RESUMEN
We report the rediscovery of the Critically Endangered cloud forest herb Gasteranthusextinctus, not seen since 1985. In 2019 and 2021, G.extinctus was recorded at five sites in the western foothills of the Ecuadorian Andes, 4-25 km from the type locality at the celebrated Centinela ridge. We describe the species' distribution, abundance, habitat and conservation status and offer recommendations for further research and conservation efforts focused on G.extinctus and the small, disjunct forest remnants it occupies.
RESUMEN
The distributions of many Northern Hemisphere organisms have been influenced by fluctuations in sea level and climatic conditions during Pleistocene interglacial periods. These cycles are associated with range contraction and refugia for northern-distributed organisms as a response to glaciers. However, lower sea levels in the tropics and sub-tropics created available habitat for expansion of the ranges of freshwater organisms. The goal of this study was to use ecological niche modeling to test the hypothesis of north to south range expansion of Vieja maculicauda associated with Pleistocene glacial cycles. Understanding the biogeography of this widespread species may help us better understand the geology and interconnectivity of Central American freshwaters. Occurrence data for V. maculicauda was based on georeferencing of all museum records of specimens recovered from FishNet2. General patterns of phylogeographic structure were assessed with mtDNA. Present day niche models were generated and subsequently projected onto paleoclimatic maps of the region during the Last Interglacial, Last Glacial Maximum, and mid-Holocene. Phylogenetic analysis of mtDNA sequence data showed no phylogeographic structure throughout the range of this widespread species. Present day niche models were congruent with the observed distribution of V. maculicauda in Central America. Results showed a lack of suitable freshwater habitat in northern Central America and Mexico during the Last Interglacial, with greatest range expansion during the Last Glacial Maximum and mid-Holocene. Results support the hypothesis of a north to south range expansion of V. maculicauda associated with glacial cycles. The wide distribution of this species compared to other closely related cichlids indicates the latter did not respond to the degree of V. maculicauda in expansion of their distributions. Future work aimed at comparisons with other species and modeling of future climatic scenarios will be a fruitful area of investigation.
Asunto(s)
Cíclidos/genética , ADN Mitocondrial/genética , Animales , América Central , América del Norte , FilogeografíaRESUMEN
Domestication of plants and animals promoted humanity's transition from nomadic to sedentary lifestyles, demographic expansion, and the emergence of civilizations. In contrast to the well-documented successes of crop and livestock breeding, processes of microbe domestication remain obscure, despite the importance of microbes to the production of food, beverages, and biofuels. Lager-beer, first brewed in the 15th century, employs an allotetraploid hybrid yeast, Saccharomyces pastorianus (syn. Saccharomyces carlsbergensis), a domesticated species created by the fusion of a Saccharomyces cerevisiae ale-yeast with an unknown cryotolerant Saccharomyces species. We report the isolation of that species and designate it Saccharomyces eubayanus sp. nov. because of its resemblance to Saccharomyces bayanus (a complex hybrid of S. eubayanus, Saccharomyces uvarum, and S. cerevisiae found only in the brewing environment). Individuals from populations of S. eubayanus and its sister species, S. uvarum, exist in apparent sympatry in Nothofagus (Southern beech) forests in Patagonia, but are isolated genetically through intrinsic postzygotic barriers, and ecologically through host-preference. The draft genome sequence of S. eubayanus is 99.5% identical to the non-S. cerevisiae portion of the S. pastorianus genome sequence and suggests specific changes in sugar and sulfite metabolism that were crucial for domestication in the lager-brewing environment. This study shows that combining microbial ecology with comparative genomics facilitates the discovery and preservation of wild genetic stocks of domesticated microbes to trace their history, identify genetic changes, and suggest paths to further industrial improvement.
