwater fish (diverging ~14.8 million years ago (Ma); ref. 29 ), however, P. picta males are markedly different from P. parae and do not resemble any of the five P. parae morphs 18,20,[30][31][32] , suggesting remarkable diversity was generated on the P. parae Y chromosome after recombination was halted with the X chromosome. Work on model systems has indeed shown that Y chromosomes can accumulate new genetic material [2][3][4][5] , yet these differences occur over long periods of time and are only evident when comparing Ys across species. ...
Loss of recombination between sex chromosomes often depletes Y chromosomes of functional content and genetic variation, which might limit their potential to generate adaptive diversity. Males of the freshwater fish Poecilia parae occur as one of five discrete morphs, all of which shoal together in natural populations where morph frequency has been stable for over 50 years. Each morph uses a different complex reproductive strategy and morphs differ dramatically in colour, body size and mating behaviour. Morph phenotype is passed perfectly from father to son, indicating there are five Y haplotypes segregating in the species, which encode the complex male morph characteristics. Here, we examine Y diversity in natural populations of P. parae. Using linked-read sequencing on multiple P. parae females and males of all five morphs, we find that the genetic architecture of the male morphs evolved on the Y chromosome after recombination suppression had occurred with the X. Comparing Y chromosomes between each of the morphs, we show that, although the Ys of the three minor morphs that differ in colour are highly similar, there are substantial amounts of unique genetic material and divergence between the Ys of the three major morphs that differ in reproductive strategy, body size and mating behaviour. Altogether, our results suggest that the Y chromosome is able to overcome the constraints of recombination loss to generate extreme diversity, resulting in five discrete Y chromosomes that control complex reproductive strategies.
... A life history strategy defines how an organism utilizes and optimizes energy to survive and reproduce (Fisher, 1930;Williams, 1966;Stearns, 1977;Roff, 1992). The optimal strategy can be influenced by extrinsic factors such as mortality rate (Strauss, 1990;Jennions et al., 2006;Riesch et al., 2013;Mukherjee et al., 2014;Olinger et al., 2016), resource availability (Reznick et al., 1992;Riesch et al., 2013;Moore et al., 2016;Zandonà et al., 2017), population density (Bronikowski et al., 2002;Schrader and Travis, 2012), and environmental conditions (e.g., salinity, gradient, elevation, etc.) (Zúñiga-Vega et al., 2007;Jourdan et al., 2016;Rius et al., 2019). Predator environments have often been used to study the effects of mortality rate on life history strategies (Law, 1979;Reznick and Endler, 1982;Johnson and Belk, 1999;Gosline and Rodd, 2008) and have been found to affect a wide variety of taxa, including fish, anurans, and insects. ...
Predation is known to have a significant effect on life history diversification in a variety of species. However, physical constraints of body shape and size can sometimes limit life history divergence. We test this idea in the Costa Rican livebearing fish Alfaro cultratus. Individuals in this species have a narrow body and keeled ventral surface, and females do not develop a distended abdomen when pregnant like other livebearing fishes. Here, we describe the life history of A. cultratus from 20 different populations across both high-predation and low-predation environments. We found significantly lower reproductive allotment in females from high-predation environments than in females from low-predation environments, but no significant difference in female or male size at maturity, number of offspring produced by females, or size of offspring. We found that A. cultratus exhibit isometric patterns of allocation for clutch dry mass in relation to female dry mass in high-predation and low-predation environments. Our results suggest that body shape constraints in this species limit the life history divergence we typically see between populations from high-predation and low-predation environments in other species.
... The number of offspring a female can carry is restricted by both the limited space available in the body cavity (physical limitation; Reznick and Miles, 1989;Pires et al., 2011) and the exacerbated negative consequences of an increase in reproductive allocation on a female's swimming ability (physiological limitation; Fleuren et al., 2019;Quicazan-Rubio et al., 2019). These factors explain (at least partly) why female size is often positively correlated with brood size (Cheong et al., 1984;Reznick et al., 1992Reznick et al., , 1993Neff et al., 2008;Schrader and Travis, 2009;Hagmayer et al., 2018Hagmayer et al., , 2020: larger females can physically carry larger broods than smaller females. Simple mathematics dictate that the larger a brood, the larger the absolute number of potential sires that can contribute to that brood (Avise and Liu, 2011): i.e., a brood of two offspring can be sired by a maximum of two fathers, while a brood of 30 offspring can be sired by a maximum of 30 different males. ...
