Albumin evolution in West Indian frogs of the genus Eleutherodactylus (Leptodactylidae): Caribbean biogeography and a calibration of the albumin immunological clock

Antisera to serum albumins from five West Indian species of the frog genus Eleutheroductylus were prepared, and the reciprocal immunological distances (IDs) obtained were used to provide a time frame for the evolution of this group in the West Indies. One-way IDS were obtained to 25 additional species within the genus, with emphasis on those from the West Indies. These immunological data support both a recent classification of Eleutheroductylus based on an analysis of slow-evolving allozyme loci, and the monophyly of the 17 native Jamaican species as indicated by a more comprehensive electrophoretic study. This is in contrast to the results of morphological studies supporting multiple invasions of Jamaica by Eleutherodactylus . Within the subgenus Euhyas , IDS ranged from6–27 between Jamaican species, whereas between species on different islands the range was29–67. The subgenus Syrrhophus in southern North America was found to be the sister group to the subgenus Euhyus , a western Caribbean clade. Pelorius , a subgenus restricted to Hispaniola, was found to be the sister group of the subgenus Eleutheroductylus in the West Indies. The largest IDs obtained for West Indian species were those between the two major groups, the subgenera Eleutheroductylus and Euhyas .
The albumin immunological clock for Eleutheroductylus was calibrated with three events in the geologic history of the Caribbean: the breakup of the proto-Antilles (65-75 million years before present [mybp]), the emergence of Jamaica (20-30 mybp), and the uplift of the Blue Mountains in Jamaica (5-10 mybp). Immunological distances corresponding to those events yield a calibration of 1 ID=0.60 million years (my), the same as that previously obtained for other groups of amphibians and thus supports the use of albumin immunological distance as a molecular chronometer in the genus Eleutherodactylus     

Molecular phylogeny and biogeography of West Indian toads (Anura: Bufonidae)

Toads of the Bufo peltocephalus Group (Anura: Bufonidae) occur throughout the Greater Antilles (Cuba to the Virgin Islands), a geographic region of relatively high endemicity. Previous morphological and immunological studies suggested that the West Indian toads are a monophyletic lineage derived from Neotropical Bufo but were unable to clarify relationships within the group. We examined the evolutionary relationships and biogeography of this group of frogs by collecting approximately 2 kb of mitochondrial DNA sequence data from eight West Indian species and selected non-West Indian species from the New World and the Old World. Our analyses support the monophyly of native West Indian toads and a New World origin for the group. Relationships among the West Indian species are less certain, but a Cuban lineage is defined in most analyses.     

Phylogeny, diversity, and distribution inExostema (Rubiaceae): Implications of morphological and molecular analyses

The neotropical genusExostema comprises 25 species of trees and shrubs, ranging in distribution from Bolivia to Mexico and throughout the West Indies, with most species endemic to the Greater Antilles. Infrageneric relationships and species-level patterns of evolution were investigated in phylogenetic analyses using morphological, molecular, and combined data sets. All data sets resolved three main species groups which correspond to the three sections recognized byMcDowell (1996). However, the analyses of ITS sequence data placed the two South American species basal to the three main clades. Otherwise, the morphological and molecular data are highly compatible, and produce a more robust yet consistent phylogeny in the combined data analysis. Morphological evolution inExostema involves many specializations for xeric habitats, reflecting repeated ecological shifts from moist forest to exposed, seasonally dry environments during the diversification of the genus. Both moth and bee pollination syndromes are found inExostema, and shifts in pollination ecology appear pivotal to the differentiation of the three sections. Biogeographically,Exostema likely originated in South America and migrated via Central America to the Greater Antilles, where the morphological diversification and speciation are most extensive.     

