Intentional genetic introgression influences survival of adults and subadults in a small, inbred felid population

SAIC-Frederick, National Cancer Institute, Frederick, MD 21702-1201, USA
Journal of Animal Ecology (Impact Factor: 4.5). 08/2011; 80(5):958 - 967. DOI: 10.1111/j.1365-2656.2011.01809.x
Source: PubMed


Summary1. Inbreeding and low genetic diversity can cause reductions in individual fitness and increase extinction risk in animal populations. Intentional introgression, achieved by releasing genetically diverse individuals into inbred populations, has been used as a conservation tool to improve demographic performance in endangered populations.2. By the 1980s, Florida panthers (Puma concolor coryi) had been reduced to a small, inbred population that appeared to be on the brink of extinction. In 1995, female pumas from Texas (P. c. stanleyana) were released in occupied panther range as part of an intentional introgression programme to restore genetic variability and improve demographic performance of panthers.3. We used 25 years (1981–2006) of continuous radiotelemetry and genetic data to estimate and model subadult and adult panther survival and cause-specific mortality to provide rigorous sex and age class-specific survival estimates and evaluate the effect of the introgression programme on these parameters.4. Genetic ancestry influenced annual survival of subadults and adults after introgression, as F1 generation admixed panthers ( = 0·98) survived better than pre-introgression type panthers ( = 0·77) and other admixed individuals ( = 0·82). Furthermore, heterozygosity was higher for admixed panthers relative to pre-introgression type panthers and positively influenced survival.5. Our results are consistent with hybrid vigour; however, extrinsic factors such as low density of males in some areas of panther range may also have contributed to higher survival of F1 panthers. Regardless, improved survival of F1 subadults and adults likely contributed to the numerical increase in panthers following introgression, and our results indicate that intentional admixture, achieved here by releasing individuals from another population, appears to have been successful in improving demographic performance in this highly endangered population.

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    • "Discussions with Florida cattlemen are consistent with the literature on human-cougar conflicts. Florida cattlemen expressed a real concern that efforts to recover the Florida panther by introducing female Texas cougars (see Benson et al. 2011) have resulted in a hybrid panther-cougar that is larger, more aggressive and more prolific than the panther (prior to the genetic introgression). Cattlemen contend that the panther is no longer afraid of humans and is openly entering people's backyards to prey on their domestic animals, including pets and hobby livestock. "
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    ABSTRACT: Recovery of the Florida panther (Puma concolor coryi) depends on habitat conservation on private rangelands. However, cattlemen-panther conflicts and lack of trust in wildlife agencies is undermining panther conservation efforts. Based on semi-structured interviews and group meetings with Florida cattlemen, we examine how cattlemen's land stewardship practices support panther conservation, and causes of conflicts with the panther and wildlife agencies. Given the heterogeneous attitudes of cattlemen and their varying economic conditions, a complementary suite of programs is needed to achieve efficient conservation of the panther and panther habitat. Current and proposed government incentive programs are unlikely to attain the level of habitat conservation required to recover the Florida panther. We suggest that efforts should be made to build social capital and trust by engaging influential cattlemen in panther conservation actions, thereby lending credibility to conservation initiatives and improving the rate of uptake and levels of commitment by other cattlemen. Moreover, providing cattlemen with payments that are contingent on keeping lands as unimproved pasture or wildlife habitat without mandating particular land management practices may be an effective policy alternative.
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    • "Since the introduction of the Texas subspecies, the incidence of inbreeding traits has decreased (Mansfield & Land, 2002; Onorato et al., 2010), heterozygosity has increased (Johnson et al., 2010), and the population size has increased (McBride et al., 2008). The F 1 hybrids had higher survival (Benson et al., 2011; Hostetler et al., 2010). However, both the F 1 hybrids and the backcross with the Texas subspecies had lower reproduction probabilities (Hostetler et al., 2012). "
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    • "Although subspecies of tigers do have morphological and behavioral differences that are likely to be locally adaptive, the question is whether conservation of the individual subspecies is practical, or even possible. Indeed, crossbreeding with another subspecies may have saved the Florida panther; after introduction of individuals from a closely related subspecies in 1995 (Seal 1994; Hedrick 1995), the population has risen to 104 individuals as of 2008 and deleterious genetic disorders are less common, genetic diversity has increased, and overall fitness is higher (Land et al. 2002; Johnson et al. 2010; Benson et al. 2011). Results from our simulations show that crossbreeding subspecies may also be a valuable conservation tool for tigers. "
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