1
|
Gvoždík V, Dolinay M, Zassi-Boulou AG, Lemmon AR, Lemmon EM, Procházka M. Central African dwarf crocodiles found in syntopy are comparably divergent to South American dwarf caimans. Biol Lett 2024; 20:20230448. [PMID: 38716586 PMCID: PMC11135362 DOI: 10.1098/rsbl.2023.0448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/18/2023] [Accepted: 03/04/2024] [Indexed: 05/31/2024] Open
Abstract
Recent molecular taxonomic advancements have expanded our understanding of crocodylian diversity, revealing the existence of previously overlooked species, including the Congo dwarf crocodile (Osteolaemus osborni) in the central Congo Basin rainforests. This study explores the genomic divergence between O. osborni and its better-known relative, the true dwarf crocodile (Osteolaemus tetraspis), shedding light on their evolutionary history. Field research conducted in the northwestern Republic of the Congo uncovered a locality where both species coexist in sympatry/syntopy. Genomic analysis of sympatric individuals reveals a level of divergence comparable to that between ecologically similar South American dwarf caimans (Paleosuchus palpebrosus and Paleosuchus trigonatus), suggesting parallel speciation in the Afrotropics and Neotropics during the Middle to Late Miocene, 10-12 Ma. Comparison of the sympatric and allopatric dwarf crocodiles indicates no gene flow between the analysed sympatric individuals of O. osborni and O. tetraspis. However, a larger sample will be required to answer the question of whether or to what extent these species hybridize. This study emphasizes the need for further research on the biology and conservation status of the Congo dwarf crocodile, highlighting its significance in the unique biodiversity of the Congolian rainforests and thus its potential as a flagship species.
Collapse
Affiliation(s)
- Václav Gvoždík
- Institute of Vertebrate Biology of the Czech Academy of Sciences, Brno, Czech Republic
- Department of Zoology, National Museum of the Czech Republic, Prague, Czech Republic
| | - Matej Dolinay
- Institute of Vertebrate Biology of the Czech Academy of Sciences, Brno, Czech Republic
| | - Ange-Ghislain Zassi-Boulou
- Department of Biology, National Institute for Research in Exact and Natural Sciences (IRSEN), Brazzaville, Republic of the Congo
| | - Alan R. Lemmon
- Department of Scientific Computing, Dirac Science Library, Florida State University, Tallahassee, FL, USA
| | - Emily M. Lemmon
- Department of Biological Sciences, Florida State University, Tallahassee, FL, USA
| | | |
Collapse
|
2
|
Karin BR, Lough-Stevens M, Lin TE, Reilly SB, Barley AJ, Das I, Iskandar DT, Arida E, Jackman TR, McGuire JA, Bauer AM. The natural and human-mediated expansion of a human-commensal lizard into the fringes of Southeast Asia. BMC Ecol Evol 2024; 24:25. [PMID: 38378475 PMCID: PMC10880348 DOI: 10.1186/s12862-024-02212-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 02/09/2024] [Indexed: 02/22/2024] Open
Abstract
BACKGROUND Human-commensal species often display deep ancestral genetic structure within their native range and founder-effects and/or evidence of multiple introductions and admixture in newly established areas. We investigated the phylogeography of Eutropis multifasciata, an abundant human-commensal scincid lizard that occurs across Southeast Asia, to determine the extent of its native range and to assess the sources and signatures of human introduction outside of the native range. We sequenced over 350 samples of E. multifasciata for the mitochondrial ND2 gene and reanalyzed a previous RADseq population genetic dataset in a phylogenetic framework. RESULTS Nuclear and mitochondrial trees are concordant and show that E. multifasciata has retained high levels of genetic structure across Southeast Asia despite being frequently moved by humans. Lineage boundaries in the native range roughly correspond to several major biogeographic barriers, including Wallace's Line and the Isthmus of Kra. Islands at the outer fringe of the range show evidence of founder-effects and multiple introductions. CONCLUSIONS Most of enormous range of E. multifasciata across Southeast Asia is native and it only displays signs of human-introduction or recent expansion along the eastern and northern fringe of its range. There were at least three events of human-introductions to Taiwan and offshore islands, and several oceanic islands in eastern Indonesia show a similar pattern. In Myanmar and Hainan, there is a founder-effect consistent with post-warming expansion after the last glacial maxima or human introduction.
