Multiplex microsatellite PCR panels for the neotropical mangrove Rhizophora mangle: combining efforts towards a cost-effective and modifiable tool to better inform conservation and management

Better-informed mangrove conservation and management practices are needed as the ecosystem services provided by these intertidal forests continue to be threatened by increasing anthropogenic pressures and climate change. Multiple layers of knowledge are required to achieve this goal, including insights into population genetics of mangrove species. Understanding the importance of population-genetic insights to conservation, multiple research groups have developed microsatellite loci for the widespread, neotropical red mangrove, Rhizophora mangle. However, although a wealth of genetic markers exist, empirical research is limited in the number of these loci employed. Here, we designed two multiplex PCR panels that combine seven novel loci developed for this work and eight previously-developed loci from three research groups to generate 15-locus genotypes, more than twice the average number of loci used in previous research, in only two PCR. We demonstrated utility in R. mangle from four sites across ~2500 km near this species’ northern latitudinal limits, and that these multiplex panels were better able to delineate populations than data subsets with numbers of loci comparable to previous research. We focus our discussion on how this tool is a more-informative, efficient (both in terms of time and resources), and easily-modifiable alternative to address many pressing conservation and management issues, such as the generation of baseline genetic data for areas not yet studied, better defining management units, and monitoring genetic effects of restoration projects. We also provide a quick protocol that outlines each step in this procedure to facilitate the use of this tool by others

Evidence for the genetic similarity rule at an expanding mangrove range limit

Premise Host-plant genetic variation can shape associated communities of organisms. These community-genetic effects include (1) genetically similar hosts harboring similar associated communities (i.e., the genetic similarity rule) and (2) host-plant heterozygosity increasing associated community diversity. Community-genetic effects are predicted to be less prominent in plant systems with limited genetic variation, such as those at distributional range limits. Yet, empirical evidence from such systems is limited. Methods We sampled a natural population of a mangrove foundation species (Avicennia germinans) at an expanding range limit in Florida, USA. We measured genetic variation within and among 40 host trees with 24 nuclear microsatellite loci and characterized their foliar endophytic fungal communities with internal transcribed spacer (ITS1) gene amplicon sequencing. We evaluated relationships among host-tree genetic variation, host-tree spatial location, and the associated fungal communities. Results Genetic diversity was low across all host trees (mean: 2.6 alleles per locus) and associated fungal communities were relatively homogeneous (five sequence variants represented 78% of all reads). We found (1) genetically similar host trees harbored similar fungal communities, with no detectable effect of interhost geographic distance. (2) Host-tree heterozygosity had no detectable effect, while host-tree absolute spatial location affected community alpha diversity. Conclusions This research supports the genetic similarity rule within a range limit population and helps broaden the current scope of community genetics theory by demonstrating that community-genetic effects can occur even at expanding distributional limits where host-plant genetic variation may be limited. Our findings also provide the first documentation of community-genetic effects in a natural mangrove system

Genetic structure of a remnant Acropora cervicornis population.

Amongst the global decline of coral reefs, hope spots such as Cordelia Bank in Honduras, have been identified. This site contains dense, remnant thickets of the endangered species Acropora cervicornis, which local managers and conservation organizations view as a potential source population for coral restoration projects. The aim of this study was to determine the genetic diversity of colonies across three banks within the protected area. We identified low genetic diversity (FST = 0.02) across the three banks, and genetic similarity of colonies ranged from 91.3 to 95.8% between the banks. Clonality rates were approximately 30% across the three banks, however, each genotype identified was unique to each bank. Despite the low genetic diversity, subtle genetic differences within and among banks were demonstrated, and these dense thickets were shown not to be comprised of a single or a few genotypes. The presence of multiple genotypes suggests A. cervicornis colonies from these banks could be used to maintain and enhance genetic diversity in restoration projects. Management of hope spots, such as Cordelia Bank, and the incorporation of genetic information into restoration projects to ensure genetic diversity within out-planted populations, will be critical in the ongoing challenge of conserving and preserving coral reefs

Blind trading: A literature review of research addressing the welfare of Ball pythons in the exotic pet trade