Multiple paternity is a common phenomenon within the live-bearing fish family Poeciliidae. There is a great variety in brood sizes of at least two orders-of-magnitude across the family. However, little is known about the ramifications of this remarkable variation for the incidence and degree of multiple paternity and reproductive skew. Mollies (subgenus Mollienesia, genus Poecilia) produce some of the largest broods in the family Poeciliidae, making them an excellent model to study the effects of intra-specific variation in brood size on patterns of multiple paternity. We collected samples of the live-bearing fish Poecilia gillii from 9 locations in Costa Rica. We measured body size of 159 adult females, of which 72 were pregnant. These samples had a mean brood size of 47.2 ± 3.0 embryos, ranging from 4 to 130 embryos. We genotyped 196 field-collected specimens with 5 microsatellite markers to obtain location-specific allele frequencies. In addition, we randomly selected 31 pregnant females, genotyped all their embryos (N = 1346) and calculated two different parameters of multiple paternity: i.e., the minimum number of sires per litter using an exclusion-based method (GERUD) and the estimated number of sires per litter using a maximum likelihood approach (COLONY). Based on these two approaches, multiple paternity was detected in 22 and 27 (out of the 31) females, respectively, with the minimum number of sires ranging from 1 to 4 (mean ± SE: 2.1 ± 0.16 sires per female) and the estimated number of fathers ranging from 1 to 9 (mean ± SE: 4.2 ± 0.35 sires per female). The number of fathers per brood was positively correlated with brood size, but not with female size. Next, we calculated the reproductive skew per brood using the estimated number of sires, and found that in 21 out of the 27 multiply sired broods sires did not contribute equally to the offspring. Skew was not correlated with either female size, brood size or the number of sires per brood. Finally, we discuss several biological mechanisms that may influence multiple paternity and reproductive skew in P. gillii as well as in the Poeciliidae in general.
... The degree of superfetation (number of simultaneous developing broods) per collection was estimated as both the average and the maximum number of developing broods within females. Further details on the procedures to obtain life-history data are described in Reznick et al. (1992) and . ...
We describe the occurence of extensive post-fertilization maternal provisioning (matrotrophy) in fish species in the subgenus Pamphorichthys (genus Poecilia: family Poeciliidae) that represents one of two independent origins of this adaptation in this genus. Matrotrophy is accompanied by a reduction in yolk in eggs at fertilization, a thickened follicle throughout development, and externalization and anterior extension of the embryonic pericardial membrane. These features resemble the anatomical adaptations for placentotrophy described in other members of this family and accompany a substantial increase in dry mass of the embryo during development. Species mean values for the increase in embryo mass range from a low of less than two-fold (Pamphorichthys minor) to greater than 50-fold (Pamphorichthys hasemani). Different populations of Pamphorichthys araguaiensis show a range from less than a two-fold to greater than 16-fold increase in dry mass during development. Such substantial differences in matrotrophy among closely related species and within species make Pamphorichthys a promising group with which to study the adaptive value and the genetic basis of matrotrophy.
... Shories, Meyer & Schartl (2009) described Poecilia (Acanthophacelus) obscura, which now represents a third species in the subgenus Acanthophacelus. Poeser et al. (2005) also placed all of Meyer's (1993) Micropoecilia species and the newly-described Poecilia (Lebistes) minima of Costa & Sarraf (1997) into Poecilia (Micropoecilia) Prior to our study, extensive data were available describing the life histories of guppies (Reznick & Endler, 1982) and there was one published study on the life history of Poecilia picta (Reznick, Miles & Winslow, 1992). Poecilia picta has a very similar life history to guppies; it lacks superfetation and appears to fully provision eggs prior to fertilization. ...
