The effects of climate change on species composition,succession and phenology: a case study

Climate change and its role in altering biological interactions and the likelihood of invasion by introduced species in marine systems have received increased attention in recent years. It is difficult to forecast how climate change will influence community function or the probability of invasion as it alters multiple marine environmental parameters including rising water temperature, lower salinity and pH. In the present study, we correlate changes in environmental parameters to shifts in species composition in a subtidal community in Newcastle, NH through comparison of two, 3‐year periods separated by 23 years (1979–1981 and 2003–2005). We observed concurrent shifts in climate related factors and in groups of organisms that dominate the marine community when comparing 1979–1981 to 2003–2005. The 1979–1981 community was dominated by perennial species (mussels and barnacles). In contrast, the 2003–2005 community was dominated by annual native and invasive tunicates (sea‐squirts). We also observed a shift in the environmental factors that characterized both communities. Dissolved inorganic nitrogen and phosphate characterized the 1979–1981 community while sea surface temperature, pH, and chlorophyll a characterized the 2003–2005 community. Elongated warmer water temperatures, through the fall and early winter months of the 2000s, extended the growing season of native organisms and facilitated local dominance of invasive species. Additionally, beta‐diversity was greater between 2003–2005 than 1979–1981 and driven by larger numbers of annual species whose life‐history characteristics (e.g., timing and magnitude of recruitment, growth and mortality) are driven by environmental parameters, particularly temperature.     

A NEW GENUS AND SPECIES OF SPHENODONTIAN FROM THE GHOST RANCH COELOPHYSIS QUARRY (UPPER TRIASSIC: APACHEAN), ROCK POINT FORMATION, NEW MEXICO, USA

Abstract: We document here a new taxon of sphenodontian, Whitakersaurus bermani gen. et sp. nov., that is also the most complete sphenodontian fossil from the Upper Triassic Chinle Group in the south‐western USA and the first Chinle sphenodontian represented by more than a single fragmentary dentulous element. The holotype was recovered during preparation of block C‐8‐82 from the famous Coelophysis (Whitaker) quarry at Ghost Ranch, New Mexico, and is the most complete small vertebrate recovered from the quarry. Detailed lithostratigraphy and geologic mapping demonstrate that the Whitaker quarry is in the Rock Point Formation of the Chinle Group, so Whitakersaurus is the first sphenodontian reported from this unit. Records of the phytosaur Redondasaurus at the quarry and elsewhere in the Chinle Group demonstrate that the quarry, and thus Whitakersaurus, is of Apachean (late Norian–Rhaetian) age. The sphenodontian specimen consists of incomplete left and right dentaries, a partial left? maxilla?, and impressions of a probable palatal element, all of which preserve multiple teeth. Whitakersaurus is distinct from other sphenodontians in possessing a unique combination of the following features: marginal dentition pleurodont anteriorly and posteriorly acrodont; pronounced heterodonty in dentary, with as many as 15 smaller, peg‐like teeth anteriorly and several larger, posterior teeth that are conical and striated; faint radial ornamentation of posterior tooth crowns; presence of c. 19 dentary teeth; and absence of a distinct flange on posterior teeth. Numerous other details distinguish it from both more primitive and more derived taxa. Whitakersaurus, therefore, helps to document further mosaic evolution and an extensive diversification event of sphenodontians during Triassic time. Although sphenodontian taxa are relatively easily recognized, widely distributed, and common small‐ or microvertebrate fossils, the long stratigraphic ranges of taxa known from multiple specimens hinders their utility as index fossils with which to correlate strata across Pangaea.     