Extensive numbers of Ball pythons are caught, bred, traded and subsequently kept in captivity across the world as part of the exotic pet industry. Despite their widespread availability as pets, relatively little is known about the potential welfare challenges affecting them. We reviewed the literature for research focused on the health and welfare of Ball pythons in the international pet trade. From a total of 88 articles returned from the search criteria, our analysis showed that very few actually focused on trade (10%) or animal welfare (17%). Instead, the majority (64%) of articles focused on veterinary science. There was a considerable bias towards physical health, with most studies neglecting the four other domains of animal welfare (behaviour, nutrition, environment and mental health). Furthermore, very few studies considered Ball pythons prior to resulting pet ownership, during wild capture and transportation or captive breeding operations. Our review demonstrates that our current understanding of welfare for Ball pythons traded as exotic pets is limited. We recommend that future research should focus on aspects of the industry that are currently overlooked, including the potential consequences of genetic selection during captive-breeding and the conditions provided for snakes prior to and during international transportation

Mating system variation in neotropical black mangrove, Avicennia germinans, at three spatial scales towards an expanding northern distributional limit

Climate-driven range expansion of ecosystem-defining foundation species can have wide-reaching ecological consequences. Expansion may also result in mating system changes in these foundation species because of the ecological characteristics of range margins, such as greater conspecific isolation and reduced pollinator availability. It is important to understand how mating systems may change during expansion due to their direct influence on intraspecific genetic and demographic dynamics. Here, we used 12 microsatellite loci to genotype progeny arrays of the neotropical black mangrove (Avicennia germinans) at six collection sites (n = 23 maternal trees; 1,612 genotyped propagules) along a latitudinal gradient towards a northern distributional limit on the Atlantic coast of Florida, USA (27.56–30.01oN), where mangroves have expanded into salt marsh over the past several decades. We assessed mating system variation at three spatial scales. First, at the species-distribution level, published outcrossing rates for tropical conspecifics were more than two times higher than those for subtropical Florida A. germinans, consistent with reductions in pollinator diversity and in mangrove abundance with latitude. Second, at the population level, Florida outcrossing rates did not systematically decline towards the northern range limit, but instead, a more open pollen-dispersal neighbourhood at the transition from mangrove to salt marsh dominance may elevate outcrossing until conspecific abundances become too low towards the range limit. Third, at the individual level, outcrossing increased as conspecific cover increased at the Florida range margin, consistent with density-dependent plastic shifts in mating system. These findings suggest that ecological structure influences the A. germinans mating system at varying spatial scales. Further research needs to evaluate the effect of A. germinans mating system variation on the survival and fitness of offspring and on the extent of population-level local adaptation at expanding distributional limits

Understanding the genetic diversity of the guayabillo (Psidium galapageium), an endemic plant of the Galapagos Islands

Oceanic archipelagos are known to host a variety of endemic plant species. The genetic diversity and structure of these species is an important indicator of their evolutionary history and can inform appropriate conservation strategies that mitigate the risks to which they’re exposed, including invasive species and environmental disturbances. A comprehensive consideration of the role of their natural history, as well as the landscape features and the geological history of the islands themselves is required to adequately understand any emerging patterns. Such is the case for the guayabillo (Psidium galapageium), an understudied endemic plant from the Galapagos Islands with important ecological and economic roles. In this study we designed and evaluated 13 informative SSR markers and used them to investigate the genetic diversity, population structure and connectivity of the guayabillo populations from San Cristobal, Isabela and Santa Cruz islands. A total of 208 guayabillo individuals were analyzed, revealing a strong population structure between islands and two distinct genetic lineages for the Santa Cruz population. Overall, the guayabillo genetic diversity is relatively high, an unusual pattern for an insular endemic species which is possibly explained by its polyploidy and the geographical features of the islands. These include their broad altitudinal ranges and habitat heterogeneity. For populations displaying a lower genetic diversity such as San Cristobal, the history of human disturbance could be an important factor explaining these observations. Some similarities between individuals in Santa Cruz and the San Cristobal population could be explained by population differentiation or distinct natural histories of separate lineages. Our findings highlight the complex population dynamics that shape the genetic diversity of species like the guayabillo and emphasize the need to explore the currently unresolved questions about this Galapagos endemic plant

The effect of multiple host species on a keystone parasitic plant and its aphid herbivores

1. The exploitation of shared resources by diverse organisms underpins the structure of ecological communities. Hemiparasitic plants and the insect herbivores feeding on them both rely, directly and indirectly, on the resources supplied by the parasite's host plant. Therefore, the identity and number of host plant species providing these resources is likely to be critical for parasite and herbivore performance. 2. We tested the effect of single and multiple host species on the biomass of the generalist parasitic plant Rhinanthus minor and the abundance of its aphid (Aphis gossypii) herbivores. 3. Parasite biomass was proportional to the number of haustorial connections to host roots and was determined by host species identity rather than host functional group. Host species identity was also an important influence on aphid population size, and parasites attached to Lotus corniculatus experienced a considerable reduction in aphid herbivory. 4. The effects on the parasite attaching to multiple hosts depended on the combination of species present. However, host mixtures generally benefitted aphids by diluting the negative effects of particular host species. 5. Our findings suggest that the specificity of host attachment alters the impact of this keystone parasitic plant on its own herbivores and, potentially, on the wider plant and herbivore community