Examining the association between trait variation and development is crucial for understanding the evolution of phenotypic differences. Male guppy ornamental caudal fin coloration is one trait that shows a striking degree of variation within and between guppy populations. Males initially have no caudal fin coloration, then gradually develop it as they reach sexual maturity. For males, there is a trade‐off between female preference for caudal fin coloration and increased visibility to predators. This trade‐off may reach unique endpoints in males from different predation regimes. Caudal fin coloration includes black melanin, orange/yellow pteridines or carotenoids, and shimmering iridescence. This study examined the phenotypic trajectory and genetics associated with color development. We found that black coloration always developed first, followed by orange/yellow, then iridescence. The ordering and timing of color appearance was the same regardless of predation regime. The increased expression of melanin synthesis genes correlated well with the visual appearance of black coloration, but there was no correlation between carotenoids or pteridine synthesis gene expression and the appearance of orange/yellow. The lack of orange/yellow coloration in earlier male caudal fin developmental stages may be due to reduced expression of genes underlying the development of orange/yellow xanthophores.
... Since then, the species has gained increasing popularity with around 95% of papers being published since 1990. The species is a popular model organism for the study of life history (Reznick et al. 1992;Reznick et al. 2001a), sperm competition and sexual selection (Matthews et al. 1997;Evans and Magurran 2001), population genetics (Shaw et al. 1994;Carvalho et al. 1996); conservation biology (van Oosterhout et al. 2007a), senescence (Reznick 1997;Reznick et al. 2001b;Reznick et al. 2004), behaviour (Magurran et al. 1995;Croft et al. 2009), parasitology (Cable and van Oosterhout 2007) and fisheries-induced evolution (Reznick and Ghalambor 2005a), to name but a few out of the breadth of fields that have benefitted from the extraordinary research qualities of this small fish. (Magurran 2005) and in addition, have several of the specific qualities that are required for specialist models of specific fields of research: their sexual polymorphism in colour and heritable colour pattern variations make them ideal for studying sexual selection (Houde 1997); the possibility of controlled mating and artificial insemination (Evans et al., 2003), combined with the ability of females to store sperm (Winge, 1922a(Winge, , 1937 and multiple paternity within broods provide a convenient setup for testing hypothesis on sperm competition and pre-and post copulatory female choice (Evans and Magurran, 2000); it is possible to tag and mark fish individually for monitoring of social interactions and survival in the wild Croft et al. 2003aCroft et al. , 2003b; their tolerance to a range of temperatures, water qualities and toxic substances, makes guppies a popular subject in toxicological studies (Haubruge et al., 2000;Magurran and Phillip, 2001). ...
Increasing evidence suggests that size-selective mortality imposed by commercial fishing results in directional changes in life histories of exploited species, including effects on maturation age, growth rate and body size. Whether these changes are the result of fisheries-induced evolution or other selective pressures in the natural environment and/ or phenotypic plasticity continues to be the subject of much debate. Currently, molecular genetic data revealing fisheries-induced shifts at candidate loci are lacking.
Here, the hypothesis that harvesting can induce genetic change over few generations was tested directly by subjecting laboratory-reared offspring of wild-caught Trinidadian guppies, Poecilia reticulata, to divergent, size-specific selection over three generations. The smallest/ largest/ random twenty percent of males was selected each generation and changes in standard length, as well as in the frequencies of alleles at neutral
microsatellite loci and putative candidate genes for selection were recorded.
Significant divergence between differently selected lines was observed for male standard length (± 7%), size (± 8-12%) and age (± 4-6%) at maturation, compared to only 1% change in standard length over generations in the random breeding control line. Significant drift between lines, but no genetic erosion or inbreeding, was apparent over generations at microsatellite markers. Signatures of selection and significant genetic divergence between selected lines were detected at five out of 17 putative candidate loci (Pr39, M9, M30, M987 and prolactin) which confirmed strong Y-linkage of genes underlying male body size in guppies, as indicated by the phenotypic data. Additionally, significant genotype-phenotype associations were obtained for twelve of the candidate genes. For two of these loci (M30 and M1046) an association between the same single
nucleotide polymorphism and a QTL for standard length had been observed previously.