Evolution of pelagic direct development in the starfish Pteraster tesselatus (Asteroidea: Velatida)

Despite a diversity of larval forms, remarkably conservative features of asteroid development define a larval body plan that occurs throughout the class. However, recent work on the starfish Pteraster tesselatus has documented a highly derived pattern of development. Several features, including radial symmetry, parallel embryonic and adult axes of symmetry, absence of a preoral lobe, and formation of coeloms in the adult orientation from seven separate enterocoels, have not been reported in asteroids before. The complete absence of the larval body plan features that are found in other asteroids, indicates that P. tesselatus develops directly from the embryo to the juvenile and has a pelagic, nonfeeding (lecithotrophic), but nonlarval mode of development. I postulate that direct development evolved over an extended period in a lineage of brooding, deep-sea velatid (probably pterastcrid) ancestors of P. tesselatus. Selection for increased developmental efficiency (loss of nonfunctional larval features) in the brooded offspring, could explain the lack of larval settlement structures, the nonlarval arrangement of coeloms, the lack of a preoral lobe, the transverse orientation of the juvenile disc, and the lack of bilateral symmetry. The pattern of coclomogenesis could have been derived from that of other velatids (e.g. solasterids) by relatively simple changes in timing and orientation of entcroeoel formation. Rotation and posterior translation of the coelomic fate map of the archenteron prior to enlerocoel formation would produce the coelomic compartments in the adult orientation that characterizes direct development in P. tesselatus. These unusual developmental features lead to a radically different interpretation for the evolution of the pelagic ‘larva’ of P. tesselatus: (1) evolution of benthie brooding, (2) extreme simplification of development involving the loss of all larval features from the life cycle, and (3) subsequent re-evolution of pelagic development. In the case of P. tesselatus, where all larval structures were lost, there do not seem to be functional constraints preventing the re-evolution of pelagic development. Analysis of pelagic and benthie larvae, in other asteroids, suggests that major ecological transitions in life histories need not be associated with substantia] changes in morphology. The loss of pelagic development should have occurred repeatedly and should be readily reversible. These findings have interesting implications for the loss and evolution of pelagic dispersal in the life histories of marine benthie invertebrates.     

Cultivar Differences in Starch Content and Protoplast Yields from Root Cortical Ex plants of Pisum salivum

Protoplasts were isolated from root cortical explants of thirteen cultivars of Pisum sativum. The roots were tested for starch in the cortical tissues. There was a considerable range in the average protoplast yields and the coefficient of variation of those yields from the thirteen cultivars. Cultivars with a higher incidence of starchy roots had lower average explam protoplast yields and greater variation in their protoplast yields. Significantly higher protoplast yields were observed from explants with no starch or few starchy cells. Increasing the germination time of the peas increased the starch content in the seedling roots and decreased the protoplast yields.     

EFFECT OF CARBONYL CYANIDE PHENYLHYDRAZONE ON CATION UPTAKE IN EXCISED BARLEY ROOTS

The generally-accepted characteristics of ion transport in planttissue do not apply completely in the case of zinc uptake. Inthis case, 5x1^–5 M CCP (which completely stops rubidiumuptake in barley roots) shows little inhibitory effect. In thisrespect it is like DNP which also shows little influence onzinc uptake in this concentration. ¹ Present Address: Department of Botany and Plant Pathology,University of Minnesota, St. Paul, Minnesota, U.S.A.     

Inhibition by kinetin of cell elongation and RNA synthesis in excised soybean hypocotyl M 2

The effects of kinetin on growth and RNA metabolism in excisedsoybean hypocotyl were investigated, and compared to the effectsof 5-fluorouracil. Kinetin inhibits auxin-induced growth, butnot control growth. RNA synthesis is also inhibited by kinetin,but in a differential fashion. Ribosomal RNA synthesis is almostcompletely inhibited, while TB-RNA synthesis is partially inhibited.D-RNA synthesis is apparently not affected. Base compositionanalysis of these fractions of RNA was carried out. The implicationsfor RNA-mediated auxin-induced growth are discussed. ¹The research was supported by NIH grant GM-10157 from the U.S. Public Health Service. ²Purdue University AES Paper No. 3334     

Synchronization of Leishmania tarentolae by Hydroxyurea

SYNOPSIS Leishmania tarentolae cells in brain-heart infusion medium were partially synchronized in terms of DNA synthesis and cell division by a 10 hour period of inhibition in 200 μg/ml hydroxyurea at 27 C. Nuclear and kinetoplast DNA synthesis commenced immediately upon removal of hydroxyurea, and kinetoplast and nuclear division occurred after about 5 hr. The Index of Synchronization (3) varied from 33-41%.
A moderate decay of the synchronicity was noted by the 2nd cell cycle. Hydroxyurea was selectively lethal to S-phase cells.