Collapse
Affiliation(s)
- Benjamin R Karin
- Museum of Vertebrate Zoology and Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA.
- Department of Biology, Villanova University, Villanova, PA, 19085, USA.
| | - Michael Lough-Stevens
- Department of Biology, Villanova University, Villanova, PA, 19085, USA
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA, USA
| | - Te-En Lin
- Endemic Species Research Institute, 1, Minsheng E Rd., Jiji Township, Nantou County, 55244, Taiwan
| | - Sean B Reilly
- Museum of Vertebrate Zoology and Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95060, USA
| | - Anthony J Barley
- Department of Evolution and Ecology, University of California, 2320 Storer Hall, Davis, CA, 95616, USA
| | - Indraneil Das
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia
| | - Djoko T Iskandar
- School of Life Sciences and Technology, Bandung Institute of Technology, 10 Jalan Ganesa, Bandung, 40132, Indonesia
- Basic Sciences Commission, Indonesian Academy of Sciences, 11 Jalan Medan Merdeka Selatan, Jakarta, 10110, Indonesia
| | - Evy Arida
- Research Center for Ecology and Ethnobiology, Badan Riset dan Inovasi Nasional (BRIN), Cibinong Science Center, Jalan Raya Jakarta-Bogor km 46, Cibinong, 16911, Indonesia
| | - Todd R Jackman
- Department of Biology, Villanova University, Villanova, PA, 19085, USA
| | - Jimmy A McGuire
- Museum of Vertebrate Zoology and Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA
| | - Aaron M Bauer
- Department of Biology, Villanova University, Villanova, PA, 19085, USA
| |
Collapse
|
3
|
Chan KO, Mulcahy DG, Anuar S. The Artefactual Branch Effect and Phylogenetic Conflict: Species Delimitation with Gene Flow in Mangrove Pit Vipers (Trimeresurus purpureomaculatus-erythrurus Complex). Syst Biol 2023; 72:1209-1219. [PMID: 37478480 DOI: 10.1093/sysbio/syad043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/19/2023] [Accepted: 07/13/2023] [Indexed: 07/23/2023] Open
Abstract
Mangrove pit vipers of the Trimeresurus purpureomaculatus-erythrurus complex are the only species of viper known to naturally inhabit mangroves. Despite serving integral ecological functions in mangrove ecosystems, the evolutionary history, distribution, and species boundaries of mangrove pit vipers remain poorly understood, partly due to overlapping distributions, confusing phenotypic variations, and the lack of focused studies. Here, we present the first genomic study on mangrove pit vipers and introduce a robust hypothesis-driven species delimitation framework that considers gene flow and phylogenetic uncertainty in conjunction with a novel application of a new class of speciation-based delimitation model implemented through the program Delineate. Our results showed that gene flow produced phylogenetic conflict in our focal species and substantiates the artefactual branch effect where highly admixed populations appear as divergent nonmonophyletic lineages arranged in a stepwise manner at the basal position of clades. Despite the confounding effects of gene flow, we were able to obtain unequivocal support for the recognition of a new species based on the intersection and congruence of multiple lines of evidence. This study demonstrates that an integrative hypothesis-driven approach predicated on the consideration of multiple plausible evolutionary histories, population structure/differentiation, gene flow, and the implementation of a speciation-based delimitation model can effectively delimit species in the presence of gene flow and phylogenetic conflict.
