Showing papers in "Annals of the Missouri Botanical Garden in 2006"
TL;DR: When the Panamanian land bridge was emplaced about 2.7 Ma, it triggered the Great American Biotic Interchange, a major mingling of land mammal faunas between North and South America, which justifies the term Neotropical Realm.
Abstract: When the Panamanian land bridge was emplaced about 2.7 Ma, it triggered the Great American Biotic Interchange (GABI), a major mingling of land mammal faunas between North and South America. Four families of northern immigrants (Procyonidae, Felidae, Tayassuidae, and Camelidae) diversified at moderate rates, while four others, Canidae, Mustelidae, Cervidae, and especially Muridae, evolved explosively. As a consequence, half of living South American genera are descendants of northern immigrants. The other major consequence of the interchange was the conquest of tropical North America by immigrants from Amazonia, an episode that justifies the term Neotropical Realm.
195 citations
TL;DR: In this article, plant microfossil and macrofossils associations obtained from six dated sections from the area of the basin of Bogota (2550 m, Eastern Cordillera, Colombia) show the evolution of the late Neogene Andean montane forest, triggered by the Andean orogeny.
Abstract: Plant microfossil and macrofossil associations obtained from six dated sections from the area of the basin of Bogota (2550 m, Eastern Cordillera, Colombia) show the evolution of the late Neogene Andean montane forest, triggered by the Andean orogeny. Progressive adaptation of warm tropical taxa to cool montane conditions, evolution of new neotropical montane taxa, and immigration of temperate Laurasian, Holarctic, and Austral-Antarctic elements gave shape to the present-day montane forest. Vegetational characteristics inferred from fossil plant associations reveal the altitude at the time of deposition. Neogene forests are floristically compared with contemporary forests at comparable altitudinal intervals in the surroundings of the Bogota basin; however, the absence of taxa that had not yet arrived, or evolved, is most salient and shows that non-analogue plant communities are common. The main phases of montane forest development are: (1) pre-uplift phase of the late Miocene with abundant lowland...
168 citations
TL;DR: Geologic evidence cannot unambiguously support or refute any of the proposed dispersal, vicariance, and land bridges models, despite claims to the contrary.
Abstract: The fauna of the West Indies includes more than 1300 native terrestrial vertebrate species and is characterized by high levels of endemism. Several theories have been proposed to explain how these animals arrived to the islands, including dispersal, vicariance, and land bridges. The dispersal theory proposes that most of the West Indian terrestrial biota arrived by flying or by flotsam. The vicariance theory suggests that there was a proto-Antillean land mass, or masses, connecting North and South America in the late Cretaceous that traveled eastward as the Caribbean geologic plate developed and carried an ancient biota with it. One widely discussed land bridge theory proposes that much of the Antillean biota originated by dispersal over an unbroken dry land connection, the Aves Ridge, between South America and the Greater Antilles 35–33 Ma. Geologic evidence cannot unambiguously support or refute any of these models, despite claims to the contrary. Other evidence bearing on these three theories,...
148 citations
TL;DR: The detailed nature of climatic change over the late Quaternary remains poorly understood for northern and central Mexico as mentioned in this paper, and a scarcity of records in the former and great complexity in the latter have hindered a thorough reconstruction of changing environments.
Abstract: The detailed nature of climatic change over the late Quaternary remains poorly understood for northern and central Mexico. A scarcity of records in the former and great complexity in the latter have hindered a thorough reconstruction of changing environments. Previously published research by Metcalfe et al. highlighted questions relating to conditions at the last glacial maximum (LGM), the nature of the transition from glacial to interglacial conditions, and change over the Holocene, including the role of phenomena such as El Nino–Southern Oscillation (ENSO). Here, data from the Sonoran Desert, the Chihuahuan Desert, and the Trans-Mexican Volcanic Belt (TMVB) (and adjacent oceans) are reviewed. In the desert regions, the mid-Pleistocene may have been drier than the late Pleistocene, which was significantly cooler than present and saw more winter precipitation derived from midlatitude frontal systems. There was a significant expansion southward of woodland taxa, although many fossil vegetation ass...
