Impact of Long-Term Pyriproxyfen Exposure on the Genetic Structure and Diversity of Aedes aegypti and Aedes albopictus in Manaus, Amazonas, Brazil.

Aedes aegypti and Aedes albopictus are responsible for transmitting major human arboviruses such as Dengue, Zika, and Chikungunya, posing a global threat to public health. The lack of etiological treatments and efficient vaccines makes vector control strategies essential for reducing vector population density and interrupting the pathogen transmission cycle. This study evaluated the impact of long-term pyriproxyfen exposure on the genetic structure and diversity of Ae. aegypti and Ae. albopictus mosquito populations. The study was conducted in Manaus, Amazonas, Brazil, where pyriproxyfen dissemination stations have been monitored since 2014 up to the present day. Double digest restriction-site associated DNA sequencing was performed, revealing that despite significant local population reductions by dissemination stations with pyriproxyfen in various locations in Brazil, focal intervention has no significant impact on the population stratification of these vectors in urban scenarios. The genetic structuring level of Ae. aegypti suggests it is more stratified and directly affected by pyriproxyfen intervention, while for Ae. albopictus exhibits a more homogeneous and less structured population. The results suggest that although slight differences are observed among mosquito subpopulations, intervention focused on neighborhoods in a capital city is not efficient in terms of genetic structuring, indicating that larger-scale pyriproxyfen interventions should be considered for more effective urban mosquito control.

Striking genetic homogeneity in the widespread South American bracken.

PREMISE: Bracken (Pteridium, Dennstaedtiaceae) is a cosmopolitan genus of aggressive disturbance colonizers that are toxic to agricultural livestock. The taxonomy of Pteridium has been treated in multiple schemes, ranging from one to six species worldwide, with numerous subspecies and varieties. Recent work has focused on the worldwide distribution and systematics of the bracken fern, but South America has been poorly represented. We present the first continent-wide sampling and analysis of Pteridium esculentum, a Southern Hemisphere diploid species. METHODS: Within South America, P. esculentum has several morphotypes, distinguished into subspecies by variation in indument and lamina architecture. We used double digest restriction site-associated DNA sequencing (ddRADSeq) to assess the phylogenetic relationships of P. esculentum subspecies. RESULTS: We found a striking genetic homogeneity in the species, being able to support only two morphotypes from molecular data: P. e. arachnoideum and P. e. campestre. We had high confidence for shallow and deep phylogenetic relationships, but less support for relationships among crown groups. CONCLUSIONS: We describe an east-west geographic pattern that would explain the relationships between populations; and, in contrast to previous studies, we detected differences with P. esculentum from Australia. These results will lay the foundations for studying variations in this species' behavior as a weed, as well as its impact on the production of agricultural livestock in South America.

Genetic Diversity Assessment in Plants from Reduced Representation Sequencing Data.

Genetic diversity refers to the variety of genetic traits within a population or a species. It is an essential aspect of both plant ecology and plant breeding because it contributes to the adaptability, survival, and resilience of populations in changing environments. This chapter outlines a pipeline for estimating genetic diversity statistics from reduced representation or whole genome sequencing data. The pipeline involves obtaining DNA sequence reads, mapping the corresponding reads to a reference genome, calling variants from the alignments, and generating an unbiased estimation of nucleotide diversity and divergence between populations. The pipeline is suitable for single-end Illumina reads and can be adjusted for paired-end reads. The resulting pipeline provides a comprehensive approach for aligning and analyzing sequencing data to estimate genetic diversity.

Using ddRADseq to assess the genetic diversity of in-farm and gene bank cacao resources in the Baracoa region, eastern Cuba, for use and conservation purposes.

