Cristian Roman Palacios

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• Wiens, J. J., Roman-palacios, C., & Moraga-lopez, D. (2022). The origins of global biodiversity on land, sea and freshwater.. Ecology letters. doi:10.1111/ele.13999
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  Many biodiversity studies focus on explaining high tropical species richness, but an equally dramatic yet understudied pattern involves the divergent richness of land, sea and freshwater. Here, we reveal the origins of these richness differences among habitats across animals and plants. Most plant and animal species are terrestrial, although these habitats cover only ~28% of Earth's surface. Marine habitats have fewer species over a larger area (~70%). Freshwater habitats have relatively high richness and exceptional phylogenetic diversity given their tiny area (2%). The relative richness of habitats is related to variation in diversification rates. Based on ancestral reconstructions of habitat, we find that most marine species are descended from marine ancestors and most terrestrial species from freshwater ancestors. Yet, most extant animal richness in freshwater is derived from terrestrial ancestors. Overall, our results reveal the origins of fundamental but neglected biodiversity patterns, and highlight the conservation importance of freshwater habitats.
• Medina, C. A., Zhan, S. H., Roman-palacios, C., & Barker, M. S. (2021). Animal chromosome counts reveal a similar range of chromosome numbers but with less polyploidy in animals compared to flowering plants.. Journal of evolutionary biology, 34(8), 1333-1339. doi:10.1111/jeb.13884
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  Understanding the mechanisms that underlie chromosome evolution could provide insights into the processes underpinning the origin, persistence and evolutionary tempo of lineages. Here, we present the first database of chromosome counts for animals (the Animal Chromosome Count database, ACC) summarizing chromosome numbers for ~15,000 species. We found remarkable a similarity in the distribution of chromosome counts between animals and flowering plants. Nevertheless, the similarity in the distribution of chromosome numbers between animals and plants is likely to be explained by different drivers. For instance, we found that while animals and flowering plants exhibit similar frequencies of speciation-related changes in chromosome number, plant speciation is more often related to changes in ploidy. By leveraging the largest data set of chromosome counts for animals, we describe a previously undocumented pattern across the Tree of Life-animals and flowering plants show remarkably similar distributions of haploid chromosome numbers.
• Roman-palacios, C., & Miller, E. C. (2021). Evolutionary time best explains the latitudinal diversity gradient of living freshwater fish diversity. Global Ecology and Biogeography, 30(3), 749-763. doi:10.1111/geb.13253
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  Abstract Aim The evolutionary causes of the latitudinal diversity gradient are debated. Hypotheses have ultimately invoked either faster rates of diversification in the tropics, or more time for diversification due to the tropical origins of higher taxa. Here we perform the first test of the diversification rate and time hypotheses in freshwater ray-finned fishes, a group comprising nearly a quarter of all living vertebrates. Location Global. Time period 368–0 mya. Major taxa studied Extant freshwater ray-finned fishes. Methods Using a mega-phylogeny of actinopterygian fishes and a global database of occurrence records, we estimated net diversification rates, the number of colonizations and regional colonization times of co-occurring species in freshwater drainage basins. We used Generalized Additive Models to test whether these factors were related to latitude. We then compared the influence of diversification rates, colonization numbers, colonization times and surface area on species richness, and how these factors are related to each other. Results While both diversification rates and time were related to richness, time had greater explanatory power and was more strongly related to latitude than diversification rates. Other factors (basin surface area, number of colonizations) also helped explain richness but were unrelated to latitude. The world’s most diverse freshwater basins (Amazon, Congo rivers) were dominated by lineages with Mesozoic origins. The temperate groups dominant today arrived near the K-Pg boundary, leaving comparatively less time to build richness. Diversification rates and colonization times were inversely related: recently colonized basins had the fastest rates, while ancient species-rich faunas had slower rates. Main conclusions We concluded that time is the lead driver of latitudinal richness disparities in freshwater fish faunas. We suggest that the most likely path to building very high species richness is through diversification over long periods of time, rather than diversifying quickly.
