Origins and biogeography of the Anolis crassulus subgroup (Squamata: Dactyloidae) in the highlands of Nuclear Central America

Historical biogeography of the genus Rhadinaea (Squamata: Dipsadinae)

Multiple geological and climatic events have created geographical or ecological barriers associated with speciation events, playing a role in biological diversification in North and Central America. Here, we evaluate the influence of the Neogene and Quaternary geological events, as well as the climatic changes in the diversification of the colubrid snake genus Rhadinaea using molecular dating and ancestral area reconstruction. A multilocus sequence dataset was generated for 37 individuals of Rhadinaea from most of the biogeographical provinces where the genus is distributed, representing 19 of the 21 currently recognized species, and two undescribed species. Our analyses show that the majority of the Rhadinaea species nest in two main clades, herein identified as "Eastern" and "Southern". These clades probably diverged from each other in the early Miocene, and their divergence was followed by 11 divergences during the middle to late Miocene, three divergences during the Pliocene, and six divergences in the Pleistocene. The ancestral distribution of Rhadinaea was reconstructed across the Sierra Madre del Sur. Our phylogenetic analyses do not support the monophyly of Rhadinaea. The Miocene and Pliocene geomorphology, perhaps in conjunction with climate change, appears to have triggered the diversification of the genus, while the climatic changes during the Miocene probably induced the diversification of Rhadinaea in the Sierra Madre del Sur. Our analysis suggests that the uplifting of the Trans-Mexican Volcanic Belt and Chiapan-Guatemalan highlands in this same period resulted in northward and southward colonization events. This was followed by more recent, independent colonization events in the Pliocene and Pleistocene involving the Balsas Basin, Chihuahuan Desert, Pacific Coast, Sierra Madre Occidental, Sierra Madre Oriental, Sierra Madre del Sur, Trans-Mexican Volcanic Belt, and Veracruz provinces, probably driven by the climatic fluctuations of the time.

Evolution of the locomotor skeleton in Anolis lizards reflects the interplay between ecological opportunity and phylogenetic inertia

Anolis lizards originated in continental America but have colonized the Greater Antillean islands and recolonized the mainland, resulting in three major groups (Primary and Secondary Mainland and Greater Antillean). The adaptive radiation in the Greater Antilles has famously resulted in the repeated evolution of ecomorphs. Yet, it remains poorly understood to what extent this island radiation differs from diversification on the mainland. Here, we demonstrate that the evolutionary modularity between girdles and limbs is fundamentally different in the Greater Antillean and Primary Mainland Anolis. This is consistent with ecological opportunities on islands driving the adaptive radiation along distinct evolutionary trajectories. However, Greater Antillean Anolis share evolutionary modularity with the group that recolonized the mainland, demonstrating a persistent phylogenetic inertia. A comparison of these two groups support an increased morphological diversity and faster and more variable evolutionary rates on islands. These macroevolutionary trends of the locomotor skeleton in Anolis illustrate that ecological opportunities on islands can have lasting effects on morphological diversification.

Cryptic Diversity, but to What Extent? Discordance Between Single-Locus Species Delimitation Methods Within Mainland Anoles (Squamata: Dactyloidae) of Northern Central America

Single-locus molecular barcoding is a useful method for identifying overlooked and undescribed biodiversity, providing the groundwork for further systematic study and taxonomic investigation. A variety of methods for delimiting species from barcoding libraries have been developed and applied, allowing for rapid estimates of species diversity in a broad range of taxa. However, tree-based and distance-based analyses can infer different group assignments, potentially over- or underestimating the number of putative species groups. Here, we explore diversity of mainland species of anole lizards from the Chortís Block biogeographical province of northern Central America using a DNA barcoding approach, generating and analyzing cytochrome oxidase subunit I (COI) sequences for over 400 samples assignable to 33 of 38 (86.8%) native and one introduced mainland species. We subsequently tested the effects different models of nucleotide substitution, different species-delimitation algorithms, and reducing our dataset had on species delimitation estimates. We performed of two distance-based (ABGD, RESL) and three tree-based (bPTP, mPTP, GMYC) analyses on both the full dataset and a dataset consisting only of unique halotypes. From 34 nominal taxa, analyses of the full dataset recovered between 34 and 64 operational taxonomic units (OTUs), while analyses of the reduced dataset inferred between 36 and 59. Reassigning individuals to either mPTP-inferred or ABGD clustered (7.2% threshold) groups improved the detection of a barcoding gap across three different models of nucleotide substitution, removing overlap between intra- and interspecific distances. Our results highlight the underestimated diversity of mainland Chortís Block anoles, but the lack of congruence between analyses demonstrates the importance of considering multiple analytical methods when dealing with single-locus datasets. We recommend future studies consider the effects of different models of nucleotide substitution on proposed barcoding gaps, as well as the effect reducing a dataset to unique haplotypes may have on proposed diversity estimates.

Phylogenetics of Ogyges Kaup and the biogeography of Nuclear Central America (Coleoptera, Passalidae)

A phylogenetic morphological analysis of the genus Ogyges Kaup, distributed in Nuclear Central America, from Chiapas, Mexico, to northwestern Nicaragua was undertaken. Five species of Proculejus Kaup, distributed north of the Isthmus of Tehuantepec in Mexico, were selected as outgroup. Ogyges was recovered as monophyletic with three species groups: championi, laevissimus, and crassulus. Each species group shows a distinct, generally allopatric distribution. The O. championi species group, with ten species, is distributed in the Maya block, more specifically in the mountainous system north of the Motozintla-Comaltitlán fault in Chiapas, and north of the dry valleys of the Cuilco and Motagua rivers in Guatemala. The two remaining species groups are distributed in the Chortis block. The O. laevissimus species group, including seven species, ranges mostly along the Pacific Volcanic Chain from Guatemala to El Salvador, and from southeastern Honduras to the northwestern area of Nicaragua. The O. crassulus species group, with ten species, is distributed from northeastern Guatemala (Merendón) to northern Honduras. The Isthmus of Tehuantepec in Mexico, the Motagua-Cuilco and Motozintla-Comaltitlán sutures zones in Chiapas and Guatemala, the lowland valleys of Colón and Comalí rivers between Nicaragua and Honduras (or, perhaps, the northern suture of the Siuna Terrane in Nicaragua), the Guayape fault system in Honduras, and the intricate dry valleys of Ulúa-Chamelecón-Olancho in Honduras, are hypothesized to have acted as barriers that affected the geographical distribution of Ogyges, as well as probably other montane organisms.