The effect of genetic variability (degree of homozygosity) on serum levels of the anterior pituitary hormones prolactin,corticotropin, and growth hormone in rats

Male and female wild Norway rats (Rattus norvegicus Erxleben) and males and female albino outbred rats (Ipf:RIZ) were crossbred. The resulting animals (F1 hybrids) were the control, noninbred group (0% inbred). By systematic full-sib mating, two experimental groups (50 and 91% of inbred) were produced. Half of each group (both males and females) was exposed to physical stress (3 days of starvation and 3 hr of swimming). The other half of each group was anesthetized using ether to collect blood. The anterior pituitary hormone concentrations of prolactin (PRL), corticotropin (ACTH), and growth hormone (rGH) in blood serum were determined by the radioimmunoassay method. Significant relationships between the PRL, ACTH, and rGH concentrations in blood serum and the inbreeding coefficient were observed: A significant PRL content decrease in blood serum occurred (linear function) and the rGH and ACTH content diminished significantly rapidly (quadratic function). These changes were affected by an increase in homozygosity. Stress significantly influenced PRL, ACTH, and rGH concentrations as well. The sex of rats significantly determined PRL and ACTH content only. Hormone levels were also influenced by interactions between the factors studied (inbred level, sex, stress).     

Protective effects of grape seed proanthocyanidins against iron overload-induced renal oxidative damage in rats

BackgroundExcessive exposure to iron can cause kidney damage, and chelating drugs such as deferoxamine and deferiprone have limited usefulness in treating iron poisoning. This study was designed to investigate the protective effects of grape seed proanthocyanidins (GSPAs) against iron overload induced nephrotoxicity in rats. The roles of GSPAs in chelating iron, antioxidant activity, renal function, pathological section, and apoptosis-related gene expression were assessed.MethodsNewly weaned male Sprague–Dawley rats aged 21 days (weight, 65 ± 5 g) were randomly divided into four groups containing 10 rats each: normal control (negative) group, iron overload (positive) group, GSPAs group, and GSPAs + iron overload (test) group. Iron dextran injections (2.5 mg⋅ kg⁻¹) and GSPAs (25 mg⋅ kg⁻¹) were intraperitoneally and intragastrically administered to rats daily for 7 weeks, respectively. Measurements included red blood cell (RBC) count and hemoglobin (Hb) level, serum total iron-binding capacity (TIBC), renal iron content, glutathione peroxidase (GSH-Px) activity, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, total antioxidant activity (T-AOC), creatinine (CR) and blood urea nitrogen (BUN) levels, pathological changes, and apoptotic Fas, Bax expressions in the kidney tissue. Differences among the dietary groups were determined using one-way analysis of variance with post-hoc Tukey’s test. P < 0.05 was considered statistically significant.ResultsRBC count, Hb level, renal iron content, MDA content, CR and BUN levels, and Fas, Bax expressions significantly increased in the positive group than in the negative group; contrarily, TIBC, GSH-Px activity, and T-AOC significantly decreased in the positive group than in the negative group (P < 0.05). Although not statistically significant, SOD activity was slightly reduced in the positive group than in the negative group. Inflammatory cell infiltration and fibrous tissue proliferation were observed in the kidney tissue of the rats in the positive group; in contrast, the rats exhibited better recovery when GSPAs were used instead of iron alone. Compared with the positive group, RBC counts, Hb levels, renal iron contents, the MDA content, CR and BUN levels, and Fas, Bax expressions significantly decreased, whereas the TIBC, the GSH-Px and SOD activities as well as T-AOC significantly increased in the test group rats (P < 0.05). There were no significant differences in the RBC counts, Hb levels, TIBC, renal iron contents, the SOD activity and MDA content, CR and BUN levels, and Fas expression between the GSPAs and negative groups. The GSH-Px activity and T-AOC were significantly increased whereas Bax expression was significantly decreased in the GSPAs group rats than in the negative group rats (P < 0.05). The rats in the GSPAs, test, and negative groups displayed glomeruli and tubules with a clear structure; further, the epithelial cells in the renal tubules were neatly arranged.ConclusionsGSPAs have protective effects on nephrotoxicity in rats with iron overload. Thus, further investigation of GSPAs as a new and natural phytochemo-preventive agent against iron overload is warranted.     