• Roman-palacios, C., Miller, E. C., Wiens, J. J., Roman-palacios, C., Miller, E. C., & Hernandez-hernandez, T. (2021). Speciation across the Tree of Life.. Biological reviews of the Cambridge Philosophical Society. doi:10.1111/brv.12698
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  Much of what we know about speciation comes from detailed studies of well-known model systems. Although there have been several important syntheses on speciation, few (if any) have explicitly compared speciation among major groups across the Tree of Life. Here, we synthesize and compare what is known about key aspects of speciation across taxa, including bacteria, protists, fungi, plants, and major animal groups. We focus on three main questions. Is allopatric speciation predominant across groups? How common is ecological divergence of sister species (a requirement for ecological speciation), and on what niche axes do species diverge in each group? What are the reproductive isolating barriers in each group? Our review suggests the following patterns. (i) Based on our survey and projected species numbers, the most frequent speciation process across the Tree of Life may be co-speciation between endosymbiotic bacteria and their insect hosts. (ii) Allopatric speciation appears to be present in all major groups, and may be the most common mode in both animals and plants, based on non-overlapping ranges of sister species. (iii) Full sympatry of sister species is also widespread, and may be more common in fungi than allopatry. (iv) Full sympatry of sister species is more common in some marine animals than in terrestrial and freshwater ones. (v) Ecological divergence of sister species is widespread in all groups, including ~70% of surveyed species pairs of plants and insects. (vi) Major axes of ecological divergence involve species interactions (e.g. host-switching) and habitat divergence. (vii) Prezygotic isolation appears to be generally more widespread and important than postzygotic isolation. (viii) Rates of diversification (and presumably speciation) are strikingly different across groups, with the fastest rates in plants, and successively slower rates in animals, fungi, and protists, with the slowest rates in prokaryotes. Overall, our study represents an initial step towards understanding general patterns in speciation across all organisms.
• Roman-palacios, C., Zhu, X., Romn-palacios, C., Liu, Y., Li, Z., He, Z., & Bai, Y. (2021). Goniurosaurus chengzheng sp. nov., a new species of Leopard Gecko from Guangxi, China (Squamata: Eublepharidae).. Zootaxa, 4996(3), 540-554. doi:10.11646/zootaxa.4996.3.8
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  Six species of geckos in the genus Goniurosaurus have been recorded from Guangxi, China. Here we describe a new species, Goniurosaurus chengzheng sp. nov. The new species is similar to allied species from Guangxi, but unique in a combination of the following characters: (1) four body bands with three between limb insertions; (2) precloacal pores 20; (3) body color reddish- brown; (4) snout to eye distance: eye to ear distance 1. We used the mitochondrial genes 16S and cytb to confirm the distinctiveness of the species and place it within a molecular phylogeny of Goniurosaurus. The type specimens are deposited in the Museum of Biology, East China Normal University (ECNU).
• Román Palacios, C., Wright, A., & Uyeda, J. (2021). treedata.table: a wrapper for data.table that enables fast manipulation of large phylogenetic trees matched to data. PeerJ, 9, e12450. doi:10.7717/peerj.12450
• Zhu, X., Wu, S., Romn-palacios, C., Roman-palacios, C., Reardon, C. R., Liu, Y., Li, Z., & He, Z. (2021). A new species of whip spider, Weygoldtia hainanensis sp. nov., from Hainan, China (Arachnida: Amblypygi: Charinidae).. Zootaxa, 5082(1), 65-76. doi:10.11646/zootaxa.5082.1.6
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  To date, only one species of whip spider has been recorded in China. Here, we describe a new species, Weygoldtia hainanensis sp. nov., from Hainan, China. The new species is morphologically similar to W. davidovi (Fage, 1946) and W. consonensis Miranda et al. 2021, but can be distinguished with a combination of the following characters: 26 segments in tibia I, 6-7 teeth on chelicerae, distitibia IV trichobothria sc and sf series each with 10-11 trichobothria. To validate our morphological inferences and support the erection of W. hainanensis sp. nov. as a new species, we sequenced the COI gene region for two individuals and performed molecular phylogenetic analyses. The inferred phylogenetic trees placed the new species within Weygoldtia and highlighted the evolutionary distinction between W. hainanensis sp. nov. and currently described whip spiders. The type specimens are deposited in the Museum of Biology, East China Normal University (ECNU).
• Roman-palacios, C., Damgaard, J., Cheng, L., Moreira, F. F., Ikawa, T., Weir, T. A., & Zettel, H. (2020). Molecular phylogeny of sea-skaters (Halobates Eschscholtz, 1822), relationship between Halobatini and Metrocorini, and a catalogue of the subfamily Halobatinae (Hemiptera: Heteroptera: Gerridae). Insect Systematics & Evolution, -1(2), 1-102. doi:10.1163/1876312x-00002197
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  We investigated the phylogenetic relationships among seven of the ten Halobatinae genera (Heteroptera: Gerridae) based on COI+II, 16S rRNA, and 28S rRNA genes. Our analyses recovered monophyly of Halobatinae, and suggested paraphyly of Metrocorini caused by the position of Ventidius and Esakia . Since our phylogenies did not infer monophyly of the subgenus Halobates (s.str.) within Halobatini, we synonymized Austrobates and Halobates ( Hilliella ) with Halobates . We confirmed that (1) the limnic lifestyle of Metrocorini was ancestral in Halobatinae, (2) the marine lifestyle evolved only once in the common ancestor of Asclepios + Halobates , (3) the limnic lifestyle of some members of Halobates was independently derived from marine ancestors, and that (4) the open ocean was colonized at least three times in Halobates . A catalogue of Halobatinae organized according to an updated classification is presented, including all known geographic distributions, bibliographical references, and additional notes to all species of the subfamily.
