General Area Cladogram Research Articles

Evolutionary biogeography of the Revillagigedo Archipelago, Mexico

ABSTRACT The biotic assembly of the Revillagigedo Archipelago, Mexico, was analysed under an evolutionary biogeographic framework. We undertook a parsimony analysis of endemicity with progressive character elimination of 194 plant and animal species, which allowed us to identify the archipelago as a complex area or node where Nearctic and Neotropical biotic components overlap. We undertook a cladistic biogeographic analysis using the phylogenetic information of 42 taxon-area cladograms, from which one general-area cladogram was obtained: (Revillagigedo, (Sonoran, (Baja California, (Veracruzan, Pacific Lowlands)))). These results suggest that the Revillagigedo Archipelago may be classified as a province, although we prefer to keep it as a district of the Pacific Lowlands province. We identified two cenocrons (temporally integrated set of taxa) that can be dated to the Pliocene–Pleistocene: one Nearctic that dispersed from the Baja California Peninsula, and another Neotropical where the species dispersed from the Pacific coast to the islands. The geological information and the general-area cladograms allowed us to propose a geobiotic scenario for the archipelago where the islands are probably the result of volcanism associated with the oceanic Mathematician Ridge, and the arrival of the cenocrons to the archipelago may have occurred during the Pliocene–Pleistocene, after the islands were available for colonisation.

SAMBA: Super area‐cladogram after resolving multiple biogeographical ambiguities

AbstractAimCladistic biogeography is all about congruence: when individual area cladograms coincide, they result in a general area cladogram that reveals shared history. However, the complexities of the natural world hamper the reconstruction of fully solved biogeographical patterns. Herein, we present SAMBA (super area‐cladogram after resolving multiple biogeographical ambiguities), a pattern‐based method combining supertrees and area cladograms to depict the relationships among areas. We also present a prototypical implementation of SAMBA as a web‐based framework named iSAMBA.LocationGlobal.TaxonAny taxon can be analysed with SAMBA.MethodsSAMBA is based on phylogenetic supertrees, a technique that combines previously calculated phylogenetic trees to produce a general area cladogram representing conciliatory and non‐ambiguous patterns of relationships. In our method, the input topologies are individual area cladograms. SAMBA is implemented through a web‐based framework named iSAMBA. We analysed a theoretical and a real scenario to compare SAMBA with primary Brooks parsimony analysis (BPA), component analysis, three area statement analysis (TAS) and the transparent method.ResultsSAMBA produces area cladograms that converge with the actual history of fragmentations of both hypothetical and real scenarios used as examples of implementation of the method. Primary BPA, component analysis, TAS and the transparent method are much more affected by the “biogeographical noise” (e.g. multiple areas in a single terminal, paralogies and missing areas) than SAMBA.Main ConclusionsSAMBA results in more informative general area cladograms than other pattern‐based biogeographical methods. SAMBA reveals shared patterns of biotic distribution without generating multiple unreliable area cladograms. The main advantage of SAMBA is the simplicity of using a single technique to extract biogeographical information from individual area cladograms and combine them to depict a non‐ambiguous general pattern of relationships among areas.

Evolutionary biogeography of the freshwater fish family Anablepidae (Teleostei: Cyprinodontiformes), a marine-derived Neotropical lineage

Cladistic biogeography is an evolutionary biogeographic approach that infers area relationships by comparing area cladograms derived from different phylogenetic hypotheses. The South American freshwater ichthyofauna is enriched by an extraordinary number of marine-derived lineages, presenting its own phylogenetic and biogeographic patterns. Here, we performed a Brooks Parsimony Analysis (BPA) with the latest phylogenetic proposals for Anablepidae to compare hypotheses about the historical relationships among areas previously recognized based on fish species from the Neotropical region. We found that the area relationships for Anablepidae are in accordance with the pattern evidenced for other marine-derived lineages. The general area cladogram obtained shows a three-area relationship pattern, where freshwater is the sister group of Pacific + Atlantic marine areas. Within the freshwater clade, Southern Brazil + Uruguay River basin and Northwestern Argentina + Midwestern Argentina form two clades. Vicariance, dispersal, and extinction events related to Miocene and Quaternary marine transgressions and ancient connections between the Iguacu and Upper Uruguay River basins supported the historical relationships among areas proposed here. Our results may be applied to patterns shown by other marine-derived lineages, as well as other freshwater organisms not necessarily having marine origins.

