Conservation Breeding Programs Research Articles

The Transmission Patterns of the Endosymbiont Wolbachia within the Hawaiian Drosophilidae Adaptive Radiation.

The evolution of endosymbionts and their hosts can lead to highly dynamic interactions with varying fitness effects for both the endosymbiont and host species. Wolbachia, a ubiquitous endosymbiont of arthropods and nematodes, can have both beneficial and detrimental effects on host fitness. We documented the occurrence and patterns of transmission of Wolbachia within the Hawaiian Drosophilidae and examined the potential contributions of Wolbachia to the rapid diversification of their hosts. Screens for Wolbachia infections across a minimum of 140 species of Hawaiian Drosophila and Scaptomyza revealed species-level infections of 20.0%, and across all 399 samples, a general infection rate of 10.3%. Among the 44 Wolbachia strains we identified using a modified Wolbachia multi-locus strain typing scheme, 30 (68.18%) belonged to supergroup B, five (11.36%) belonged to supergroup A, and nine (20.45%) had alleles with conflicting supergroup assignments. Co-phylogenetic reconciliation analysis indicated that Wolbachia strain diversity within their endemic Hawaiian Drosophilidae hosts can be explained by vertical (e.g., co-speciation) and horizontal (e.g., host switch) modes of transmission. Results from stochastic character trait mapping suggest that horizontal transmission is associated with the preferred oviposition substrate of the host, but not the host's plant family or island of occurrence. For Hawaiian Drosophilid species of conservation concern, with 13 species listed as endangered and 1 listed as threatened, knowledge of Wolbachia strain types, infection status, and potential for superinfection could assist with conservation breeding programs designed to bolster population sizes, especially when wild populations are supplemented with laboratory-reared, translocated individuals. Future research aimed at improving the understanding of the mechanisms of Wolbachia transmission in nature, their impact on the host, and their role in host species formation may shed light on the influence of Wolbachia as an evolutionary driver, especially in Hawaiian ecosystems.

Genomics of founders for conservation breeding: the Jasper caribou case.

The online version contains supplementary material available at 10.1007/s10592-023-01540-3.

The Increasing Role of Short-Term Sperm Storage and Cryopreservation in Conserving Threatened Amphibian Species.

Multidisciplinary approaches to conserve threatened species are required to curb biodiversity loss. Globally, amphibians are facing the most severe declines of any vertebrate class. In response, conservation breeding programs have been established in a growing number of amphibian species as a safeguard against further extinction. One of the main challenges to the long-term success of conservation breeding programs is the maintenance of genetic diversity, which, if lost, poses threats to the viability and adaptive potential of at-risk populations. Integrating reproductive technologies into conservation breeding programs can greatly assist genetic management and facilitate genetic exchange between captive and wild populations, as well as reinvigorate genetic diversity from expired genotypes. The generation of offspring produced via assisted fertilisation using frozen-thawed sperm has been achieved in a small but growing number of amphibian species and is poised to be a valuable tool for the genetic management of many more threatened species globally. This review discusses the role of sperm storage in amphibian conservation, presents the state of current technologies for the short-term cold storage and cryopreservation of amphibian sperm, and discusses the generation of cryo-derived offspring.

Adapting conservation breeding techniques using a data-driven approach to restore the 'Alalā (Hawaiian crow, Corvus hawaiiensis).

For some critically endangered species, conservation breeding is a vital steppingstone toward re-establishing wild populations. The 'Alalā (Hawaiian crow, Corvus hawaiiensis), currently extinct in the wild, exists today only in a conservation breeding program, which, for many years, utilized successful hands-on husbandry approaches such as separating and resocializing pairs, providing partially manmade nests, artificially incubating eggs, and puppet rearing nestlings. Yet, a top priority of any conservation breeding program is to retain natural behaviors essential to postrelease survival and reproduction, to achieve successful reintroduction and restoration to the wild. We describe how we are adapting 'Alalā husbandry techniques to strengthen pair bonds through full-time socialization, enable pairs to build robust nests, encourage females to incubate eggs to hatch, and provide pairs and their offspring with vital parental rearing experiences. We discuss the use of standardized, data-driven methods to objectively track our progress towards successful parental breeding and to select release candidates based on their likelihood to survive and breed in the wild. The information shared in this report can be applied to other conservation breeding programs, particularly those implementing or transitioning to husbandry techniques geared towards preparing species to thrive in the wild.