The Baracoa region, eastern Cuba, hosts around 80 % of the country cacao (Theobroma cacao L.) plantations. Cacao plants in farms are diverse in origin and propagation, with grafted and hybrid plants being the more common ones. Less frequent are plants from cuttings, TSH progeny, and traditional Cuban cacao. A national cacao gene bank is also present in Baracoa, with 282 accessions either prospected in Cuba or introduced from other countries. A breeding program associated with the gene bank started in the 1990s based on agro-morphological descriptors. The genetic diversity of cacao resources in Baracoa has been poorly described, except for traditional Cuban cacao, affecting the proper development of the breeding program and the cacao planting policies in the region. To assess the population structure and genetic diversity of cacao resources in Baracoa region, we genotyped plants from both cacao gene bank (CG) and cacao farms (CF) applying a new ddRADseq protocol for cacao. After data processing, two SNPs datasets containing 11,425 and 6,481 high-quality SNPs were generated with 238 CG and 135 CF plants, respectively. SNPs were unevenly distributed along the 10 cacao chromosomes and laid mainly in noncoding regions of the genome. Population structure analysis with these SNP datasets identified seven and four genetic groups in CG and CF samples, respectively. Clustering using UPGMA and principal component analysis mostly agree with population structure results. Amelonado was the predominant cacao ancestry, accounting for 49.22 % (CG) and 57.73 % (CF) of the total. Criollo, Contamana, Iquitos, and Nanay ancestries were detected in both CG and CF samples, while Nacional and Marañon backgrounds were only identified in CG. Genetic differentiation among CG (FST ranging from 0.071 to 0.407) was higher than among CF genetic groups (FST: 0.093-0.282). Genetic diversity parameters showed similar values for CG and CF samples. The CG and CF genetic groups with the lowest genetic diversity parameters had the highest proportion of Amelonado ancestry. These results should contribute to reinforcing the ongoing breeding program and updating the planting policies on cacao farms, with an impact on the social and economic life of the region.

Genomic insights into isolation of the threatened Florida crested caracara (Caracara plancus).

We conducted a population genomic study of the crested caracara (Caracara plancus) using samples (n = 290) collected from individuals in Florida, Texas, and Arizona, United States. Crested caracaras are non-migratory raptors ranging from the southern tip of South America to the southern United States, including a federally protected relict population in Florida long thought to have been isolated since the last ice age. Our objectives were to evaluate genetic diversity and population structure of Florida's apparently isolated population and to evaluate taxonomic relationships of crested caracaras at the northern edge of their range. Using DNA purified from blood samples, we conducted double-digest restriction site associated DNA sequencing and sequenced the mitochondrial ND2 gene. Analyses of population structure using over 9,000 SNPs suggest that two major clusters are best supported, one cluster including only Florida individuals and the other cluster including Arizona and Texas individuals. Both SNPs and mitochondrial haplotypes reveal the Florida population to be highly differentiated genetically from Arizona and Texas populations, whereas, Arizona and Texas populations are moderately differentiated from each other. The Florida population's mitochondrial haplotypes form a separate monophyletic group, while Arizona and Texas populations share mitochondrial haplotypes. Results of this study provide substantial genetic evidence that Florida's crested caracaras have experienced long-term isolation from caracaras in Arizona and Texas and thus, represent a distinct evolutionary lineage possibly warranting distinction as an Evolutionarily Significant Unit (ESU) or subspecies. This study will inform conservation strategies focused on long-term survival of Florida's distinct, panmictic population.

Phylogenomics of the narrowly endemic Eurycheilichthys (Siluriformes: Loricariidae): Sympatric species with non-sister relationships suggest mainly allopatric speciation.

Armored catfishes of the genus Eurycheilichthys are endemic to Southern Brazil and Misiones (Argentina) comprising nine species of small size, with a high degree of sympatry and species diversity distributed in two river basins. Here we use new genome-wide data to infer a species phylogeny and test species boundaries for this poorly known group. We estimate 1) the phylogenetic relationships of the species of Eurycheilichthys based on 29,350 loci in 65 individuals of nine species plus outgroups, and 2) the population structure and differentiation based on 43,712 loci and 62 individuals to estimate how geography may have acted on speciation and formation of the sympatric species groups. Analyses support the monophyly of the genus and suggest two species-inclusive clades (East and West) with high support and very recently diverged species. Western clade contains E. limulus (from upper Jacuí River basin) that is sister to Western species of the Taquari-Antas basin plus E. paucidens. The Eastern clade contains E. pantherinus (from Uruguay River basin) sister to the Eastern species of the Taquari-Antas basin E. coryphaenus, plus the central-distributed species E. planus and E. vacariensis, and the more widely-distributed species E. luisae. Eurycheilichthys luisae is not monophyletic and may contain one or more cryptic species or hybrid individuals. A stronger diversity on structure of lineages on the Taquari-Antas, when compared to upper Uruguay and Jacuí River basins, and the fact that most of the sympatrically distributed taxa have non-sister relationships suggest a scenario of mainly allopatric speciation and may indicate a more dynamic landscape with headwater capture events among these tributaries.