To our knowledge, this is the first study where selection on body size with known intensity and direction has been compared directly with both a phenotypic response and changes at individual genetic marker loci. Hereby, this study forms one of the first pieces of molecular genetic evidence for fisheries-induced evolution: by demonstrating that phenotypic shifts in body size resulting from size-selective harvesting, comparable to commercial fisheries in principle, are underlain by quantifiable genetic change.
Sex chromosomes form once recombination is halted between the X and Y chromosomes. This loss of recombination quickly depletes Y chromosomes of functional content and genetic variation, which is thought to severely limit their potential to generate adaptive diversity. We examined Y diversity in Poecilia parae , where males occur as one of five discrete morphs, all of which shoal together in natural populations where morph frequency has been stable for over 50 years. Each morph utilizes different complex reproductive strategies, and differ dramatically from each other in color, body size, and mating behavior. Remarkably, morph phenotype is passed perfectly from father to son, indicating there are five Y haplotypes segregating in the species, each of which encodes the complex male morph characteristics. Using linked-read sequencing on multiple P. parae females and males of all five morphs from natural populations, we found that the genetic architecture of the male morphs evolved on the Y chromosome long after recombination suppression had occurred with the X. Comparing Y chromosomes between each of the morphs revealed that although the Ys of the three minor morphs that differ predominantly in color are highly similar, there are substantial amounts of unique genetic material and divergence between the Ys of the three major morphs that differ in reproductive strategy, body size and mating behavior. Taken together, our results reveal the extraordinary ability of evolution to overcome the constraints of recombination loss to generate extreme diversity resulting in five discrete Y chromosomes that control complex reproductive strategies.
Significance Statement
The loss of recombination on the Y chromosome is thought to limit the adaptive potential of this unique genomic region. Despite this, we describe an extraordinary case of Y chromosome adaptation in Poecilia parae . This species contains five co-occurring male morphs, all of which are Y-linked, and which differ in reproductive strategy, body size, coloration, and mating behavior. The five Y-linked male morphs of P. parae evolved after recombination was halted on the Y, resulting in five unique Y chromosomes within one species. Our results reveal the surprising magnitude to which non-recombining regions can generate adaptive diversity and have important implications for the evolution of sex chromosomes and the genetic control of sex-linked diversity.
Once recombination is halted between the X and Y chromosome, sex chromosomes begin to differentiate and transition to heteromorphism. While there is a remarkable variation across clades in the degree of sex chromosome divergence, far less is known about variation in sex chromosome differentiation within clades. Here, we combined whole genome and transcriptome sequencing data to characterise the structure and conservation of sex chromosome systems across Poeciliidae, the livebearing clade that includes guppies. We found that the Poecilia reticulata XY system is much older than previously thought, being shared not only with its sister species, Poecilia wingei, but also with Poecilia picta, which diverged 30 mya. Despite the shared ancestry, we uncovered an extreme heterogeneity across these species in the proportion of the sex chromosome with suppressed recombination, and the degree of Y chromosome decay. The sex chromosomes in P. reticulata are largely homomorphic, with recombination persisting over a substantial fraction. However, the sex chromosomes in P. picta are completely non-recombining and strikingly heteromorphic. In addition to being highly divergent, the sex chromosome system in P. picta includes a neo-sex chromosome, the result of a fusion between the ancestral sex chromosome and part of chromosome 7. Remarkably, the profound degradation of the ancestral Y chromosome in P. picta is counterbalanced by the evolution of complete dosage compensation in this species, the first such documented case in teleost fish. Our results offer important insight into the initial stages of sex chromosome evolution and dosage compensation.
Nutrient-releasing artificial substrata were deployed in streams draining clearcut and forested watersheds to evaluate resources potentially limiting to populations of benthic algae. Nitrogen, phosphorus, and calcium were released singly and in combination in the two streams that differed primarily in light availability. Periphyton were harvested after one- and two-month exposure periods and analyzed for chlorophyll. The two-month substrata were additionally ana- lyzed for algal community structure. Algal periphyton in the clearcut stream accumulated more chlorophyll and biovolume than in the forested stream across all nutrient treatments. Algal com- munity structure was significantly different between streams but not between nutrient treatments. Algal physiognomies were also significantly different between streams with filamentous green algae dominating the clearcut stream and erect diatoms dominating the forested stream. Light appears to limit algal accumulation in the forested stream and there is evidence that some popu- lations in the clearcut stream may be nutrient limited. Adequate light also resulted in a more architecturally diverse community.