Do phytogeographic patterns reveal biomes or biotic regions?

We present the largest comparative biogeographical analysis that has complete coverage of Australia's geography (20 phytogeographical subregions), using the most complete published molecular phylogenies to date of large Australian plant clades (Acacia, Banksia and the eucalypts). Two distinct sets of areas within the Australian flora were recovered, using distributional data from the Australasian Virtual Herbarium (AVH) and the Atlas of Living Australia (ALA): younger Temperate, Eremaean and Monsoonal biomes, and older southwest+west, southeast and northern historical biogeographical regions. The analyses showed that by partitioning the data into two sets, using either a Majority or a Frequency method to select taxon distributions, two equally valid results were found. The dataset that used a Frequency method discovered general area cladograms that resolved patterns of the Australian biomes, whereas if widespread taxa (Majority method, with >50% of occurrences outside a single subregion) were removed the analysis then recovered historical biogeographical regions. The study highlights the need for caution when processing taxon distributions prior to analysis as, in the case of the history of Australian phytogeography, the validity of both biomes and historical areas have been called into question.

A novel approach to time-slicing areas within biogeographic-area classifications: Wallacea as an example

Time-slicing of areas is a novel biogeographic method that helps resolve conflicting area relationships and assess temporal overlap as an explanation for the conflict. The method differs from others currently popular in biogeography in that it does not date nodes before analysis (e.g. divergence dating) to infer area relationships and classification. Here, time-slicing is used as a proof of concept approach to interpret the inter-relationships of Neogene and Palaeogene biotic areas of Wallacea, a well-studied area of biogeographic overlap between South-East Asia and Australasia. We used 18 Palaeogene and 25 Neogene areas within Wallacea, represented in 28 areagrams from 25 published phylogenetic hypotheses. Areas were delimited using palaeogeographical reconstructions and biotic distribution data. Paralogy-free subtree and transparent methods of analysis were used to find a general area cladogram (GA), which was then compared with palaeogeographical reconstructions. Palaeogene areas formed clades different from those of Neogene areas. Area relationships correlated strongly with palaeogeographical reconstructions of the Neogene and the Palaeogene. The new approach demonstrated that Palaeogene and Neogene areas have distinct biogeographic histories. Wallacea is a temporal, as well as a geographic, composite that lies between two inferred barriers of distribution, namely the Palaeogene Wallace’s line and the Neogene Weber’s line.

Historical relationships of areas of endemism of the Brazilian Atlantic rain forest: a cladistic biogeographic analysis of harvestman taxa (Arachnida: Opiliones).

Based on a cladistic biogeographic analysis of 6 species-level phylogenies of harvestman taxa, we searched for congruence in the historical relationships of 12 areas of endemism of the Brazilian Atlantic Rain Forest. We constructed general area cladograms using Primary Brooks Parsimony Analysis (BPA), BPA of nodes, and paralogy-free subtree analysis. These analyses resulted in 6 general area cladograms, that allow to infer a general pattern of the relationships among areas of endemism from the Brazilian Atlantic Rain Forest. Northern areas resulted related basally showing main disjunctions at the Doce River Valley and Todos os Santos Bay/São Francisco River Valley. The remaining areas of endemism were included in a southern and a southeastern block, separated by the Ribeira do Iguape Valley. Incongruence Length Differences tests showed no significant incongruence among the resulting cladograms and other matrix partitions. We concluded that tectonism and ancient marine transgressions were the probable processes responsible for the main disjunctions, whereas Neogene refugia seem to have caused the more recent disjunctions. The general pattern and redundancy in area relationships suggest a model of main reiterative barriers in diversification at multiple times for the evolution of the Atlantic Rain Forest. The renewal of cladistic biogeography and the search for common biogeographic patterns are discussed.