Biogeographical patterns of the avifaunas of the Caribbean Basin Islands: a parsimony perspective

We analyzed the avifaunas of the Caribbean islands and nearby continental areas and their relationships using Parsimony Analysis of Endemicity (PAE), in order to assess biogeographical patterns and their concordance with geological and phylogenetic evidence. Using distributional information of birds obtained from published literature, a presence/absence matrix for 695 genera and 2026 species of land and freshwater birds was constructed and analyzed. Three different analyses were performed: for species, for genera, and for species and genera combined. In the combined analysis, the Lesser Antilles appear paraphyletic at the base of the cladogram. Then, two major clades are identified: South America (Andes, Venezuelan lowlands, Dutch West Indies and Trinidad and Tobago) and North America, including the Greater Antilles in a clade that is the sister area to Yucatan and the Central American countries nested from north to south. PAE results support Caribbean vicariant models and cladistic biogeographical hypotheses on area relationships, and show relative congruence with available phylogenetic data. Bird biogeography on the Caribbean islands appears to have been caused by both vicariance and dispersal processes. © The Willi Hennig Society 2007.     

Mainland colonization by island lizards

Aim We investigate biogeographic relationships within the lizard genus Anolis Daudin, 1802 to test the hypothesis that the mainland (Central and South American) Norops‐clade species descended from a West Indian Anolis ancestor. Previous hypotheses have suggested that close island relatives of mainland Norops species (the Cuban Anolis sagrei and Jamaican A. grahami series) represent over‐water dispersal from a mainland ancestor. These previous hypotheses predict that the A. sagrei and A. grahami series should be phylogenetically nested within a Norops clade whose ancestral geography traces to the mainland. If Norops is West Indian in origin, then West Indian species should span the deepest phylogenetic divergences within the Norops clade. Location Central and South America and West Indian islands. Methods The phylogenetic relationships of Anolis lizards are reconstructed from aligned DNA sequences using both parsimony and Bayesian approaches. Hypotheses are tested in two ways: (1) by reconstructing the ancestral geographic location for the Norops clade using Pagel & Lutzoni's (2002) Bayesian approach, and (2) by testing alternative topological arrangements via Wilcoxon Signed‐Ranks tests ( Templeton, 1983 ) and Shimodaira–Hasegawa tests ( Shimodaira & Hasegawa, 1999 ). Results Our evidence supports an origin of mainland Norops anoles from a West Indian ancestor. A West Indian ancestor to the Norops clade is statistically supported, and alternatives to the biogeographic pattern [Cuban (Jamaican, Mainland)] are statistically rejected by Shimodaira–Hasegawa tests, although not by Wilcoxon Signed‐Ranks tests. Main conclusions Our data support the hypothesis of a West Indian origin for mainland Norops. This result contradicts previous hypotheses and suggests that island forms may be an important source for mainland biodiversity.     

Molecular systematics of Selenops spiders (Araneae: Selenopidae) from North and Central America: implications for Caribbean biogeography

The Caribbean region includes a geologically complex mix of islands, which have served as a backdrop for some significant studies of biogeography, mostly with vertebrates. Here, we use the tropical/subtropical spider genus Selenops (Selenopidae) to obtain a finer resolution of the role of geology in shaping patterns of species diversity. We obtained a broad geographic sample from over 200 localities from both the islands and American mainland. DNA sequence data were generated for three mitochondrial genes and one nuclear gene for eleven outgroup taxa and nearly 60 selenopid species. Phylogenetic analysis of the data revealed several biogeographic patterns common to other lineages that have diversified in the region, the most significant being: (1) a distinct biogeographic break between Northern and Southern Lesser Antilles, although with a slight shift in the location of the disjunction; (2) diversification within the islands of Jamaica and Hispaniola; (3) higher diversity of species in the Greater Antilles relative to the Lesser Antilles. However, a strikingly unique pattern in Caribbean Selenops is that Cuban species are not basal in the Caribbean clade. Analyses to test competing hypotheses of vicariance and dispersal support colonization through GAARlandia, an Eocene–Oligocene land span extending from South America to the Greater Antilles, rather than over‐water dispersal. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 288–322.     

ORIGINAL ARTICLE: Cycads in the insular South‐west Pacific: dispersal or vicariance?

