A new species of Bursera (Burseraceae) from Cuba

A revision of Bursera in the Greater Antilles has revealed the first new species of the genus to be described from the Caribbean in almost 45 years. Bursera gibarensis is known only from coastal scrub on dogtooth limestone near Gibara in Holguín Province.     

The relationship of terpene composition,morphology, and distribution of populations of Bursera microphylla (Burseraceae)

On the basis of terpene composition, populations ofB. microphylla show north to south affinities on both the Baja California peninsula and the northwest coast of Mexico. The lack of east to west population affinities corresponds with the presumed absence of land connections between the peninsula and mainland throughout the history of this taxon. Morphological similarities between populations in an east-west direction are explained on the basis of contemporary parallel selective influences and not by the closeness of relationship.     

Phylogeography of palo santo trees (Bursera graveolens and Bursera malacophylla; Burseraceae) in the Galápagos archipelago

Two species of palo santo trees are distributed in the Galápagos archipelago, the native Bursera graveolens and the endemic Bursera malacophylla (Burseraceae). However, a zone of individuals morphologically intermediate between the two exists on northern Santa Cruz Island and south‐eastern Santiago Island, suggesting that they may not be reproductively isolated. Here we review the species' distributional and morphological differences and test for evidence of hybridization between the two species using DNA sequence and AFLP data. We find that the species lack distinguishing synapomorphies across the five nuclear and plastid regions examined. Population assignment tests and population genetic analyses of AFLP data indicate that genetically similar palo santo individuals (N = 87), including putative hybrids, partition into two genealogical groups that do not uniformly correspond to island‐ or taxon‐based membership. Furthermore, genotypic admixture levels among morphologically intermediate individuals do not indicate widespread hybridization. Thus, we recommend recognizing the endemic palo santo taxon as B. graveolens subspecies malacophylla (B.L.Rob.) A. Weeks & Tye comb. & stat. nov. in light of its close genetic relationship to B. graveolens subsp. graveolens and its distinctive morphology and distribution. Future research should quantify phenotypic variation in palo santo populations as another means for understanding the basis of morphological differences between the subspecies. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 396–410.     

Historical biogeographical patterns of the species of Bursera (Burseraceae) and their taxonomic implications

Aim The plant genus Bursera, with 104 species of trees and shrubs, has been used as a model for biogeographical analyses because of its high species richness and large number of endemic species. The biogeographical patterns of Bursera and their implications for its phylogenetic classification are reviewed in order that some hypotheses on the historical biogeography of tropical Mexico can be proposed. Location Bursera is found in the south‐western USA, most of Mexico, mainly below 1700 m elevation in tropical forests, with some species in xeric shrublands, diversifying along the Pacific slope, Central America, and north‐western South America. A few species occur on the Galapagos and Revillagigedo archipelagos, some of which are endemics, whereas in the Antilles species are distributed extensively, with several endemics in the Bahamas, Cuba, Jamaica, and Hispaniola. Methods Data from specimens in herbaria and the literature were used to construct a matrix of 104 species in 160 areas. Distributional patterns of the species of Bursera were inferred applying track analysis, parsimony analysis of endemicity (PAE), and Brooks parsimony analysis (BPA). Results Track analysis revealed four individual tracks: (1) a circum‐Caribbean track, comprising species of the Bursera simaruba species group; (2) an Antillean track, including species that have been transferred to Commiphora based on their pollen traits; (3) a Mexican Pacific track, including species of the B. fragilis, B. microphylla, and B. fagaroides species groups, called ‘cuajiotes’; and (4) a Neotropical Pacific track, including the two species groups assigned to section Bullockia, in which the individual track of the Bursera copallifera species group is nested within the track of the B. glabrifolia species group. The four tracks overlap in a node in the Mexican Pacific slope, where they are highly diversified. PAE allowed us to identify 22 areas of endemism: 12 in Mexico (11 along the Mexican Pacific slope), six in the Antilles, two in Central America, one in South America, and one in the Galapagos. The general area cladogram obtained by BPA has two main clades: one includes the greater Antilles; and the other, 12 Mexican areas of endemism. Main conclusions Bursera fragilis, B. microphylla, and B. fagaroides species groups can be treated together as a new section within Bursera, sect. Quaxiotea, because they are segregated from the other groups of sect. Bursera based on morphological, anatomical, molecular and geographical evidence.     