Early life experience with predators impacts development, behavior, and post‐translocation outcomes in an endangered amphibian

AbstractPre‐release training is becoming a standard practice in conservation breeding and translocation programs for mammals and birds, but is still relatively neglected for herpetofauna, likely stemming from widespread beliefs that amphibians are “hard‐wired” and are thus predicted to benefit little from experiential learning. However, experience during development can drive both morphological and behavioral modifications that could benefit post‐translocation survival. Here, we developed an anti‐predator training program for the endangered mountain yellow‐legged frog Rana muscosa and evaluated its impact on morphometrics, developmental rates, behavior, and post‐release outcomes. Using a controlled, balanced factorial experimental design, we exposed individuals at two developmental stages (tadpoles and post‐metamorphic) to visual and olfactory cues from one of its principal predators, the two‐striped garter snake Thamnophis hammondii. We found that exposure to predators during the tadpole stage impacted tadpole development, morphology, and behavior. However, we found no evidence that post‐metamorphic behavior or post‐release outcomes were influenced by tadpole predator exposure, either on its own or in interaction with post‐metamorphic training treatments. Training of post‐metamorphic frogs, however, yielded evidence of learning, with downstream effects on behavior and apparent survival after release into the wild. Our findings produce novel insights on the value of anti‐predator training in amphibian conservation translocation programs, bolster recent evidence re‐evaluating the importance of learning and developmental experience for amphibian species, and provide guidance for selecting optimal developmental windows for training.

Carry‐over effects of nestling physical condition predict first‐year survival of a critically endangered migratory parrot

AbstractConservation breeding programs are an increasingly important tool to help supplement declining wild populations, but captive‐bred animals generally do not survive well post‐release. Early life in captivity has the potential to influence growth and development, with impacts carrying over to affect survival. Understanding carry‐over effects of captivity and consequences on survival is critically important for conservation efforts globally but remains poorly understood. We examined the relationship between early‐life environment, physical condition, and juvenile survival of wild and captive‐bred critically endangered orange‐bellied parrots (Neophema chrysogaster). Using nestling growth models, we calculated a body condition index for 1,039 wild and captive‐bred orange‐bellied parrots hatched over six breeding seasons. Nestling body condition varied with year, provenance, and brood position. Wild nestlings had consistently higher body condition than captive‐bred nestlings, and first‐hatched nestlings were typically heavier than later hatched siblings. We then investigated first‐year survival for 298 wild‐born and captive‐bred released parrots in the wild. Overall, first‐year survival was 27.5%, and individual body condition was more influential than provenance in predicting survival. Our findings could be used to aid the selection of individuals for release that have the best prospects of surviving in the wild. This study addresses important questions about the post‐release fitness of captive‐bred animals, and our metric of assessing physical condition provides a straightforward tool for other conservation breeding programs to adapt management techniques to improve survival outcomes.

Identifying factors affecting captive breeding success in a critically endangered species

ABSTRACT Captive breeding programs are an increasingly important tool for species’ conservation efforts, but not all species reproduce well in captivity. Identifying factors that affect the reproductive success of captive populations is crucial to improving the performance and management of conservation-breeding programs, both by providing individuals for release and informing decision making. We examined breeding records collected from the long-running conservation-breeding program for the critically endangered Orange-bellied Parrot Neophema chrysogaster over an 11-year period. We examined egg hatching rate, nestling survival rate, and offspring sex ratio in response to a wide range of variables related to characteristics of individual birds, breeding events, and the captive environment. The hatch rate of eggs was higher in first clutches compared to second clutches and was lower than the wild population. The survival rate of nestlings through to fledging was variable between years but became higher and more consistent over the last five years of the study period. Variation in brood sex ratio was not related to any of the potential explanatory variables that we examined. This is one of the first studies to examine reproductive data in a long-running conservation-breeding program and shows that many common metrics do not explain reproductive variation. Our approach provides a framework for managers to investigate factors affecting reproductive success in conservation breeding programs more broadly.