A New Assessment of Robust Capuchin Monkey (Sapajus) Evolutionary History Using Genome-Wide SNP Marker Data and a Bayesian Approach to Species Delimitation.

Robust capuchin monkeys, Sapajus genus, are among the most phenotypically diverse and widespread groups of primates in South America, with one of the most confusing and often shifting taxonomies. We used a ddRADseq approach to generate genome-wide SNP markers for 171 individuals from all putative extant species of Sapajus to access their evolutionary history. Using maximum likelihood, multispecies coalescent phylogenetic inference, and a Bayes Factor method to test for alternative hypotheses of species delimitation, we inferred the phylogenetic history of the Sapajus radiation, evaluating the number of discrete species supported. Our results support the recognition of three species from the Atlantic Forest south of the São Francisco River, with these species being the first splits in the robust capuchin radiation. Our results were congruent in recovering the Pantanal and Amazonian Sapajus as structured into three monophyletic clades, though new morphological assessments are necessary, as the Amazonian clades do not agree with previous morphology-based taxonomic distributions. Phylogenetic reconstructions for Sapajus occurring in the Cerrado, Caatinga, and northeastern Atlantic Forest were less congruent with morphology-based phylogenetic reconstructions, as the bearded capuchin was recovered as a paraphyletic clade, with samples from the Caatinga biome being either a monophyletic clade or nested with the blond capuchin monkey.

Phenotypic and genetic characterization of Africanized Apis mellifera colonies with natural tolerance to Varroa destructor and contrasting defensive behavior.

Africanized Apis mellifera colonies with promising characteristics for beekeeping have been detected in northern Argentina (subtropical climate) and are considered of interest for breeding programs. Integral evaluation of this feral material revealed high colony strength and resistance/tolerance to brood diseases. However, these Africanized honeybees (AHB) also showed variable negative behavioral traits for beekeeping, such as defensiveness, tendency to swarm and avoidance behavior. We developed a protocol for the selection of AHB stocks based on defensive behavior and characterized contrasting colonies for this trait using NGS technologies. For this purpose, population and behavioral parameters were surveyed throughout a beekeeping season in nine daughter colonies obtained from a mother colony (A1 mitochondrial haplotype) with valuable characteristics (tolerance to the mite Varroa destructor, high colony strength and low defensiveness). A Defensive Behavior Index was developed and tested in the colonies under study. Mother and two daughter colonies displaying contrasting defensive behavior were analyzed by ddRADseq. High-quality DNA samples were obtained from 16 workers of each colony. Six pooled samples, including two replicates of each of the three colonies, were processed. A total of 12,971 SNPs were detected against the reference genome of A. mellifera, 142 of which showed significant differences between colonies. We detected SNPs in coding regions, lncRNA, miRNA, rRNA, tRNA, among others. From the original data set, we also identified 647 SNPs located in protein-coding regions, 128 of which are related to 21 genes previously associated with defensive behavior, such as dop3 and dopR2, CaMKII and ADAR, obp9 and obp10, and members of the 5-HT family. We discuss the obtained results by considering the influence of polyandry and paternal lineages on the defensive behavior in AHB and provide baseline information to use this innovative molecular approach, ddRADseq, to assist in the selection and evaluation of honey bee stocks showing low defensive behavior for commercial uses.

Phylogenomic analyses resolve relationships among garter snakes (Thamnophis: Natricinae: Colubridae) and elucidate biogeographic history and morphological evolution.