A temporally dynamic approach for cladistic biogeography and the processes underlying the biogeographic patterns of North American deserts

We implemented a temporally dynamic approach to the cladistic biogeographic analysis of 13 areas of North American deserts and several plant and animal taxa. We undertook a parsimony analysis of paralogy-free subtrees based on 43 phylogenetic hypotheses of arthropod, vertebrate and plant taxa, assigning their nodes to three different time slices based on their estimated minimum ages: Early-Mid-Miocene (23−7 Ma), Late Miocene/Pliocene (6.9−2.5 Ma) and Pleistocene (2.4−0.011 Ma). The analyses resulted in three general area cladograms, one for each time slice, showing different area relationships. They allowed us to detect influences of different geological and palaeoclimatological events of the Early-Mid-Miocene, Late Miocene/Pliocene and Pleistocene that might have affected the diversification of the desert biota. Several diversification events in the deserts of North America might have been driven by Neogene uplift, marine incursion and the opening of the California Gulf during the Miocene–Pliocene, whereas climatic fluctuations had the highest impact during the Pleistocene.

Evolutionary biogeography of South American weevils of the tribe Naupactini (Coleoptera: Curculionidae)

AbstractAimNaupactini are highly diverse weevils, widespread in the Neotropical region. Their evolution may have been driven by geological and environmental changes. Our main goals were to explain the biotic diversification of this tribe in South America and to test previous hypotheses on the relationships between distribution areas.LocationNeotropical South America.MethodsWe compiled geographical records for 165 species of South American Naupactini. We then applied a track analysis and a parsimony analysis of paralogy‐free subtrees to obtain generalized tracks and a general area cladogram, respectively.ResultsWe retrieved 11 generalized tracks that coincided broadly with biogeographical areas of Neotropical South America: Northern Venezuelan, Galápagos Islands, Ecuadorian, Yungas, Cerrado, Caatinga, Puna+Pacific coastal deserts, Chacoan, Atlantic+Parana forests, Monte and Pampean. The single general area cladogram obtained showed the following topology: ((Northern Venezuelan–Ecuadorian) (Galápagos Islands–Puna+Pacific coastal deserts) (Yungas (Cerrado (Monte (Pampean (Chacoan–Atlantic+Parana forests)))))).Main conclusionsThe general patterns identified agree with biogeographical provinces of modern regionalizations, assumed to have been caused by vicariance. These biogeographical units form two main components, one from north‐western South America and the other from south‐eastern South America, separated by the barrier of the Andean cordillera. The absence of other discernible geological barriers and the influence of the Plio‐Pleistocene cycles make it difficult to elucidate the historical relationships between most forest areas and nearby open areas of South America. These observations indicate that the taxa under consideration underwent dispersal at different times, contributing to complex biogeographical patterns.

Cladistic biogeography of the Neotropical region: identifying the main events in the diversification of the terrestrial biota.

