Attempts at historical reconstruction are based on limited data. We are more likely to produce accurate historical reconstructions by utilizing information from diverse sources and pooling data within the relevant research communities which will allow us to build up a moving picture of the geological, climatic, and biological evolution of our planet. We suggest that dated phylogenies of plants can contribute greatly to a better understanding of Earth history. Timing of phylogenetic splits of lowland restricted lineages on either side of the Andes could provide information on the timing of montane uplift and associated climatic changes. The timing of the arrival and diversification of organisms restricted to specific climatic regimes at a particular altitude can provide information on the age at which mountains reached a height adequate for that climate once corrected for global climate changes. As a model for study, we discuss how dated phylogenies in biome rich Colombia may contribute to an understanding of geological and climatic change in north‐western South America. Lowland wet forest restricted lineages separated from the mid‐Miocene, whereas lineages primarily restricted to mid‐altitude cloud forests began to diversify from the mid‐ to late‐Miocene and the majority of high‐altitude Páramo lineages began to diversify during the Pliocene. The age of diversification of altitudinally restricted lineages therefore gives an indication of the age at which particular altitudes may have been reached.
Understanding how species diversify and evolve in species-rich areas like the lowland rain forest in the Neotropics is critical for conservation in times of unprecedented threats. To determine how the Andean uplift, the formation of the Panama land bridge, and Pleistocene climatic fluctuations affected dispersal and diversification in the Sapotaceae subfamily Chrysophylloideae, we collected 146 Chrysophylloideae accessions in previously under-explored areas, generating one of the most geographically complete data sets for neotropical Sapotaceae. Sapotaceae is a good model to test diversification hypotheses in lowland neotropical rain forests as it predominantly occurs <1000 m altitude, and it is an abundant and species-rich group in this biome. We generated a time calibrated phylogeny of 123 Sapotaceae species based upon the nuclear ribosomal internal transcribed spacer region that suggests migration between lineages to the east and the west Andean Cordilleras occurred before and after periods of major uplift, indicating that the Andes did not represent a significant barrier to dispersal for Sapotaceae, although it may have promoted vicariance in some cases. Dispersal between South and Central America occurred mainly prior to the formation of the Panama land bridge, suggesting that this event did not affect migration patterns in Chrysophylloideae. We inferred diversification rates and detected three shifts in the phylogeny, but they are not congruent with tectonic movements during the middle Miocene and climatic changes during the Pleistocene. Finally, some species with restricted distributions appear to be phylogenetically nested within species with broader ranges, suggesting ancestor descendent relationships and insights into patterns of speciation in rain forest trees.
Identification of individuals in the absence of reproductive traits or in juvenile stages can be difficult. Incorrect identification will result in inaccurate biodiversity inventories that are an impediment to effective conservation management. Here, we present data in which we argue that the generation of DNA barcode reference libraries using DNA extracted from type specimens could resolve issues related to correct identification. The genus Micropholis (Sapotaceae) is diverse and ecologically important in Neotropical lowland rain forests. We first assessed the capacity of the molecular markers ITS2, matK and rbcL in differentiating species in the genus. Based on a phylogenetic reconstruction we found that many individuals in our study were incorrectly identified, and we argue that if we had access to a type specimen DNA barcode reference library we would have more rapidly and correctly identified individuals.
