Genetic Diversity, Population Size, and Fitness in Central and Peripheral Populations of a Rare Plant Lychnis viscaria

Abstract: Genetic diversity is expected to decrease in small and isolated populations as a consequence of bottlenecks, founder effects, inbreeding, and genetic drift. The genetics and ecology of the rare perennial plant Lychnis viscaria (Caryophyllaceae) were studied in both peripheral and central populations within its distribution area. We aimed to investigate the overall level of genetic diversity, its spatial distribution, and possible differences between peripheral and central populations by examining several populations with electrophoresis. Our results showed that the level of genetic diversity varied substantially among populations (  H _exp = 0.000–0.116) and that the total level of genetic diversity (mean H _exp = 0.056) was low compared to that of other species with similar life-history attributes. The peripheral populations of L. viscaria had less genetic variation (mean H _exp = 0.034) than the central ones (0.114). Analysis of genetic structure suggested limited gene flow (mean F _ST = 0.430) and high differentiation among populations, emphasizing the role of genetic drift (  N _e m = 0.33). Isolation was even higher than expected based on the physical distance among populations. We also focused on the association between population size and genetic diversity and possible effects on fitness of these factors. Population size was positively correlated with genetic diversity. Population size and genetic diversity, however, were not associated with fitness components such as germination rate, seedling mass, or seed yield. There were no differences in the measured fitness components between peripheral and central populations. Even though small and peripheral populations had lower levels of genetic variation, they were as viable as larger populations, which emphasizes their potential value for conservation.     

Temporal Changes in Allele Frequencies and a Population's History of Severe Bottlenecks

Monitoring temporal changes in genetic variation has been suggested as a means of determining if a population has experienced a demographic bottleneck. Simulations have shown that the variance in allele frequencies over time ( F ) can provide reasonable estimates of effective population size ( N_e ). This relationship between F and N_e suggests that changes in allele frequencies may provide a way to determine the severity of recent demographic bottlenecks experienced by a population. We examined allozyme variation in experimental populations of the eastern mosquitofish ( Gambusia holbrooki ) to evaluate the relationship between the severity of demographic bottlenecks and temporal variation in allele frequencies. Estimates of F from both the fish populations and computer simulations were compared to expected rates of drift. We found that different methods for estimating F had little effect on the analysis. The variance in estimates of F was large among both experimental and simulated populations experiencing similar demographic bottlenecks. Temporal changes in allele frequencies suggested that the experimental populations had experienced bottlenecks, but there was no relationship between observed and expected values of F . Furthermore, genetic drift was likely to be underestimated in populations experiencing the most severe bottlenecks. The weak relationship between F and bottleneck severity is probably due to both sampling error associated with the number of polymorphic loci examined and the loss of alleles during the bottlenecks. For populations that may have experienced severe bottlenecks, caution should be used in making evolutionary interpretations or management recommendations based on temporal changes in allele frequencies.     

Field and Genetic Survey of the Endangered Butte County Meadowfoam—Limnanthes floccosa subsp. californica (Limnanthaceae)

The Butte County meadowfoam ( Limnanthes floccosa subsp, californica ), an endangered annual endemic to vernal pools in Butte County, California, is of agronomic interest as a sperm whale oil substitute. Because it is threatened by rapid development of the community of Chico, a field and genetic survey was required to guide a conservation program. Eight new populations were discovered, bringing the total known to eleven. Population sizes varied from 220 to 45,689 plants; mean seed set per flower, a bioassay of site quality, ranged from 0.82 to 2.56 among populations. The array of associated taxa, an indicator of appropriate habitat was fairly uniform across populations. Based on allozyme and morphometric data no introgression between L. floccosa subsp, californica and L. alba subsp, alba at sympatric sites was found. Populations were remarkably monomorphic, probably due to past population bottlenecks in conjunction with high selfing rates. Electrophoretic analysis of 28 isozyme loci revealed that 96% of total genetic diversity was distributed among populations. The migration rate, Nm , calculated from the mean frequency of private alleles, ( P (1)), and from the proportion of genetic variation distributed between populations, Gst , estimated exchange between local populations of one diploid individual every 50 to 100 generations, respectively. Mean genetic identity among populations was 0.91 ± 0.068. Grouping of populations on the basis of genetic distance identified two distinct populations and three clusters of populations that deserve high priority for preservation because they are likely to have high frequencies of locally adapted alleles. The low migration rates and substantial differentiation among populations suggest a conservation plan that emphasizes preservation of as many populations as possible, at possible expense of numbers of individuals.     