A cladistic biogeographical analysis was undertaken to identify the main events in the biotic diversification of the terrestrial Neotropical biota. For the 36 animal and plant taxa analysed, a component×area matrix was constructed, associating geographical data only with informative nodes, and it was analysed under implied weights using the software TNT. The general area cladogram obtained shows that the Neotropical region constitutes a monophyletic unit, with a first split separating the Antilles and a second one dividing the continental areas into a north-western and a south-eastern component. Within the north-western component the areas split following the sequence northern Amazonia, south-western Amazonia, north-western South America, and Mesoamerica. Within the south-eastern component the areas split following the sequence south-eastern Amazonia, Chaco, and Parana. The three main components are treated as subregions: Antillean, Amazonian (northern Amazonian, south-western Amazonian, Mesoamerican, and north-western South American dominions), and Chacoan (south-eastern Amazonian, Chacoan, and Parana dominions). Dispersal and vicariant events postulated to explain these pattens might have occurred during the Cretaceous, when the Caribbean plate collided with the Americas, a combination of eustatic sea-level changes and tectonic deformations of the continental platform exposed large parts of South America to episodes of marine transgressions, and the Andean uplift reconfigured the Amazonian area. Tertiary and Quaternary events are assumed to have later induced the diversification within these large biogeographical units.

Generalized tracks, area cladograms and tectonics in the Caribbean

AbstractAimTo test the ‘naturalness’, or integrity as a biogeographical unit, of the Caribbean subregion.LocationA wide geographical range in the Caribbean (32° N, 115° W; 10° S, 56° W). As units of analysis, 43 biogeographical provinces were used: 24 assigned to the Caribbean subregion, and 19 provinces situated north and south of this subregion, which were used as outgroup areas.MethodsWe analysed 895 plant and animal taxa distributed in the Caribbean. We used parsimony analysis of endemicity with progressive character elimination (PAE‐PCE) to identify generalized tracks and nodes, and parsimony analysis of paralogy‐free subtrees to infer their historical relationships.ResultsWe obtained 10 generalized tracks and five nodes from the panbiogeographical analysis and 14 most parsimonious general area cladograms from the cladistic biogeographical analysis. In general terms, the results of both analyses are congruent, reflecting a similar history of vicariant events in the Caribbean area.Main conclusionsPanbiogeographical and cladistic biogeographical analyses reflected a similar history of vicariant events in the Caribbean: the Caribbean subregion as it is currently defined does not represent a ‘natural’ biogeographical unit; the Isthmus of Tehuantepec might not represent a conspicuous biogeographical barrier; and the biogeographical relevance of the Isthmus of Panama exceeds the last 3 million years, which is the time it has operated as a connection between North and South America.

Tree squirrels: A key to understand the historic biogeography of Mesoamerica?

A multi-taxon historical biogeography approach (Brooks Parsimony Analysis) was used to estimate relationships among the Mesoamerican lowland and highland areas and the particular biogeographic history of Mesoamerican squirrels (Sciurus, Microsciurus and Syntheosciurus species). A total of 15 lowland areas and 12 highland areas plus 41 clades comprising 240 species (45,135 records) were employed to obtain Taxon-Area Cladograms and Area Cladograms. A single most parsimonious General Area Cladogram indicated a strong vicariant relationship between Southern Mexico and the remainder of Mesoamerica, and identified several vicariant nodes (Modern Chiapanencan Volcanic Arc, Honduras’ Great Central Depression, and Nicaraguan Depression) as well as historically independent highland areas. A secondary BPA in relation with Sciurus species showed several instances of post speciation dispersal or range expansion, lack of response to vicariant events, and, possibly, lineage duplication. The results obtained suggest that Mesoamerican biotas have been subjected to several major vicariant events, but the reticulated nature of some of its areas also indicates that dispersal (post-speciation dispersal and range expansion) had been important in the diversification of the Mesoamerican biota. This trend was also observed in the particular biogeographic history of Mesoamerican tree squirrels.