Garter snakes (Thamnophis) are a successful group of natricines endemic to North America. They have become important natural models for ecological and evolutionary research, yet prior efforts to resolve phylogenetic relationships have resulted in conflicting topologies and weak support for certain relationships. Here, we use genomic data generated with a reduced representation double-digest RADseq approach to reassess evolutionary relationships across Thamnophis. We then use the resulting phylogeny to better understand how biogeography and feeding ecology have influenced lineage diversification and morphological evolution. We recovered highly congruent and strongly supported topologies from maximum likelihood and Bayesian analyses, but some discordance with a multispecies coalescent approach. All phylogenomic estimates split Thamnophis into two clades largely defined by northern and southern North American species. Divergence time estimates and biogeographic analyses indicate a mid-Miocene origin of Thamnophis in Mexico. In addition, historic vicariant events thought to explain biogeographic patterns in other lineages (e.g., Isthmus of Tehuantepec, Rocky Mountain Range, and Trans-Mexican Volcanic Belt) appear to have influenced patterns of diversification in Thamnophis as well. Analyses of morphological traits associated with feeding ecology showed moderate to strong phylogenetic signal. Nevertheless, phylogenetic ANOVA suggested significant differences in certain cranial morphologies between aquatic specialists and garter snakes that are terrestrial-aquatic generalists, independent of evolutionary history. Our new estimate of Thamnophis phylogeny yields an improved understanding of the biogeographic history and morphological evolution of garter snakes, and provides a robust framework for future research on these snakes.

Population genomics and phylogeography of the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), in the United States, northern Mexico, and Argentina.

The boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), is an important pest of commercial cotton across the Americas. In the United States, eradication of this species is complicated by re-infestations of areas where eradication has been previously successful and by the existence of morphologically similar variants that can confound identification efforts. To date, no study has applied a high-throughput sequencing approach to better understand the population genetic structure of the boll weevil. Furthermore, only a single study has investigated genetic relationships between populations in North and South America. We used double digest restriction site-associated DNA sequencing (ddRADseq) to resolve the population genomic structure of the boll weevil in the southern United States, northern Mexico, and Argentina. Additionally, we assembled the first complete mitochondrial genome for this species and generated a preliminary whole genome assembly, both of which were used to improve the identification of informative loci. Downstream analyses revealed two main lineages-one consisting of populations found geographically west of the Sierra Madre Occidental mountain range and the second consisting of populations found to the east-were revealed, and both were sub-structured. Population geographic structure was consistent with the isolation by distance model, indicating that geogrpahic distance is likely a primary mechanism driving divergence in this species. Boll weevil populations from Argentina were found to be more closely related to the eastern lineage, suggesting a recent colonization of South America by the eastern lineage, but additional sampling across Mexico, Central America and South America is needed to further clarify their origin. Finally, we uncovered an instance of population turnover or replacement, highlighting the temporal instability of population structure.

By Animal, Water, or Wind: Can Dispersal Mode Predict Genetic Connectivity in Riverine Plant Species?

Seed dispersal is crucial to gene flow among plant populations. Although the effects of geographic distance and barriers to gene flow are well studied in many systems, it is unclear how seed dispersal mediates gene flow in conjunction with interacting effects of geographic distance and barriers. To test whether distinct seed dispersal modes (i.e., hydrochory, anemochory, and zoochory) have a consistent effect on the level of genetic connectivity (i.e., gene flow) among populations of riverine plant species, we used unlinked single-nucleotide polymorphisms (SNPs) for eight co-distributed plant species sampled across the Rio Branco, a putative biogeographic barrier in the Amazon basin. We found that animal-dispersed plant species exhibited higher levels of genetic diversity and lack of inbreeding as a result of the stronger genetic connectivity than plant species whose seeds are dispersed by water or wind. Interestingly, our results also indicated that the Rio Branco facilitates gene dispersal for all plant species analyzed, irrespective of their mode of dispersal. Even at a small spatial scale, our findings suggest that ecology rather than geography play a key role in shaping the evolutionary history of plants in the Amazon basin. These results may help improve conservation and management policies in Amazonian riparian forests, where degradation and deforestation rates are high.

New species boundaries and the diversification history of marsh rat taxa clarify historical connections among ecologically and geographically distinct wetlands of South America.

Taxa with broad geographic ranges that occur in different biomes and exhibit plastic morphological traits and/or adaptations to particular habitats make inferences about species boundaries especially challenging. However, technological and conceptual advances in the generation and analysis of genomic data have advanced the description of biodiversity. Here we address the outstanding questions about the delimitation of species in the genus Holochilus, a rodent with morphological specializations to wetland habitats distributed throughoutthe South America, using genome-wide SNP and morphometric data. Specifically, we apply a Bayesian model-based species delimitation that revealed significant re-arrangements of species boundaries based on consideration of both morphometric and genomic data alone, or in combination. With these shifts in species boundaries, our results provide an insightful framework for inferring the group's biogeographic history and considering possible connections between disjoint biomes in South America. Because of the ecological constraints of the marsh rats, and with the proposed taxonomic re-arrangements, the significance of our findings extends beyond systematics and suggests how diversification might be associated with past ecological/environmental changes during the Pleistocene. Overall, this study highlights how genomic data can provide phylogenetic information for resolving relationships among species of Holochilus, but also the importance of integrative approaches to identify evolutionary independent species. For the relatively understudied vast wetlands of South America, a robust species delimitation framework therefore becomes a critical source of data relevant to hypotheses about the history of the biomes themselves.