Translating effects of inbreeding depression on component vital rates to overall population growth in endangered bighorn sheep

Evidence of inbreeding depression is commonly detected from the fitness traits of animals, yet its effects on population growth rates of endangered species are rarely assessed. We examined whether inbreeding depression was affecting Sierra Nevada bighorn sheep (Ovis canadensis sierrae), a subspecies listed as endangered under the U.S. Endangered Species Act. Our objectives were to characterize genetic variation in this subspecies; test whether inbreeding depression affects bighorn sheep vital rates (adult survival and female fecundity); evaluate whether inbreeding depression may limit subspecies recovery; and examine the potential for genetic management to increase population growth rates. Genetic variation in 4 populations of Sierra Nevada bighorn sheep was among the lowest reported for any wild bighorn sheep population, and our results suggest that inbreeding depression has reduced adult female fecundity. Despite this population sizes and growth rates predicted from matrix-based projection models demonstrated that inbreeding depression would not substantially inhibit the recovery of Sierra Nevada bighorn sheep populations in the next approximately 8 bighorn sheep generations (48 years). Furthermore, simulations of genetic rescue within the subspecies did not suggest that such activities would appreciably increase population sizes or growth rates during the period we modeled (10 bighorn sheep generations, 60 years). Only simulations that augmented the Mono Basin population with genetic variation from other subspecies, which is not currently a management option, predicted significant increases in population size. Although we recommend that recovery activities should minimize future losses of genetic variation, genetic effects within these endangered populations-either negative (inbreeding depression) or positive (within subspecies genetic rescue)-appear unlikely to dramatically compromise or stimulate short-term conservation efforts. The distinction between detecting the effects of inbreeding depression on a component vital rate (e.g., fecundity) and the effects of inbreeding depression on population growth underscores the importance of quantifying inbreeding costs relative to population dynamics to effectively manage endangered populations.     

Genetic Depletion in the European Bison (Bison bonasus) and the Significance of Electrophoretic Heterozygosity for Conservation

Starch gel electrophoresis was used to screen 35 lowland bison from the herd in the Biażlowieża Primeval Forest for genetic variation at 69 presumptive structural loci. Average heterozygosity ( H = 1.2%) proved to be three times lower than that based on 20 loci ( H = 3.5%) reported in a previous study by other authors. These earlier results were interpreted as evidence that the passage of the species through an extreme genetic bottleneck (12 founder genomes) had not had much influence on genetic variation. A comparison of estimates of H and the proportion of polymorphic loci ( P ) among different species or populations of Artiodactyla revealed that P was the only parameter to be significantly reduced in those that had experienced genetic bottlenecks. However, the data also show that, in spite of similar H values in species or populations with or without bottlenecks, average heterozygosity is only useful as an indicator of overall genetic variability in the latter. To draw conclusions about genetic depletion on the basis ofelectrophoretic data, we strongly recommend that H , together with its variance among a large number of loci, and additional parameters such as P and the ratio H:P be taken into account.     

The triple helix of Plantago lanceolata: genetics and the environment interact to determine population dynamics

The theory of evolution via natural selection predicts that the genetic composition of wild populations changes over time in response to the environment. Different genotypes should exhibit different demographic patterns, but genetic variation in demography is often impossible to separate from environmental variation. Here, we asked if genetic variation is important in determining demographic patterns. We answer this question using a long-term field experiment combined with general linear modeling of deterministic population growth rates (lambda), deterministic life table response experiment (LTRE) analysis, and stochastic simulation of demography by paternal lineage in a short-lived perennial plant, Plantago lanceolata, in which we replicated genotypes across four cohorts using a standard breeding design. General linear modeling showed that growth rate varied significantly with year, spatial block, and sire. In LTRE analysis of all cohorts, the strongest influences on growth rate were from year x spatial block, and cohort x year x spatial block interactions. In analysis of genetics vs. temporal environmental variation, the strongest impacts on growth rate were from year and year x sire. Finally, stochastic simulation suggested different genetic composition among cohorts after 100 years, and different population growth rates when genetic differences were accounted for than when they were not. We argue that genetic variation, genotype x environment interactions, natural selection, and cohort effects should be better integrated into population ecological studies, as these processes should result in deviations from projected deterministic and stochastic population parameters.     