Collapse
Affiliation(s)
- Kin Onn Chan
- Lee Kong Chian Natural History Museum, National University of Singapore, 2 Conservatory Drive, Singapore 117377, Singapore
- School of Biological Sciences, Universiti Sains Malaysia, 11800 Gelugor, Penang, Malaysia
| | - Daniel G Mulcahy
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
| | - Shahrul Anuar
- School of Biological Sciences, Universiti Sains Malaysia, 11800 Gelugor, Penang, Malaysia
| |
Collapse
|
4
|
Alexander Pyron R. Unsupervised machine learning for species delimitation, integrative taxonomy, and biodiversity conservation. Mol Phylogenet Evol 2023; 189:107939. [PMID: 37804960 DOI: 10.1016/j.ympev.2023.107939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/25/2023] [Accepted: 10/04/2023] [Indexed: 10/09/2023]
Abstract
Integrative taxonomy, combining data from multiple axes of biologically relevant variation, is a major goal of systematics. Ideally, such taxonomies will derive from similarly integrative species-delimitation analyses. Yet, most current methods rely solely or primarily on molecular data, with other layers often incorporated only in a post hoc qualitative or comparative manner. A major limitation is the difficulty of devising quantitative parametric models linking different datasets in a unified ecological and evolutionary framework. Machine Learning (ML) methods offer flexibility in this arena by easily learning high-dimensional associations between observations (e.g., individual specimens) across a wide array of input features (e.g., genetics, geography, environment, and phenotype) to delimit statistically meaningful clusters. Here, I implement an unsupervised method using Self-Organizing (or "Kohonen") Maps (SOMs) for such purposes. Recent extensions called "SuperSOMs" can integrate multiple layers, each of which exerts independent influence on a two-dimensional output grid via empirically estimated weights. The grid cells are then delimited into K distinct units that can be interpreted as species or other entities. I show empirical examples in salamanders (Desmognathus) and snakes (Storeria) with layers representing alleles, space, climate, and traits. Simulations reveal that the SuperSOM approach can detect K = 1, tends not to over-split, reflects contributions from all layers, and limits large layers (e.g., genetic matrices) from overwhelming other datasets, desirable properties addressing major concerns from previous studies. Finally, I suggest that these and similar methods could integrate conservation-relevant layers such as population trends and human encroachment to delimit management units from an explicitly quantitative framework grounded in the ecology and evolution of species limits and boundaries.
Collapse
Affiliation(s)
- R Alexander Pyron
- Department of Biological Sciences, The George Washington University, Washington, DC 20052 USA.
| |
Collapse
|
5
|
Tapondjou Nkonmeneck WP, Allen KE, Hime PM, Knipp KN, Kameni MM, Tchassem AM, Gonwouo LN, Brown RM. Diversification and historical demography of Rhampholeon spectrum in West-Central Africa. PLoS One 2022; 17:e0277107. [PMID: 36525408 PMCID: PMC9757597 DOI: 10.1371/journal.pone.0277107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 10/19/2022] [Indexed: 12/23/2022] Open
Abstract
Pygmy Chameleons of the genus Rhampholeon represent a moderately diverse, geographically circumscribed radiation, with most species (18 out of 19 extant taxa) limited to East Africa. The one exception is Rhampholeon spectrum, a species restricted to West-Central African rainforests. We set out to characterize the geographic basis of genetic variation in this disjunctly distributed Rhampholeon species using a combination of multilocus Sanger data and genomic sequences to explore population structure and range-wide phylogeographic patterns. We also employed demographic analyses and niche modeling to distinguish between alternate explanations to contextualize the impact of past geological and climatic events on the present-day distribution of intraspecific genetic variation. Phylogenetic analyses suggest that R. spectrum is a complex of five geographically delimited populations grouped into two major clades (montane vs. lowland). We found pronounced population structure suggesting that divergence and, potentially, speciation began between the late Miocene and the Pleistocene. Sea level changes during the Pleistocene climatic oscillations resulted in allopatric divergence associated with dispersal over an ocean channel barrier and colonization of Bioko Island. Demographic inferences and range stability mapping each support diversification models with secondary contact due to population contraction in lowland and montane refugia during the interglacial period. Allopatric divergence, congruent with isolation caused by geologic uplift of the East African rift system, the "descent into the Icehouse," and aridification of sub-Saharan Africa during the Eocene-Oligocene are identified as the key events explaining the population divergence between R. spectrum and its closely related sister clade from the Eastern Arc Mountains. Our results unveil cryptic genetic diversity in R. spectrum, suggesting the possibility of a species complex distributed across the Lower Guinean Forest and the Island of Bioko. We highlight the major element of species diversification that modelled today's diversity and distributions in most West-Central African vertebrates.