Biogeografía de la Zona de Transición Mexicana con base en un análisis de árboles reconciliados

We analyzed the relationships of the areas of endemism of the Mexican Transition Zone through 3 hypotheses of regionalization. We used a reconciled trees method based on the phylogenies of 10 genera of beetles, gymnosperms, lizards and snakes. Seven general area cladograms were generated using assumptions 0 and 1 and the Nelson and majority consensus. They showed 2 groups of areas, 1 with Neotropical affinities and the other with Nearctic affinities. The Sierra Madre del Sur resulted as the sister area of the Trans-Mexican Volcanic Belt. Other constant patterns were the area that involves Tamaulipas and Texas as sister area of the Chihuahuan and Sonoran deserts, and the highlands of Chiapas and Guatemala were always recovered as the sister area of the Talamanca ridge. Our results suggest that the most important vicariant events within the Mexican Transition Zone are the Trans-Mexican Volcanic Belt, which divides the majority of the endemism areas with Neartic affinities (north to this) from those endemism areas of Neotropical affinities (south to this) and the Tehuantepec Isthmus; which together with the Nicaraguan depression isolates Nuclear Central America. Other patterns appear in either regionalization proposal, but not within the 3, and require future studies in order to find well supported explanations. Even though our results have appeared in previous hypotheses, there are worth due to the fact that we include phylogenetic information of different taxa, we employed reconciled trees, an insufficiently used method, and we searched for congruence between results using 3 regionalization proposals.

A protocol for temporal calibration of general area cladograms

AbstractAim To describe a protocol for incorporating a temporal dimension into historical biogeographical analysis, while maintaining the essential independence of all datasets, involving the generation of general area cladograms.Location Global.Methods General area cladograms (GACs) are a reconstruction of the evolutionary history of a set of areas and unrelated clades within those areas. Nodes on a GAC correspond to speciation events in a group of taxa; general nodes are those at which multiple unrelated clades speciate. We undertake temporal calibration of GACs using molecular clock estimates of splitting events between extant taxa as well as first appearance data from the fossil record. We present two examples based on re‐analysis of previously published data: first, a temporally calibrated GAC generated from secondary Brooks parsimony analysis (BPA) of six extant bird clades from the south‐west of North America using molecular clock estimates of divergence times; and second, an analysis of African Neogene mammals based on a phylogenetic analysis for comparing trees (PACT) analysis.Results A hypothetical example demonstrates how temporal calibration reveals potentially critical information about the timing of both unique and general events, while also illustrating instances of incongruence between dates generated from molecular clock estimates and fossils. For the African Neogene mammal dataset, our analysis reveals that most mammal clades underwent geodispersal associated with the Neogene climatic optimum (c. 16 Ma) and vicariant speciation in central Africa correlated with increased aridity and cooler temperatures around 2.5 Ma.Main conclusions Temporally calibrated GACs are valuable tools for assessing whether coordinated patterns of speciation are associated with large‐scale climatic or tectonic phenomena.

Island evolutionary biogeography: analysis of the weevils (Coleoptera: Curculionidae) of the Falkland Islands (Islas Malvinas)

Aim I analysed distributional and phylogenetic information on weevils (Coleoptera: Curculionidae) from the Falklands, and integrated it with molecular, palaeontological and geological information to infer a geobiotic scenario. Location Falkland Islands (Islas Malvinas). Methods The panbiogeographical analysis was based on data on 23 Falkland species and their related taxa from southern South America. For the cladistic biogeographical analysis I analysed six weevil taxa for which phylogenetic hypotheses are available (the generic groups Cylydrorhinus, Strangaliodes and Falklandius, and the genera Antarctobius, Germainiellus and Puranius). Results from this analysis were compared with previous regionalizations. Cenocrons (sets of taxa that share the same biogeographical history) were identified by considering temporal information provided by fossils and molecular clocks. Finally, a geobiotic scenario was proposed by integrating the available information. Results Six generalized tracks were detected: Maule–Valdivian forests, Magellanic forest, Magellanic moorland, Falkland Islands, Magellanic forest–Magellanic moorland, and Magellanic forest–Falkland Islands. A node was identified in the Magellanic forest, based on the overlap of two generalized tracks. A single general area cladogram was obtained, implying the following sequence: (Magellanic moorland (Maule–Valdivian forests (Magellanic forest, Falkland Islands))). The Falklands are classified here as a biogeographical province in the Austral realm, Andean region and Subantarctic subregion. Falkland weevils seem to belong to a single Subantarctic cenocron. The sequence of events deduced implies the following steps: development of the Subantarctic biota in southern South America, arrival of the Falkland crustal block from South Africa in the Early Cretaceous, geodispersal of the Subantarctic cenocron from southern South America to the Falklands during the Early Oligocene, vicariance of the Magellanic moorland, vicariance of the Maule–Valdivian forests, and final vicariance between the Magellanic forest and the Falkland Islands. Main conclusions The biotic components identified support the connection of the Falkland weevils with the Magellanic forest. Falkland weevils belong to a single cenocron, dated to at least the Early Oligocene, when geodispersal from southern South America may have occurred. An older African cenocron may have been replaced completely by the Subantarctic one when the proto-Falklands made contact with the Patagonian continental shelf. A geobiotic scenario implying vicariance events related to sea-level variations could explain the distributional patterns analysed herein.