Aim Cycads constitute an ancient plant group that is generally believed to disperse poorly. However, one group of cycads (subsection Rumphiae) is thought to have dispersed relatively recently from a Malesian source area westwards to East Africa and eastwards into the Pacific, using a floatation‐facilitating layer in their seeds. We use morphological and allozyme characters to investigate the relationships among the species within this group and to deduce whether the wide distribution was achieved by recent dispersal (as evidenced by high genetic similarity) or more distant vicariance events (high genetic differentiation). Location We examined specimens collected throughout the range of subsection Rumphiae, from East Africa through Southeast Asia to Tonga in the South‐west Pacific. Methods We investigated relationships within subsection Rumphiae of the genus Cycas by analysing 18 variable (11 informative) morphological characters and 22 allozyme loci for seven of the 10 species currently assigned to this taxon. Results Distinctive morphological characters are few and fail to resolve relationships within the group. Allozyme data show that species within this subsection are closely related and suggest that there are two groups within the subsection, one comprising Cycas thouarsii (East Africa) and C. edentata (the Philippines), and the other the remaining species (from Malesia and the Pacific). The Australian species C. silvestris is sister to subsection Rumphiae in the morphological analysis but is closely allied to C. rumphii (nested within the subsection) in the allozyme analysis, suggesting that Rumphiae may be paraphyletic and that characters thought to be taxonomically important may need to be re‐evaluated. Main conclusions Cycads within subsection Rumphiae are closely related, and the wide distribution of this group was probably achieved through relatively recent oceanic dispersal events. Separate events probably account for the dispersal of these cycads into the Pacific and to Africa. The origin and distribution of C. silvestris (Australia) could be explained by a dispersal event from New Guinea or may have resulted from a former land connection between Australia and New Guinea.     

Glass in the water: Molecular phylogenetics and evolution of Indian glassy perchlets (Teleostei: Ambassidae)

Glassfishes of the family Ambassidae, comprising around 50 species, are distributed in the Indo‐West Pacific where they inhabit marine, estuarine, and freshwater ecosystems. We investigated for the first time the molecular phylogenetic and evolutionary relationships of this group using a combined dataset of mitochondrial and nuclear genes, particularly focusing on the taxa occurring in the Indian subcontinent. Results revealed that marine and freshwater genera of Ambassidae diverged during the Paleocene (~62 mya). The enigmatic monotypic genus Chanda is nested within the larger clade currently recognized as Parambassis, indicating its paraphyly. Based on cleared and stained osteological preparations and phylogenetic placement of Chanda nama, we hypothesize that the elongated and protruding lower jaw is an autapomorphic character that might have evolved for the lepidophagous habit of the species. The southern Indian species of Parambassis, Parambassis dayi, and Parambassis thomassi, which formed a monophyletic group, probably diverged from other species of Parambassis and Chanda nama around the Eocene (~42 mya) and can potentially be recognized as a distinct genus in view of the apomorphic characters such as the presence of serration on the ventral fringe of interopercle, densely serrated palatine and ectopterygoid, and the presence of more than 30 serrations along the lower preopercle and the posterior edge. Our analysis provides new insights into the evolution and phylogenetic relationships of glassy perchlets, including detailed relationships among the Indian species within this family.     

Phylogenetic relationships of xenodontine snakes inferred from 12S and 16S ribosomal RNA sequences

The phylogenetic relationships of xenodontine snakes are inferred from sequence analyses of portions of two mitochondrial genes (12S and 16S ribosomal RNA) in 85 species. Although support values for most of the basal nodes are low, the general pattern of cladogenesis observed is congruent with many independent molecular, morphological, and geographical data. The monophyly of xenodontines and the basal position of North American xenodontines in comparison with Neotropical xenodontines are favored, suggesting an Asian-North American origin of xenodontines. West Indian xenodontines (including endemic genera and members of the genus Alsophis) appear to form a monophyletic group belonging to the South American clade. Their mid-Cenozoic origin by dispersal using ocean currents is supported. Within South American mainland xenodontines, the tribes Hydropsini, Pseudoboini, and Xenodontini are monophyletic. Finally, our results suggest that some morphological and ecological traits concerning maxillary dentition, macrohabitat use, and foraging strategy have appeared multiple times during the evolution of xenodontine snakes.     