122 citations
TL;DR: A molecular study of the Cardueae using one nuclear region (ITS) and two chloroplastic markers (trnL-trnF and matK) in addition to a more appropriate outgroup was performed in this paper.
Abstract: The new outline of relationships in basal branches of the family Compositae Giseke confirms that the sister group to the tribe Cardueae Cass. are not Mutisieae Cass., but rather a group of African genera now classified as the tribe Tarchonantheae Kostel. This change implies that the monophyly of the Cardueae must be reassessed on a molecular basis. Moreover, new collections in recent years allow us to extend our sampling to 70 of the 74 genera of the tribe. We performed a new molecular study of the tribe using one nuclear region (ITS) and two chloroplastic markers (trnL-trnF and matK) in addition to a more appropriate outgroup. Our results confirm that the Cardueae is a natural group but indicate some changes in subtribal delineation: the subtribe Cardopatiinae Less. is recognized and some genera are moved to other subtribes (Myopordon Boiss., Nikitinia Iljin, Syreitschikovia Pavlov, and the Xeranthemum L. group). A recapitulation of a number of interesting questions that remain unresolved in the...
119 citations
TL;DR: Current available geologic and paleontologic data are most consistent with the Africa-first model, suggesting that Africa was the first of the major Gondwanan landmasses to be fully isolated prior to the Albian/Cenomanian boundary, and that its terrestrial vertebrate faunas became progressively more provincial during the Cretaceous, while those on other Gondwana landmassed remained relatively cosmopolitan until the later stages of the Late Cret Jurassic.
Abstract: The Mahajanga Basin Project, initiated in 1993 and centered in Upper Cretaceous strata of northwestern Madagascar, has resulted in the discovery of some of the most complete, well-preserved, and significant specimens of Late Cretaceous vertebrate animals from the Southern Hemisphere and indeed the world. Among the most important finds are various specimens of crocodyliforms, non-avian dinosaurs, and mammals; these finds have the potential to provide key insights into the biogeographic and paleogeographic history of Gondwana. Madagascar has been physically isolated from Africa for over 160 million years and from all other major landmasses for more than 85 million years. The closest known relatives of many of the Late Cretaceous Malagasy taxa are penecontemporaneous forms from South America (primarily Argentina) and India, thus documenting a previously unrecognized high level of cosmopolitanism among Gondwanan vertebrates near the end of the Cretaceous. The family-level taxa that are shared among M...
109 citations
TL;DR: The general trends of the floral traits and plant-pollinator interactions at the Bocaina grasslands resemble those of biogeographic-connected ecosystems, such as the Venezuelan arbustal, and the Brazilian campo rupestre and cerrado.
Abstract: Surveys of local assemblages of plants and their pollinators are among the most useful ways to evaluate specialization in pollination and to discuss the patterns of plant-pollinator interactions among ecosystems The high-altitude grasslands from southeastern Brazil constitute diminutive island-like formations surrounded by montane rainforests We registered the floral traits of 124 species from the Serra da Bocaina grasslands (about 60% of the animal-pollinated species of this flora), and determined the pollinators of 106 of them Asteraceae (40 species) and Melastomataceae (10 species) were prominent, while most families were represented by few species The predominant floral traits were: dish or short-tubular shape; nectar as a reward; and greenish or violaceous colors Pollinators were divided into eight functional groups (small bees, syrphids, other dipterans, etc) and small bees, wasps, and large bees were the most important pollinators Butterflies, beetles, and hummingbirds were poorly r
96 citations
TL;DR: A corpus of historical data from lake sediments relating to the climate, vegetation, and human land use of the lowland Central American tropical forest between ca. 20,000 BP and the time of European contact is reviewed in this paper.
Abstract: The corpus of historical data from lake sediments relating to the climate, vegetation, and human land use of the lowland Central American tropical forest between ca. 20,000 BP and the time of European contact is reviewed. Pollen, phytolith, and charcoal records identify the distribution and composition of tropical vegetation and fire patterns during the late Pleistocene, when they were significantly altered from today's, and earliest Holocene, when plant communities reassembled and interglacial representatives began to coalesce on the landscape. The significance of the environmental perturbations that occurred during the transition from the Pleistocene to the Holocene for human occupation of the lowland tropical forest and the geography and chronology of agricultural origins is discussed. Fire was employed by hunters and gatherers and farmers alike during the past 11,000 years as a primary tool of forest modification. The profound effects of an ancient pre-Columbian development of plant food prod...
