10 research outputs found
Modeling the ecology and evolution of biodiversity: Biogeographical cradles, museums, and graves
Individual processes shaping geographical patterns of biodiversity are increasingly understood, but their complex interactions on broad spatial and temporal scales remain beyond the reach of analytical models and traditional experiments. To meet this challenge, we built a spatially explicit, mechanistic simulation model implementing adaptation, range shifts, fragmentation, speciation, dispersal, competition, and extinction, driven by modeled climates of the past 800,000 years in South America. Experimental topographic smoothing confirmed the impact of climate heterogeneity on diversification. The simulations identified regions and episodes of speciation (cradles), persistence (museums), and extinction (graves). Although the simulations had no target pattern and were not parameterized with empirical data, emerging richness maps closely resembled contemporary maps for major taxa, confirming powerful roles for evolution and diversification driven by topography and climate
Landscape dynamics and diversification of the megadiverse South American freshwater fish fauna
Landscape dynamics are widely thought to govern the tempo and mode of continental radiations, yet the effects of river network rearrangements on dispersal and lineage diversification remain poorly understood. We integrated an unprecedented occurrence dataset of 4,967 species with a newly compiled, time-calibrated phylogeny of South American freshwater fishesâthe most species-rich continental vertebrate fauna on Earthâto track the evolutionary processes associated with hydrogeographic events over 100 Ma. Net lineage diversification was heterogeneous through time, across space, and among clades. Five abrupt shifts in net diversification rates occurred during the Paleogene and Miocene (between 30 and 7 Ma) in association with major landscape evolution events. Net diversification accelerated from the Miocene to the Recent (c. 20 to 0 Ma), with Western Amazonia having the highest rates of in situ diversification, which led to it being an important source of species dispersing to other regions. All regional biotic interchanges were associated with documented hydrogeographic events and the formation of biogeographic corridors, including the Early Miocene (c. 23 to 16 Ma) uplift of the Serra do Mar and Serra da Mantiqueira and the Late Miocene (c. 10 Ma) uplift of the Northern Andes and associated formation of the modern transcontinental Amazon River. The combination of high diversification rates and extensive biotic interchange associated with Western Amazonia yielded its extraordinary contemporary richness and phylogenetic endemism. Our results support the hypothesis that landscape dynamics, which shaped the history of drainage basin connections, strongly affected the assembly and diversification of basin-wide fish fauna
Spatially explicit paleoclimate reconstruction of South America for the last 800 thousand years
For each 500-year time interval from 800 Ka (years ago) to the present (1600 time steps), we used a paleoclimate model to assign to each of the 4820 map cells an estimate of the mean temperature of the warmest and coolest quarters and the mean daily precipitation of the wettest and driest quarters. These four factors, on two environmental axes (annual temperature and annual precipitation) characterize the changing climate in each grid cell over the time-course of the simulation.
The database consists of the paleoclimate data used in this simulation. It is composed of one text file for each climate variable: (1) minimum annual precipitation, (2) maximum annual precipitation, (3) minimum annual temperature, and (4) maximum annual temperature. Within each file, each row represents a single map cell (4820 in total). The first two columns are the geographical coordinates of each grid cell (latitude and longitude in decimal degrees). The succeeding columns describe the climate variable at each time slice of the series, at successive 500-year intervals. Each column is labeled Tx, where x is thousands of years before present. For example, column âT795.5â of file âPrecipAvgAnnualMax.txtâ contains the map cell data for maximum annual precipitation at 795.5kya
Landscape dynamics and diversification of the megadiverse South American freshwater fish fauna
Landscape dynamics are widely thought to govern the tempo and mode of continental
radiations, yet the effects of river network rearrangements on dispersal and lineage diver-
sification remain poorly understood. We integrated an unprecedented occurrence dataset
of 4,967 species with a newly compiled, time-calibrated phylogeny of South American
freshwater fishesâthe most species-rich continental vertebrate fauna on Earthâto
track the evolutionary processes associated with hydrogeographic events over 100 Ma.
Net lineage diversification was heterogeneous through time, across space, and among
clades. Five abrupt shifts in net diversification rates occurred during the Paleogene and
Miocene (between 30 and 7 Ma) in association with major landscape evolution events.
Net diversification accelerated from the Miocene to the Recent (c. 20 to 0 Ma), with
Western Amazonia having the highest rates of in situ diversification, which led to it
being an important source of species dispersing to other regions. All regional biotic
interchanges were associated with documented hydrogeographic events and the forma-
tion of biogeographic corridors, including the Early Miocene (c. 23 to 16 Ma) uplift of
the Serra do Mar and Serra da Mantiqueira and the Late Miocene (c. 10 Ma) uplift of
the Northern Andes and associated formation of the modern transcontinental Amazon
River. The combination of high diversification rates and extensive biotic interchange
associated with Western Amazonia yielded its extraordinary contemporary richness and
phylogenetic endemism. Our results support the hypothesis that landscape dynamics,
which shaped the history of drainage basin connections, strongly affected the assembly
and diversification of basin-wide fish faunas.Instituto de CiĂȘncias BiolĂłgicas (IB)Departamento de Ecologia (IB ECL
Hunter color dimensions, sugar content and volatile compounds in pasteurized yellow passion fruit juice (Passiflora edulis var. flavicarpa) during storage
Changes in Hunter L, a and b values, glucose, fructose and sucrose contents, concentration of four volatile compounds (ethyl butirate, ethyl caproate, hexyl butirate and hexyl caproate) and furfural, were studied in yellow passion fruit juice (Passiflora edulis var. flavicarpa) pasteurized at 75ÂșC/60s, 80ÂșC/41s or 85ÂșC/27s, during storage at room temperature (25±5ÂșC) and refrigeration (5±1ÂșC) for 120 days. While the sucrose content decreased, the glucose and fructose contents increased significantly over storage time. The Hunter L and b values behaved similarly, with a tendency to decrease over time, inversely to Hunter a value. Volatile compound concentrations also decreased over time, inversely to the furfural content. Pasteurization at 85ÂșC/27s resulted minimum changes in the studied passion fruit characteristics, while that at 75ÂșC/60s was the most harmful. Storage under refrigeration tended to keep the best quality characteristics of the juice.<br>Foi estudada a variação dos valores "L", "a" e "b" do sistema de Hunter, dos teores de glucose, frutose e sacarose, e da concentração de quatro compostos volĂĄteis (butirato de etila, caproato de etila, butirato de hexila e caproato de hexila) e furfural, em suco de maracujĂĄ-amarelo (Passiflora edulis var. flavicarpa) submetido Ă pasteurização (75ÂșC/60 s, 80ÂșC/41 s e 85ÂșC/27 s), durante o armazenamento a temperatura ambiente (25±5ÂșC) e refrigerada (5±1ÂșC) por 120 dias. Enquanto os teores de sacarose diminuĂram, aqueles de glucose e frutose aumentaram significativamente. Os valores "L" e "b" apresentaram comportamento semelhante, com tendĂȘncia a diminuir ao longo do tempo, inversamente ao valor "a". As concentraçÔes dos compostos volĂĄteis tambĂ©m diminuĂram, exceto para o furfural. A pasteurização a 85ÂșC/27 s proporcionou as menores alteraçÔes nas caracterĂsticas estudadas, enquanto aquela Ă 75ÂșC/60 s foi a mais prejudicial. O armazenamento sob refrigeração apresentou melhor tendĂȘncia na manutenção das caracterĂsticas