PACT in practice: comparative historical biogeographic patterns and species-area relationships of the Greater Antillean and Hawaiian Island terrestrial biotas

Aim To compare the evolutionary and ecological patterns of two extensively studied island biotas with differing geological histories (the Hawaiian Islands and the GreaterAntilles).We evaluated the results from PACT (phylogenetic analysis for comparing trees), an innovative approach that has been proposed to reveal general patterns of biotic expansion (between regions) and in situ (within a region) diversification, as well as species‐area relationships (SAR) and the taxon pulse dynamic. Location The Hawaiian Islands and Greater Antilles. Methods We used the PACT algorithm to construct general area cladograms and identified biotic expansion and in situ nodes. We analysed the power-law SAR and relative contribution of biotic expansion and in situ diversification events using power-law and linear regression analyses.

The South American Biogeographic Transition Zone: An analysis from Asteraceae

AbstractIn order to elucidate the biotic diversification of Asteraceae inhabiting the South American Transition Zone, we undertook a panbiogeographic analysis (based on a parsimony analysis of endemicity) and a cladistic biogeographic analysis. The study units were the six biogeographic provinces of this zone plus the seven subregions of the Neotropical and Andean regions, considered as “outgroups”. Species analyzed belonged to the generaArnaldoa, Barnadesia, Belloa, Berroa, Chevreulia, Chuquiraga, Cuatrecasiella, Dasyphyllum, Doniophyton, Duseniella, Facellis, Fulcaldea, Gamochaetopsis, Huarpea, Hypochaeris, Jalcophila, Lucilia, Luciliocline, andSchlechtendalia. A parsimony analysis of endemicity, based on presence/absence data of the 66 individual tracks ranged on two or more areas, allowed to identify four generalized tracks: (1) Coastal Peruvian Desert and Puna provinces; (2) Central Chilean, Patagonian, and Subantarctic subregions; (3) Amazonian, Chacoan, and Parana subregions; and (4) Puna province and Parana and Chacoan subregions. The Puna and Parana provinces, connected with two different generalized tracks each, constitute nodes. A cladistic biogeographic analysis, based on the paralogy–free subtrees extracted from the taxonomic area cladograms ofBarnadesia, Chuquiraga, Dasyphyllum, Hypochaeris, and the Lucilia group, allowed obtaining a general area cladogram, which indicates a basic separation between the Atacama, Monte, and Prepuna provinces closely related to the Andean region, and the North Andean Paramo, Coastal Peruvian Desert, and Puna provinces closely related to the Neotropical region. Our results corroborate once again the transitional character of the provinces assigned to the South American Transition Zone, and allow speculating on their close affinities with the Andean and Neotropical regions.