Interactive effects of environmental stress and inbreeding on reproductive traits in a wild bird population

1. Conservation biologists are concerned about the interactive effects of environmental stress and inbreeding because such interactions could affect the dynamics and extinction risk of small and isolated populations, but few studies have tested for these interactions in nature. 2. We used data from the long-term population study of song sparrows Melospiza melodia on Mandarte Island to examine the joint effects of inbreeding and environmental stress on four fitness traits that are known to be affected by the inbreeding level of adult birds: hatching success, laying date, male mating success and fledgling survival. 3. We found that inbreeding depression interacted with environmental stress to reduce hatching success in the nests of inbred females during periods of rain. 4. For laying date, we found equivocal support for an interaction between parental inbreeding and environmental stress. In this case, however, inbred females experienced less inbreeding depression in more stressful, cooler years. 5. For two other traits, we found no evidence that the strength of inbreeding depression varied with environmental stress. First, mated males fathered fewer nests per season if inbred or if the ratio of males to females in the population was high, but inbreeding depression did not depend on sex ratio. Second, fledglings survived poorly during rainy periods and if their father was inbred, but the effects of paternal inbreeding and rain did not interact. 6. Thus, even for a single species, interactions between the inbreeding level and environmental stress may not occur in all traits affected by inbreeding depression, and interactions that do occur will not always act synergistically to further decrease fitness.     

妊娠期糖尿病患者体内铁负荷状态及氧化应激水平的研究

为了探讨铁代谢在妊娠期糖尿病(GDM)发病中的作用,对GDM患者体内铁负荷状态、氧化应激水平及抗氧化状态进行分析研究.在912例孕24～28周产前检查的孕妇中,按血糖筛查和糖耐量试验筛选出GDM孕妇32例为实验组,随机选择糖耐量正常孕妇26例作为对照组,分别测定两组孕妇的血红蛋白(Hb)等指标,以评价机体铁代谢状况;测...     

Males Benefit from Mating with Outbred Females in Drosophila littoralis: Male Choice for Female Genetic Quality?

The evolution and expression of mate choice behaviour in either sex depends on the sex‐specific combination of mating costs, benefits of choice and constraints on choice. If the benefits of choice are larger for one sex, we would expect that sex to be choosier, assuming that the mating costs and constraints on choice are equal between sexes. Because deliberate inbreeding is a powerful genetic method for experimental manipulation of the quality of study organisms, we tested the effects of both male and female inbreeding on egg and offspring production in Drosophila littoralis. Female inbreeding significantly reduced offspring production (mostly due to lower egg‐to‐adult viability), whereas male inbreeding did not affect offspring production (despite a slight effect of paternal inbreeding on egg‐to‐adult viability). As inbreeding depressed female quality more than male quality, the benefits of mate choice were larger for males than for females. In mate choice experiments, inbreeding did not affect male mating success (measured as a probability to be accepted as a mate in a large group), suggesting that females did not discriminate among inbred and outbred males. In contrast, female mating success was affected by inbreeding, with outbred females having higher mating success than inbred females. This result was not explained by lower activity of inbred females. Our results show that D. littoralis males benefit from mating with outbred females of high genetic quality and suggest adaptive male mate choice for female genetic quality in this species. Thus, patterns of mating success in mate choice trials mirrored the benefits of choice: the sex that benefited more from choice (i.e. males) was more choosy.     

Inbreeding depression in an insect with maternal care: influences of family interactions,life stage and offspring sex

Although inbreeding is commonly known to depress individual fitness, the severity of inbreeding depression varies considerably across species. Among the factors contributing to this variation, family interactions, life stage and sex of offspring have been proposed, but their joint influence on inbreeding depression remains poorly understood. Here, we demonstrate that these three factors jointly shape inbreeding depression in the European earwig, Forficula auricularia. Using a series of cross‐breeding, split‐clutch and brood size manipulation experiments conducted over two generations, we first showed that sib mating (leading to inbred offspring) did not influence the reproductive success of earwig parents. Second, the presence of tending mothers and the strength of sibling competition (i.e. brood size) did not influence the expression of inbreeding depression in the inbred offspring. By contrast, our results revealed that inbreeding dramatically depressed the reproductive success of inbred adult male offspring, but only had little effect on the reproductive success of inbred adult female offspring. Overall, this study demonstrates limited effects of family interactions on inbreeding depression in this species and emphasizes the importance of disentangling effects of sib mating early and late during development to better understand the evolution of mating systems and population dynamics.     