Restricted gene flow in fragmented populations of a wind-pollinated tree

Fragmentation of natural populations can have negative effects at the genetic level, thus threatening their evolutionary potential. Many of the negative genetic impacts of population fragmentation can be ameliorated by gene flow and it has been suggested that in wind-pollinated tree species, high or even increased levels of gene flow are a feature of fragmented populations, although several studies have disputed this. We have used a combination of nuclear microsatellites and allele-specific PCR (AS-PCR) analysis of chloroplast single nucleotide polymorphisms (SNPs) to examine the levels and patterns of genetic diversity and population differentiation in fragmented populations of juniper (Juniperus communis) in Ireland and inform conservation programs for the species. Significant population differentiation was found for both chloroplast and nuclear markers, indicating restricted gene flow, particularly over larger geographic scales. For conservation purposes, the existence of genetically distinct clusters and geographically localised chloroplast haplotypes suggests that the concept of provenance should be taken into account when formulating augmentation or reintroduction strategies. Furthermore, the potential lack of seed dispersal and seedling establishment means that ex-situ approaches to seed and seedling management may have to be considered.     

Insights into the historical construction of species-rich Mesoamerican seasonally dry tropical forests: the diversification of Bursera (Burseraceae, Sapindales)

? Mesoamerican arid biomes epitomize neotropical rich and complex biodiversity. To document some of the macroevolutionary processes underlying the vast species richness of Mesoamerican seasonally dry tropical forests (SDTFs), and to evaluate specific predictions about the age, geographical structure and niche conservatism of SDTF-centered woody plant lineages, the diversification of Bursera is reconstructed. ? Using a nearly complete Bursera species-level phylogeny from nuclear and plastid genomic markers, we estimate divergence times, test for phylogenetic and temporal diversification heterogeneity, test for geographical structure, and reconstruct habitat shifts. ? Bursera became differentiated in the earliest Eocene, but diversified during independent early Miocene consecutive radiations that took place in SDTFs. The late Miocene average age of Bursera species, the presence of phylogenetic geographical structure, and its strong conservatism to SDTFs conform to expectations derived from South American SDTF-centered lineages. ? The diversification of Bursera suggests that Mesoamerican SDTF richness derives from high speciation from the Miocene onwards uncoupled from habitat shifts, during a period of enhanced aridity resulting mainly from global cooling and regional rain shadows.     

Nuclear ribosomal DNA phylogeny and its implications for evolutionary trends in Mexican Bursera (Burseraceae)

The genus Bursera (Burseraceae) is one of the most diversified and abundant groups of plants of the tropical dry forests of Mexico. In order to provide a basis for better understanding of its evolutionary biology, we reconstructed a phylogeny of 57 species and varieties using the nucleotide sequences of the internal transcribed spacer regions (ITS1 and ITS2) of 18S–26S and the 5.8S coding region of nuclear ribosomal DNA. We used four species of the allied genera Commiphora and Boswellia and one species of Spondias (Anacardiaceae) as outgroups. Our results support the views that Bursera is monophyletic and more closely related to Commiphora than to Boswellia. The division of Bursera into sections Bullockia and Bursera is also strongly supported by our phylogeny. Several other subclades also had high bootstrap values, especially within section Bursera. We use the phylogeny as a basis for discussing evolutionary tendencies in bark, leaves, breeding systems, and fruits.     