Explicación histórica del origen de la herpetofauna de México

A hypothesis of historical area relationships for Mexico, Central, and South America was investigated by a cladistic biogographic analysis using 10 taxon cladograms of the herpetofauna of Mexico. A hypothesis is presented based on previous narrative biogeographic scenarios and compared with the general area cladograms (GACs) obtained using reconciled trees of COMPONENT 2.0 and Brooks Parsimony Analysis (BPA). For tree reconciliation, 1 000 trees were saved after the analysis. BPA yielded 18 GACs (CI = 0.805, RI= 0.549). The GAC derived from tree reconciliation is more or less pectinate and has only 3 groups of 2 areas each. These groups consist of the Chihuahuan and Sonoran deserts as sister areas on the one hand (DCHI, DSON), and the Sierra Madre Oriental and Occidental as sister areas on the other (SMOR, SMOC). This latter clade is sister to the Chihuahuan and Sonoran desert clade. The third group has the Transvolcanic Belt and Sierra Madre del Sur as sister areas (TVA, SMEX). The GAC obtained by BPA showed 4 main groups of areas: the fi rst is comprised of the Pacifi c coast of Mexico and the Balsas Depression (PCBAL), the Sierra Madre del Sur (SMEX), and the Transvolcanic Belt (TVA); the second group includes the Sierra Madre Oriental (SMOR), Sierra Madre Occidental (SMOC), Sonoran (DSON) and Chihuahuan deserts (DCHI); the third comprised the Highlands of Chiapas and Guatemala (CHIG), the Eastern Lowlands, on the Atlantic coast (ELL) and the Semiarid Lands of Tamaulipas-Texas (TAMS); the fourth group contains the Western Lowlands, in the Pacifi c coast (WLL) and northern South America (SA); the Talamanca Ridge (TALA) is isolated at the base of the 3 fi rst groups. The GAC from narrative biogeography contains 3 groups: the fi rst has areas of northern Mexico (DSON, DCHI, TAMPS), the second has areas from central Mexico (PCBAL, SMOR, SMOC, TVA), and third has areas from southern Mexico and Central America (SMEX, CHIG, TALA, WLL, ELL, SA). In general, the GAC from the BPA analysis shared more groups with the hypothesis of narrative biogeography; when compared to the GAC obtained via reconciled trees; however, all the GACs obtained are topologically distinct. Accounting for the lack of congruence between the narrative biogeography GAC, reconciled tree analysis and BPA, is challenging due to several factors: 1), erroneous interpretation of vicariant events when constructing the narrative area cladogram; 2), lack of congruence among patterns of speciation and endemism for the taxa used in this analysis; 3), the region under study is a geologically complex zone and the history of the inhabiting biota is equally complex; 4), there are many widespread species present in this region, and may obscure the relationship among the areas of endemism; 5), the patterns of endemicity are poorly-defi ned and -studied in Mexico and Central America; 6), the incorrect selection of the areas of endemism used in this study. Despite these issues the results presented here are evidence of the multi-dimensional complexity of historical biogeographical processes in the region.

Historical relationships among areas of endemism in the tropical South America using Brooks Parsimony Analysis (BPA)

Areas of endemism are the smallest units of biogeographical analysis. One of its definitions is that these areas harbor organisms with restricted distributions caused by non random historical factors. The aim of this study was to examine historical relationships among areas of endemism in the Neotropics using Brooks Parsimony Analysis (BPA). We applied BPA to 12 unrelated taxa distributed within two sets of endemic areas in order to: (1) compare the proposed endemic area classifications; (2) examine whether Amazonia and Atlantic Forest are true biogeographic units and, (3) examine whether the inclusion of open area formations influence area relationships of the surrounding forests. General area cladograms revealed a basal split between Amazonian and Atlantic forests, suggesting that these areas have been isolated for a long period of time. All Atlantic forest endemic areas formed a monophyletic cluster, showing a sequence of vicariant events from north to south. The hypothesis that Amazonia is a composite area, made up of different historical units, is herein corroborated. When Cerrado and Caatinga (grasslands and savannas) are included, internal area relationships within Amazonia change, indicating that area classification schemes comprising forests and open formations should be preferred given the complementary history of these areas.

