Tick Infection of Caiman crocodilus fuscus at the Hidroprado Hydroelectric Dam in Colombia: New Records, Parasite Prevalence, and Blood Loss Rate

The main goal of this research was to identify the hard ticks (Acari: Ixodidae) found in 10 individuals of spectacled caiman (Caiman crocodilus fuscus) from 349 individuals captured at the Hidroprado hydroelectric dam in the Department of Tolima, Colombia. Parasite prevalence was 2.9%. A total of 40 ticks were collected and two species identified: Amblyomma dissimile (n = 39) and Rhipicephalus sanguineus (n = 1). This is the second record of A. dissimile in C. crocodilus in Colombia and the first record of R. sanguineus in crocodilians. The natural infection of C. c. fuscus by A. dissimile establishes this species as a host in the life cycle of this tick. Similarly, parasitism by R. sanguineus indicates C. c. fuscus as a potential host for this tick, which is important since it is associated with domestic animals and has a high potential for transmission of zoonotic diseases. Our results highlight the parasitic relationship between ticks and one of the most resistant wild vertebrates: caimans. The prevalence, although not high, establishes the potential of ticks to parasitize different species and to be a vector of diseases for new groups of hosts.Fil: Mora Rivera, Nohora Cristina. Universidad del Tolima; ColombiaFil: Suarez Páez, Fernando. Universidad Cooperativa de Colombia; ColombiaFil: Pacheco Sierra, Gualberto Jesus. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Vargas Cuevas, Laura. Universidad Cooperativa de Colombia; ColombiaFil: Padilla Barreto, Mónica. Universidad Cooperativa de Colombia; Colombi

Ancestral Hybridization Yields Evolutionary Distinct Hybrids Lineages and Species Boundaries in Crocodiles, Posing Unique Conservation Conundrums

Interspecific hybridization can lead to adaptation and speciation, especially in the context of recent radiations. The emblematic Crocodylus (true crocodiles) is the most broadly distributed, ecologically diverse, and species-rich crocodylian genus. Nonetheless, their within-species evolutionary processes are poorly resolved mainly due to their potential for hybridization. Notably, the evolutionary outcomes when hybridization is ancient and involves long-lived species, like crocodiles, remain largely unexplored. Here, we evaluate the genomic admixture between the American (Crocodylus acutus) and the Morelet's (Crocodylus moreletii) species, and demonstrate that this hybridization system challenges the definition of species boundaries and poses a triple conservation conundrum: what has been recognized as C. acutus is actually two distinct species, therefore its taxonomic reassessment is needed; we identified two evolutionary distinct hybrids lineages, which are genetically discernible from the parental species; the remaining C. moreletii populations evidence its likely extinction as a species and/or evolution via hybridization. Hence, the crocodiles' distinct species and hybrids lineages warrant recognition and need urgent conservation efforts

Data from: Genetic and morphological evidence of a geographically widespread hybrid zone between two crocodile species, Crocodylus acutus and Crocodylus moreletii

Hybrid zones represent natural laboratories to study gene flow, divergence and the nature of species boundaries between closely related taxa. We evaluated the level and extent of hybridization between Crocodylus moreletii and C. acutus using genetic and morphological data on 300 crocodiles from 65 localities. To our knowledge, this is the first genetic study that includes the entire historic range and sympatric zone of the two species. Contrary to expectations, Bayesian admixture proportions and maximum likelihood estimates of hybrid indexes revealed that most sampled crocodiles were admixed and that the hybrid zone is geographically extensive, extending well beyond their historical region of sympatry. We identified a few geographically isolated, non-admixed populations of both parental species. Hybrids do not appear to be F1s or recent backcrosses, but rather are more likely later-generation hybrids, suggesting that hybridization has been going on for several to many generations and is mostly the result of natural processes. C. moreletii is not the sister species of C. acutus, suggesting that the hybrid zone formed from secondary contact rather than primary divergence. Non-admixed individuals from the two species were distinguishable based on morphological characters, whereas hybrids had a complex mosaic of morphological characters that hinders identification in the wild. Very few non-admixed C. acutus and C. moreletii populations exist in the wild. Consequently, the last non-admixed C. moreletii populations have become critically endangered. Indeed, not only the parental species but also the naturally occurring hybrids should be considered for their potential conservation value

SNPs data

Acutus_moreletii_SNPs.vcf - This file includes 12879 SNP markers identified in Crocodylus acutus and C. moreletii from Mexico

Data from: Ancestral hybridization yields evolutionary distinct hybrids lineages and species boundaries in crocodiles, posing unique conservation conundrums