87 citations
TL;DR: Analysis of patterns of genetic differentiation in allozymes and mtDNA in relation to the geological history of California is used to generate biogeographic scenarios to help explain the contrast between Batrachoseps and Ensatina.
Abstract: How many species one recognizes within a given taxon remains a difficult question, especially when morphology is relatively stable or when clinal variation is present, thus complicating diagnosis. I accept the general lineage concept of species, and my goal is to recognize historically distinct evolutionary lineages that are likely to remain distinct. Here I analyze this task with respect to patterns of species formation in two genera of plethodontid salamanders in California. Ensatina is a ring species complex surrounding the Central Valley of California. At present it is a single species with seven subspecies that are linked by apparent clinal variation in intergrade zones, but there are also some narrow hybrid zones where morphologically and ecologically differentiated forms interact. In contrast, Batrachoseps, which has much the same distribution, has about 20 species in California, most occurring in sympatry with Ensatina. Divergence in the two taxa is based on two fundamentally different ph...
81 citations
TL;DR: Based on the unequaled southern Late Cretaceous-Cenozoic record, the history of South American land mammals is divisible into two major episodes we term the Gondwanan Episode and the South American Episode.
Abstract: Based on the unequaled southern Late Cretaceous–Cenozoic record, the history of South American land mammals is divisible into two major episodes we term the Gondwanan Episode and the South American Episode. The former episode is distinguished by the northern and central Patagonian Argentinian record, while the latter is mostly based on the extra-Patagonian Argentinian record. The Gondwanan Episode is so termed because it is exclusively represented by endemic mammals of Gondwanan origin, i.e., Mesozoic lineages. In contrast, the South American Episode is almost exclusively distinguished by endemic Therian mammals whose ancestors emigrated from the Laurasian North American Continent. These two major, successive, and for some time superimposed episodes are the result of the geologic history of the South American Plate. (1) This plate was part of the Gondwana Supercontinent until about 120 millions of years before Present (mybP), when it began to separate and drifted westward (but always south and re...
80 citations
TL;DR: The answer is that the classic model of ecological interactions as the driving force in adaptive radiation can account for this aspect of anole evolutionary diversity in the Caribbean anole radiations, but not entirely.
Abstract: Caribbean Anolis lizards are a classic case of adaptive radiation, repeated four times across islands of the Greater Antilles. On each island, very similar patterns of evolutionary divergence have occurred, resulting in the evolution of the same set of ecological specialists—termed ecomorphs—on each island. However, this is only part of the story of the Caribbean anole radiations. Indeed, much of the species diversity of Caribbean Anolis occurs within clades of ecomorphs, which contain as many as 14 ecologically-similar species on a single island. We ask to what extent the classic model of ecological interactions as the driving force in adaptive radiation can account for this aspect of anole evolutionary diversity. Our answer is that it can in part, but not entirely. More generally, the most complete understanding of evolutionary diversification and radiation is achieved by studying multiple hierarchical evolutionary levels from clades to populations.
TL;DR: Ten species are recognized, including two new species, Capparis atlantica and C. zoharyi, including four new subspecies, and a full taxonomic treatment, keys, and distribution maps of the recognized species are provided.
Abstract: A systematic revision of Capparis sect. Capparis, from western and Central Asia, North Africa, and Europe, is presented here. The taxonomy of this section has been approached combining morphological, biogeographical and molecular data when available. Ten species are recognized, including two new species, Capparis atlantica and C. zoharyi. In addition, four new subspecies are presented: Capparis ovata subsp. myrtifolia, C. parviflora subsp. sphaerocarpa, C. sicula subsp. mesopotamica, and C. sicula subsp. sindiana. Lectotypes are designated for C. aegyptia, C. hereroensis, C. mucronifolia, C. elliptica, C. mucronifolia Boiss. subsp. rosanoviana, C. rupestris, C. ovata, C. parviflora, C. spinosa var. canescens, C. sicula subsp. herbacea, and C. sicula subsp. leucophylla. A full taxonomic treatment, keys, and distribution maps of the recognized species are provided. The two new species are illustrated.