Venation patterns of Bursera species Jacq. ex L. (Burseraceae) and systematic significance

The taxonomy of the genus Bursera has been traditionally supported by morphological characters such as fruit form, bark and leaves. Nonetheless, leaf architecture, another important source of phylogenetic information, has not been well studied in this group. For this purpose, venation patterns of 30 species of the genus Bursera in Mexico were studied. Clarified leaves allowed finding four types of venation patterns: brochidodromous and eucamptodromous in complex B. simaruba (section Bursera); a cladodromous pattern in fragilis, microphylla and fagaroides groups (herein informally called group Quaxiotea (section Bursera), and semicraspedodromous in section Bullockia species. Only bipinnated species of section Bullockia showed a brochidodromous venation pattern. Furthermore, section Bullockia and complex Simaruba presented reticulate tertiary veins, whereas the group of Quaxiotea species presented a ramified pattern in the tertiary veins and tracheoblasts.     

Morphology and biometry of three populations of Artemia (Branchiopoda: Anostraca) from the Dominican Republic and Puerto Rico

Data from five key regions are presented to produce thematic plots of winter nutrient (dissolved available inorganic nitrogen and phosphorus) concentrations for the Irish Sea. It is suggested that riverine discharges are the biggest contributor of nutrients to the system, however, anthropogenic point source discharges are also major contributors of these nutrient salts in the eastern Irish Sea. Comparison of the thematic maps produced in this study are made with similar maps produced almost a decade previously, the comparisons show a great many similarities between the two studies. However, waters in the north-eastern Irish Sea show that dissolved available inorganic phosphorus (DAIP) appears to have decreased in concentration in recent years whilst no such change is seen with respect to dissolved available inorganic nitrogen (DAIN). The use of nutrient-salinity regressions indicate that during winter 1997 anthropogenic discharges along the Cumbria coast combined with remobilisation of sedimented material was a major contributing factor of nutrient salts to the system.     

A new species of Lepanthes (Orchidaceae) from Puerto Rico

A new species,Lepanthes caritensis, is described and illustrated. There are now nine species ofLepanthes known to occur in Puerto Rico. Plant habitat and floral morphology ofL. caritensis is most similar to that ofL. sanguinea. A survey of the area where the new species is located suggests that it is rare and should be protected under the Federal Endangered Species Act. Una especic nueva,Lepanthes caritensis, es descrita e ilustrada para Puerto Rico. Con ésta hay ahora nueve especies deLepanthes en Puerto Rico. El hábito de la planta y la morfología de la flor deL. caritensis es más similar aL. sanguinea. Un muestreo del área donde se encuentra la nueva especie sugiere que ésta es rara y que debería ser protegida por el Federal Endangered Species Act.     

A frequent tyrosinase gene mutation associated with type I-A (tyrosinase-negative) oculocutaneous albinism in Puerto Rico.

We have determined the mutations in the tyrosinase gene from 12 unrelated Puerto Rican individuals who have type I-A (tyrosinase-negative) oculocutaneous albinism (OCA). All but one individual are of Hispanic descent. Nine individuals were homozygous for a missense mutation (G47D) in exon I at codon 47. Two individuals were heterozygous for the G47D mutation, with one having a missense mutation at codon 373 (T373K) in the homologous allele and the other having an undetermined mutation in the homologous allele. One individual with negroid features was homozygous for a nonsense mutation (W236X). The population migration between Puerto Rico and the Canary Islands is well recognized. Analysis of three individuals with OCA from the Canary Islands showed that one was a compound heterozygote for the G47D mutation and for a novel missense mutation (L216M), one was homozygous for a missense mutation (P81L), and one was heterozygous for the missense mutation P81L. The G47D and P81L missense mutations have been previously described in extended families in the United States. Haplotypes were determined using four polymorphisms linked to the tyrosinase locus. Haplotype analysis showed that the G47D mutation occurred on a single haplotype, consistent with a common founder for all individuals having this mutation. Two different haplotypes were found associated with the P81L mutation, suggesting that this may be either a recurring mutation for the tyrosinase gene or a recombination between haplotypes.     

