Seven types of adaptationism

Godfrey-Smith (2001) has distinguished three types of adaptationism. This article builds on his analysis, and revises it in places, by distinguishing seven varieties of adaptationism. This taxonomy allows us to clarify what is at stake in debates over adaptationism, and it also helps to cement the importance of Gould and Lewontin’s ‘Spandrels’ essay. Some adaptationists have suggested that their essay does not offer any coherent alternative to the adaptationist programme: it consists only in an exhortation to test adaptationist hypotheses more thoroughly than was usual in the 1970s. Here it is argued that the ‘Spandrels’ paper points towards a genuinely non-adaptationist methodology implicit in much evolutionary developmental biology. This conclusion helps to expose the links between older debates over adaptationism and more recent questions about the property of evolvability.

Emergence of neuron types

Neuron types are the building blocks of the nervous system, and therefore, of functional circuits. Understanding the origin of neuronal diversity has always been an essential question in neuroscience and developmental biology. While knowledge on the molecular control of their diversification has largely increased during the last decades, it is now possible to reveal the dynamic mechanisms and the actual stepwise molecular changes occurring at single-cell level with the advent of single-cell omics technologies and analysis with high temporal resolution. Here, we focus on recent advances in the field and in technical and analytical tools that enable detailed insights into the emergence of neuron types in the central and peripheral nervous systems.     

Exploration types of ectomycorrhizae

There is a need to quantify and qualify the ability of ectomycorrhizae to improve tree growth and nutrition and, in particular, to define criteria to classify ectomycorrhizae with respect to ecologically relevant features. Whereas the numbers of ectomycorrhizae and morphotypes give useful information when related to root biomass, root length or soil volume, the development and differentiation of the extramatrical mycelium may represent important predicative features relevant to the ecological classification of ectomycorrhizae. Here, different exploration types of ectomycorrhizae are distinguished based on the amount of emanating hyphae or the presence and differentiation of rhizomorphs. Their putative ecological importance is discussed. Accepted: 27 March 2001     

Eight newSalmonella types

Summary Eight newSalmonella types are described.S. houten, 43; Z₄, Z₂₃ :−, was isolated from a frog,S.tuindorp, 43: Z₄, Z₃₂: −,S. vleuten, 44: fg: −,S.zeist, 18: Z₁₀: Z₆, andS.soesterberg. 21: Z₄, Z₂₃: −, were isolated from lizards. S. kralingen (8), 20: y: Z₆, was isolated from peanuts andS. assen, 21: a: −, was isolated from a swine. All these strains were isolated in the Netherlands. S.mim, 13, 22: a: 1,6, was isolated from a rat in Ghana.     

Seven newSalmonella types

Seven hitherto unrecognizedSalmonella types are described.S.leiden (13, 22, 36 : z 38),S. enschede (35 : z 10 : l,w) andS. hillegersberg (9, 46 : z 35 : 1,5) were isolated from patients in the Netherlands.S. lawra (44 : k : e,n,z 15) was isolated from a healthy student in Ghana.S. overvecht (30 : a : 1,2),S. woerden (17 : c : z 39) andS. odijk (30 : a : z 39) were isolated from animals kept in zoological gardens in the Netherlands.     

Halkomelem clitic types

In the Salish language Halkomelem, there are numerous functional elements that we identify as clitics. In this study, we seek to improve our understanding of Halkomelem clitics by classifying them according to their syntactic and phonological properties. We look in particular at data from the Island dialect, called Hul’q’umi’num’. First, based on their patterns of syntactic placement, we classify Hul’q’umi’num’ clitics into two general types, inner and outer. Inner clitics are more constrained in their placement than outer clitics. When they co-occur, inner clitics are closer to the host than outer clitics are. Second, we examine Hul’q’umi’num’ clitics in terms of phonological integration, showing that clitics are less integrated than affixes, and, furthermore, that clitics that follow their hosts are more integrated than those that precede their hosts. Finally, we analyze the prosodic representations of Hul’q’umi’num’ clitics within Prosodic Clitic Theory. We propose that clitics receive at least three different parses in Hul’q’umi’num’, namely internal enclisis, adjoined proclisis, and free clisis. That is, clitics can be parsed at the right edge of a prosodic word, at the left edge of a recursive prosodic word, or directly by a phonological phrase. While Hul’q’umi’num’ clitics exhibit a range of behaviors, those clitics with more constrained syntactic placement are generally more phonologically integrated, and vice-versa.     