Assessment of genetic diversity and population structure of Indian common bean accessions using microsatellite markers

AbstractCommon bean (Phaseolus vulgaris L.) is an important crop of family Fabaceae used as a potential source of proteins, fibres and minerals. Thus, characterization of existing germplasm is useful for improvement and conservation. The Indian Himalayan Region harbours plentiful varieties of common bean, but it is nearly unexplored till date. In the present study, physical and genetic diversity of common bean was examined. Fifteen newly designed chloroplast microsatellite (cpSSR) markers were used to assess genetic diversity and population structure in 119 common bean individuals from 20 diverse accessions gathered from Uttarakhand, India. Significantly, positive (p< 0.05) relationship of seed weight was found with seed length (r = 0.813), seed width (r = 0.692) and seed length- width ratio (r = 0.694) using Pearson correlation analysis. A total of 20 alleles were identified using eight cpSSR markers. Mean number of alleles per locus (Na = 1.55), effective allele number (Ne = 1.370), expected heterozygosity (He = 0.213), average polymorphic loci (10.9) and Shannon information index (I = 0.313) were estimated based on cpSSR data. Maximum genetic diversity (He) was recorded in the AKJ/KK/DP/Jhalla/23 accession and minimum in the AKJ/YB/PS/Supi/43 accession. Bayesian-based STRUCTURE evaluation using cpSSR-based information partitioned 20 accessions into two distinct clusters which were also supported by neighbor-joining cluster analysis. These cpSSR markers also demonstrated transferability among other members like Vigna radiata, Macrotyloma uniflorum, Glycine max, Vigna mungo of Fabaceae family, therefore can be used to monitor their genetic heterogeneity. The findings from the study might be valuable to identify elite common bean accessions for production, conservation and future breeding programmes.

Pheromones for amphibian conservation – considering new approaches in conservation breeding programmes

Pheromones for amphibian conservation – considering new approaches in conservation breeding programmes

Assessing stress physiology within a conservation breeding program for an endangered species.

Conservation breeding programs typically involve the management of individuals both in and ex situ, so it is vital to understand how the physiology of managed species changes in these environments to maximize program outcomes. The Vancouver Island marmot (VIM; Marmota vancouverensis) is one species that has been managed in a conservation breeding program to recover the critically low wild population. Previous research has shown there are differences in hair glucocorticoid concentrations for VIMs in different managed groups in the program. Therefore, we used >1000 blood samples collected since the program's inception to assess the neutrophil to lymphocyte (N:L) ratio among captive, pre-release, post-release and wild populations as another metric of stress. In situ VIM populations were found to have a significantly higher N:L ratio than ex situ populations, suggesting that the wild is a more physiologically challenging environment than managed care. Moreover, the effect of age, sex and the month of sampling on the N:L ratio were found to be different for each population. Age had the greatest magnitude of effect in the wild population, and sex was only significant in ex situ populations. This study provided previously unknown insights into the physiology of VIMs and increased post-release monitoring will be useful in the future to fully understand how physiology may be contributing to differences in survival of VIMs in the program.

Ovarian ultrasound analysis for developing temporal and spatially explicit hormone regimens for induced ovulation and egg deposition in the tiger salamander (Ambystoma tigrinum)