TL;DR: A multi-disciplinary approach has helped to elucidate the selective factors that have promoted speciation and shifts in breeding systems in Schiedea (Caryophyllaceae), the fifth largest lineage in the native Hawaiian flora and the most diverse lineage with respect to breeding systems.
Abstract: A multi-disciplinary approach, including phylogenetic analysis, population biology, and quantitative genetics, has helped to elucidate the selective factors that have promoted speciation and shifts in breeding systems in Schiedea (Caryophyllaceae). Schiedea is the fifth largest lineage in the native Hawaiian flora and the most diverse lineage with respect to breeding systems. The genus is monophyletic and shares a common ancestor with a clade consisting of two arctic or boreal-north temperate species. Most inter-island colonizations were from older to younger islands, and most movement between islands led to sufficient isolation to result in formation of new species that are single-island endemics rather than species with multi-island distributions. Closely related species pairs occurring on older islands tend to differ in habitat and are isolated ecologically on the same island, while species pairs on younger islands tend to be in similar habitat on different islands. Speciation within this line...
TL;DR: Ongoing work includes searches for the molecular signature of selection during hybrid Speciation, surveys of gene expression shifts associated with hybrid speciation, and experiments that evaluate the role of new hybrid gene combinations versus reproductive isolation in the ecological divergence of hybrid lineages.
Abstract: Hybrid speciation refers to the establishment of novel hybrid genotypes that are reproductively isolated from their parental species and genetically stabilized. Most frequently, reproductive isolation is achieved via an increase in ploidy. However, in some instances new hybrid species arise and become reproductively isolated without a change in chromosome number, a process known as diploid or “homoploid” hybrid speciation. The annual sunflowers of the genus Helianthus provide a well-studied example of this latter mode of speciation. Here, I review this work, placing individual studies in their proper context. These include (1) computer simulations that describe the evolutionary conditions under which hybrid speciation is most likely; (2) molecular phylogenetic studies that document the origins of three hybrid sunflower species; (3) comparative genetic mapping studies that describe the karyotypic changes associated with hybrid speciation; (4) experimental re-creations of homoploid hybrid species t...
TL;DR: The essentialism story, a narrative that has most pre-Darwinian biologists steeped in the world view of Plato and Aristotle, is ill-founded and improbable.
Abstract: The current picture of the history of taxonomy incorporates A. J. Cain's claim that Linnaeus strove to apply the logical method of definition taught by medieval followers of Aristotle. Cain's argument does not stand up to critical examination. Contrary to some published statements, there is no evidence that Linnaeus ever studied logic. His use of the words “genus” and “species” ruined the meaning they had in logic, and “essential” meant to him merely “taxonomically useful.” The essentialism story, a narrative that has most pre-Darwinian biologists steeped in the world view of Plato and Aristotle, is ill-founded and improbable.
TL;DR: Maximum parsimony analysis was conducted on a data set comprising DNA sequences from five plastid loci and morphological data for 65 taxa of Mesechiteae and its affinities to other genera in the tribe, and Mandevilla was found to be monophyletic, whereas Woodson's circumscription proved to be polyphyletic.
Abstract: In order to test the monophyly of Mandevilla Lindl., the largest genus in tribe Mesechiteae (Apocynaceae, Apocynoideae), and its affinities to other genera in the tribe, maximum parsimony analysis was conducted on a data set comprising DNA sequences from five plastid loci (rpl16, rps16, and trnK introns; trnSGCU-trnGUUC intergenic spacer; and matK gene), as well as morphological data for 65 taxa of Mesechiteae (48, Mandevilla) and nine taxa from other tribes of the subfamily. Mandevilla, as circumscribed by Pichon, was found to be monophyletic, whereas Woodson's circumscription proved to be polyphyletic. Thus defined, Mandevilla forms a strongly supported clade that can be divided into six clades of species groups. Most of the infrageneric taxa of Mandevilla proposed by Woodson and Pichon are polyphyletic. Many of the diagnostic characters previously used to define taxonomic groups are shown to have arisen multiple times, rendering them unsuitable for classificatory purposes. The similar growth f...