Phylogeny of the Asian Eutropis (Squamata: Scincidae) reveals an 'into India' endemic Indian radiation

Recent generic rearrangement of the circumtropical distributed skink genus 'Mabuya' has raised a lot of debate. According to this molecular phylogeny based rearrangement, the tropical Asian members of this genus have been assigned to Eutropis. However, in these studies the Asian members of 'Mabuya' were largely sampled from Southeast (SE) Asia with very few species from Indian subcontinent. To test the validity of this assignment and to determine the evolutionary origin of Indian members of this group we sequenced one nuclear and two mitochondrial genes from most of the species from the Indian subregion. The nuclear and mitochondrial trees generated from these sequences confirmed the monophyly of the tropical Asian Eutropis. Furthermore, in the tree based on the combined mitochondrial and nuclear dataset an endemic Indian radiation was revealed that was nested within a larger Asian clade. Results of dispersal-vicariance analysis and molecular dating suggested an initial dispersal of Eutropis from SE Asia into India around 5.5-17 million years ago, giving rise to the extant members of the endemic Indian radiation. This initial dispersal was followed by two back dispersals from India into SE Asia. We also discuss the relationships within the endemic Indian radiation and its taxonomic implications.     

Phylogenetic relationships among members of the subfamily sedoideae (Crassulaceae) inferred from the ITS region sequences of nuclear rDNA

Nucleotide sequences of the nuclear rDNA ITS regions were determined in 20 species of the subfamily Sedoideae (Crassulaceae). The phylogenetic relationships of these species with other members of the subfamily, occurring mainly in Southeast Asia, were analyzed. It was shown that the genus Orostachys was not monophyletic; its typical subsection was reliably included into the clade of the genus Hylotelephium. Synapomorphic substitutions and indels, specific for the subsection Orostachys, were detected in ITS1. Sister relationships were established between clades Aizopsis and Phedimus, based on which they can be recognized as isolated genera.     

Genetic relationships among American species of the genus Prosopis (Mimosoideae, Leguminosae) inferred from ITS sequences: evidence for long-distance dispersal

Aim  The genus Prosopis includes 44 species and has a pseudoamphitropical, disjunct distribution. We aimed to determine whether American Prosopis sections arose in North or South America, and to explain the current distribution of their species on the basis of their genetic relationships.
Location  South-western USA, Mexico, Caribbean Antilles, Peru–Ecuador, central and northern Argentina, south-western Argentina (Patagonia) and Cuyo, south-western Asia and northern Africa.
Methods  Internal transcribed spacer fragments from 21 species of Prosopis were sequenced and the data were used to analyse the phylogenetic relationships using Microlobius and Mimosa as outgroups. Genetic distances were calculated to estimate the degree of divergence. Dispersal–vicariance (DIVA) analysis was conducted to help understand the biogeographical history of the genus.
Main conclusions  The sections Strombocarpa and Algarobia are not monophyletic. Prosopis argentina (section Monilicarpa ) and the species of Algarobia are included in single clade. The phylogeny, DIVA analysis, and the pattern of genetic distances indicate that the ancestral area for the American species was wide, from south-western USA to Central and northern Argentina. Successive vicariance events split this area, and long-distance dispersal episodes (perhaps mediated by birds) led to recolonizations from North to South America, and vice versa .     

Review of Antillean Glyptolenus Bates (Coleoptera: Carabidae), with description of a new species precinctive to St. Vincent

The Neotropical genus Glyptolenus Bates is represented in the West Indies by five species, three of which are geographically restricted to single islands; G. latelytra (Darlington) in Jamaica, G. simplicicollis Darlington in Dominica, and G. smithi, new species from St. Vincent. Glyptolenus chalybaeus (Dejean), widespread on the eastern South American mainland, extends northward through the Lesser Antilles to Montserrat. The fifth species, G. negrei Perrault, also widespread on the northern rim of South America, ranges only as far north as the continental island of Trinidad. The first four taxa have most likely achieved their distributions by over‐water dispersal from mainland South and Central America, possibly as many as four separate times. Their absence from the Greater Antilles of Cuba and Hispaniola is contrasted to the occurrence of multiple lineages on those islands in the closely related genus Platynus Bonelli.     

The uneven phylogeny and biogeography of Erodium (Geraniaceae): radiations in the Mediterranean and recent recurrent intercontinental colonization

Background and Aims

The genus Erodium is a common feature of Mediterranean-type climates throughout the world, but the Mediterranean Basin has significantly higher diversity than other areas. The aim here is to reveal the biogeographical history of the genus and the causes behind the evolution of the uneven distribution.