Conservation breeding programs (CBPs) for threatened salamander species depend on reliable reproduction. We followed ovarian maturation and oviposition in eastern tiger salamander (Ambystoma tigrinum) females treated with exogenous hormone regimens developed within a framework of grading their initial follicular stages based on oocyte size and echogenicity (G0 = little/no development; G1 = minor development; G2 = moderate development; G3 = extensive development). The exogenous hormones used in this study included human chorionic gonadotropin (hCG) and gonadotropin releasing hormone (GnRH), where lower concentrations of hCG were used as a priming hormone compared to the ovulatory dose, which included both hCG and GnRH. The three hormone treatment regimens consisted of: (1) an extended prime plus ovulatory dose; (2) a short prime plus an ovulatory dose; and (3) an ovulatory dose only. The three exogenous hormone regimens were trialed for optimal spawning success based on ovarian ultrasound grades 1–3, in which higher doses of priming hormones were administered to salamanders with less developed follicles to stimulate oogenesis, prior to a final ovulatory dose. The three exogenous hormone regimens and three ovarian grades were used in a 3 × 3 factorial design, with n = 6 females for each factorial combination, and efficacy assessed by ovarian grade and/or exogenous hormone regimen on proportion of animals laying eggs, egg numbers, and latency to egg deposition. The salamanders in the most advanced initial stage of follicular development (G3) were most likely to ovulate and lay eggs and those with low follicular development (G1) the least likely. Initial follicular stages also affected the egg numbers, with G3 females laying the most eggs and G1 laying the fewest. Moreover, we found a significant interaction effect of exogenous hormone treatment and ovarian grade, in which G1 females required the greatest numbers and levels of exogenous hormone doses to induce oviposition and G3 the least. These findings show that ultrasound can be used with Ambystomid species to develop optimal spatial and temporal hormone regimens for ovulation and oviposition, depending on follicular maturation, thereby enhancing the efficiency of CBPs, improving animal welfare, and advancing genetic diversity management.

Amphibians and conservation breeding programmes: how do we determine who should be on the ark?

Amphibians and conservation breeding programmes: how do we determine who should be on the ark?

Bridging conservation across the ex situ-in situ spectrum: Insights into the reproductive ecology of the threatened narrow-headed gartersnake (Thamnophis rufipunctatus).

Zoo-based (ex situ) conservation breeding programs provide invaluable opportunities to uncover enigmatic behaviors and traits of focal species under managed care, which can support research and conservation management efforts. A suite of factors and a limited range have yielded population declines in the threatened narrow-headed gartersnake (Thamnophis rufipunctatus). Better understanding its cryptic ecology and life history (e.g., reproductive ecology) offers conservation benefits. We analyzed data on courtship behavior, parity and litter size, offspring size, and neonatal growth from an ex situ T. rufipunctatus population at the Phoenix Zoo from 2009 to 2018. Courtship behavior and parturition phenology are likely linked with the North American monsoon season, yet the courtship window may be wider than realized. We document the first instances of interannual iteroparity and multigenerational rearing of successful breeders at the ex situ level. Litter sizes varied but were relative to maternal body mass, suggesting that fecundity may be driven by intrinsic condition (e.g., age and size) of breeding females. Mean offspring body masses were equivalent between sexes, and neonate growth trends were quadratic during their first 9 months. Sexual dimorphism became apparent around 4-5 months age. Much of these data are novel for T. rufipunctatus and provide insight into their reproductive ecology. Phenology of reproductive ecology and body size metrics can guide field surveillance, age estimations, and population ecology monitoring, as well as inform ex situ adaptive management practices. Strategies spanning the ex situ-in situ spectrum are applicable to other imperiled taxa to better inform conservation management decisions.

Effects of wild, semi‐captive, and captive management on male Chiricahua leopard frog sperm quality with implications for conservation breeding programs

AbstractThe Chiricahua leopard frog (Lithobates chiricahuensis) is a threatened species endemic to the southwestern United States and Northern Mexico. Captive breeding programs were established to support reintroduction efforts, yet reproductive output has been lower than needed for recovery of the species. This study aimed to evaluate the effects of captivity on amphibian reproduction by (1) determining if captive, semi‐captive, and wild male L. chiricahuensis produce sperm at similar rates and concentration in response to hormone treatment; and (2) evaluating the quality of sperm obtained over time from these populations. Males from captive, semi‐captive, and wild locations were administered a combination of human chorionic gonadotropin and gonadotropin‐releasing hormone to stimulate sperm production and release. A high percentage of males in the captive (60%), semi‐captive (100%), and wild (95.3%) populations produced sperm following treatment. Sperm quality (forward progressive motility and total sperm motility) did not differ between groups. However, sperm quantity (sperm/ml) differed (p < .05) between populations, with semi‐captive and wild males producing higher concentrations of sperm than captive males. These results suggest that Chiricahua leopard frog sperm quantity, but not quality, may become negatively impacted by long‐term captivity in indoor, controlled settings.