Molecular phylogenetics and evolutionary history of ariid catfishes revisited: a comprehensive sampling.

BackgroundAriids or sea catfishes are one of the two otophysan fish families (out of about 67 families in four orders) that inhabit mainly marine and brackish waters (although some species occur strictly in fresh waters). The group includes over 150 species placed in ~29 genera and two subfamilies (Galeichthyinae and Ariinae). Despite their global distribution, ariids are largely restricted to the continental shelves due in part to their specialized reproductive behavior (i.e., oral incubation). Thus, among marine fishes, ariids offer an excellent opportunity for inferring historical biogeographic scenarios. Phylogenetic hypotheses available for ariids have focused on restricted geographic areas and comprehensive phylogenies are still missing. This study inferred phylogenetic hypotheses for 123 ariid species in 28 genera from different biogeographic provinces using both mitochondrial and nuclear sequences (up to ~4 kb).ResultsWhile the topologies obtained support the monophyly of basal groups, up to ten genera validated in previous morphological studies were incongruent with the molecular topologies. New World ariines were recovered as paraphyletic and Old World ariines were grouped into a well-supported clade that was further divided into subclades mainly restricted to major Gondwanan landmasses. A general area cladogram derived from the area cladograms of ariines and three other fish groups was largely congruent with the geological area cladogram of Gondwana. Nonetheless, molecular clock estimations provided variable results on the timing of ariine diversification (~105-41 mya).ConclusionThis study provides the most comprehensive phylogeny of sea catfishes to date and highlights the need for re-assessment of their classification. While from a topological standpoint the evolutionary history of ariines is mostly congruent with vicariance associated with the sequence of events during Gondwanan fragmentation, ambiguous divergence time estimations hinders assessing the vicariant hypothesis on a temporal framework. Further examination of ariid fossils might provide the basis for more accurate inferences on the timing of ariine diversification.

Historical biogeography of New World emballonurid bats (tribe Diclidurini): taxon pulse diversification

AbstractAim To reconstruct the biogeographical history of New World emballonurid bats (tribe Diclidurini). Although bats are the second most species‐rich order of mammals, they have not contributed substantially to our understanding of the historical biogeography of mammals in the Neotropics because of a poor fossil record. In addition, being the only group of mammals that fly, bats typically have large distributions with relatively few species endemic to restricted areas that are amenable to vicariant biogeographical approaches.Location Central and South America.Methods Phylogenetic analysis for comparing trees (PACT) is a new algorithm that incorporates all spatial information from taxon area cladograms into a general area cladogram. There were nine biogeographical areas identified in Central and South America for New World emballonurid bats. Molecular dating was used to incorporate the temporal aspect of historical biogeography. This method was compared with dispersal–vicariance analysis (DIVA), which assumes vicariance as the default mode of speciation.Results Of the 45 speciation events in a fully resolved phylogeny, eight that were hypothesized by DIVA as vicariance were considered by PACT as two peripheral isolations and six within‐area events. DIVA was less parsimonious because it required six more post‐speciation dispersal events in addition to the 73 hypothesized by PACT. DIVA reconstructed a widely distributed ancestor, suggesting that most dispersal events occurred earlier, whereas the ancestral area for PACT based on character optimization was the Northern Amazon, suggesting that dispersal events were more recent phenomena.Main conclusions The general area cladogram from PACT indicated that within‐area events, and not vicariance, provide the major mode of speciation for New World emballonurid bats. There was no biological evidence supporting or rejecting sympatric speciation in New World emballonurid bats. However, the geological history, combined with fluctuations in temperature and sea level, suggested within‐area speciation in a changing and heterogeneous environment in the Northern Amazon during the Miocene. This scenario is similar to the taxon‐pulse hypothesis of biotic diversification, which posits repeated episodes of range expansions and contractions from a stable core area such as the Guiana Shield within the Northern Amazon.