Methods

Seventy-eight new nrITS sequences were incorporated with existing plastid data to explore the phylogenetic relationships and biogeography of Erodium using several reconstruction methods. Divergence times for major clades were calculated and contrasted with other previously published information. Furthermore, topological and temporal diversification rate shift analyses were employed using these data.

Key Results

Phylogenetic relationships among species are widely congruent with previous plastid reconstructions, which refute the classical taxonomical classification. Biogeographical reconstructions point to Asia as the ancestral area of Erodium, arising approx. 18 MYA. Four incidences of intercontinental dispersal from the Mediterranean Basin to similar climates are demonstrated. Increases in diversification were present in two independent Erodium lineages concurrently. Two bursts of diversification (3 MYA and 0·69 MYA) were detected only in the Mediterranean flora.

Conclusions

Two lineages diverged early in the evolution of the genus Erodium: (1) subgenus Erodium plus subgenus Barbata subsection Absinthioidea and (2) the remainder of subgenus Barbata. Dispersal across major water bodies, although uncommon, has had a major influence on the distribution of this genus and is likely to have played as significant role as in other, more easily dispersed, genera. Establishment of Mediterranean climates has facilitated the spread of the genus and been crucial in its diversification. Two, independent, rapid radiations in response to the onset of drought and glacial climate change indicate putative adaptive radiations in the genus.     

The historical biogeography of two Caribbean butterflies (Lepidoptera: Heliconiidae) as inferred from genetic variation at multiple loci

Mitochondrial DNA and allozyme variation was examined in populations of two Neotropical butterflies, Heliconius charithonia and Dryas iulia. On the mainland, both species showed evidence of considerable gene flow over huge distances. The island populations, however, revealed significant genetic divergence across some, but not all, ocean passages. Despite the phylogenetic relatedness and broadly similar ecologies of these two butterflies, their intraspecific biogeography clearly differed. Phylogenetic analyses of mitochondrial DNA sequences revealed that populations of D. iulia north of St. Vincent are monophyletic and were probably derived from South America. By contrast, the Jamaican subspecies of H. charithonia rendered West Indian H. charithonia polyphyletic with respect to the mainland populations; thus, H. charithonia seems to have colonized the Greater Antilles on at least two separate occasions from Central America. Colonization velocity does not correlate with subsequent levels of gene flow in either species. Even where range expansion seems to have been instantaneous on a geological timescale, significant allele frequency differences at allozyme loci demonstrate that gene flow is severely curtailed across narrow ocean passages. Stochastic extinction, rapid (re)colonization, but low gene flow probably explain why, in the same species, some islands support genetically distinct and nonexpanding populations, while nearby a single lineage is distributed across several islands. Despite the differences, some common biogeographic patterns were evident between these butterflies and other West Indian taxa; such congruence suggests that intraspecific evolution in the West Indies has been somewhat constrained by earth history events, such as changes in sea level.     

The West Indies as a laboratory of biogeography and evolution

Islands have long provided material and inspiration for the study of evolution and ecology. The West Indies are complex historically and geographically, providing a rich backdrop for the analysis of colonization, diversification and extinction of species. They are sufficiently isolated to sustain endemic forms and close enough to sources of colonists to develop a dynamic interaction with surrounding continental regions. The Greater Antilles comprise old fragments of continental crust, some very large; the Lesser Antilles are a more recent volcanic island arc, and the low-lying Bahama Islands are scattered on a shallow oceanic platform. Dating of island lineages using molecular methods indicates over-water dispersal of most inhabitants of the West Indies, although direct connections with what is now southern Mexico in the Early Tertiary, and subsequent land bridges or stepping stone islands linking to Central and South America might also have facilitated colonization. Species-area relationships within the West Indies suggest a strong role for endemic radiations and extinction in shaping patterns of diversity. Diversification is promoted by opportunities for allopatric divergence between islands, or within the large islands of the Greater Antilles, with a classic example provided by the Anolis lizards. The timing of colonization events using molecular clocks permits analysis of colonization-extinction dynamics by means of species accumulation curves. These indicate low rates of colonization and extinction for reptiles and amphibians in the Greater Antilles, with estimated average persistence times of lineages in the West Indies exceeding 30Myr. Even though individual island populations of birds might persist an average of 2Myr on larger islands in the Lesser Antilles, recolonization from within the archipelago appears to maintain avian lineages within the island chain indefinitely. Birds of the Lesser Antilles also provide evidence of a mass extinction event within the past million years, emphasizing the time-heterogeneity of historical processes. Geographical dynamics are matched by ecological changes in the distribution of species within islands over time resulting from adaptive radiation and shifts in habitat, often following repeatable patterns. Although extinction is relatively infrequent under natural conditions, changes in island environments as a result of human activities have exterminated many populations and others--especially old, endemic species--remain vulnerable. Conservation efforts are strengthened by recognition of aesthetic, cultural and scientific values of the unique flora and fauna of the West Indies.     