Individual‐based assessment of post‐translocation fitness of ungulates: Lessons from the critically endangered Derby eland conservation programme

AbstractTranslocations have become an essential tool in animal conservation for establishing and maintaining viable populations. Yet, the viability of a population is implicitly based on the individual fitness, that is on the survival and reproduction of individuals. Individual‐based assessments of post‐translocation fitness are challenging in the wild while conservation breeding programs may provide vital insights. Long‐term breeding records of semi‐captive (fenced) small population of the Western Derby eland (Taurotragus derbianus derbianus) running in two fenced reserves in Senegal present a case study. This study shows that transport distance and the individual's age at translocation influence animal post‐translocation survival rates and individual reproductive performance. The most critical period for the antelope's post‐translocation survival was the first 2 years following the event, with higher mortalities reported after long‐distance transport in an ecologically novel environment. The first successful calving of translocated females was postponed by 1 year, but the life‐long reproductive performance was not affected. However, higher calf survival in a habitat similar to that in the wild suggests a non‐negligible effect of the habitat on individual fitness, thus crucial to conservation decisions on translocating threatened species.

Endocrine correlates of female reproductive activity in the roan antelope (Hippotragus equinus)

AbstractAlthough ovarian endocrine activity has been described in most members of the tribe Hippotragini, little is known about the reproductive endocrine correlates of the roan antelope (Hippotragus equinus), an endangered antelope species of southern Africa. This study characterised the endocrine pattern of the reproductive activity (oestrous cycle, pregnancy and post‐partum period) in the female roan antelope by monitoring faecal progestogen metabolite (fPM) concentrations and oestrogen metabolite (fEM) concentrations for cyclicity and observing reproductive behaviours. The study was carried out over the course of 12 months. At the beginning of this study, all 18 focal females (nulliparous, primiparous and multiparous) were monitored for cyclicity (for between 3 and 4 months). Following observed copulation, pregnancy in multiparous females (n = 10) was subsequently monitored until parturition and 21 days post‐partum. Individual faecal samples were collected three times per week during the presumed period of cyclicity, twice per week during pregnancy and daily for 21 days post‐partum. Mating births, courtship events, and copulations were recorded when observed. In eight of the 18 females monitored, the patterns of fPM and fEM concentrations indicated oestrous cycle lengths (n = 10) of approximately 30.8 ± 2.1 days. The determined lengths of luteal and follicular phases were approximately 15.8 ± 1.5 days and 14.6 ± 2.1 respectively. Pregnancy was marked by a pronounced increase in fPM concentrations until parturition, and lasted approximately 280.4 ± 4.8 days; whereas the intercalving period ranged between 306 and 380 days (n = 9; mean: 333.2 ± 7.4 days). Twenty‐one day after parturition, 78% of the focal females (n = 5) did not show a resumption of the ovarian activity. This study demonstrated that monitoring faecal reproductive hormone metabolite patterns is a valuable approach for estimating ovarian activity in roan antelope and may be used to assist respective conservation breeding programmes by improving management practices.

Strategies for establishing and using genome resource banks to protect genetic diversity in conservation breeding programs.

Genome resource banks (GRBs) have the potential to preserve the genetic diversity of a species over time, yet they are rarely utilized as effective components of conservation breeding programs. Advances have been made in reproductive biology, collection and storage techniques, and use of stored gametes for achieving successful reproduction, but there are few guidelines for integrating GRBs into established breeding programs. Here we present basic guidelines, focusing on strategies for the collection, maintenance, and use of semen GRBs for protecting genetic diversity. These guidelines should be applied in the context of the specific purposes and roles of a breeding program's GRB, which will differ among species depending on vulnerability to loss and the status of rescue and conservation efforts. We recommend establishing up to three types of collections: (1) a National Reserve to preserve a species' genetic diversity, to be used only as a last resort; (2) a Savings Account to be used periodically to invigorate a genetically depauperate population; and (3) a Checking Account to be used as a regular part of the breeding program. We present methods for identifying donors to maximize genetic diversity in a GRB, as well as strategies for maintaining and optimally using GRBs.

Y Chromosome Haplotypes Enlighten Origin, Influence, and Breeding History of North African Barb Horses.