Genetic Structure of Endangered Clapper Rail (Rallus longirostris) Populations in Southern California

We assessed the genetic structure of two subspecies of endangered Clapper Rails ( Rallus longirostris ) in Southern California using DNA fingerprinting to uncover variation in minisatellite DNA. Minisatellite DNA variation in the Salton Sea population of the R. l. yumanensis subspecies was at a level typical of outbred avian species (average proportion of fragments shared, or S, was 0.33). Variation was extremely low (S from 0.63 to 0.77), however, within four coastal, salt-marsh populations of the subspecies R. l. levipes located along a transect extending about 260 km northwest from the Mexican border. Between-population similarity (S_ij) was also high for the four levipes populations, although individuals of the small, isolated population at Mugu Lagoon consistently clustered separately in phenograms constructed using neighbor-joining or other algorithms. Individuals of yumanensis always clustered as a sister group to all levipes individuals. The minisatellite data were contrasted with the extremely low mtDNA and RAPD variation we found in both subspecies. We propose that variation in these less-mutable markers was lost in a bottleneck that occurred at least 1000 years ago, thus allowing sufficient time for recovery of variation in the rapidly mutating (μ≈} 0.001/gamete/generation) minisatellites (t = 1/μ, or 1000 generations). A second, more-recent bottleneck, or series of bottlenecks within a metapopulation structure, likely resulted in the depauparate variation seen in levipes today. We suggest that translocations from large to small levipes populations could restore important genetic variation to the small populations and would not compromise genetic boundaries.     

Latitudinal variability in spatial genetic structure in the invasive ascidian, Styela plicata

Increases in temperature can shorten planktonic larval durations, so that higher temperatures may reduce dispersal distances for many marine animals. To test this prediction, we first quantified how minimum time to settlement is shortened at higher temperatures for the ascidian Styela plicata. Second, using latitude as a correlate for ocean temperature and spatial genetic structure as a proxy for dispersal, we tested for a negative correlation between latitude and spatial genetic structure within populations, as measured by anonymous DNA markers. Spatial genetic structure was variable among latitudes, with significant structure at low and intermediate latitudes (high and medium temperatures) and there was no genetic structure within high-latitude (low temperature) populations. In addition, we found consistently high genetic diversity across all Australian populations, showing no evidence for recent local bottlenecks associated S. plicata’s history as an invasive species. There was, however, significant genetic differentiation between all populations indicating limited ongoing gene flow.     

Endangered Greater One-horned Rhinoceros Carry High Levels of Genetic Variation

Abstract: The population of Rhinoceros unicornis in the Chitwan Valley, Nepal, was reduced to an estimated effective population size (N_e of 21–28 individuals (60–80 total animals) in 1962. Protein electrophoresis shows that heterozygosity remains very high in this population (H_o= 9.9%) despite its near extinction. We attribute this high heterozygosity to large N_e's prior to the population bottleneck, the recent occurrence of the bottleneck, and long generation time. These results illustrate the importance of considering historical demography and life history parameters when evaluating the possible genetic effects of bottlenecks in wild populations. They also offer support to recent arguments that the erosion of genetic diversity attributed to bottlenecks may be overemphasized.     

Inbreeding and Loss of Genetic Variation in a Reintroduced Population of Mauritius Kestrel

Abstract:  Many populations have recovered from severe bottlenecks either naturally or through intensive conservation management. In the past, however, few conservation programs have monitored the genetic health of recovering populations. We conducted a conservation genetic assessment of a small, reintroduced population of Mauritius Kestrel ( Falco punctatus ) to determine whether genetic deterioration has occurred since its reintroduction. We used pedigree analysis that partially accounted for individuals of unknown origin to document that (1) inbreeding occurred frequently (2.6% increase per generation; N _eI= 18.9), (2) 25% of breeding pairs were composed of either closely or moderately related individuals, (3) genetic diversity has been lost from the population (1.6% loss per generation; N _eV= 32.1) less rapidly than the corresponding increase in inbreeding, and (4) ignoring the contribution of unknown individuals to a pedigree will bias the metrics derived from that pedigree, ultimately obscuring the prevailing genetic dynamics. The rates of inbreeding and loss of genetic variation in the subpopulation of Mauritius Kestrel we examined were extreme and among the highest yet documented in a wild vertebrate population. Thus, genetic deterioration may affect this population's long-term viability. Remedial conservation strategies are needed to reduce the impact of inbreeding and loss of genetic variation in this species. We suggest that schemes to monitor genetic variation after reintroduction should be an integral component of endangered species recovery programs.     