Collapse
Affiliation(s)
- Walter Paulin Tapondjou Nkonmeneck
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America
- Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States of America
| | - Kaitlin E. Allen
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America
- Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States of America
| | - Paul M. Hime
- Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States of America
| | - Kristen N. Knipp
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America
- Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States of America
| | - Marina M. Kameni
- Laboratory of Zoology, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
| | - Arnaud M. Tchassem
- Laboratory of Zoology, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
| | - LeGrand N. Gonwouo
- Laboratory of Zoology, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
| | - Rafe M. Brown
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, United States of America
- Biodiversity Institute, University of Kansas, Lawrence, Kansas, United States of America
| |
Collapse
|
6
|
Pyron RA, O’Connell KA, Lemmon EM, Lemmon AR, Beamer DA. Candidate‐species delimitation in
Desmognathus
salamanders reveals gene flow across lineage boundaries, confounding phylogenetic estimation and clarifying hybrid zones. Ecol Evol 2022; 12:e8574. [PMID: 35222955 PMCID: PMC8848459 DOI: 10.1002/ece3.8574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 01/05/2022] [Accepted: 01/10/2022] [Indexed: 12/19/2022] Open
Abstract
Dusky Salamanders (genus Desmognathus) currently comprise only 22 described, extant species. However, recent mitochondrial and nuclear estimates indicate the presence of up to 49 candidate species based on ecogeographic sampling. Previous studies also suggest a complex history of hybridization between these lineages. Studies in other groups suggest that disregarding admixture may affect both phylogenetic inference and clustering‐based species delimitation. With a dataset comprising 233 Anchored Hybrid Enrichment (AHE) loci sequenced for 896 Desmognathus specimens from all 49 candidate species, we test three hypotheses regarding (i) species‐level diversity, (ii) hybridization and admixture, and (iii) misleading phylogenetic inference. Using phylogenetic and population‐clustering analyses considering gene flow, we find support for at least 47 candidate species in the phylogenomic dataset, some of which are newly characterized here while others represent combinations of previously named lineages that are collapsed in the current dataset. Within these, we observe significant phylogeographic structure, with up to 64 total geographic genetic lineages, many of which hybridize either narrowly at contact zones or extensively across ecological gradients. We find strong support for both recent admixture between terminal lineages and ancient hybridization across internal branches. This signal appears to distort concatenated phylogenetic inference, wherein more heavily admixed terminal specimens occupy apparently artifactual early‐diverging topological positions, occasionally to the extent of forming false clades of intermediate hybrids. Additional geographic and genetic sampling and more robust computational approaches will be needed to clarify taxonomy, and to reconstruct a network topology to display evolutionary relationships in a manner that is consistent with their complex history of reticulation.
Collapse
Affiliation(s)
- Robert Alexander Pyron
- Department of Biological Sciences The George Washington University Washington District of Columbia USA
- Division of Amphibians and Reptiles Department of Vertebrate Zoology National Museum of Natural History Smithsonian Institution Washington District of Columbia USA
| | - Kyle A. O’Connell
- Department of Biological Sciences The George Washington University Washington District of Columbia USA
- Division of Amphibians and Reptiles Department of Vertebrate Zoology National Museum of Natural History Smithsonian Institution Washington District of Columbia USA
- Global Genome Initiative National Museum of Natural History Smithsonian Institution Washington District of Columbia USA
- Biomedical Data Science Lab Deloitte Consulting LLP Arlington Virginia USA
| | | | - Alan R. Lemmon
- Department of Scientific Computing Florida State University Tallahassee Florida USA
| | - David A. Beamer
- Department of Natural Sciences Nash Community College Rocky Mount North Carolina USA
| |
Collapse
|
7
|
Blackburn DC, Nielsen SV, Ghose SL, Burger M, Gonwouo LN, Greenbaum E, Gvoždík V, Hirschfeld M, Kouete MT, Kusamba C, Lawson D, McLaughlin PJ, Zassi-Boulou AG, Rödel MO. Phylogeny of African Long-Fingered Frogs (Arthroleptidae: Cardioglossa) Reveals Recent Allopatric Divergences in Coloration. ICHTHYOLOGY & HERPETOLOGY 2021. [DOI: 10.1643/h2020165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|