Interspecific hybridization can lead to adaptation and speciation, especially in the context of recent radiations. The emblematic Crocodylus (true crocodiles) is the most broadly distributed, ecologically diverse, and species-rich crocodylian genus. Nonetheless, their within-species evolutionary processes are poorly resolved mainly due to their potential for hybridization. Notably, the evolutionary outcomes when hybridization is ancient and involves long-lived species, like crocodiles, remain largely unexplored. Here, we evaluate the genomic admixture between the American (Crocodylus acutus) and the Morelet’s (Crocodylus moreletii) species, and demonstrate that this hybridization system challenges the definition of species boundaries and poses a triple conservation conundrum: what has been recognized as C. acutus is actually two distinct species, therefore its taxonomic reassessment is needed; we identified two evolutionary distinct hybrids lineages, which are genetically discernible from the parental species; the remaining C. moreletii populations evidence its likely extinction as a species and/or evolution via hybridization. Hence, the crocodiles’ distinct species and hybrids lineages warrant recognition and need urgent conservation efforts

microsatellite genotypes table

Genotypes for 374 crocodile individuals obtained in the study based on 12 polymorphic microsatellites loc

Coord_msat_alleles

File contains data for each sample with the locality (name of locality), coordinates (WGS84) and microsatellite genotypes for all individual

Phylogeographical analysis and phylogenetic inference based on the cytochrome b gene in the genus Caiman (Crocodylia: Alligatoridae) in Central and South America

The genus Caiman is one of the most taxonomically conflictive among crocodilians due to different views about the phylogenetic position of Caiman crocodilus, which has four subspecies: Caiman crocodilus crocodilus, Caiman crocodilus fuscus, Caiman crocodilus chiapasius and Caiman crocodilus apaporiensis, but some studies recognize C. yacare as a subspecies of C. crocodilus or as a Caiman crocodilus/yacare complex. In Argentina, Caiman latirostris and Caiman yacare are present and included in sustainable use programs although they are scarcely studied at the genetic level. The present study had two main objectives: 1) to study the genetic diversity, structure, and phylogeny of C. yacare and C. latirostris in Argentina and, 2) to perform a phylogenetic analysis of the genus Caiman throughout its entire distribution. The results show high haplotype diversity for both species but low nucleotide diversity for C. latirostris. Phylogenetic analysis shows a clear separation between both species, but surprisingly, a well-differentiated clade belonging to the Chaco region is was observed. The phylogenetic analysis exhibited determined clades made up of the sequences of each Caiman species, with some inconsistencies: in the clade of C. crocodilus, one sequence of C. yacare is included, and one clade is observed including sequences from C. c. fuscus and C. c. chiapasius. These data indicate the need to undertake interdisciplinary studies to clarify the taxonomic status of these crocodilian species.Fil: Amavet, Patricia Susana. Universidad Nacional del Litoral. Facultad de Humanidades y Ciencias. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Pacheco Sierra, Gualberto Jesus. Universidad Nacional Autonoma de Mexico. Facultad de Ciencias; México. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Uhart, Marcela María. University of California; Estados UnidosFil: Prado, Walter. Secretaría de Ambiente y Desarrallo Sustentable de la Nación; ArgentinaFil: Siroski, Pablo Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; Argentin

Mantel_Matrix

Matrix of individual pairwise geographic distance (kilometers; below diagonal) and genetic distances (above diaginal; Nei´s DA; Nei et al. 1983)

Genomic and environmental insights and conservation challenges for two hybridizing iconic crocodile species across Mexico: Crocodylus acutus and C. moreletii

Hybridization is of key relevance for conservation of wild species, and yet it is still one of the most controversial issues in conservation. Identifying historical and contemporary factors promoting the formation and maintenance of hybrids is crucial for the management of endangered species, as well as characterizing the environmental factors and patterns of habitat use among parental species and their hybrids. Crocodiles are a conservation priority group since all 23 species recognized worldwide are in a protected category and hybridization occurs between many of their species, particularly between Crocodylus acutus and C. moreletii. Their hybridization system encompasses a geographically extensive hybrid zone, where two distinct hybrids and two C. acutus lineages have diverged and only a few geographically isolated populations of both parental species remain. We used a combined approach of genome-wide sequencing and ecological niche modeling to discern the geographic and temporal patterns of introgression, migration, and demography, and to assess the ecological niches of the distinct lineages. Our approach enabled us to determine the spatial and temporal components of the divergence and admixture events of hybrids and non-admixed lineages, to describe the environmental characteristics and geographic extent of areas of sympatry, and to confirm human-mediated hybridization events. Our findings also showed overall distinct ranges and ecological niches among lineages, where hybrids presented a different set of environmental requirements from both parental species. This approach can be readily applied to different taxa and ecological contexts, providing species information on genetics and the environment with direct conservation relevance. We additionally describe the various conservation challenges that C. acutus and C. moreletii currently face, highlighting that these distinct crocodile species and hybrid lineages warrant recognition and need urgent conservation effort.ISSN:1367-9430ISSN:1469-179