Highly Differentiated Populations of the Narrow Endemic Plant Maguire Primrose (Primula maguirei)

Maguire primrose (Primula maguirei) is a geographically restricted plant species, known only from a 19-km stretch of Logan Canyon in northern Utah (U.S.A.). We examined variation at 13 isozyme loci from 25 individuals of P. maguirei at each of eight sites. At individual loci we detected no statistically significant deviations from Hardy-Weinberg proportions within sites (subpopulations). However, some loci were almost fixed for different alleles at the upper reaches of the species' range relative to populations approximately 10 km away. The total mean gene diversity among loci was 0.22, of which 55% was partitioned within subpopulations, 0.7% among subpopulations within populations (100 m spatial scale), 3% among populations separated by about 1 km, and 41% between an Upper Canyon group of populations and a Lower Canyon group (10-km scale). We detected no gametic disequilibria among loci within subpopulations (and populations). Two hypotheses are proposed to explain the results: (1) past genetic bottlenecks and (2) genetic divergence as a by-product of local adaptations to different habitats. Regardless of the causes of allozymic differentiation, our results suggest that plans for artificial establishment or reestablishment of P. maguirei populations should use source populations within 1 km of the establishment site. This study emphasizes the potential use of data on population genetic structure for managing and monitoring rare species.     

Effective Population Size in Red-Cockaded Woodpeckers: Population and Model Differences

Loss of genetic variability in isolated populations is an important issue for conservation biology. Most studies involve only a single population of a given species and a single method of estimating rate of loss. Here we present analyses for three different Red-cockaded Woodpecker ( Picoides borealis ) populations from different geographic regions. We compare two different models for estimating the expected rate of loss of genetic variability, and test their sensitivity to model parameters. We found that the simpler model (Reed et al. 1988) consistently estimated a greater rate of loss of genetic variability from a population than did the Emigh and Pollak (1979) model. The ratio of effective population size (which describes the expected rate of loss of genetic variability) to breeder population size varied widely among Red-cockaded Woodpecker populations due to geographic variation in demography. For this species, estimates of effective size were extremely sensitive to survival parameters, but not to the probability of breeding or reproductive success. Sensitivity was sufficient that error in estimating survival rates in the field could easily mask true population differences in effective size. Our results indicate that accurate and precise demographic data are prerequisites to determining effective population size for this species using genetic models, and that a single estimate of rate of loss of genetic variability is not valid across populations.     

The roles of competition and environmental heterogeneity in the maintenance of behavioral variation and covariation

Many models of selection predict that populations will lose variation in traits that affect fitness. Nonetheless, phenotypic variation is commonly observed in natural populations. We tested the influences of competition and spatial heterogeneity on behavioral variation within and among populations of Merriam's kangaroo rats (Dipodomys merriami) and tested for the differential expression of trait correlations. We found that populations of D. merriami exhibited more aggression at sites with more competition. Contrary to theoretical predictions and empirical results in other systems, the sites with the greatest spatial heterogeneity and highest levels of competition did not exhibit the most behavioral variation among individuals. However, the greatest within-individual behavioral variability in boldness (response to cues of predator presence) was exhibited where spatial heterogeneity was highest. Aggression and boldness of D. merriami were highly repeatable, that is, individuals behaved in a consistent manner over time, and the two behaviors were also highly correlated. Interestingly, the strength of this correlation was greatest where the competitive community was least diverse. These findings add to increasing evidence that natural populations of animals exhibit patterns of behavioral covariance, or personality structure, and suggest that competitive variation may act to erode personality structure.     

Effects of habitat fragmentation on the genetic structure and connectivity of the black-lipped pearl oyster Pinctada margaritifera populations in French Polynesia

Habitat destruction leading to increased fragmentation is detrimental to species by reducing population size and genetic diversity and by restraining population connectivity. However, little is known about the effects of naturally fragmented habitats on wild populations, especially when it comes to marine benthic invertebrates with long pelagic larval duration. In this framework, we investigated the connectivity and genetic diversity variation among nine wild populations of the black-lipped pearl oyster, Pinctada margaritifera, throughout French Polynesia using ten microsatellite DNA markers. Despite the naturally fragmented habitat (South Pacific oceanic islands), we found high values of genetic diversity and population admixture, indicating connectivity at small and large spatial scales within sampled sites of the Tuamotu, and between the Society and Tuamotu Archipelagos. In the meantime, habitat geomorphology increased genetic drift in populations occurring in small, closed lagoons. Significant genetic structure not correlated to geographic distance was detected mainly between closed and open lagoons. The Marquesas Islands hosted the most divergent populations, likely a result of vicariance. Our results also highlight that migration patterns among lagoons are not symmetrical. Altogether, the general pattern of gene flow, nonsymmetrical migration rates among populations, absence of isolation by distance and absence of recent extinction events found in our study strongly suggest that P. margaritifera populations of French Polynesia follow an asymmetrical island model of dispersal.     