TL;DR: The results indicate an early north-south disjunction in Sinningieae and pinpoint the need for a phylogenetic framework to correctly understand area relationships and the relative contribution of dispersal and vicariance events in present-day distribution patterns.
Abstract: The historical biogeography of the tribe Sinningieae (Gesneriaceae) was analyzed based on distribution data and a molecular species-level phylogeny of 76 species. This plant group is distributed from Mexico to northern Argentina, but by far the highest diversity occurs within the Brazilian Atlantic forest. The dispersal-vicariance analysis method and a cladistic approach were used to infer ancestral areas as well as patterns of dispersal and vicariance. Results indicate that the Sinningieae probably arose in the coastal rain forest or in the neighboring tropical area delimited by the Sao Francisco river in Brazil. The majority of the dispersal-vicariance episodes were reconstructed between the Brazilian Atlantic rain forests and their neighboring inland areas (i.e., Parana and Sao Francisco regions). In contrast, few dispersal-vicariance events were reconstructed between the tropical and subtropical areas of the Atlantic rain forest and between the Parana and Sao Francisco regions. These results,...
TL;DR: Results indicate that Guettarda and two smaller genera, Antirhea and Stenostomum, are polyphyletic; other features, such as inflorescence architecture, sexual system, and palynology, appear to correlate more closely with the molecular phylogeny.
Abstract: The genus Guettarda (Guettardeae–Rubiaceae) comprises approximately 150 species, ranging from eastern Africa through the islands of the Indian and Pacific Oceans to the Neotropics. Sequence data from the nuclear ribosomal DNA internal transcribed spacer (ITS) region were used to test the monophyly of Guettarda and its relationships to closely related genera within Guettardeae. The results indicate that Guettarda and two smaller genera, Antirhea and Stenostomum, are polyphyletic. Most Guettarda species fall into two distinct groups: a Neotropical lineage that also includes the widespread Indo-Pacific strand species G. speciosa (the type of the genus), and a New Caledonian lineage that, along with Antirhea and Timonius, comprises a dioecious Paleotropical clade. The Hawaiian endemic Bobea, traditionally considered close to Timonius and assumed to be of Old World origin, appears to be more closely related to Neotropical Guettarda species, suggesting that dioecy may have evolved twice within the trib...
TL;DR: In reconstructing the biogeographic history of Rhizophora in the Caribbean region, it is worthwhile noting that molecular-defined lineages may have been introduced and gone extinct on multiple occasions, which allows for variation in molecular patterns and apparent stasis in the fossil record.
Abstract: The fossil record of the Rhizophoraceae includes numerous questionable identifications from strata of unconfirmed age, together with others representing clear evidence of the family in deposits whose age is well constrained by independent or multiple lines of evidence Bruguiera or the Bruguiera lineage, and Ceriops are known from the early Eocene, Kandelia from the middle Eocene, and Rhizophora from the late Eocene Combretocarpus is likely present by the middle Miocene, but it belongs to a family (Anisophylleaceae) earlier placed in the Rhizophoraceae that is now considered unrelated to that family Rhizophora, as a genus, has existed essentially uninterruptedly in the Caribbean region since the late Eocene, but cooling events at ca 15–14 Ma, ca 34 Ma, and ca 16 Ma, and the subsequent 18 to 20 glacial intervals provide a mechanism for development of the cold(er) tolerant populations toward the northern part of its range in the New World In reconstructing the biogeographic history of Rhizo
TL;DR: An analysis of the karyological differentiation with respect to chromosome numbers was performed, and these patterns were correlated with data on pollen viability and population genetic measures in order to deduce modes of reproduction and evolutionary phenomena of Boechera.
Abstract: The North American–Greenlandic genus Boechera A. Love & D. Love (Brassicaceae) is distinguished from other phylogenetic lineages recognized within the artificial taxon Arabis L. s.l., in which it has formerly been included, by its base chromosome number x = 7. Based on outgroup comparisons, we consider this chromosome number to be derived from an ancestral genome comprising eight chromosomes. Chromosome counts are now available for about half of the species names listed in the most recent taxonomic treatments of the genus. An analysis of the karyological differentiation with respect to chromosome numbers was performed, and these patterns were correlated with data on pollen viability and population genetic measures in order to deduce modes of reproduction. This approach allowed us to distinguish three main groups: sexual, amphi-apomictic, and apomictic species, respectively. We focused further on the cytology of gametes, especially on that of pollen, and we discuss its role in the formation of new...