Effects of inbreeding and temperature stress on life history and immune function in a butterfly

Theory predicts that inbreeding depression should be more pronounced under environmental stress due to an increase in the expression of recessive deleterious alleles. If so, inbred populations may be especially vulnerable to environmental change. Against this background, we here investigate effects of inbreeding, temperature stress and its interactions with inbreeding in the tropical butterfly Bicyclus anynana. We use a full‐factorial design with three levels of inbreeding (F = 0/0.25/0.38) and three temperature treatments (2 h exposure to 1, 27 or 39 °C). Despite using relatively low levels of inbreeding significant inbreeding depression was found in pupal mass, pupal time, thorax mass, abdomen fat content, egg hatching success and fecundity. However, stress resistance traits (heat tolerance, immune function) were not affected by inbreeding and interactions with temperature treatments were virtually absent. We thus found no support for an increased sensitivity of inbred individuals to environmental stress, and suspect that such patterns are restricted to harsher conditions. Our temperature treatments evidently imposed stress, significantly reducing longevity, fecundity, egg hatching success and haemocyte numbers, while fat content, protein content and lysozyme activity remained unaffected. Males and females differed in all traits measured except pupal time, protein content and phenoloxidase (PO) activity. Correlation analyses revealed, among others, a trade‐off between PO and lysozyme activity, and negative correlations between fat content and several other traits. We stress that more data are needed on the effects of inbreeding, temperature variation and sexual differences on insect immune function before more general conclusions can be drawn.     

Effect of 2,3,7,8-Tetrachlorodibenzo-p-dioxin on the Hepatic Distribution of Iron,Copper, Zinc,and Magnesium in Rats

The distribution of iron, copper, zinc, and magnesium in hepatic subcellular fractions of male and female rats treated with 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) was determined. Animals received 40 μg TCDD per kilogram per day for three days by mouth (PO) or the vehicle and were killed seven or nine days posttreatment. Iron, copper, zinc, and magnesium were determined by atomic absorption spectroscopy. The iron content of liver from female animals was twofold higher than male animals. The administration of TCDD increased the iron content of mitochondria in female and male rats and decreased iron content of microsomes of both sexes. Significant increases occurred in the copper content of whole liver, mitochondria, and cytosol of male rats and in whole liver and cytosol of female rats. Decreases in the copper content of the microsomes of male rats were observed following TCDD treatment; however, TCDD produced no changes in the zinc content of hepatic subcellular fractions of either sex. The magnesium content of female TCDD-treated rats increased in whole liver, mitochondria, and cytosol, while the magnesium content of microsomes was not altered. With respect to the subcellular distribution of iron, copper, zinc, and magnesium, TCDD produces differential effects. The altered distribution of some cations may contribute to the broad range of effects of TCDD.     

Effects of Subchronic Aluminum Exposure on Serum Concentrations of Iron and Iron-Associated Proteins in Rats

The purpose of the study was to investigate the effect of subchronic aluminum (Al) exposure on iron (Fe) homeostasis in rats. One hundred Wistar rats were divided into two groups. Experimental rats were given drinking water containing aluminum chloride (AlCl₃, 430 mg Al³⁺·L^?1), while control rats were given distilled water for up to 150 days. Ten rats were sacrificed in each group every 30 days. Mean corpuscular hemoglobin (MCH), and serum levels of Al, Fe, transferrin (TF), total iron binding capacity (TIBC), and soluble transferrin receptor (sTfR) were measured. Al-treated rats showed significantly decreased bodyweight and increased Al and Al/Fe levels during the experimental period. Fe levels and MCH were higher on day 150 in the experimental group than in the control group. TF content and TIBC were higher, whereas erythrocyte counts and sTfR content were lower in the experimental group than in the control group from days 90 and 60, respectively. Longer duration of Al administration increased the serum levels of Al, TF, Al/Fe, and TIBC and decreased sTfR. MCH and Fe levels decreased first, and then increased. The results indicate that chronic exposure to Al disturbed Fe homeostasis.     