Among vertebrate taxa, salmonids and sculpins were more abundant in streams without riparian shading than in shaded streams. Abundance of salamanders was not affected by canopy type. Densities of both salamanders and sculpins were correlated with substrate composition, whereas salmonid abundance was not or only weakly so. Salamanders were found only at high-gradient sites with coarse substrates, and sculpins were most abundant at lower-gradient sites with finer-sized sediments. An interaction was observed between the influence of canopy and that of physical setting on density of both invertebrate prey and total vertebrates. Among shaded sites, densities decreased as percent fine sediment increased, but a similar relationship did not exist among open sites. Removal of the riparian vegetation surrounding a stream may therefore mask detrimental effects of fine sediment. -from Authors
Within the family Poeciliidae, a wide range of adaptations accompanying viviparity has evolved. The reproductive mechanisms of five representative species were examined and related to the habitats in which they are employed. Poecilia reticulata, the guppy, represents the majority of poeciliids which have a single stage of embryos in the ovary at a time. Most of the nutrients are prepack-aged in the eggs before fertilization; no specialized placental adaptations have evolved. The major variable among species utilizing this mechanism is in the yolk loading time; some eggs are mature and ready to be fertilized immediately after the birth of a clutch of embryos, others take a week or more. The mechanism may be thought of as a generalist-type, being employed throughout the range of poeciliids and in all varieties of habitats. Poeciliopsis monacha has embryos of two different ages occurring simultaneously in the ovary. Its large eggs provide the embryo's entire nutrient supply. Mature embryos weigh 47% less than mature eggs. This species lives in a harsh, montane environment with an unpredictable food supply; its reproductive mechanism is well suited to fluctuating resources. When conditions are favorable, a large clutch of eggs is loaded, but if food is in short supply, clutch sizes are small or only one stage is produced. During starvation conditions, no eggs are produced; but, with restoration of food supply, reproduction resumes quickly. Poeciliopsis lucida has medium-sized eggs and three stages of embryos. At birth, young weigh slightly more than mature ova. This weight gain plus the energy utilized for embryonic metabolism constitutes a significant maternal contribution during development. P. lucida is wide-spread in the three rivers that comprise its range but it does not enter the depauperate rocky arroyos occupied by P. monacha. P. lucida requires a stable food supply characteristic of the fertile and productive downstream regions. Poeciliopsis prolifica carries as many as five stages of embryos which are born at short brood intervals of two to eight days. Ova sizes are small and embryos receive almost all of their nutrients through a placenta. P. prolifica lives in a rich environment where food resources are stable. It is the smallest species in the genus and it produces the smallest young, yet its habitat seems precarious. Living on the steep slope between deep and shallow water it is wedged between deep and shallow water competitors, having to cope with large deep water fish predators as well. Poeciliopsis turneri is the largest of the five species studied and occupies a habitat somewhat unusual for poeciliids. Three stages of embryos are present in the ovary but brood sizes are usually small (ave. 3.6). The ova are small yet the mature embryos are large, weighing almost 19 times more than the ova. Brood sizes in neither P. prolifica nor P. turneri become larger as female size increases. P. turneri is adapted to life in deep swift water where large adults, large offspring and streamlining are important. The other four species can risk the swollen pregnant-look typical of poeciliids, whereas P. turneri cannot. Superfetation (multiple stages of embryos) is advantageous in that it avoids the surge of energy required to load a single large clutch of eggs. The energy for reproduction is sequentially divided among two to five small clutches. Reduction of ova size increases the space available for more stages of embryos. Although embryos with small yolk supplies place a nutrient drain directly on the mother, surges in demand are avoided since embryonic stages enter the growth phase at different times. A continuous food supply to the female is essential; otherwise, embryos will die and the reproductive effort to that point is lost.