Evolution of Mexican Bursera (Burseraceae) inferred from ITS,ETS, and 5S nuclear ribosomal DNA sequences

I reconstructed a phylogeny of 66 species and varieties of Bursera and 9 outgroup species using sequences of the internal transcribed spacer region (ITS), the 5S non-transcribed region (5S-NTS), and the external transcribed region (ETS) of nuclear ribosomal DNA. This study extends a previously proposed parsimony-based phylogenetic study that used the ITS sequences of 57 Bursera species and five outgroups. Parsimony and maximum likelihood methods were used to infer the phylogeny in this new study. Analyses of the combined data sets largely confirmed the phylogenetic relationships proposed by the previous molecular study but generated a considerably more robust topology. The new phylogenies corroborate the monophyly of the genus, and its division into the two monophyletic subgenera or sections, Bursera and Bullockia. The current analyses also identify four main groups of species in section Bursera, and two in section Bullockia, confirming some of the previously proposed groups based on fruit, flower, and leaf morphology. One previously problematic species B. sarcopoda, which has sometimes been placed in Commiphora, is shown to belong in Bursera. Another controversial species, Commiphora leptophloeos, which was thought to belong to Bursera, falls within Commiphora.     

Frugivory and Seed Fate in Bursera inversa (Burseraceae) at Tinigua Park,Colombia: Implications for Primate Conservation1

The large ateline primates are efficient seed dispersers in Neotropical forests and hunting is driving their populations to extinction, but we do not know whether other frugivores could substitute primates in their ecological role as seed dispersers. In this study we test this possibility using a potential keystone species (Bursera inversa) at Tinigua Park, Colombia. This plant species allows us to compare seed removal rates between emergent, isolated trees, without primate visitors and trees with connected crowns. We used traps to estimate fruit production and seed removal rates in six different trees, and fruiting trees were observed during 2 yr to quantify the number of seeds manipulated by different animal species. We carried out seed predation experiments to test if seed removal by predators was affected by distance or density effects. We found that the most productive trees attracted more visiting species and seed removal rates differed among trees, the lowest corresponding to trees without primate access. Seed removal rates from the ground by predators were not higher below parental trees than away from them, but the distribution of saplings in the forest suggests that seed dispersal is advantageous. Although it is likely that the effect of primate extinctions will vary depending on tree species traits, conserving the populations of primate seed dispersers is critical to maintain the ecological processes in this forest.     

Incorporating urban infrastructure into biogeochemical assessment of urban tropical streams in Puerto Rico

The influence of built urban infrastructure on stream chemistry was quantified throughout the drainage network of the tropical Río Piedras watershed, San Juan metropolitan area, Puerto Rico. Urbanization and failing domestic wastewater infrastructure appeared to drive changes in surface water chemistry throughout the watershed. Mean baseflow concentrations of chloride (Cl), ammonium (NH₄), dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and phosphate (PO₄) all increased with urban infrastructure, while nitrate (NO₃) and dissolved oxygen (DO) decreased. These patterns in stream chemistry suggest that sewage effluent from failing or illegally connected sewer pipes has a major impact on surface water quality. Concentrations of Cl, DO, and NH₄ in stream water were most strongly related to sewer pipe volume, demonstrating the tight connection between urban infrastructure and stream chemistry. The loading and transformation of NO₃ and NH₄ were modeled along the river network and NH₄ loading rates from the landscape were strongly related to urban infrastructure, whereas NO₃ loading rates showed only weak relationships, highlighting the importance for incorporating NH₄ dynamics into river network models in urban environments. Water quality appears to be severely impacted by sewage in this tropical basin, despite large investments in built infrastructure. The high temperatures in the Río Piedras exacerbate water quality problems by reducing saturation DO levels in streams, and intense rainstorms tax the ability of built infrastructure to adequately manage overland flows. These problems are likely typical of much of the urbanized humid tropics.     