Phylogeny and colonization history of Pringlea antiscorbutica (Brassicaceae), an emblematic endemic from the South Indian Ocean Province

The origins and evolution of sub-Antarctic island floras are not well understood. In particular there is uncertainty about the ages of the contemporary floras and the ultimate origins of the lineages they contain. Pringlea R. Br. (Brassicaceae) is a monotypic genus endemic to four sub-Antarctic island groups in the southern Indian Ocean. Here we used sequences from both the chloroplast and nuclear genomes to examine the phylogenetic position of this enigmatic genus. Our analyses confirm that Pringlea falls within the tribe Thelypodieae and provide a preliminary view of its relationships within the group. Divergence time estimates and ancestral area reconstructions imply Pringlea diverged from a South American ancestor ～5Myr ago. It remains unclear whether the ancestor of Pringlea dispersed directly to the South Indian Ocean Province (SIOP) or used Antarctica as a stepping-stone; what is clear, however, is that following arrival in the SIOP several additional long-distance dispersal events must be inferred to explain the current distribution of this species. Our analyses also suggest that although Pringlea is likely to have inherited cold tolerance from its closest relatives, the distinctive morphology of this species evolved only after it split from the South American lineage. More generally, our results lend support to the hypothesis that angiosperms persisted on the sub-Antarctic islands throughout the Pliocene and Pleistocene. Taken together with evidence from other sub-Antarctic island plant groups, they suggest the extant flora of sub-Antarctic is likely to have been assembled over a broad time period and from lineages with distinctive biogeographic histories.     

Phylogenetic relationships among members of the subfamily Sedoideae (Crassulaceae) inferred from the ITS region sequences of nuclear rDNA

Nucleotide sequences of the nuclear rDNA ITS regions were determined in 20 species of the subfamily Sedoideae (Crassulaceae). The phylogenetic relationships of these species with other members of the subfamily, occurring mainly in Southeast Asia, were analyzed. It was shown that the genus Orostachys was not monophyletic; its type subsection was significantly included into the clade of the genus Hylotelephium. Synapomorphic substitutions and indels, specific for the subsection Orostachys, were detected in ITS1. Sister relationships were established between clades Aziopsis and Phedimus, based on which they can be recognized as isolated genera.     

Molecular phylogenetics and character evolution of the "sacaca" clade: novel relationships of Croton section Cleodora (Euphorbiaceae)

Phylogenetic relationships of Croton section Cleodora (Klotzsch) Baill. were evaluated using the nuclear ribosomal ITS and the chloroplast trnL-F and trnH-psbA regions. Our results show a strongly supported clade containing most previously recognized section Cleodora species, plus some other species morphologically similar to them. Two morphological synapomorphies that support section Cleodora as a clade include pistillate flowers in which the sepals overlap to some degree, and styles that are connate at the base to varying degrees. The evolution of vegetative and floral characters that have previously been relied on for taxonomic decisions within this group are evaluated in light of the phylogenetic hypotheses. Within section Cleodora there are two well-supported clades, which are proposed here as subsections (subsection Sphaerogyni and subsection Spruceani). The resulting phylogenetic hypothesis identifies the closest relatives of the medicinally important and essential oil-rich Croton cajucara Benth. as candidates for future screening in phytochemical and pharmacological studies.