AimTo evaluate Morrone's (2001, Biogeografia de America Latina y el Caribe. Zaragoza, Spain: CYTED, ORCYT‐UNESCO, Sociedad Entomológica Aragonesa (SEA)) Neotropical regionalization by testing the prediction that biotas are more homogeneous within than among biogeographic units.LocationNeotropics.MethodsWe conducted pairwise comparisons of beta diversity of Sapotaceae species within and between biogeographic units in the hierarchical regionalization proposed by Morrone (2001, Biogeografia de America Latina y el Caribe. Zaragoza, Spain: CYTED, ORCYT‐UNESCO, Sociedad Entomológica Aragonesa (SEA)), at a spatial resolution of 1‐degree cells. We used a null model to control differences in sampling effort across 1‐degree cells and performed beta‐diversity comparisons conditional on geographic distance to control for distance decay of biotic similarity.ResultsNone of the biogeographic units proposed by Morrone (2001, Biogeografia de America Latina y el Caribe. Zaragoza, Spain: CYTED, ORCYT‐UNESCO, Sociedad Entomológica Aragonesa (SEA)) was biotically homogeneous with respect to all other units at the same hierarchical level. This was the case even for units commonly reported to be isolated and to host distinctive taxa like “Choco.” However, five of 45 biogeographic units were biotically homogenous relative to several other units. These units were “Cuba,” “Chaco,” “Varzea,” “Cauca” and “Costa Pacífica Mexicana.” Also, beta diversity within units was often lower than beta diversity between units at relatively short geographic distances.Main conclusionsThe distribution of Sapotaceae species showed generally low biotic homogeneity within Morrone's (2001, Biogeografia de America Latina y el Caribe. Zaragoza, Spain: CYTED, ORCYT‐UNESCO, Sociedad Entomológica Aragonesa (SEA)) biogeographic units and did not support his biogeographic regionalization. This result suggests a strong role for dispersal and biotic interchange among biogeographic units and across barriers like the Andes. It also casts doubt on the usefulness of Morrone's (2001, Biogeografia de America Latina y el Caribe. Zaragoza, Spain: CYTED, ORCYT‐UNESCO, Sociedad Entomológica Aragonesa (SEA)) biogeographic units as tools for the identification of priority areas for the conservation of biodiversity. However, relatively high biotic homogeneity within some biogeographic units suggests that they capture significant spatial patterns. In particular, noteworthy biotic homogeneity within “Cuba,” “Cauca” and “Costa Pacifica Mexicana” could be explained by isolation. Also, in “Costa Pacifica Mexicana,” patterns of biotic homogeneity could reflect closer affinities to humid lowland montane forest in Central America than to lowland rain forest in South America. Finally, substantial biotic homogeneity within “Varzea” could result from common adaptation to edaphic environments near the Amazon River.
The larval fish abundance and species composition of the Gulf of Tehuantepec are described based on the analysis of samples obtained from oblique zooplankton tows during summer 2007 and spring 2008. Changes in species composition and abundance between both periods were also described. A total of 145 taxa were obtained from which 73 were identified to species level, 43 to genus and 29 to family. The larval fish assemblage of the Gulf of Tehuantepec showed distinctive characteristics from other regions of the American Pacific, such as: A) a dominance of coastal-pelagic species (mainly Bregmaceros bathymaster); B) high diversity and abundance of shallow demersal species even along the oceanic stations of the study area; and C) a low proportion of mesopelagic species, an unusual condition in areas with narrow continental shelf. The diversity estimations suggest that Gulf of Tehuantepec is one of the most diverse ecosystems of the American Pacific, even as compared with other regions considered of highest diversity such as the Gulf of California. The high abundance, as well as the presence of the larval, juvenile and adult stages of B. bathymaster, suggests the importance of this region as a reproductive, nursery and recruitment for this species. Cambios en la composición de especies y abundancia de larvas de peces en el Golfo de Tehuantepec, México Se describen la composición de especies y abundancia de larvas de peces del Golfo de Tehuantepec a partir del análisis de muestras obtenidas en arrastres oblicuos de zooplancton. Así mismo, se describen los cambios en composición y abundancia entre un periodo de verano y uno de primavera. Se obtuvieron 145 taxa de los que 73 se identificaron a nivel especie, 43 a género y 29 a familia. La comunidad de larvas de peces del Golfo de Tehuantepec mostró rasgos distintivos de otras regiones similares del Pacífico Americano, tales como: A) dominancia de especies pelágico-costeras (particularmente Bregmaceros bathymaster); B) alta diversidad y abundancia de especies demersales someras aún en las estaciones mas oceánicas del área de estudio; y C) una proporción menor de especies de peces mesopelágicos, condición poco común en áreas con plataforma continental estrecha. Las estimaciones de diversidad ubican al Golfo de Tehuantepec como uno de los ecosistemas más diversos del Pacífico americano, aún comparándolo con regiones consideradas de alta diversidad a nivel mundial como es el caso del Golfo de California. La abundancia y la presencia de estadios larvales, juveniles y adultos de B. bathymaster reflejan la importancia de esta zona como área de reproducción, crianza y reclutamiento de esta especie.
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