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Díaz S, Kattge J, Cornelissen J, Wright I, Lavorel S, Dray S et al. (2015)
Earth is home to a remarkable diversity of plant forms and life histories, yet comparatively few essential trait combinations have proved evolutionarily viable in today’s terrestrial biosphere. By analysing worldwide variation in six major traits critical to growth, survival and reproduction within the largest sample of vascular plant species ever compiled, we found that occupancy of six-dimensional trait space is strongly concentrated, indicating coordination and trade-offs. Three-quarters of trait variation is captured in a two-dimensional global spectrum of plant form and function. One major dimension within this plane reflects the size of whole plants and their parts; the other represents the leaf economics spectrum, which balances leaf construction costs against growth potential. The global plant trait spectrum provides a backdrop for elucidating constraints on evolution, for functionally qualifying species and ecosystems, and for improving models that predict future vegetation based on continuous variation in plant form and function.
Ingley S, Reina R, Bermingham E, Johnson J (2015)
Phylogenetic analyses provide insights into the historical biogeography and evolution of Brachyrhaphis fishes.
Molecular phylogenetics and evolution 89 104-14.
The livebearing fish genus Brachyrhaphis (Poeciliidae) has become an increasingly important model in evolution and ecology research, yet the phylogeny of this group is not well understood, nor has it been examined thoroughly using modern phylogenetic methods. Here, we present the first comprehensive phylogenetic analysis of Brachyrhaphis by using four molecular markers (3mtDNA, 1nucDNA) to infer relationships among species in this genus. We tested the validity of this genus as a monophyletic group using extensive outgroup sampling based on recent phylogenetic hypotheses of Poeciliidae. We also tested the validity of recently described species of Brachyrhaphis that are part of the B. episcopi complex in Panama. Finally, we examined the impact of historical events on diversification of Brachyrhaphis, and made predictions regarding the role of different ecological environments on evolutionary diversification where known historical events apparently fail to explain speciation. Based on our results, we reject the monophyly of Brachyrhaphis, and question the validity of two recently described species (B. hessfeldi and B. roswithae). Historical biogeography of Brachyrhaphis generally agrees with patterns found in other freshwater taxa in Lower Central America, which show that geological barriers frequently predict speciation. Specifically, we find evidence in support of an 'island' model of Lower Central American formation, which posits that the nascent isthmus was partitioned by several marine connections before linking North and South America. In some cases where historic events (e.g., vicariance) fail to explain allopatric species breaks in Brachyrhaphis, ecological processes (e.g., divergent predation environments) offer additional insight into our understanding of phylogenetic diversification in this group.
Keywords: Brachyrhaphis, Ecology, Historical biogeography, Lower Central America, Phylogeny, Poeciliidae
Paz A, Ibáñez R, Lips K, Crawford A (2015)
Testing the role of ecology and life history in structuring genetic variation across a landscape: a trait-based phylogeographic approach.
Molecular ecology 24(14) 3723-3737.
Hypotheses to explain phylogeographic structure traditionally invoke geographic features, but often fail to provide a general explanation for spatial patterns of genetic variation. Organisms' intrinsic characteristics might play more important roles than landscape features in determining phylogeographic structure. We developed a novel comparative approach to explore the role of ecological and life-history variables in determining spatial genetic variation and tested it on frog communities in Panama. We quantified spatial genetic variation within 31 anuran species based on mitochondrial DNA sequences, for which hierarchical approximate Bayesian computation analyses rejected simultaneous divergence over a common landscape. Regressing ecological variables, on genetic divergence allowed us to test the importance of individual variables revealing that body size, current landscape resistance, geographic range, biogeographic origin and reproductive mode were significant predictors of spatial genetic variation. Our results support the idea that phylogeographic structure represents the outcome of an interaction between organisms and their environment, and suggest a conceptual integration we refer to as trait-based phylogeography.