Evidence for the Pleistocene Arc Hypothesis from genome-wide SNPs in a Neotropical dry forest specialist, the Rufous-fronted Thornbird (Furnariidae: Phacellodomus rufifrons).

South American dry forests have a complex and poorly understood biogeographic history. Based on the fragmented distribution of many Neotropical dry forest species, it has been suggested that this biome was more widely distributed and contiguous under drier climate conditions in the Pleistocene. To test this scenario, known as the Pleistocene Arc Hypothesis, we studied the phylogeography of the Rufous-fronted Thornbird (Phacellodomus rufifrons), a widespread dry forest bird with a disjunct distribution closely matching that of the biome itself. We sequenced mtDNA and used ddRADseq to sample 7,167 genome-wide single-nucleotide polymorphisms from 74 P. rufifrons individuals across its range. We found low genetic differentiation over two prominent geographic breaks - particularly across a 1,000 km gap between populations in Bolivia and Northern Peru. Using demographic analyses of the joint site frequency spectrum, we found evidence of recent divergence without subsequent gene flow across those breaks. By contrast, parapatric morphologically distinct populations in northeastern Brazil show high genetic divergence with evidence of recent gene flow. These results, in combination with our paleoclimate species distribution modelling, support the idea that currently disjunct patches of dry forest were more connected in the recent past, probably during the Middle and Late Pleistocene. This notion fits the major predictions of the Pleistocene Arc Hypothesis and illustrates the importance of comprehensive genomic and geographic sampling for examining biogeographic and evolutionary questions in complex ecosystems like Neotropical dry forests.

The potential of genome-wide RAD sequences for resolving rapid radiations: a case study in Cactaceae.

The reconstruction of relationships within recently radiated groups is challenging even when massive amounts of sequencing data are available. The use of restriction site-associated DNA sequencing (RAD-Seq) to this end is promising. Here, we assessed the performance of RAD-Seq to infer the species-level phylogeny of the rapidly radiating genus Cereus (Cactaceae). To examine how the amount of genomic data affects resolution in this group, we used datasets and implemented different analyses. We sampled 52 individuals of Cereus, representing 18 of the 25 species currently recognized, plus members of the closely allied genera Cipocereus and Praecereus, and other 11 Cactaceae genera as outgroups. Three scenarios of permissiveness to missing data were carried out in iPyRAD, assembling datasets with 30% (333 loci), 45% (1440 loci), and 70% (6141 loci) of missing data. For each dataset, Maximum Likelihood (ML) trees were generated using two supermatrices, i.e., only SNPs and SNPs plus invariant sites. Accuracy and resolution were improved when the dataset with the highest number of loci was used (6141 loci), despite the high percentage of missing data included (70%). Coalescent trees estimated using SVDQuartets and ASTRAL are similar to those obtained by the ML reconstructions. Overall, we reconstruct a well-supported phylogeny of Cereus, which is resolved as monophyletic and composed of four main clades with high support in their internal relationships. Our findings also provide insights into the impact of missing data for phylogeny reconstruction using RAD loci.

Maintaining genetic integrity with high promiscuity: Frequent hybridization with low introgression in multiple hybrid zones of Melocactus (Cactaceae).

Hybridization and introgression between species in contact/hybrid zones provide important insight into the genetic and ecological mechanisms of speciation. Cactaceae represents the most important radiation of true succulent angiosperms in the New World. This diversification continues to date, with species experiencing few intrinsic barriers to gene flow and the frequent occurrence of natural hybridization. Here, we used RAD-Seq single-nucleotide polymorphism (SNP) data to investigate the genetic architecture of hybridization in four hybrid zones hosting Melocactus concinnus and four congeneric species (M. ernestii, M. glaucescens, M. paucispinus, and M. zehntneri). Our results revealed that M. concinnus is highly promiscuous in sympatric areas and hybridizes with various species distributed in Morro do Chapéu (Diamantina Plateau, Bahia), eastern Brazil. However, the contemporary genomic introgression among the investigated species is very low (c. 2-5%), confirming that even in the face of hybridization, Melocactus species maintain their genetic integrity. The genomic cline approach showed a large fraction of loci deviating from a model of neutral introgression, where most of the loci are consistent with selection favoring parental genotypes. Our results suggest the occurrence of weak premating but strong postmating reproductive isolation in the analyzed cactus species. Furthermore, as most of the Melocactus species are restricted in distribution, hybridization might negatively affect their integrity if hybrids replace the parental species.