Effects of Population Size, Mating System, and Evolutionary Origin on Genetic Diversity in Spiranthes sinensis and S. hongkongensis

Hong Kong once supported more than 109 species of wild orchids, of which approximately 30% were endemic. Most of the local wild orchids have now become rare or endangered. I conducted a comparative study of genetic diversity in two closely related terrestrial orchids, an allotetraploid, Spiranthes hongkongensis , and its diploid progenitor, S. sinensis , to assess the effects of the population bottleneck associated with the origin of the polyploid and to investigate the relationships between number of breeding individuals, mating system, and level of isozyme variation in their populations. Nearly complete genetic uniformity was observed both within and among populations of S. hongkongensis . In contrast, S. sinensis had high levels of genetic variation for all of the genetic parameters examined. Regression analysis of population size and several components of genetic diversity in S. sinensis revealed that, among various measures of within-population variation, the proportion of polymorphic loci ( P ) and average number of alleles per locus ( A ) or per polymorphic locus ( A _p ) were the most sensitive to population size ( R ² = 0.942, p = 0.001; R ² = 0.932, p = 0.002; and R ² = 0.923, p = 0.002 respectively). The highly negative correlation ( r = −0.999, p < 0.01) between population size and the mean frequency of private alleles in pairwise population comparisons, p (1), indicated that population size may also be used to predict the extent of population differentiation caused by random genetic drift. Conservation of genetic diversity in S. sinensis could be maximized by protecting several of both large and small populations, whereas fewer populations may be needed to achieve this goal for S. hongkongensis.     

Genetic population structure in the black-spot sea bream (<Emphasis Type="Italic">Pagellus bogaraveo</Emphasis> Brünnich, 1768) from the NE Atlantic

The depletion of shallow-water fish stocks through overexploitation has led to increasing fishing pressure on deep-sea species. Poor knowledge of the biology of commercially valuable deep-water fish has led to the serial depletion of stocks of several species across the world. Data regarding the genetic structure of deep-sea fish populations is important in determining the impact of overfishing on the overall genetic variability of species and can be used to estimate the likelihood of recolonisation of damaged populations through immigration of individuals from distant localities. Here the genetic structure of the commercially fished deep-water species the blackspot sea bream, Pagellus bogaraveo is investigated in the northeastern Atlantic using partial DNA sequencing of mitochondrial cytochrome b (cyt-b) and D-loop regions and genotyping of microsatellite loci. An absence of variation in cyt-b and low genetic variation in D-loop sequences potentially indicate that P. bogaraveo may have undergone a severe bottleneck in the past. Similar bottlenecks have been detected in other Atlantic species of fish and have possibly originated from the last glaciation. P. bogaraveo may have been particularly vulnerable to the effects of low temperature and a fall in sea level because stages of its life history occur in shallow water and coastal sites. However, there are other explanations of low genetic variability in populations of P. bogaraveo, such as a low population size and the impacts of fishing on population structure. Analysis of population structure using both D-loop and microsatellite analysis indicates low to moderate, but significant, genetic differentiation between populations at a regional level. This study supports studies on other deep-sea fish species that indicate that hydrographic or topographic barriers prevent dispersal of adults and/or larvae between populations at regional and oceanographic scales. The implications for the management and conservation of deep-sea fish populations are discussed.Communicated by J.P. Thorpe, Port Erin     

Rapid Loss of Genetic Variation in Large Captive Populations of Drosophila Flies: Implications for the Genetic Management of Captive Populations