Inbreeding depression and haplodiploidy: experimental measures in a parasitoid and comparisons across diploid and haplodiploid insect taxa

Abstract. It has long been assumed that inbreeding depression in haplodiploid organisms is low due to their ability to purge genetic load in haploid males. It has been suggested that this low genetic load could facilitate the evolution of inbreeding behaviors driven by local mate competition in hymenopteran parasitoids. I have examined inbreeding depression in haplodiploids in two ways. First I show that an outbreeding haplodiploid wasp Uscana semifumipennis (Hymenoptera: Trichogrammatidae) suffers substantial inbreeding depression. Longevity was 38% shorter, fecundity was 32% lower, and sex ratio was 5% more male for experimentally inbred wasps when compared to outbred controls. There were interactions between size and both fecundity and sex ratio for inbred wasps that were not seen for outbred individuals. Second, an analysis of data from the literature suggests that when inbreeding is experimentally imposed on populations, haplodiploid insects and mites as a group do suffer less from inbreeding depression than diploid insects, although substantial inbreeding depression in haplodiploid taxa does exist. The meta-analysis revealed no difference in inbreeding depression between gregarious haplodiploid wasps, which are likely to have a history of inbreeding, and solitary haplodiploid species, which are assumed to be primarily outbred.     

Female‐biased sex allocation and lack of inbreeding avoidance in Cubitermes termites

Sexually reproducing organisms face a strong selective pressure to find a mate and ensure reproduction. An important criterion during mate‐selection is to avoid closely related individuals and subsequent potential fitness costs of resulting inbred offspring. Inbreeding avoidance can be active through kin recognition during mate choice, or passive through differential male and female‐biased sex ratios, which effectively prevents sib‐mating. In addition, sex allocation, or the resources allotted to male and female offspring, can impact mating and reproductive success. Here, we investigate mate choice, sex ratios, and sex allocation in dispersing reproductives (alates) from colonies of the termite Cubitermes tenuiceps. Termites have a short time to select a mate for life, which should intensify any fitness consequences of inbreeding. However, alates did not actively avoid inbreeding through mate choice via kin recognition based on genetic or environmental cues. Furthermore, the majority of colonies exhibited a female‐biased sex ratio, and none exhibited a male‐bias, indicating that differential bias does not reduce inbreeding. Sex allocation was generally female‐biased, as females also were heavier, but the potential fitness effect of this costly strategy remains unclear. The bacterium Wolbachia, known in other insects to parasitically distort sex allocation toward females, was present within all alates. While Wolbachia is commonly associated with termites, parasitism has yet to be demonstrated, warranting further study of the nature of the symbiosis. Both the apparent lack of inbreeding avoidance and potential maladaptive sex allocation implies possible negative effects on mating and fitness.     

Genome‐wide regulatory deterioration impedes adaptive responses to stress in inbred populations of Drosophila melanogaster*

Inbreeding depression is often intensified under environmental stress (i.e., inbreeding–stress interaction). Although the fitness consequences of this phenomenon are well‐described, underlying mechanisms such as an increased expression of deleterious alleles under stress, or a lower capacity for adaptive responses to stress with inbreeding, have rarely been investigated. We investigated a fitness component (egg‐to‐adult viability) and gene‐expression patterns using RNA‐seq analyses in noninbred control lines and in inbred lines of Drosophila melanogaster exposed to benign temperature or heat stress. We find little support for an increase in the cumulative expression of deleterious alleles under stress. Instead, inbred individuals had a reduced ability to induce an adaptive gene regulatory stress response compared to controls. The decrease in egg‐to‐adult viability due to stress was most pronounced in the lines with the largest deviation in the adaptive stress response (R² = 0.48). Thus, we find strong evidence for a lower capacity of inbred individuals to respond by gene regulation to stress and that this is the main driver of inbreeding‐stress interactions. In comparison, the altered gene expression due to inbreeding at benign temperature showed no correlation with fitness and was pronounced in genomic regions experiencing the highest increase in homozygosity.     