TL;DR: The results suggest that Solms-laubachia be expanded to include Desideria and P. jafrii, and more species of Desidersia, Parrya, and Phaeonychium are needed to further test the findings.
Abstract: Sequences of the plastid maturase (matK) and nuclear chalcone synthase (Chs) were analyzed separately and in combination to assess phylogenetic relationships of Solms-laubachia Muschl. (all nine known species and two undescribed ones) to the genera Baimashania Al-Shehbaz, Parrya R. Br., Desideria Pamp., Leiospora (C. A. Mey.) Dvorak, Christolea Cambess., and Phaeonychium O. E. Sschulz (Brassicaceae). Baimashania is clustered with Aubrieta deltoidea(L.) DC. and Arabis blepharophylla Hook. & Arn. Solms-laubachia, Desideria, Leiospora, Christolea. and Phaeonychium are more closely related to Matthiola R. Br. than to Parrya, and they form a Well-supported clade. Within this clade. Leiospora is sister to a subclade containing the sister groups Christolea and Solms-laubachia s.l. The Solms-laubachia s.l. group contains Solms-laubachia, Desideria, and a species of Phaeonychium. Neither Solms-laubachia nor Desideria is monophyletic, whereas Phaeonychium jafrii Al-Shehbaz is embedded within the group. Therefore, our results suggest that Solms-laubachia he expanded to include Desideria and P. jafrii. Nevertheless, more species of Desideria. Parrya, and Phaeonychium are needed to further test our findings.
TL;DR: Results of recent investigations have shown that highly dynamic evolutionary change in Madiinae, both in phenotypic characters and in modes and patterns of diversification, extends to even finer-scale evolutionary levels than indicated by Clausen et al.'s elegant studies.
Abstract: Jens C. Clausen, David D. Keck, and William M. Hiesey's biosystematic research on continental tarweeds (Madiinae; Compositae) provided diverse examples of evolutionary change for Clausen's synthesis, Stages in the Evolution of Plant Species. Subsequent anatomical work by Sherwin Carlquist demonstrated that the tarweed lineage also includes a spectacular example of adaptive radiation, the Hawaiian silversword alliance. Molecular phylogenetic data and evidence from genetic and hybridization studies have allowed additional perspectives on Clausen et al.'s and Carlquist's hypotheses of tarweed–silversword evolution. In Californian Layia, Clausen et al.'s evidence for gradual allopatric diversification for the n = 7 taxa accords with patterns of molecular divergence and decay of interfertility across lineages inferred from a rate-constant rDNA tree. In contrast, recent evidence on patterns and timing of diversification in an n = 8 Layia clade indicates multiple examples of accelerated phenotypic evolu...
TL;DR: Chromosome numbers and observations on meiotic chromosome behavior of 37 taxa of American Panicoideae are given and nine counts are first reports for Echinochloa chacoensis are reported.
Abstract: Chromosome numbers and observations on meiotic chromosome behavior of 37 taxa of American Panicoideae are given. The taxa studied are: Axonopus scoparius (Flugge) Kuhlm., Cenchrus myosuroides Kunth, Dichanthelium aciculare var. aciculare (Desv. ex Poir.) Gould & C. A. Clark, D. acuminatum var. acuminatum (Sw.) Gould & C. A. Clark, Echinochloa chacoensis P. W. Michael ex Renvoize, Eriochloa montevidensis Griseb., Isachne arundinacea (Sw.) Griseb., Panicum hirticaule J. Presl, P. stoloniferum Poir., P. trichanthum Nees, Paspalum blodgettii Chapm., P. buchtienii Hack., P. caespitosum Flugge, P. candidum (Humb. & Bonpl. ex Flugge) Kunth, P. ceresia (Kuntze) Chase, P. clavuliferum C. Wright, P. commune Lillo, P. denticulatum Trin., P. ekmanianum Henrard, P. ellipticum Doll, P. fimbriatum Kunth, P. glabrinode (Hack.) Morrone & Zuloaga, P. glaucescens Hack., P. hartwegianum E. Fourn., P. inconstans Chase, P. indecorum Mez, P. juergensii Hack., P. pauciciliatum (Parodi) Herter, P. penicillatum Hook. f., ...