Levels of variation in eight large captive populations of D. melanogaster (census sizes ∼ 5000) that had been in captivity for periods from 6 months to 23 years (8 to 365 generations) were estimated from allozyme heterozygosities, lethal frequencies, and inversion heterozygosities and phenotypic variances, additive genetic variances ( V _A), and heritabilities ( h ²) for sternopleural bristle numbers. Correlations between all measures of variation except lethal frequencies were high and significant. All measures of genetic variation declined with time in captivity, with those for average heterozygosities, V _A, and h ² being significant. The effective population size ( N _e) was estimated to be 185–253 in these populations, only 0.037–0.051 of census size (N). Levels of allozyme heterozygosities declined rapidly in two large captive populations founded from another wild stock, being reduced by 86% and 62% within 2.5 years in spite of being maintained at sizes of approximately 1000 and 3500. Estimates of N _e/ N for these populations were only 0.016 and 0.004. Two estimates of N _e/ N for captive populations of D. pseudoobscura from data in the literature were also low at 0.036 and 0.012. Consequently, the rate of loss of genetic variation in captive populations and endangered species may be more rapid than hitherto recognized. Merely maintaining captive populations at large census sizes may not be sufficient to maintain essential genetic variation.     

Genetic Analyses Through DNA Fingerprinting of Captive Populations of Hawaiian Geese

DNA fingerprinting was used to assess levels of genetic variation in 106 Hawaiian Geese, or Nene ( Branta sandvicensis ), from two captive colonies in Hawaii and Slimbridge, England. Mantel tests were used to determine differences in mean similarity coefficients obtained from DNA fingerprints between unrelated and related Nene within and between captive colonies and to determine whether pedigree-based estimates of relatedness correlated with DNA fingerprint-based estimates. Between colonies, mean similarity coefficients for unrelated and related Slimbridge Nene were higher than those for Hawaiian Nene. Within each colony, related Nene bad higher mean similarity coefficients than did unrelated Nene. A positive relationship was found between coancestry coefficients and similarity coefficients. A greater number of founders for the Hawaiian colony contributed to the lower mean similarity coefficients. As genetic variation decreases, difficulty in distinguishing relatedness among individuals using DNA fingerprinting may increase. Lower genetic variation also may increase tine error in estimating the relationship between coancestry and similarity coefficients. DNA fingerprinting of Nene identified unique alleles and can determine optimal pairings between individuals. The calibrated similarity coefficient distributions can help determine the relatedness of individuals in wild populations of Nene.     

Choosing between darkness and light: The ecological genetics of photic behaviour in the planktonic larva of Spirorbis borealis

The light-dark preference of individual Spirorbis borealis larvae was measured by the relative amount of time spent in the lighted half of a container. Specimens taken from a tidal pool were 20% more photonegative than those obtained outside the pool, probably because of natural selection against being washed out of the pool at high tide. The between-population behavioural difference was maintained in the laboratory, and is genetic in origin. Applying biometrical genetic analysis to larvae grouped into half-sib families, the within-population variation was used to estimate an upper limit to the heritability of 0.36. It is concluded that the differences among populations greatly exceed heritable variation within populations. A numerical selection model based on the estimated maximum heritability suggests, however, that the populations could diverge by 20% in less than a year, in response to local differences in the selection regime.     

Long-term demographic and genetic effects of releasing captive-born individuals into the wild

Because of continued habitat destruction and species extirpations, the need to use captive breeding for conservation purposes has been increasing steadily. However, the long-term demographic and genetic effects associated with releasing captive-born individuals with varied life histories into the wild remain largely unknown. To address this question, we developed forward-time, agent-based models for 4 species with long-running captive-breeding and release programs: coho salmon (Oncorhynchus kisutch), golden lion tamarin (Leontopithecus rosalia), western toad (Anaxyrus boreas), and Whooping Crane (Grus americana). We measured the effects of supplementation by comparing population size and neutral genetic diversity in supplemented populations to the same characteristics in unaltered populations 100 years after supplementation ended. Releasing even slightly less fit captive-born individuals to supplement wild populations typically resulted in reductions in population sizes and genetic diversity over the long term when the fitness reductions were heritable (i.e., due to genetic adaptation to captivity) and populations continued to be regulated by density-dependent mechanisms over time. Negative effects for species with longer life spans and lower rates of population replacement were smaller than for species with shorter life spans and higher rates of population replacement. Programs that released captive-born individuals over fewer years or that avoided breeding individuals with captive ancestry had smaller reductions in population size and genetic diversity over the long term. Relying on selection in the wild to remove individuals with reduced fitness mitigated some negative demographic effects, but at a substantial cost to neutral genetic diversity. Our results suggest that conservation-focused captive-breeding programs should take measures to prevent even small amounts of genetic adaptation to captivity, quantitatively determine the minimum number of captive-born individuals to release each year, and fully account for the interactions among genetic adaptation to captivity, population regulation, and life-history variation.