Effects of Resistance Exercise on Iron Absorption and Balance in Iron-Deficient Rats

We have previously reported that resistance exercise improved the iron status in iron-deficient rats. The current study investigated the mechanisms underlying this exercise-related effect. Male 4-week-old rats were divided into a group sacrificed at the start (week 0) (n?=?7), a group maintained sedentary for 6 weeks (S) or a group that performed exercise for 6 weeks (E), and all rats in the latter groups were fed an iron-deficient diet (12 mg iron/kg) for 6 weeks. The rats in the E group performed climbing exercise (5 min?×?6 sets/day, 3 days/week). Compared to the week 0 rats, the rats in the S and E groups showed lower tissue iron content, and the hematocrit, hemoglobin, plasma iron, and transferrin saturation values were all low. However, the tissue iron content and blood iron status parameters, and the whole body iron content measured using the whole body homogenates of the rats, did not differ between the S group and the E group. The messenger RNA (mRNA) expression levels of hepcidin, duodenal cytochrome b, divalent metal transporter 1, and ferroportin 1 did not differ between the S group and the E group. The apparent absorption of iron was significantly lower in the E group than in the S group. Therefore, it was concluded that resistance exercise decreases iron absorption, whereas the whole body iron content is not affected, and an increase in iron recycling in the body seems to be responsible for this effect.     

Metabolomic signatures of inbreeding at benign and stressful temperatures in Drosophila melanogaster

While the population genetics of inbreeding is fairly well understood, the effects of inbreeding on the physiological and biochemical levels are not. Here we have investigated the effects of inbreeding on the Drosophila melanogaster metabolome. Metabolite fingerprints in males from five outbred and five inbred lines were studied by nuclear magnetic resonance spectroscopy after exposure to benign temperature, heat stress, or cold stress. In both the absence and the presence of temperature stress, metabolite levels were significantly different among inbred and outbred lines. The major effect of inbreeding was increased levels of maltose and decreased levels of 3-hydroxykynurenine and a galactoside [1-O-(4-O-(2-aminoethyl phosphate)-beta-d-galactopyranosyl)-x-glycerol] synthesized exclusively in the paragonial glands of Drosophila species, including D. melanogaster. The metabolomic effect of inbreeding at the benign temperature was related to gene expression data from the same inbred and outbred lines. Both gene expression and metabolite data indicate that fundamental metabolic processes are changed or modified by inbreeding. Apart from affecting mean metabolite levels, inbreeding led to an increased between-line variation in metabolite profiles compared to outbred lines. In contrast to previous observations revealing interactions between inbreeding and environmental stress on gene expression patterns and life-history traits, the effect of inbreeding on the metabolite profile was similar across the different temperature treatments.     

Preference for Outbreeding in Inbred Littledale’s Whistling Rats <Emphasis Type="Italic">Parotomys littledalei</Emphasis>

Inbreeding is sometimes tolerated in species occupying patchy, unpredictable habitats, when it becomes too costly to outbreed. Although traits leading to inbreeding depression may be selected against, the accumulation of deleterious alleles from constant inbreeding might promote outbreeding. Littledale’s whistling rat Parotomys littledalei occupies patchy habitats in arid western South Africa, and inbreeds in captivity without suffering inbreeding depression. We tested whether female whistling rats make different mate choice decisions based on their inbreeding status, by providing inbred and outbred females with male odours in four pairwise combinations: unrelated outbred (r = 0) versus either familiar littermate sibling (r = 0.5), half-sibling (r = 0.25), first cousin (r = 0.125), or unrelated inbred (r = 0). Inbred females generally preferred unrelated males, but did not show a preference between unrelated males and first cousins. In contrast, outbred females did not generally show a preference, but preferred first cousins to unrelated males. In breeding trials, reproductive success (output and viability of young) of outbred females paired with unrelated or related males was equally high, whereas inbred females suffered reduced reproductive success when paired with closely-related males. Our results indicate that the inbreeding status of female whistling rats influences their decision to outbreed or inbreed, which might influence their fitness. While outbred whistling rats do not suffer inbreeding depression, the costs of constant inbreeding could promote outbreeding by inbred females. We propose that the choice to inbreed or outbreed in female whistling rats depends on their inbreeding status and the genetic relatedness of available mates, with outbreeding more likely to occur unless unrelated mates are not available.     