TL;DR: The adaptive radiation of Darwin's finches in the Galapagos archipelago stands as a model of species multiplication, and results challenge some current notions of species.
Abstract: The adaptive radiation of Darwin's finches in the Galapagos archipelago stands as a model of species multiplication. The radiation began two to three million years ago, and resulted in 14 species being derived from the original colonizing species. This system is highly suitable for investigating the causes of speciation because closely related species occur sympatrically in several combinations and in environments with relatively little anthropogenic disturbance. The role of natural selection and adaptation to feeding niches in the allopatric phase of speciation has been demonstrated repeatedly. In the sympatric phase of speciation, differences in song and morphology act as a premating barrier to gene exchange. This form of reproductive isolation evolves at least partly as a passive consequence or byproduct of adaptive divergence in beak morphology. Song characteristics diverge in allopatry, largely independent of beak morphology and for a variety of reasons, not all of which are well understood....
TL;DR: The flora of Araceae of Cabo Corrientes was most similar to that of La Selva, Barro Colorado Island, and Bajo Calima; similarity with Río Palenque was low.
Abstract: We studied the Araceae of the Cabo Corrientes region on the Pacific Coast of Colombia and compared its aroid flora with those of La Selva (Costa Rica), Barro Colorado Island (Panama), Bajo Calima (Colombia), Rio Palenque (Ecuador), and Iquitos (Peru). We found 114 native species in 14 genera at Cabo Corrientes; the largest genera were Anthurium (38 species), and Philodendron (36), which together accounted for 65% of the species. Seventy-four percent of the species were exclusively epiphytic or hemiepiphytic. Most of the epiphytic species belonged to the genera Anthurium, Philodendron, Rhodospatha, Syngonium, Monstera, and Stenospermation, the latter three containing exclusively epiphytic or hemiepiphytic species. The flora of Araceae of Cabo Corrientes was most similar to that of La Selva, Barro Colorado Island, and Bajo Calima; similarity with Rio Palenque was low. Our findings support Lellinger's view that the Choco biogeographic region extends to the Nicaragua-Costa Rica border and is divided into a northern and a southern flora.
TL;DR: A taxonomic revision of the genus Acaena in Chile was carried out, using morphological characters for recognizing species are inflorescence type, the form of leaflets, as well as the form and ornamentation of the fruit.
Abstract: A taxonomic revision of the genus Acaena in Chile was carried out, using morphological characters. Twenty species belonging to six sections are recognized for continental Chile and Juan Fernandez Archipelago. The most useful characters for recognizing species are inflorescence type, the form of leaflets, as well as the form and ornamentation of the fruit. The following species are lectotypified: A. alpina Poepp. ex Walp., A. caespitosa Gillies ex Hook. et Arn., A. integerrima Gillies ex Hook. et Arn., A. macrocephala Poepp., A. magellanica (Lam.) Vahl, A. pinnatifida Ruiz et Pav., A. platyacantha Speg., A. splendens Hook. et Arn., and A. tenera Alboff. The following species were neotypified: A. lucida (Aiton ) Vahl, A. sericea J. Jacq., and A. trifida Ruiz et Pav. var. glabrescens Regel et Korn. The following synonyms were lectotypified: A. argentea Ruiz et Pav. var. breviscapa Bitter, A. argentea Ruiz et Pav. var. coriacea Bitter, A. argentea Ruiz et Pav. var. interrupte-pinnata Bitter, A. argen...
TL;DR: Sixteen species are here considered within Axonopus series Suffulti, principally distributed in South America, with A. ciliatifolius Swallen and A. jeanyae Davidse endemic species of Belize and Panama, respectively.