Keywords: DNA barcoding, ecological niche modelling, hierarchical approxi-, ispersal ability, landscape resistance, mate Bayesian computation, phylogeography
Sheehan M, Botero C, Hendry T, Sedio B, Jandt J, Weiner S et al. (2015)
Different axes of environmental variation explain the presence vs. extent of cooperative nest founding associations in Polistes paper wasps.
Ecology letters 18(10) 1057-67.
Ecological constraints on independent breeding are recognised as major drivers of cooperative breeding across diverse lineages. How the prevalence and degree of cooperative breeding relates to ecological variation remains unresolved. Using a large data set of cooperative nesting in Polistes wasps we demonstrate that different aspects of cooperative breeding are likely to be driven by different aspects of climate. Whether or not a species forms cooperative groups is associated with greater short-term temperature fluctuations. In contrast, the number of cooperative foundresses increases in more benign environments with warmer, wetter conditions. The same data set reveals that intraspecific responses to climate variation do not mirror genus-wide trends and instead are highly heterogeneous among species. Collectively these data suggest that the ecological drivers that lead to the origin or loss of cooperation are different from those that influence the extent of its expression within populations.
Keywords: Bet hedging, climate predictability, ecological constraints, group size, helping behaviour, reproductive skew, social evolution, social insects, thermoregulation
Forasiepi A, Soibelzon L, Gomez C, Sánchez R, Quiroz L, Jaramillo C et al. (2014)
We report two fossil procyonids, Cyonasua sp. and Chapalmalania sp., from the late Pliocene of Venezuela (Vergel Member, San Gregorio Formation) and Colombia (Ware Formation), respectively. The occurrence of these pre-Holocene procyonids outside Argentina and in the north of South America provides further information about the Great American Biotic Interchange (GABI). The new specimens are recognized in the same monophyletic group as procyonids found in the southern part of the continent, the "Cyonasua group," formed by species of Cyonasua and Chapalmalania. The phylogenetic analysis that includes the two new findings support the view that procyonids dispersed from North America in two separate events (initially, previous to the first major migration wave-GABI 1-and then within the last major migration wave-GABI 4-). This involved reciprocal lineage migrations from North to South America, and included the evolution of South American endemic forms.
Keywords: Pliocene, neotropics, procyonidae, south america
Quintero I, González-Caro S, Zalamea P, Cadena C (2014)
Asynchrony of Seasons: Genetic Differentiation Associated with Geographic Variation in Climatic Seasonality and Reproductive Phenology
The American Naturalist Forthcoming.
Many organisms exhibit distinct breeding seasons tracking food availability. If conspecific populations inhabit areas that experience different temporal cycles in food availability spurred by variation in precipitation regimes, then they should display asyn- chronous breeding seasons. Thus, such populations might exhibit a temporal barrier to gene flow, which may potentially promote genetic differentiation.We test a central prediction of this hypothesis, namely, that individuals living in areas with more asynchronous precipitation regimes should be more genetically differentiated than individuals living in areas with more similar precipitation regimes. Using mi- tochondrial DNA sequences, climatic data, and geographical/ecolog- ical distances between individuals of 57 New World bird species mostly from the tropics, we examined the effect of asynchronous precipitation (a proxy for asynchronous resource availability) on ge- netic differentiation.We found evidence for a positive and significant cross-species effect of precipitation asynchrony on genetic distance after accounting for geographical/ecological distances, suggesting that current climatic conditions may play a role in population differen- tiation. Spatial asynchrony in climate may thus drive evolutionary divergence in the absence of overt geographic barriers to gene flow; this mechanism contrasts with those invoked by most models of biotic diversification emphasizing physical or ecological changes to the landscape as drivers of divergence.
Keywords: allochronic speciation, birds, breeding phenology, genetic distance, reproduction, temporal asynchrony
Steidinger B, Turner B, Corrales A, Dalling J (2014)
Variability in potential to exploit different soil organic phosphorus compounds among tropical montane tree species
Functional Ecology Forthcoming.