Speciation across mountains: Phylogenomics, species delimitation and taxonomy of the Liolaemus leopardinus clade (Squamata, Liolaemidae).

Organisms rapidly diversifying across unstable environments such as mountain tops provide substantial challenges for resolving evolutionary histories and delimiting species. The Liolaemus leopardinus clade is a group of five species of lizards adapted to high altitudes in central Chile, with most species found in the Andes, but one species, L. frassinettii is found in the independent Costa Cordillera. Despite their allopatric distributions, they display shallow mitochondrial divergences, making phylogenetics and species delimitation of this clade hard to resolve. We use an integrative approach to delimit species by considering morphological data (linear and landmark-based), mitochondrial DNA (mtDNA), and nuclear DNA (Sequences and SNPs collected with ddRADseq). We find strong conflicting signals between phylogenetic analyses of the nuclear and mtDNA data. While mtDNA places L. frassinettii as sister to the rest of the clade, the SNPs support a south to north order of divergences, with southernmost species (new taxon described here) as sister to the rest of the clade. Moreover, species delimitation using mtDNA only supports two species (one in the Costa and one in the Andes), whereas combined analyses using the nuclear data and morphology support multiple Andean taxa, including a new one we describe here. Based on these results, population structure analyses and our knowledge of the geological and climatic history of the Andes, we argue that this mito-nuclear discordance is explained by past introgression among the Andean taxa, likely during glacial periods that forced these lizards to lower altitudes where they would hybridize. The complete isolation between the Costa and Andes cordilleras has prevented any further contact between taxa on either mountain chain. Our study highlights the importance of using multiple lines of evidence to resolve evolutionary histories, and the potential misleading results from relying solely on mtDNA.

Coalescent-based species delimitation in the sand lizards of the Liolaemus wiegmannii complex (Squamata: Liolaemidae).

Coalescent-based algorithms coupled with the access to genome-wide data have become powerful tools for assessing questions on recent or rapid diversification, as well as delineating species boundaries in the absence of reciprocal monophyly. In southern South America, the diversification of Liolaemus lizards during the Pleistocene is well documented and has been attributed to the climatic changes that characterized this recent period of time. Past climatic changes had harsh effects at extreme latitudes, including Patagonia, but habitat changes at intermediate latitudes of South America have also been recorded, including expansion of sand fields over northern Patagonia and Pampas). In this work, we apply a coalescent-based approach to study the diversification of the Liolaemus wiegmannii species complex, a morphologically conservative clade that inhabits sandy soils across northwest and south-central Argentina, and the south shores of Uruguay. Using four standard sequence markers (mitochondrial DNA and three nuclear loci) along with ddRADseq data we inferred species limits and a time-calibrated species tree for the L. wiegmannii complex in order to evaluate the influence of Quaternary sand expansion/retraction cycles on diversification. We also evaluated the evolutionary independence of the recently described L. gardeli and inferred its phylogenetic position relative to L. wiegmannii. We find strong evidence for six allopatric candidate species within L. wiegmannii, which diversified during the Pleistocene. The Great Patagonian Glaciation (∼1 million years before present) likely split the species complex into two main groups: one composed of lineages associated with sub-Andean sedimentary formations, and the other mostly related to sand fields in the Pampas and northern Patagonia. We hypothesize that early speciation within L. wiegmannii was influenced by the expansion of sand dunes throughout central Argentina and Pampas. Finally, L. gardeli is supported as a distinct lineage nested within the L. wiegmannii complex.

Holocene Population Decline and Conservation Implication for the Western Hercules Beetle, Dynastes grantii (Coleoptera, Scarabaeidae).