In Heterandria formosa, a viviparous cyprinodont fish of the family Poecitiidae, nearly all of the nourishment for embryonic development is obtained from the mother after fertilization through a pseudoplacentat association (Scrimshaw, 1944). Similar although less complicated associations between mother and embryo exist in other species of this family (Turner, 1937, 1940) . These species are for the most part considered to be ovoviviparous. The distinction is based on the difference between live bearing forms which retain an egg with a full supply of nourishment for development and those whose embryos receive nourishment froni the mother. The latter are considered truly viviparous. Turner (1937) referred to all species of Poecitiidae as bvoviviparous. He obviously used this term in a general sense for he suggested in discussing the data of Bailey (1933) that Xiphophorus helleri could receive nutriment from the parent. Turner also pointed out (1937) that the small Heterandria egg cannot contain enough nourishment to account for the size of the larvae and suggested that the follicle cells surrounding the embryo furnish food materials. The weight values reported by Bailey for various embryonic stages in Xipho phorus show no decrease in the weight of the total yolk-embryo system. Since energy is used for maintenance metabolism, the total weight of this system de creases in forms depending entirely on yolk. Gray (1928) reported a decrease of 37 per cent for the oviparous trout, Salnto fario, and Hsiao (1941) found a de crease of 34 per cent in the truly ovoviviparous perch, Seba.stes marinus. Accord ingly, although he does not suggest this, Bailey's data show that some nourishment must be obtained from the mother by the developing embryo of Xiphophorus. It is true that most poeciliid fishes are more dependent on the yolk laid down before fertilization than upon maternally supplied nourishment after that time. However, the evidence presented below shows that the members of this family do utilize nourishment outside of that contained in the yolk and hence are not ovo viviparous in the strict sense of the term. Embryos of such species as Heterandria formosa and Aulo phallus elongatus are truly viviparous and as dependent on the mother for nourishment as are those of a placental mammal. Gray (1926, 1928) reported the relationships between nourishment and growth rate in the oviparous trout, Salmo fario. The problems of oviparity and ovo viviparity are similar in that in each the embryo has its own supply of nourishment and receives food and water from its environment. When these conditions are compared with true viviparity, striking differences are noted (Scrimshaw, 1944). The present study was undertaken to find and describe intermediate stages between ‘¿�Now at the School of Medicine and Dentistry, University of Rochester, Rochester, New York. The author gratefully acknowledgesthe advice and assistance of Dr. Leigh Hoadley of the Harvard Biological Laboratories.
Density of fish and salamanders in relation to riparian canopy and physical habitat in streams of the northwestern United States Genetic control of size at maturity in Xiphophorus, p. 163-184. In: Ecology and evolution of live bearing fishes (Poeciliidae)
- Literature Cited Hawkins
- M L Murphy
- N H Anderson
- And M A Wilzbach
- K D Kallman
COPEIA, 1992, NO. 3
LITERATURE CITED
HAWKINS, C. P., M. L. MURPHY, N. H. ANDERSON,
AND M. A. WILZBACH. 1983. Density of fish and
salamanders in relation to riparian canopy and
physical habitat in streams of the northwestern
United States. Can. J. Fish. Aqu. Sci. 40:1173-1185.
KALLMAN, K. D. 1989. Genetic control of size at
maturity in Xiphophorus, p. 163-184. In: Ecology
and evolution of live bearing fishes (Poeciliidae). G.
K. Meffe and F. F. Snelson, Jr. (eds.). Prentice-Hall,
Englewood Cliffs, New Jersey.
The impact of predation of life history evolution in Trinidadian guppies: (Poecilia reticulata) Ibid A review of life history patterns in poeciliid fishes In: Ecology and evolution of live-bearing fishes (Poeciliidae )
- And J A Endler
- D B And
- Miles
-,
AND J. A. ENDLER. 1982. The impact of predation of life history evolution in Trinidadian guppies: (Poecilia reticulata). Ibid. 36:160-177.
, AND D. B. MILES. 1989. A review of life history patterns in poeciliid fishes, p. 125-148. In:
Ecology and evolution of live-bearing fishes (Poeciliidae ). G. K. Meffe and F. F. Snelson, Jr. (eds.).
Tropical fishes for the home
- F H Stoye
STOYE, F. H. 1935. Tropical fishes for the home.
Carl Mertens, New York, New York.