• Roman-palacios, C., Roman-palacios, C., Molina-henao, Y. F., & Barker, M. S. (2020). Polyploids increase overall diversity despite higher turnover than diploids in the Brassicaceae.. Proceedings. Biological sciences, 287(1934), 20200962. doi:10.1098/rspb.2020.0962
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  Although polyploidy is widespread across the plant Tree of Life, its long-term evolutionary significance is still poorly understood. Here, we examine the effects of polyploidy in explaining the large-scale evolutionary patterns within angiosperms by focusing on a single family exhibiting extensive interspecific variation in chromosome numbers. We inferred ploidy from haploid chromosome numbers for 80% of species in the most comprehensive species-level chronogram for the Brassicaceae. After evaluating a total of 94 phylogenetic models of diversification, we found that ploidy influences diversification rates across the Brassicaceae. We also found that despite diversifying at a similar rate to diploids, polyploids have played a significant role in driving present-day differences in species richness among clades. Overall, in addition to highlighting the complexity in the evolutionary consequences of polyploidy, our results suggest that rare successful polyploids persist while significantly contributing to the long-term evolution of clades. Our findings further indicate that polyploidy has played a major role in driving the long-term evolution of the Brassicaceae and highlight the potential of polyploidy in shaping present-day diversity patterns across the plant Tree of Life.
• Roman-palacios, C., Wiens, J. J., & Roman-palacios, C. (2020). Recent responses to climate change reveal the drivers of species extinction and survival.. Proceedings of the National Academy of Sciences of the United States of America, 117(8), 4211-4217. doi:10.1073/pnas.1913007117
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  Climate change may be a major threat to biodiversity in the next 100 years. Although there has been important work on mechanisms of decline in some species, it generally remains unclear which changes in climate actually cause extinctions, and how many species will likely be lost. Here, we identify the specific changes in climate that are associated with the widespread local extinctions that have already occurred. We then use this information to predict the extent of future biodiversity loss and to identify which processes may forestall extinction. We used data from surveys of 538 plant and animal species over time, 44% of which have already had local extinctions at one or more sites. We found that locations with local extinctions had larger and faster changes in hottest yearly temperatures than those without. Surprisingly, sites with local extinctions had significantly smaller changes in mean annual temperatures, despite the widespread use of mean annual temperatures as proxies for overall climate change. Based on their past rates of dispersal, we estimate that 57-70% of these 538 species will not disperse quickly enough to avoid extinction. However, we show that niche shifts appear to be far more important for avoiding extinction than dispersal, although most studies focus only on dispersal. Specifically, considering both dispersal and niche shifts, we project that only 16-30% of these 538 species may go extinct by 2070. Overall, our results help identify the specific climatic changes that cause extinction and the processes that may help species to survive.
• Zhu, X., Roman-palacios, C., Li, Z., He, Z., & Chen, G. (2020). Goniurosaurus gezhi sp. nov., a new gecko species from Guangxi, China (Squamata: Eublepharidae).. Zootaxa, 4852(2), zootaxa.4852.2.6. doi:10.11646/zootaxa.4852.2.6
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  Five species of geckos in the genus Goniurosaurus had been recorded from Guangxi, China. Here we describe a new species, Goniurosaurus gezhi sp. nov. Zhu, He Li. The new species is similar to those found in Guangxi and Guizhou provinces of China and Northern Vietnam, but unique in a combination of the following characters: (1) three body bands between limb insertions; (2) precloacal pores 18-20; (3) body small (SVL=70.6-83.8 mm); (4) body color orange to yellow. We evaluated the phylogenetic position of this new species based on the 16S mitochondrial gene. Molecular phylogenies validate this new species as distinct to currently described lineages within Goniurosaurus. The type specimens are deposited in the Museum of Biology, East China Normal University (ECNU).
