Classification: More than Just Branching Patterns of Evolution

The past 35 years in biological systematics have been a time of remarkable philosophical and methodological developments. For nearly a century after Darwin\u27s Origin of Species, systematists worked to understand the diversity of nature based on evolutionary relationships. Numerous concepts were presented and elaborated upon, such as homology, parallelism, divergence, primitiveness and advancedness, cladogenesis and anagenesis. Classifications were based solidly on phylogenetic concepts; they were avowedly monophyletic. Phenetics emphasized the immense challenges represented by phylogeny reconstruction and advised against basing classifications upon it. Pheneticists forced reevaluation of all previous classificatory efforts, and objectivity and repeatability in both grouping and ranking were stressed. The concept of character state was developed, and numerous debates focused on other concepts, such as unit character, homology, similarity, and distance. The simultaneous availability of computers allowed phenetics to explore new limits. Despite numerous positive aspects of phenetics, the near absence of evolutionary insights led eventually to cladistics. Drawing directly from phenetics and from the Hennigian philosophical school, cladistics evolved as an explicit means of deriving branching patterns of phylogeny and upon which classifications might be based. Two decades of cladistics have given us: refined arguments on homology and the evolutionary content of characters and states, views of classifications as testable hypotheses, and computer algorithms for constructing branching patterns of evolution. In contrast to the phenetic movement, which was noteworthy for seeking newer concepts and methods, even including determining evolutionary relationships (which led eventually to numerical cladistics), many cladists have solidified their approaches based on parsimony, outgroups, and holophyly. Instead of looking for newer ways to represent phylogeny, some cladists have attempted to use branching patterns: (1) as a strict basis for biological classification and nomenclature and (2) to explain the origin of biological diversity even down to the populational level. This paper argues that cladistics is inappropriate to both these goals due to: (1) inability of branching patterns to reveal all significant dimensions of phylogeny; (2) acknowledged patterns of reticulate evolution, especially in flowering plants; (3) documented nonparsimonious pathways of evolution: and (4) nondichotomous distribution of genetic variation within populations. New concepts and methods of reconstructing phylogeny and developing classifications must be sought. Most important is incorporation of genetic-based evolutionary divergence within lineages for purposes of grouping and ranking

New Student Orientation at the Two-Year College – An Appreciative Approach

Over the years, New Student Orientation (NSO) at Midlands Technical College (MTC) has become more intentionally student-focused. The NSO team at MTC is striving to develop intentional positive relationships with students by implementing the six phases of the appreciative education model into on-campus orientation. After a brief overview of the six phases of appreciative education, as they are outlined in the 2013 article by Bloom, et. al., there will be detailed examples of how MTC has implemented all six phases of appreciative education – disarm, discover, dream, design, deliver, don’t settle – into NSO. The next section will be used to share some of our orientation survey data, as it correlates with the overall goal of the AE model and its phases. Finally, the concluding remarks will summarize why using an appreciative model for NSO at a two-year college increases the potential for developing positive relationships with students.

Plant Species Disjunctions

The use of molecular data in the study of plant species disjunctions is reviewed and evaluated. The major reason for employing molecular information is to estimate genetic divergence between morphologically similar disjunct species. Flavonoid chemistry offers few advantages over morphology because it is difficult, if not impossible, to infer genetic divergence from the arrays of flavonoid compounds sequestered by two species. Also, flavonoids can, like morphological characters, undergo stasis. Rather direct evidence for this comes from the fact that extant and fossil species may have identical or nearly identical flavonoids. Enzyme electrophoresis is useful for estimating divergence between disjunct species at gene loci encoding soluble enzymes. Disjunct species pairs in several genera are highly divergent at isozyme loci despite their morphological similarity. Restriction site analysis of chloroplast DNA (cpDNA) has proven useful for measuring divergence between disjunct species. The conservative rate of nucleotide substitutions in cpDNA allows one to estimate (albeit with several assumptions) sequence divergence between the DNAs. Whether isozyme and cpDNA data can be used to estimate divergence times with reasonable confidence remains an open question. In two studies employing both methods, similar divergence times were calculated with each. As two species become more divergent at isozyme loci, the variance in estimates of divergence times becomes larger, and the calculated times become less certain. Despite limitations, enzyme electrophoresis and cpDNA restriction site data are valuable for estimating genetic divergence between disjunct species. Future studies of plant species disjunctions will likely include nucleic acid sequence data. The molecular information should always be part of a broader study of species disjunctions, including detailed investigations of morphological features, chromosome numbers, ecology, and the geological histories of the species

Anxiety in the Doing: Impressionist Tales of Adults Learning to be Educational Researchers

This study investigated the inner experiences of adults learning to become educational researchers. Through narrative analysis of doctoral students’ tales of memorable early encounters in conducting research, insight was gained into the tension, conflict, and drama they experienced

Regular Vetoes and Pocket Vetoes: In Brief

This report presents information on the process by which Congress can override regular vetoes, the number of vetoes by each President, and the use of vetoes in relation to appropriations acts

Genetic consequences of cladogenetic vs. anagenetic speciation in endemic plants of oceanic islands

Adaptive radiation is a common mode of speciation among plants endemic to oceanic islands. This pattern is one of cladogenesis, or splitting of the founder population, into diverse lineages in divergent habitats. In contrast, endemic species have also evolved primarily by simple transformations from progenitors in source regions. This is anagenesis, whereby the founding population changes genetically and morphologically over time primarily through mutation and recombination. Gene flow among populations is maintained in a homogeneous environment with no splitting events. Genetic consequences of these modes of speciation have been examined in the Juan Fernández Archipelago, which contains two principal islands of differing geological ages. This article summarizes population genetic results (nearly 4000 analyses) from examination of 15 endemic species, involving 1716 and 1870 individuals in 162 and 163 populations (with amplified fragment length polymorphisms and simple sequence repeats, respectively) in the following genera: Drimys (Winteraceae), Myrceugenia (Myrtaceae), Rhaphithamnus (Verbenaceae), Robinsonia (Asteraceae, Senecioneae) and Erigeron (Asteraceae, Astereae). The results indicate that species originating anagenetically show high levels of genetic variation within the island population and no geographic genetic partitioning. This contrasts with cladogenetic species that show less genetic diversity within and among populations. Species that have been derived anagenetically on the younger island (1–2 Ma) contain less genetic variation than those that have anagenetically speciated on the older island (4 Ma). Genetic distinctness among cladogenetically derived species on the older island is greater than among similarly derived species on the younger island. An important point is that the total genetic variation within each genus analysed is comparable, regardless of whether adaptive divergence occurs