Species concepts should not conflict with evolutionary history, but often do

Many phylogenetic systematists have criticized the Biological Species Concept (BSC) because it distorts evolutionary history. While defenses against this particular criticism have been attempted, I argue that these responses are unsuccessful. In addition, I argue that the source of this problem leads to previously unappreciated, and deeper, fatal objections. These objections to the BSC also straightforwardly apply to other species concepts that are not defined by genealogical history. What is missing from many previous discussions is the fact that the Tree of Life, which represents phylogenetic history, is independent of our choice of species concept. Some species concepts are consistent with species having unique positions on the Tree while others, including the BSC, are not. Since representing history is of primary importance in evolutionary biology, these problems lead to the conclusion that the BSC, along with many other species concepts, are unacceptable. If species are to be taxa used in phylogenetic inferences, we need a history-based species concept

The Future of Systematics: Tree-Thinking Without the Tree

Phylogenetic trees are meant to represent the genealogical history of life and apparently derive their justification from the existence of the tree of life and the fact that evolutionary processes are tree-like. However, there are a number of problems for these assumptions. Here it is argued that once we understand the important role that phylogenetic trees play as models which contain idealizations, we can accept these criticisms and deny the reality of the tree while justifying the continued use of trees in phylogenetic theory and preserving nearly all of what defenders of trees have called “the importance of tree-thinking.

Axiomatic opportunities and obstacles for inferring a species tree from gene trees

The reconstruction of a central tendency `species tree' from a large number of conflicting gene trees is a central problem in systematic biology. Moreover, it becomes particularly problematic when taxon coverage is patchy, so that not all taxa are present in every gene tree. Here, we list four apparently desirable properties that a method for estimating a species tree from gene trees could have (the strongest property states that building a species tree from input gene trees and then pruning leaves gives a tree that is the same as, or more resolved than, the tree obtained by first removing the taxa from the input trees and then building the species tree). We show that while it is technically possible to simultaneously satisfy these properties when taxon coverage is complete, they cannot all be satisfied in the more general supertree setting. In part two, we discuss a concordance-based consensus method based on Baum's `plurality clusters', and an extension to concordance supertrees.Comment: 19 pages, 2 figure

NITROGEN DYNAMICS IN INTEGRATED AGRICULTURAL SYSTEMS IN CENTRAL MEXICO

Smallholdings (<5 ha) represent 73% of the total agricultural production systems in Mexico. Many are of low productivity, and little quantitative data has been published on the impact of traditional nitrogen (N) management practices on environmental performance at farm scale. Nitrogen is the most important nutrient for increasing crop yields. While the benefits from the use of N fertilizer are self evident, it has resulted in low efficiency of N utilization and environmental problems. This project aimed to assess N dynamics in Integrated Agricultural Systems (lASs) in central Mexico. Nitrogen inputs, outputs and internal transfers were assessed and the impact of selected management practices on nitrogen flow, productivity and environmental performance were analyzed using nitrogen use efficiency (NUE) indices. A predictive framework tool was developed following whole farm methodologies to quantify N flow, and to assess selected (NUE) indices such as 0/1 ratio, N loss, accumulated N, and the change of N in the soil pool at farm scale. Data used for the development of the predictive framework was derived from experimental evaluations of ammonia emissions during vermicomposting, and integrated with data from the literature, together with data from an integrated agricultural systems prototype in Montecillo Mexico. The main N inputs into integrated agricultural systems in the Texcoco region were estimated to be in the following order of significance: biological N fixation (11 - 532), manure (15 - 225), fertilizer (0 - 140) and rainfall water (30 - 35 kg haˉ¹ aˉ¹). The main N outputs were: N losses (70 - 528 kg haˉ¹ aˉ¹) and exported N in marketable products (72 - 338 kg haˉ¹ aˉ¹). Experimentally derived estimates of ammonia emissions during vermicomposting of sheep manure ranged from 10 - 15 kg Mgˉ¹ DM which corresponded to 42 - 47% of the initial N content in the manure substrate. The impact of current management practices showed 0/1 ratios ranging from 0.30 - 0. 76, N losses ranged from 76 to 210 kg haˉ¹ aˉ¹ and N depletion/ accumulation ranged from -25 - 143 kg haˉ¹ aˉ¹. The effect of selected management practices on 0/1 ratio was as follows: crop sequence > stocking density > livestock type > manure management. Whereas for N loss it was stocking density > livestock type > manure management > crop sequence. Higher productivity together with a more benign environmental impact could be attained in smallholder by implementing simple recommended manure management practices at farm scale