Extreme temperatures increase the deleterious consequences of inbreeding under laboratory and semi-natural conditions

The majority of experimental studies of the effects of population bottlenecks on fitness are performed under laboratory conditions, which do not account for the environmental complexity that populations face in nature. In this study, we test inbreeding depression in multiple replicates of inbred when compared with non-inbred lines of Drosophila melanogaster under different temperature conditions. Egg-to-adult viability, developmental time and sex ratio of emerging adults are studied under low, intermediate and high temperatures under laboratory as well as semi-natural conditions. The results show inbreeding depression for egg-to-adult viability. The level of inbreeding depression is highly dependent on test temperature and is observed only at low and high temperatures. Inbreeding did not affect the developmental time or the sex ratio of emerging adults. However, temperature affected the sex ratio with more females relative to males emerging at low temperatures, suggesting that selection against males in pre-adult life stages is stronger at low temperatures. The coefficient of variation (CV) of egg-to-adult viability within and among lines is higher for inbred flies and generally increases at stressful temperatures. Our results contribute to knowledge on the environmental dependency of inbreeding under different environmental conditions and emphasize that climate change may impact negatively on fitness through synergistic interactions with the genotype.     

Association between Rh and plasma iron binding (transferrin)

Summary In order to establish the mechanism involved in the maintenance of the Rh polymorphism and fetomaternal compatibility relationships, we examined a sample of children from the North Area of Santiago (Chile), with respect to their growth and development patterns since 1973. This sample had shown large sib-sib segregation distortions for the Rh system. Metric variables, such as plasma protein fractions and iron, academic performance at the end of the last secondary grade and adult stature, were studied in relation to genetic markers, viz., sex, ABO, Xg, MN, Rh, haptoglobins, phosphoglucomutase, and esterase D, by means of unbalanced one way analyses of variance. Highly significant results were found for Rh phenotypes and total iron binding capacity (TIBC, transferrin). However, plasma iron did not differ significantly among Ph phenotypes. Children with the C (Rh) specificity had higher values of TIBC than non-C or c individuals (P < 0.00001). Evolutionary considerations regarding iron transport and erythroblastosis, relationships between Rh and the transferrin receptor at the plasma membrane, and the location of the Blym-I oncogene (that shares common sequences with transferrins) close to Rh in chromosome 1 are discussed. Less significant results were found between phosphoglucomutase and stature, gamma globulin level and sex, and academic performance (history) and sex.     

Effect of Mineral Fortification on Plasma Biochemical Profile in Rats

This study aimed at investigating the changes in biochemical profile of male rats following 8 weeks administration of different concentration of elemental iron, sodium iron ethylenediaminetetraacetate (NaFeEDTA), zinc sulfate (ZnSO₄), and zinc oxide (ZnO) in whole wheat flour. Eight groups comprising five rats each were fed fortified whole wheat flour in the form of baked pallets, while one group served as control. Concentration of total cholesterol, high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), triglycerides, total proteins, albumin, globulin, plasma glucose, and blood urea nitrogen were assayed. Supplementing mineral-fortified diet to male rats did not indicate any significant (p ≤ 0.05) effect on total cholesterol concentration. Diets containing NaFeEDTA alone increased HDL-C and decreased LDL-C; however, the differences remained non significant. Likewise, plasma triglycerides content of male rats remained unchanged on feeding fortified diets. Diets containing iron as NaFeEDTA and elemental iron exerted little effect on total protein concentration in the plasma of rats. Plasma glucose and blood urea nitrogen levels did not exhibit any significant change as a result of ingesting mineral supplemented diets. The study concludes that the forms of fortificants and the fortification levels used in the current study are undamaging for lipid profile, renal function, and glucose levels in rats, suggesting that these may be safely used in wheat flour to combat iron and zinc deficiency in vulnerable groups.     

Inbreeding depression effects on extinction time in a predator—prey system

Summary Traditional methods of assessing population viability ignore both genetic—demographic interactions as well as community level dynamics. We address these deficiencies by presenting a model that investigates the effects of predation on a prey population experiencing inbreeding depression. Beginning with a simple Lotka—Volterra predator—prey system, we rewrite prey per capita mortality as a function of inbreeding. Inbreeding varies as a function of population size. Using computer simulation, we find that prey extinction times are inversely related to the level of inbreeding depression with and without predation. For all but very low levels of inbreeding depression, predation appreciably reduces persistence time. At moderate levels of inbreeding, predators go extinct before prey. When migration is introduced at low and moderate rates, persistence times only improve for those populations with low inbreeding depression measures. At a higher migration rate, persistence times are lengthened for low and moderately depressed prey populations. Increasing birth rates produce a visible, though noisy, trend towards increased times to extinction for low to moderate levels of inbreeding.