Characterizing the genetic diversity of the Andean blueberry (Vaccinium floribundum Kunth.) across the Ecuadorian Highlands

The Ecuadorian páramo, a high altitude tundra-like ecosystem, is a unique source of various ecosystem services and distinct biodiversity. Anthropogenic activities are associated with its fragmentation, which alters ecological factors and directly threatens resident species. Vaccinium floribundum Kunth., commonly known as Andean blueberry or mortiño, is a wild shrub endemic to the Andean region and highly valued in Ecuador for its berries, which are widely used in food preparations and hold an important cultural value. Since it is a wild species, mortiño could be vulnerable to environmental changes, resulting in a reduction of the size and distribution of its populations. To evaluate the extent of these effects on the mortiño populations, we assessed the genetic diversity and population structure of the species along the Ecuadorian highlands. We designed and developed a set of 30 species-specific SSR (simple sequence repeats) markers and used 16 of these to characterize 100 mortiño individuals from 27 collection sites. Our results revealed a high degree of genetic diversity (HE = 0.73) for the Ecuadorian mortiño, and a population structure analyses suggested the existence of distinct genetic clusters present in the northern, central and southern highlands. A fourth, clearly differentiated cluster was also found and included individuals from locations at higher elevations. We suggest that the population structure of the species could be explained by an isolation-by-distance model and can be associated with the geological history of the Andean region. Our results suggest that elevation could also be a key factor in the differentiation of mortiño populations. This study provides an extensive overview of the species across its distribution range in Ecuador, contributing to a better understanding of its conservation status. These results can assist in the development of conservation programs for this valuable biological and cultural resource and for the páramo ecosystem as a whole

Hurricanes overcome migration lag and shape intraspecific genetic variation beyond a poleward mangrove range limit

Expansion of many tree species lags behind climate‐change projections. Extreme storms can rapidly overcome this lag, especially for coastal species, but how will storm‐driven expansion shape intraspecific genetic variation? Do storms provide recruits only from the nearest sources, or from more distant sources? Answers to these questions have ecological and evolutionary implications, but empirical evidence is absent from the literature. In 2017, Hurricane Irma provided an opportunity to address this knowledge gap at the northern range limit of the neotropical black mangrove (Avicennia germinans ) on the Atlantic coast of Florida, USA. We observed massive post‐hurricane increases in beach‐stranded A. germinans propagules at, and past, this species’ present‐day range margin when compared to a previously‐surveyed, non‐hurricane year. Yet, propagule dispersal does not guarantee subsequent establishment and reproductive success (i.e., effective dispersal). We also evaluated prior effective dispersal along this coastline with isolated A. germinans trees identified beyond the most northern established population. We used 12 nuclear microsatellite loci to genotype 896 hurricane‐driven drift propagules from nine sites and 10 isolated trees from four sites, determined their sources of origin, and estimated dispersal distances. Almost all drift propagules and all isolated trees came from the nearest sources. This research suggests that hurricanes are a prerequisite for poleward range expansion of a coastal tree species and that storms can shape the expanding gene pool by providing almost exclusively range‐margin genotypes. These insights and empirical estimates of hurricane‐driven dispersal distances should improve our ability to forecast distributional shifts of coastal species

The genetics of indirect ecological effects-plant parasites and aphid herbivores.

When parasitic plants and aphid herbivores share a host, both direct and indirect ecological effects (IEEs) can influence evolutionary processes. We used a hemiparasitic plant (Rhinanthus minor), a grass host (Hordeum vulgare) and a cereal aphid (Sitobion avenae) to investigate the genetics of IEEs between the aphid and the parasitic plant, and looked to see how these might affect or be influenced by the genetic diversity of the host plants. Survival of R. minor depended on the parasite's population of origin, the genotypes of the aphids sharing the host and the genetic diversity in the host plant community. Hence the indirect effects of the aphids on the parasitic plants depended on the genetic environment of the system. Here, we show that genetic variation can be important in determining the outcome of IEEs. Therefore, IEEs have the potential to influence evolutionary processes and the continuity of species interactions over time