Simple SummaryBred over centuries in the Maghreb region, on a corridor between the Arab and the Western world, the North African Barb horse has been touched by many influences in the course of history. The present study investigated the paternally inherited Y chromosome in today´s Barbs and Arab-Barbs collected from North Africa and Europe, with the aim to link genetic patterns and narrative history. A broad Y chromosomal spectrum was observed, as well as regional disparities among populations. Y chromosomal patterns illustrated a tight connection of Barb horses with Arabians and several other breeds, including Thoroughbreds. Besides, results depict footprints of past migrations between North Africa and the Iberian Peninsula. In horses, demographic patterns are complex due to historical migrations and eventful breeding histories. Particularly puzzling is the ancestry of the North African horse, a founding horse breed, shaped by numerous influences throughout history. A genetic marker particularly suitable to investigate the paternal demographic history of populations is the non-recombining male-specific region of the Y chromosome (MSY). Using a recently established horse MSY haplotype (HT) topology and KASP™ genotyping, we illustrate MSY HT spectra of 119 Barb and Arab-Barb males, collected from the Maghreb region and European subpopulations. All detected HTs belonged to the Crown haplogroup, and the broad MSY spectrum reflects the wide variety of influential stallions throughout the breed’s history. Distinct HTs and regional disparities were characterized and a remarkable number of early introduced lineages were observed. The data indicate recent refinement with Thoroughbred and Arabian patrilines, while 57% of the dataset supports historical migrations between North Africa and the Iberian Peninsula. In the Barb horse, we detected the HT linked to Godolphin Arabian, one of the Thoroughbred founders. Hence, we shed new light on the question of the ancestry of one Thoroughbred patriline. We show the strength of the horse Y chromosome as a genealogical tool, enlighten recent paternal history of North African horses, and set the foundation for future studies on the breed and the formation of conservation breeding programs.

Activity patterns and reproductive behavior of the Critically Endangered Bermuda skink (Plestiodon longirostris).

The study of rare or cryptic species in zoos can provide insights into natural history and behavior that would be difficult to obtain in the field. Such information can then be used to refine population assessment protocols and conservation management. The Bermuda skink (Plestiodon longirostris) is an endemic Critically Endangered lizard. Chester Zoo's successful conservation breeding program is working to safeguard, increase and reinforce skink populations in the wild. A key aim of this program is to develop our understanding of the behavior of this species. In this study, using 24 hvideo recordings, we examined the daily activity patterns, basking behavior and food preferences of four pairs of Bermuda skinks. The skinks displayed a bimodal pattern of activity and basking, which may have evolved to avoid the strength of the midday sun in exposed habitats in Bermuda. Captive Bermuda skinks appear to prefer a fruit-based diet to orthopteran prey. We also documented their reproductive behavior and compared it against two closely related species. Although there were many similarities between the courtship and mating behaviors of the three species, there was a significantly shorter period of cloacal contact in the Bermuda skink. Oophagia was also documented for the first time in this species. This knowledge has enabled the evaluation of the current ex-situ management practices of this species, filled gaps in knowledge that would be challenging to obtain in the field, and enabled the enhancement of both animal husbandry and reproductive success for the conservation breeding program.

Conservation Biology and Reproduction in a Time of Developmental Plasticity.

The objective of this review is to ask whether, and how, principles in conservation biology may need to be revisited in light of new knowledge about the power of epigenetics to alter developmental pathways. Importantly, conservation breeding programmes, used widely by zoological parks and aquariums, may appear in some cases to reduce fitness by decreasing animals’ abilities to cope when confronted with the ‘wild side’ of their natural habitats. Would less comfortable captive conditions lead to the selection of individuals that, despite being adapted to life in a captive environment, be better able to thrive if relocated to a more natural environment? While threatened populations may benefit from advanced reproductive technologies, these may actually induce undesirable epigenetic changes. Thus, there may be inherent risks to the health and welfare of offspring (as is suspected in humans). Advanced breeding technologies, especially those that aim to regenerate the rarest species using stem cell reprogramming and artificial gametes, may also lead to unwanted epigenetic modifications. Current knowledge is still incomplete, and therefore ethical decisions about novel breeding methods remain controversial and difficult to resolve.