Twelve newSalmonella types

Twelve hitherto unrecognizedSalmonella types are described. S. heerlen (11 : i : 1,6) andS. sloterdijk (1, 4, 12, 27 : z 35 : z 6) were isolated from patients in the Netherlands,S. maartensdijk (40 : g, p) was isolated from a healthy calf,S. maastricht (11 : z 41 : 1, 2(7)) from imported fishmeal,S. parera (11 : z 4, z 23 : -.) from water on the island Bonaire,S. putten (13, 23, 36 : d : 1, w),S. hoograven (50 : z 10 : z 6 : z 42),S. schalkwijk ((6), 14, (24) : i : e, n, ...),S. hilversum (30 : k : 1, 2) andS. harmelen (51 : z 4, z 23 : -.) from reptiles,S. breukelen (6, 8 : 1, z 13 : e, n, z 15) from a cuscus andS. maarssen (9, 46 : z 4, z 24 : z 39 : z 42) from a lizard.     

Stomatal types ofCactaceae

The stomatal types (i.e. the arrangement of epidermal cells in the vicinity of a stomatal pore in superficial view) have been examined in more than 150 taxa ofCactaceae, mostly using documented material. Preparations have been made by mazerating pieces of tissue with modified Jeffrey's Solution and staining with chlore-zinc-jodine.—The examined members of the subfamilyCactoideae showed parallelocytic stomata with only minor deviations in a number of cases. Members of the subfamiliesPereskioideae andOpuntioideae show parallelocytic stomata on the leaves, but the stomatas of the stem represent a different type, which apparently is not yet described. It is termed opuntioid here. In most cases the stomata are superficial but a few taxa show markedly sunken or hidden stomata.—In taxa of the subfamiliesPereskioideae andOpuntioideae the stomata are generally oriented parallel to the stem axis with only minor deviations. The stomata of taxa of the subfamilyCactoideae do in general not show a particular orientation with the notable exception of a number of epiphytic genera from the tribeHylocereeae.—The results of these investigations in general coincide well with the generic classification of theCactaceae byHunt (1967). A few cases where stomatal characters suggest a differing classification merit further investigations.—Additionally, the possibilities to distinguish between paracytic and parallelocytic stomata are discussed and an amended definition for the latter is given.     

Cell type-specific association between two types of spectrin and two types of intermediate filaments

We have demonstrated a differential association between two types of spectrin, from erythrocytes and brain, with two types of intermediate filaments, vimentin filaments and neurofilaments. Electron microscopy showed that erythrocyte spectrin promoted the binding of vimentin filaments to red cell inside-out vesicles via lateral associations with the filaments. In vitro binding studies showed that the association of spectrin with vimentin filaments was apparently saturable, increased with temperature, and could be prevented by heat denaturation of the spectrin. Comparisons were made between erythrocyte and brain spectrin binding to both vimentin filaments and neurofilaments. We found that vimentin filaments bound more erythrocyte spectrin than brain spectrin, while neurofilaments bound more brain spectrin than erythrocyte spectrin. Our results show that both erythroid and nonerythroid spectrins are capable of binding to intermediate filaments and that such associations may be characterized by differential affinities of the various types of spectrin with the several classes of intermediate filaments present in cells. Our results also suggest a role for both erythroid and nonerythroid spectrins in mediating the association of intermediate filaments with plasma membranes or other cytoskeletal elements.