Species concepts should not conflict with evolutionary history, but often do

Many phylogenetic systematists have criticized the Biological Species Concept (BSC) because it distorts evolutionary history. While defenses against this particular criticism have been attempted, I argue that these responses are unsuccessful. In addition, I argue that the source of this problem leads to previously unappreciated, and deeper, fatal objections. These objections to the BSC also straightforwardly apply to other species concepts that are not defined by genealogical history. What is missing from many previous discussions is the fact that the Tree of Life, which represents phylogenetic history, is independent of our choice of species concept. Some species concepts are consistent with species having unique positions on the Tree while others, including the BSC, are not. Since representing history is of primary importance in evolutionary biology, these problems lead to the conclusion that the BSC, along with many other species concepts, are unacceptable. If species are to be taxa used in phylogenetic inferences, we need a history-based species concept

It’s All about Relationships: AMF-Plant Associations, the Rhizosphere, and Our Changing World

Arbuscular mycorrhizal fungi are obligate biotrophic organisms that facilitate nutrient uptake in exchange for organic carbon as part of a symbiotic association with their host plants. This symbiotic relationship is among the oldest known and has been important for the coevolution of both symbionts. This review explores the relationship between Arbuscular mycorrhizal fungi and their hosts, the role AMF play in the invasive strategies of certain plants, and how severe pressure affects the reciprocal relationship. This review hopes to add to the body of knowledge and to the conversation about these dynamic relationships and the timescale on which they operate, because this information will prove valuable as humanity attempts to manage lands and produce food in an unstable climate

Phylogeny as population history

The construction and use of phylogenetic trees is central to modern systematics. But it is unclear exactly what phylogenies and phylogenetic trees represent. They are sometimes said to represent genealogical relationships between taxa, between species, or simply between “groups of organisms.” But these are incompatible representational claims. This paper focuses on how trees are used to make inferences and then argues that this focus requires that phylogenies represent the histories of populations

Plan de marketing digital para la Empresa “Post Sport”, de la ciudad de Ambato

El presente trabajo de investigación titulado Plan de Marketing digital para la empresa Post Sport de la ciudad de Ambato tiene como objetivo principal implementar el uso de herramientas de marketing digital y web 2.0 en la empresa. Para dar cumplimiento a este objetivo se realizó un trabajo de investigación el cual se aplicó una encuesta al PEA Población Económicamente Activa de la ciudad de Ambato con el fin de conocer los medios digitales y redes sociales más utilizadas en la actualidad. Además también se elaboró un análisis de la situación actual de la empresa en el mercado mediante la elaboración de una matriz FODA y matrices de perfil competitivo. Se pudo determinar la preferencia de los usuarios en cuanto a medios digitales y redes sociales, con el análisis elaborado de la empresa se determinó las falencias existentes en la empresa, entre ellas la inexistencia de un área de marketing, la falta de personal con conocimiento en esta área y la inexistencia de manejo de redes sociales. La propuesta contiene herramientas de marketing digital como Similar web y NeilPatel, así como la creación del área de Marketing dentro de la empresa. Se recomienda aplicar el Plan de Marketing Digital propuesto y utilizar herramientas estadísticas que permitirán medir el alcance de las páginas y fanpages gestionadas.The present research work entitled Digital Marketing Plan for the Post Sport company in the Ambato city has as main objective to implement the use of digital marketing tools and web 2.0 in the company. In order to comply with this objective, a research work was carried out which applied a survey to the Economically Active Population of the Ambato City in order to know the most used digital media and social networks at present. In addition, an analysis of the current situation of the company in the market was elaborated through the elaboration of a SWOT matrix and competitive profile matrices. It was possible to determine the preference of the users in terms of digital media and social networks, with the elaborated analysis of the company, the shortcomings existing in the company were determined, among them the lack of a marketing area, the lack of personnel with knowledge in this area and the lack of management of social networks. The proposal contains digital marketing tools such as Similar web and NeilPatel, as well as the creation of the Marketing area within the company. It is recommended to apply the proposed Digital Marketing Plan and use statistical tools that will allow to measure the scope of pages and fanpage managed