• Roman-palacios, C., Scholl, J. P., Wiens, J. J., Scholl, J. P., & Roman-palacios, C. (2019). Evolution of diet across the animal tree of life.. Evolution letters, 3(4), 339-347. doi:10.1002/evl3.127
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  What an animal eats is a fundamental aspect of its biology, but the evolution of diet has not been studied across animal phylogeny. Here, we performed a large-scale phylogenetic analysis to address three unresolved questions about the evolution of animal diets. (i) Are diets conserved across animal phylogeny? (ii) Does diet influence rates of species proliferation (diversification) among animal phyla? (iii) What was the ancestral diet of animals and major animal clades? We analyzed diet data for 1087 taxa, proportionally sampled among animal phyla based on the relative species richness of phyla. Our survey suggests that across animals, carnivory is most common (∼63%), herbivory less common (∼32%), and omnivory relatively rare (∼3%). Despite considerable controversy over whether ecological traits are conserved or labile, we found strong conservatism in diet over extraordinarily deep timescales. We found that diet is unrelated to rates of species diversification across animal phyla, contrasting with previous studies showing that herbivory increased diversification within some important groups (e.g., crustaceans, insects, and mammals). Finally, we estimated that the ancestor of all animals was most likely carnivorous, as were many major phyla (e.g., arthropods, molluscs, and chordates). Remarkably, our results suggest that many carnivorous species living today may have maintained this diet through a continuous series of carnivorous ancestors for >800 million years.
• Roman-palacios, C., Tavera, J. J., & Castaneda, M. D. (2018). When did anoles diverge? An analysis of multiple dating strategies.. Molecular phylogenetics and evolution, 127, 655-668. doi:10.1016/j.ympev.2018.06.012
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  Whereas most of the studies that discuss the evolutionary divergence of Anolis lizards have dated the clade's crown group in between 31 and 64 Ma, a single study has recovered a significantly older age for the same node (87 Ma). These differences also entail notable consequences on the preferred biogeographical hypothesis for the whole clade. Here we analyze a total of seven dating strategies by combining three calibration sources in independent BEAST runs to infer the most probable divergence timing for anole lizards (a mitochondrial rate for ND2 gene, the Anolis dominicanus fossil, and a group of fossils assigned to the Priscagamines, Iguanines, and Idontosaurus clades). Based on the estimated timing, we also addressed whether chronograms differ the most in deeper or shallower nodes by exploring the trend in the standard deviation of mean ages between chronograms across time. Next, we focus on the pattern for a single shallow node by hypothesizing the biogeography of the island-endemic Malpelo anole (Anolis agassizi), and evaluating the temporal congruence between the species' divergence and the island geology. The estimated set of ages suggests that anoles most likely diverged 72 Ma (71-73 Ma), with the crown group established around 58 Ma (51-65 Ma). Dispersal is therefore supported as the major driver in the biogeography of the group (and in Caribbean lineages in particular). Our analyses also indicated that (1) rate-based analyses pulled dates toward younger ages, (2) the differences in node ages between chronograms decrease towards the tips regardless of the position of the constrained node, and that (3) the estimated age for deep nodes (e.g. Anolis stem) is highly influenced when deep nodes are also constrained. The latter two results imply that the estimated age for shallower nodes is largely unaffected by the used temporal constraint. The congruence of all chronograms for the Malpelo anole also supports this finding. Anolis agassizi was found to have diverged before the emergence of Malpelo island in each analysis (anole: 19-31 Ma vs. Malpelo island: 16-17 Ma). Finally, we recommend when performing absolute dating analyses to first test for sequence saturation in the analyzed dataset (especially when calibrations are based on molecular rates). Our study also points out the importance of using multiple node constraints, especially when placed deeply in the tree, for fossil-based divergence dating analyses.
• Roman-palacios, C., Wiens, J. J., & Roman-palacios, C. (2018). The Tortoise and the Finch: Testing for island effects on diversification using two iconic Galápagos radiations. Journal of Biogeography, 45(8), 1701-1712. doi:10.1111/jbi.13366
• Roman-palacios, C., Wiens, J. J., Roman-palacios, C., & Meyer, A. L. (2018). BAMM gives misleading rate estimates in simulated and empirical datasets.. Evolution; international journal of organic evolution, 72(10), 2257-2266. doi:10.1111/evo.13574
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  In a previous paper, we used simulations and empirical data to show that BAMM (Bayesian Analysis of Macroevolutionary Mixtures) can give misleading estimates of rates and rate shifts. In simulations, BAMM underestimated rate shifts across every tree analyzed, and assigned incorrect rates to most clades in most trees. In empirical analyses, BAMM behaved as expected from simulations, and assigned different rates to clades when clades were analyzed alone versus across the tree (i.e., with rate heterogeneity). Rabosky recently criticized our paper, focusing primarily on the idea that our comparison of BAMM to another approach (method-of-moments estimators of Magallón and Sanderson, or MS estimators) was unfair to BAMM. Here, we provide further evidence that BAMM gives misleading rate estimates in empirical studies. We then describe how Rabosky's rown method comparisons were either acknowledged as being problematic or were described inaccurately (to favor BAMM). Finally, we show that the MS estimators can perform well when rates vary over time, despite untested assertions that they require constant rates to be accurate. Many other methods are available for analyzing diversification rates: we argue that BAMM should be avoided for estimating both diversification rates and rate shifts.