We hypothesized that tropical plant species with different mycorrhizal associations reduce competition for soil phosphorus (P) by specializing to exploit different soil organic P compounds. We assayed the activity of root/mycorrhizal phosphatase enzymes of four tree species with contrasting root symbiotic relationships–arbuscular mycorrhizal (angiosperm and conifer), ectomycorrhizal and non-mycorrhizal–collected from one of three soil sites within a montane tropical forest. We also measured growth and foliar P of these seedlings in an experiment with P provided exclusively as inorganic orthophosphate, a simple phosphomonoester (glucose phosphate), a phosphodiester (RNA), phytate (the sodium salt of myo-inositol hexakisphosphate), or a no-P control. The ectomycorrhizal tree species expressed twice the phosphomonoesterase activity as the arbuscular mycorrhizal tree species, but had similar phosphodiesterase activity. The non-mycorrhizal Proteaceae tree had markedly greater activity of both enzymes than the mycorrhizal tree species, with root clusters expressing greater phosphomonoesterase activity than fine roots. Both the mycorrhizal and non-mycorrhizal tree species contained significantly greater foliar P than in no-P controls when limited to inorganic phosphate, glucose phosphate, and RNA. The ectomycorrhizal species did not perform better than the arbuscular mycorrhizal tree species when limited to organic P in any form. In contrast, the non-mycorrhizal Proteaceae tree was the only species capable of exploiting phytate, with nearly three times the leaf area and more than twice the foliar P of the no-P control. Our results suggest that arbuscular and ectomycorrhizal tree species exploit similar forms of P, despite differences in phosphomonoesterase activity. In contrast, the mycorrhizal tree species and non-mycorrhizal Proteaceae appear to differ in their ability to exploit phytate. We conclude that resource partitioning of soil P plays a coarse but potentially ecologically important role in fostering the coexistence of tree species in tropical montane forests.
Keywords: cluster roots, mycorrhiza, resource partitioning, soil organic phosphorus, tropical montane
D'Apolito C, Absy M, Latrubesse E (2013)
Quaternary Science Reviews 76 140-155.
The new analyses of a sedimentary record of Lake Pata in the Hill of Six Lakes, in NW Amazon and its correlation with other Quaternary proxy records in the region provide new insights regarding the vegetation and climate of the lowland forest during the Last Glacial. Despite what has been reported previously in the literature, the sedimentary and pollen records are not continuous. The hill remained forested; however, clear signals of structural change are seen in the record, which indicate that the area experienced a significantly drier climate during the Last Glacial Maximum (LGM). The herbs and taxa that are known to be more dominant in seasonally dry forests were all more abundant during the glacial part of the record, and the cool-adapted elements were mixed with warm lowland elements, which indicates a temperature depression. A comparison of the palaeoecological data with other regional geoenvironmental records of the Upper Negro River basin and other areas of the Amazon provides additional support for a cooler and more seasonal environment during the middle Pleniglacial, which then became drier during the LGM. A “wet” LGM is strongly refuted; therefore, the palaeoclimatic and ecological models that used the previous proxy data from Six Lakes to sustain “wet” conditions and a “continuous forest record” during the LGM to reconstruct the palaeoenvironmental conditions in the Amazon should be reviewed.
Keywords: cluster roots, mycorrhiza, resource partitioning, soil organic phosphorus, tropical montane
Diaz R, Menocal O, Montemayor C, Overholt W (2013)
Biology and Host Specificity of Anthonomus tenebrosus (Coleoptera: Curculionidae): A Herbivore of Tropical Soda Apple
Annals of the Entomological Society of America 106(4) 491-502.