Biology of the Mongoose (Herpestes javanicus) in a Rain Forest of Puerto Rico1

Ecological aspects of the mongoose (Herpestes javanicus) were studied in the Luquillo Mountains, a rain forest region in eastern Puerto Rico. Information was obtained by removal trapping of mongoose from grids placed in tree plantations, colorado and tabonuco forests. Trapping efficiency was two mongoose per 100 trap-days, suggesting mongoose abundance is low in wet montane forests of Puerto Rico. Sex ratio was biased (2.6:1) in favor of males. Body masses of male mongoose inhabiting rain forests of the Luquillo Mountains were larger than those in dry forests at Guánica (P < 0.0001). Stomach contents from 18 mongoose were examined, animal matter comprised 75 percent of the total food items encountered. Of these, 33 percent were from vertebrates. The food items most frequently encountered were lizards (Anolis spp.), centipedes (Scolopendra spp.), and cockroaches (Blatellidae).     

Barriers to gene flow from oilseed rape (Brassica napus) into populations of Sinapis arvensis

One concern over growing herbicide-tolerant crops is that herbicide-tolerance genes may be transferred into the weeds they are designed to control. Brassica napus (oilseed rape) has a number of wild relatives that cause weed problems and the most widespread of these is Sinapis arvensis (charlock). Sinapis arvensis seed was collected from 102 populations across the UK, within and outside B. napus-growing areas. These populations were tested for sexual compatibility with B. napus and it was found that none of them hybridized readily in the glasshouse. In contrast to previous studies, we have found that hybrids can be formed naturally with S. arvensis as the maternal parent. Six diverse B. napus cultivars (Capricorn, Drakkar, Falcon, Galaxy, Hobson and Regent) were tested for their compatibility with S. arvensis but no cultivar hybridized readily in the glasshouse. We were unable to detect gene transfer from B. napus to S. arvensis in the field, confirming the extremely low probability of hybridization predicted from the glasshouse work.     

Cecropia schreberiana in the Luquillo Mountains of Puerto Rico

Cecropia schreberiana Miq. (Cecropiaceae) is a common tree in the Luquillo Mountains of Puerto Rico because it is a pioneer that establishes abundantly after recurrent hurricanes that damage Luquillo forests. In these forestsC. schreberiana typically reaches about 20 m in height and 60 cm dbh and has few branches, these bearing large, deeply lobed leaves. The wood is light and weak. Unlike most of its congeners,C. schreberiana in Puerto Rico does not have symbiotic ants. It is dioecious and produces wind-pollinated flowers in spikes and abundant minute seeds broadly dispersed by birds and bats. Forest soils contain a high density of its seeds, which lie dormant until canopy opening stimulates germination. With adequate nutrientsC. schreberiana grows fast in high light, while nondominant individuals suffer heavy mortality. An individual of the species is thought to live 30 to 50 years. Cecropia schreberiana is uncommon in abandoned pastures in the Luquillo Mountains. It colonizes road cuts, landslides, and infrequent, large treefall gaps. Yet these disturbances provide only a limited “background regeneration,” which is not sufficient to maintain the species’ observed high abundance in Luquillo forests. However, there is widespread and abundantC. schreberiana regeneration after hurricane damage opens the forest canopy. Despite high mortality among these post-hurricane colonizers, enough survive and grow so thatC. schreberiana is generally among the ten most common canopy trees in the widespread “tabonuco” forest type. Post-hurricane colonizers mature, senesce, and decline in number, butC. schreberiana remains abundant as seeds in the soil ready to form tree cohorts after disturbance. The status of theC. schreberiana population indicates the developmental status of the forest as a whole. Moreover,C. schreberiana performs a key function in the reorganization of Luquillo forest ecosystems after disturbance, when its abundant regeneration and rapid growth capture and store nutrients. Also, its colonizing saplings may facilitate succession to mature forest by excluding grasses, herbs, and vines that hinder forest development. The biology of this species both reflects and helps drive the dynamics of forests in the Luquillo Mountains.