Abstract: The taxonomic revision of species of the genus Axonopus P. Beauv. series Suffulti G. A. Black is presented. This series includes perennial species, frequently growing in savannas and in grasslands, on argillaceous or sandy ground with rocky outcrops, at altitudes up to 3500 m. The plants are rhizomatous or stoloniferous, with conduplicate sheaths and narrowly linear to linear-lanceolate blades, flat to folded along their entire length, or open toward the apex. The inflorescences are exserted from the apex of the culms; they consist of spiciform racemes of variable number, mainly digitate. The rachis of each raceme is triquetrous, sinuous, with hispidulous angles, sometimes with long and rigid hairs. The upper lemma and the upper palea are indurate, dark brown, papillose, and shiny. Sixteen species are here considered within Axonopus series Suffulti, principally distributed in South America, with A. ciliatifolius Swallen and A. jeanyae Davidse endemic species of Belize and Panama, respectively. De...
TL;DR: Results suggest that Bouchetia is the closest taxon to Nierembergia, while Leptoglossis, Petunia, and Fabiana appear more distant, and chromosome number evolution in the tribe is speculated based on molecular phylogenetic studies by other authors.
Abstract: Chromosome counts and karyotype information from 41 populations of 20 species and 6 varieties of Nicotianeae (Solanaceae) from South America belonging to Bouchetia Dunal (x = 8), Fabiana Ruiz & Pav. (x = 9), Leptoglossis Benth. (x = 10), Nierembergia Ruiz & Pav. (x = 8, 9), and Petunia Juss. (x = 7, 9) are given, including first reports from 14 taxa: F. densa Remy, N. ericoides Miers, and P. patagonica (Speg.) Millan, with 2n = 2x = 18, and N. browallioides Griseb., N. calycina Hook., N. graveolens A. St.-Hil., N. linariifolia Graham var. glabriuscula (Dunal) A. A. Cocucci & Hunz., var. pampeana (Millan) A. A. Cocucci & Hunz., and var. pinifolioides (Millan) A. A. Cocucci & Hunz., N. pulchella Miers var. pulchella and var. macrocalyx (Millan) A. A. Cocucci & Hunz., N. rivularis Miers, N. tucumanensis Millan, and N. veitchii Hook., with 2n = 2x = 16. All species studied are diploids, and most have 2n = 16. In addition, infraspecific polyploidy is recorded for the first time in ...
TL;DR: Wind and ocean transport of organisms and propagules throughout the Tertiary, and especially at peaks of warmth, was likely a more important means of dispersal than would seem plausible under present conditions.
Abstract: The combination of factors that account for present-day distributions of organisms is unique to individual lineages and varies over time. An observation relevant to some lineages at some point in their history is that hurricane frequency and intensity appears to be increasing with global warming. If so, then directional winds from Africa to the Caribbean region (the trade winds), from South America to Africa (the westerlies), the ocean currents they induce, and the transport of the floating islands they carry, were likely more intense during the generally warmer-than-present Tertiary Period and especially at peaks of exceptional warmth. These peaks occurred in the Paleocene/Eocene (65–45 Ma), in the early to middle Miocene (broadly between ∼23–12 Ma), in the middle Pliocene (3–4 Ma), and probably extended slightly later in the lower latitudes. The Paleocene/Eocene interval includes the time when the distance between Africa and South America was one-half to two-thirds that of the present, and when...
TL;DR: It appears that pedate laminar morphologies in Adiantopsis independently originated multiple times via hybridization, which provides testable hypotheses of morphological and reticulate evolution in the genus and presents a novel view of Caribbean Adiantops.
Abstract: Adiantopsis Fee (Pteridaceae) is a relatively unstudied tropical cheilanthoid fern genus. In the present work, we evaluated the taxonomy and relationships among Caribbean Adiantopsis by examining 136 characters from approximately 500 herbarium specimens. This study identified nine Caribbean Adiantopsis species, three of which are newly described (A. parvisegmenta, A. pentagona, and A. vincentii). Additionally, an intriguing pattern of morphological and reticulate evolution was revealed by the analyses. Adiantopsis consists of three different laminar morphologies; palmate, pedate, and pinnate. The two pedate taxa are hypothesized to be fertile allotetraploid derivatives of the palmate A. radiata (L.) Fee and two different pinnate taxa. In this regard they parallel the origin of the South American A. ×australopedata Hickey, M. S. Barker & Ponce. Based on our analyses, it appears that pedate laminar morphologies in Adiantopsis independently originated multiple times via hybridization. This study pro...