• Roman-palacios, C., Fernandez-garzon, S., Valencia-zuleta, A., Jaramillo-martinez, A. F., Vega, R. A., Zuleta, A. V., Viafara-vega, R. A., Palacios, C. R., Martinez, A. F., & Garzon, S. F. (2017). Lista anotada de la herpetofauna del departamento del Quindío, Colombia. Biota Colombiana, 18(1), 251-281. doi:10.21068/c2017.v18n01a16
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  The increasing uncertainty about the conservation status of the different biological groups emphasizes the importance of concentrating efforts on gathering diversity records. In Colombia, biological explorations have revealed priority areas for conservation, but the lack of information about topics as species distribution, restricts both the emphasis and efficiency of conservation efforts. In particular, Quindio department represents an important area of faunal interest due to its geographical position and climatic conditions. However, still lacks of basic information for an comprehensive discussion of local diversity. This works aims to summarize the information on richness, geographic distribution and diversity of the herpetofauna in the department. Published information from different bibliographic resources indicates that about 108 species of amphibians and reptiles (48 and 57 spp. respectively) coexist within the political boundaries. Among these, the genus Anolis and Pristimantis recorded the highest species diversity. Despite the reduced department’s size, the species that have been recorded exhibit remarkable ecological importance and also act as a reservoir of diversity regarding surrounding areas.
• Roman-palacios, C., Aldrete, A. N., & Obando, R. G. (2016). Historical biogeography of Thyrsophorini psocids and description of a new neotropical species of Thyrsopsocopsis (Psocodea: Psocomorpha: Psocidae). European journal of taxonomy. doi:10.5852/ejt.2016.194
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  When based on phylogenetic proposals, biogeographic historic narratives have a great interest for hypothesizing paths of origin of the current biodiversity. Among the many questions that remain unsolved about psocids, the distribution of Thyrsophorini represents still a remarkable enigma. This tribe had been considered as exclusively Neotropical, until the description of Thyrsopsocopsis thorntoni Mockford, 2004, from Vietnam. Three hypotheses have been proposed to explain this atypical distribution, recurring to dispersal, vicariance and morphological parallelism between lineages, but the lack of evidence has not allowed a unique support. Here, we describe a new Neotropical species of Thyrsopsocopsis , and also attempt to test the three biogeographical hypotheses in a phylogenetic context. In our analyses, the position of Cycetes (Cycetini) and Thyrsopsocopsis among Thyrsophorini psocids is well resolved, suggesting a dispersal event from the Neotropics for both genera.
• Roman-palacios, C., Obando, R. G., & Aldrete, A. N. (2016). Uncovering the diversity of the neotropical genus Elaphopsocus ('Psocoptera': Psocidae: Amphigerontiinae): from one to ten species.. Zootaxa, 4162(2), 373-80. doi:10.11646/zootaxa.4162.2.11
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  For 75 years, the genus Elaphopsocus was considered a monotypic lineage of neotropical psocids. As a result of recent work in South America, this genus presently includes seven species from Brazil and Colombia. We here describe three new species from the East Colombian high Andes.
• Roman-palacios, C., & Roman-valencia, C. (2015). Hábitos tróficos de dos especies sintópicas de carácidos en una quebrada de alta montaña en los Andes colombianos. Revista Mexicana De Biodiversidad, 86(3), 782-788. doi:10.1016/j.rmb.2015.06.009
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  To analyze the degree of trophic overlap, 2 species of Neotropical characins were considered: Hemibrycon brevispini and Bryconamericus caucanus. Both species have been identified as having an insectivorous diet with a tendency to consume mayflies, hymenopterans, and dipterans. It was found that these fish share 65% of food items, which is reflected in their high trophic overlap (QS = 0.620). There is also no difference between the abundances of prey consumed. The values of trophic breadth, diversity, evenness, and richness were higher in B. caucanus than in H. brevispini, which explains the ecological flexibility exhibited by B. caucanus throughout its wide range of geographical distribution compared to H. brevispini. In these taxa, syntopy is mainly due to the high abundance of resources available during the year