The Western Hercules beetle (Dynastes grantii) is endemic to the highland forest habitats of southwestern United States and northern Mexico. The habitats harbor many endemic species, but are being threatened by rapid climate change and urban development. In this study, the genetic structure of D. grantii populations from southwestern United States was investigated. Specifically, genomic data from double-digest restriction-site-associated DNA sequencing libraries were utilized to test whether geographically distant populations from the Mogollon Rim (Arizona [N = 12 individuals] and New Mexico [N = 10 individuals]) are genetically structured. The study also estimated the effective population size of the Mogollon Rim populations based on genetic diversity. The results indicated that the 2 geographic populations from the Mogollon Rim were not genetically structured. A population size reduction was detected since the end of the last glacial period, which coincided with a reduction of forest habitat in the study area. The results implied that the connectivity and the size of highland forest habitats in the Mogollon Rim could have been the major factors shaping the population genetic structure and demographic history of D. grantii. The Western Hercules beetle could be a useful flagship species for local natural history education and to promote the conservation of highland forest habitats.

Phylogenomics clarifies biogeographic and evolutionary history, and conservation status of West Indian tremblers and thrashers (Aves: Mimidae).

The West Indian avifauna has provided fundamental insights into island biogeography, taxon cycles, and the evolution of avian behavior. Our interpretations, however, should rely on robust hypotheses of evolutionary relationships and consistent conclusions about taxonomic status in groups with many endemic island populations. Here we present a phylogenetic study of the West Indian thrashers, tremblers, and allies, an assemblage of at least 5 species found on 29 islands, including what is considered the Lesser Antilles' only avian radiation. We improve on previous phylogenetic studies of this group by using double-digest restriction site-associated DNA sequencing (ddRAD-seq) to broadly sample loci scattered across the nuclear genome. A variety of analyses, based on either nucleotide variation in 2223 loci recovered in all samples or at 13,282 loci confidently scored as present or absent in all samples, converged on a single well-supported phylogenetic hypothesis. Results indicate that the resident West Indian taxa form a monophyletic group, exclusive of the Neotropical-Nearctic migratory Gray Catbird Dumetella carolinensis, which breeds in North America; this outcome differs from earlier studies suggesting that Gray Catbird was nested within a clade of island resident species. Thus, our findings imply a single colonization of the West Indies without the need to invoke a subsequent 'reverse colonization' of the mainland by West Indian taxa. Additionally, our study is the first to sample both endemic subspecies of the endangered White-breasted Thrasher Ramphocinclus brachyurus. We find that these subspecies have a long history of evolutionary independence with no evidence of gene flow, and are as genetically divergent from each other as other genera in the group. These findings support recognition of R. brachyurus (restricted to Martinique) and the Saint Lucia Thrasher R. sanctaeluciae as two distinct, single-island endemic species, and indicate the need to re-evaluate conservation plans for these taxa. Our results demonstrate the utility of phylogenomic datasets for generating robust systematic hypotheses.

Isolation by instability: Historical climate change shapes population structure and genomic divergence of treefrogs in the Neotropical Cerrado savanna.

Although the impact of Pleistocene glacial cycles on the diversification of the tropical biota was once dismissed, increasing evidence suggests that Pleistocene climatic fluctuations greatly affected the distribution and population divergence of tropical organisms. Landscape genomic analyses coupled with paleoclimatic distribution models provide a powerful way to understand the consequences of past climate changes on the present-day tropical biota. Using genome-wide SNP data and mitochondrial DNA, combined with projections of the species distribution across the late Quaternary until the present, we evaluate the effect of paleoclimatic shifts on the genetic structure and population differentiation of Hypsiboas lundii, a treefrog endemic to the South American Cerrado savanna. Our results show a recent and strong genetic divergence in H. lundii across the Cerrado landscape, yielding four genetic clusters that do not seem congruent with any current physical barrier to gene flow. Isolation by distance (IBD) explains some of the population differentiation, but we also find strong support for past climate changes promoting range shifts and structuring populations even in the presence of IBD. Post-Pleistocene population persistence in four main areas of historical stable climate in the Cerrado seems to have played a major role establishing the present genetic structure of this treefrog. This pattern is consistent with a model of reduced gene flow in areas with high climatic instability promoting isolation of populations, defined here as "isolation by instability," highlighting the effects of Pleistocene climatic fluctuations structuring populations in tropical savannas.