Asunto(s)
Saccharomyces cerevisiae/genética , Secuencia de Aminoácidos , Secuencia de Bases , Clasificación , Ecología , Datos de Secuencia Molecular , Saccharomyces cerevisiae/clasificaciónRESUMEN
A plot established in 1943 in a subtropical wet forest at the Luquillo Experimental Forest of Puerto Rico has been assessed periodically for changes in species and size of all trees >4cm diameter. Forest dynamics on a 0.72ha plot (EV-3) at 400masl at El Verde show recovery principally from hurricanes of 1928 and 1932, timber stand improvement in 1958, and from Hurricanes Hugo and Georges in 1989 and 1998. Damage from Hurricane Hugo only temporarily slowed aboveground biomass accretion of the developing forest. Stand increases in basal area and biomass continue to be due principally to growth of the dominant overstory species, Dacryodes excelsa and Manilkara bidentata, ingrowth of which was stimulated by Hugo. The pioneer species Cecropia schreberiana filled gaps abundantly following the Hurricane and the understory tree Psychotria berteriana proliferated. Ingrowth of Prestoea montana has been greater than for all other species since 1976 and was stimulated by Hugo and Georges as well as prior hurricanes, so that by 2005 it was the most abundant species. Hurricane Hugo caused low mortality among the largest trees on the plot. As a few species have become more dominant species evenness has declined. Species richness is only slightly greater today than in 1943. Results are discussed in terms of "building" and "thinning" phases associated with major hurricanes. Hurricanes have stimulated the addition of species to the forest in "building years," but have maintained that richness in the intervening "thinning years", lending credence to the "intermediate disturbance hypothesis".
Una parcela de crecimiento establecida en 1943 en un bosque subtropical húmedo en Puerto Rico ha sido evaluada periódicamente en relación a cambios en las especies y tamaño de los árboles con diámetro >4cm. La dinámica forestal en una parcela de 0,72ha (EV-3, situada en El Verde a 400msnm) muestra principalmente la recuperación de los huracanes de 1928 y 1932, de aclareos para el mejoramiento de rodales madereros en 1958 y de los huracanes Hugo y Georges en 1989 y 1998. Los daños de Hugo disminuyeron solo temporalmente la acumulación de biomasa arbórea del bosque en desarrollo. Se siguieron registrando aumentos de área basal y biomasa del rodal, principalmente por crecimiento de las especies dominantes Dacryodes excelsa y Manilkara bidentata, cuya renovación fue estimulada. La pionera Cecropia schreberiana se estableció abundantemente en espacios abiertos por el huracán y en el sotobosque proliferó Psychotria berteriana. El crecimiento de la regeneración de Prestoea montana ha sido el mayor registrado desde 1976 y fue estimulado por Hugo y George, así como por huracanes anteriores, siendo la especie más abundante en 2005. Hugo causó poca mortalidad de árboles grandes. En la medida en que pocas especies han llegado a ser dominantes, la uniformidad de las parcelas ha declinado. La riqueza de especies es ligeramente mayor que en 1943. Los resultados se discuten en términos de fases de "construcción" y "aclareo" asociadas con el paso de huracanes. Éstos han estimulado la adición de especies en "años de construcción", pero han mantenido la riqueza en "años de aclareo", añadiendo credibilidad a la hipótesis de perturbaciones intermedias.
Uma parcela de crescimento estabelecida em 1943 em um bosque subtropical úmido em Puerto Rico tem sido avaliada periodicamente em relação às mudanças nas espécies e tamanho das árvores com diâmetro >4 cm. A dinâmica florestal em uma parcela de 0,72ha (EV-3, situada em El Verde a 400msnm) mostra principalmente a recuperação dos furacões de 1928 e 1932, de clareiras para o melhoramento de lotes madeireiros em 1958 e dos furacões Hugo e Georges em 1989 e 1998. Os danos de Hugo diminuíram somente temporalmente a acumulação de biomassa arbórea do bosque em desenvolvimento. Seguiram-se registrando aumentos de área basal e biomassa do lote, principalmente por crescimento das espécies dominantes Dacryodes excelsa e Manilkara bidentata, cuja renovação foi estimulada. A pioneira Cecropia schreberiana se estabeleceu abundantemente em espaços abertos pelo furacão e no sotobosque proliferou Psychotria berteriana. O crescimento da regeneração de Prestoea montana tem sido o maior registrado desde 1976 e foi estimulado por Hugo e George, assim como por furacões anteriores, sendo a espécie mais abundante em 2005. Hugo causou pouca mortalidade de árvores grandes. Na medida em que poucas espécies têm chegado a ser dominantes, a uniformidade das parcelas tem declinado. A riqueza de espécies é ligeiramente maior que em 1943. Os resultados se discutem em termos de fases de "construção" e "clareiras" associadas com a passagem de furacões. Estes têm estimulado a adição de espécies em "anos de construção", mas tem mantido a riqueza em "anos de clareiras", acrescentando credibilidade à hipótese de perturbações intermediarias.