Tropical soda apple (Solanum viarum Dunal) is a major exotic weed in pastures and conservation areas in subtropical regions. Anthonomus tenebrosus Boheman (Coleoptera: Curculion- idae) was found feeding on the ßowers of tropical soda apple in southern Brazil and was considered a potential biological control agent. The objectives of this study were to examine the life history and host speciÞcity of A. tenebrosus. The development from egg to adult was measured at eight constant temperatures in growth chambers. The presence of reproductive diapause was measured by using a two-way factorial design with three temperatures (20, 22.5, and 25?C) and two photoperiods (14:10 and10:14[L:D]h).Temperatureinßuencedthedevelopmentaltimefromeggto adult of A. tenebrosus, which ranged from 49.6 d at 16?Cto13.6dat28?C. The longevity of males ranged from 64 to 190 d, whereas females lived from 44 to 204 d. When exposed to 10:14 (L:D) h and 20?C, 35% of females entered reproductive diapause. The fundamental host range of A. tenebrosusÑbased on several life-history aspects, including adult longevity, oogenesis,andovipositionÑandimmaturedevelopment of A. tenebrosus were studied. Under no-choice conditions,?80% of adults survived for 30 d on several Solanum melongena L. varieties, Solanum capsicoides, S. viarum, and Solanum carolinense L. A. ten- ebrosus completed development from egg to adult on a number of S. melongena varieties, the native plant S. carolinense, and the exotic plants S. capsicoides All., S. viarum, and Solanum tampicense Dunal. Under paired-choice conditions, adult feeding occurred on all species, whereas oviposition occurred only on S. viarum, S. capsicoides, and S. carolinense. Because of the nontarget attack to S. melongena and a native plant, A. tenebrosus should not be considered for release as a biological control agent of tropical soda apple in the United States.
Keywords: Solanaceae, Solanum viarum, flower-feeding weevil, insect-plant interaction
Rymer P, Dick C, Vendramin G, Buonamici A, Boshier D (2013)
Recent phylogeographic structure in a widespread ‘weedy’ Neotropical tree species, Cordia alliodora (Boraginaceae)
Journal of Biogeography 40(4) 693-706.
Aim Although hundreds of tree species have broad geographic ranges in the Neotropics, little is known about how such widespread species attained disjunct distributions around mountain, ocean and xeric barriers. Here, we examine the phylogeographic structure of a widespread and economically important tree, Cordia alliodora, to: (1) test the roles of vicariance and dispersal in establishing major range disjunctions, (2) determine which geographic regions and/or habitats contain the highest levels of genetic diversity, and (3) infer the geographic origin of the species. Location: Twenty-five countries in Central and South America, and the West Indies. Methods: Chloroplast simple sequence repeats (cpSSR; eight loci) were assayed in 67 populations (240 individuals) sampled from the full geographic range of C. alliodora. Chloroplast (trnH–psbA) and nuclear (internal transcribed spacer, ITS) DNA sequences were sampled from a geographically representative subset. Genetic structure was determined with samova, structure and haplotype networks. Analysis of molecular variance (AMOVA) and rarefaction analyses were used to compare regional haplotype diversity and differentiation. Results Although the ITS region was polymorphic it revealed limited phylogeographic structure, and trnH–psbA was monomorphic. However, structure analysis of cpSSR variation recovered three broad demes spanning Central America (Deme 1), the Greater Antilles and the Chocó (Deme 2), and the Lesser Antilles and cis-Andean South America (Deme 3). samova showed two predominant demes (Deme 1 + 2 and Deme 3). The greatest haplotype diversity was detected east of the Andes, while significantly more genetic variation was partitioned among trans-Andean populations. Populations experiencing high precipitation seasonality (dry ecotype) had greater levels of genetic variation. Main conclusions Cordia alliodora displayed weak cis- and trans-Andean phylogeographic structure based on DNA sequence data, indicative of historical dispersal around this barrier and genetic exchange across its broad range. The cpSSR data revealed phylogeographic structure corresponding to three biogeographic zones. Patterns of genetic diversity are indicative of an origin in the seasonally dry habitats of South America. Therefore, C. alliodora fits the disperser hypothesis for widespread Neotropical species. Dispersal is evident in the West Indies and the northern Andean cordilleras. The dry ecotype harbours genetic variation that is likely to represent the source for the establishment of populations under future warmer and drier climatic scenarios.
Keywords: amazon basin, andes mountains, correspondence, hawkesbury, neotropics, paul d, phylogeography, rymer, samova, structure, tropical trees, vicariance