Evolution in a tropical archipelago: comparative phylogeography of Philippine fauna and flora reveals complex patterns of colonization and diversification

An unusual geological setting and a high level of endemism makes the Philippine islands of great interest to biogeography. These islands lie adjacent to the continental (Sunda) shelf, yet the majority of the islands have never been directly attached to the mainland. Existing hypotheses of colonization and diversification processes have been tested across multiple taxa, but only in ahistorical contexts. We present explicit phylogenetic predictions based on these hypotheses, and then test them using new molecular datasets for four Philippine birds. Two proposed colonization routes to the northern Philippines (from mainland Asia and Palawan) are difficult to differentiate from each other, except on the basis of outgroup, as are the two routes from the south (Sulu archipelago and Sulawesi). We find unique colonization and diversification patterns for each taxon. These results contrast with expectations from Pleistocene geography, with Luzon and Mindoro indistinguishable genetically, and Negros and Panay are often nonsister taxa. Combining these data with a literature search for studies addressing these patterns, Philippine organisms shows some evidence for each proposed colonization route but the greatest support is for the two routes from Borneo. Many taxa exhibit multiple colonization events using several of these routes, contrasting with past assumptions of single colonization events. Island‐by‐island differentiation within the Philippines follows, with patterns reflecting colonization patterns rather than Pleistocene geography, particularly for highland species. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 620–639.     

Phytophthora cryptogea root rot of tomato in rock woo] nutrient culture. II. Effect of root zone temperature on infection, sporulation and symptom development

The effect of root-zone temperature on Phytophthora cryptogea root rot was studied in tomato cv. Counter grown under winter and summer conditions in rockwool culture. A nutrient temperature of 25°C resulted in increased root initiation and growth, higher in winter-grown than in summer-grown plants. Rhizosphere zoospore populations were greatly reduced at 25°C and above. Growth of P. cryptogea in vitro was optimal between 20°C and 25°C and completely suppressed at 30°C. Encystment was enhanced by increased temperatures above 20°C. Zoospore release in vitro occurred in cultures maintained at constant temperatures in the absence of the normal chilling stimulus. Optimal release was at 10°C; no zoospores were released at 30°C. Inoculated, winter-grown tomato plants maintained at 15°C developed acute aerial symptoms and died after 21 days. Comparable plants grown at a root-zone temperature of 25°C remained symptomless for the 3-months duration of the experiment. Summer-grown infected plants at the higher root temperature wilted but did not die. Enhanced temperature was ineffective as a curative treatment in summer-grown plants with established infection. Aerial symptoms of Phytophthora infection are seen as a function of the net amount of available healthy root. With high root zone temperatures this is determined by new root production and decreased inoculum and infection.     

Role of Luteinizing Hormone in Regulation of the Rat Estrous Cycle

The role of luteinizing hormone (LH) in regulation of secretionof ovarian steroids during the preovnlatory phase of the ratestrous cycle has been discussed. Evidence indicating an involvementof these steroids in control of the uterine growth, vaginalcornification, mating behavior and LH secretion which occurduring this phase has been reviewed. A positive feedback controlsystem has been proposed in which both ovarian and adrenal steroidsparticipate to initiate the preovulatory "LH surge" which culminatesin ovulation and luteinization     

Solar UVB and warming affect decomposition and earthworms in a fen ecosystem in Tierra del Fuego, Argentina

Combined effects of co-occurring global climate changes on ecosystem responses are generally poorly understood. Here, we present results from a 2-year field experiment in a Carex fen ecosystem on the southernmost tip of South America, where we examined the effects of solar ultraviolet B (UVB, 280–315 nm) and warming on above- and belowground plant production, C : N ratios, decomposition rates and earthworm population sizes. Solar UVB radiation was manipulated using transparent plastic filter films to create a near-ambient (90% of ambient UVB) or a reduced solar UVB treatment (15% of ambient UVB). The warming treatment was imposed passively by wrapping the same filter material around the plots resulting in a mean air and soil temperature increase of about 1.2 °C. Aboveground plant production was not affected by warming, and marginally reduced at near-ambient UVB only in the second season. Aboveground plant biomass also tended to have a lower C : N ratio under near-ambient UVB and was differently affected at the two temperatures (marginal UVB × temperature interaction). Leaf decomposition of one dominant sedge species ( Carex curta ) tended to be faster at near-ambient UVB than at reduced UVB. Leaf decomposition of a codominant species ( Carex decidua ) was significantly faster at near-ambient UVB; root decomposition of this species tended to be lower at increased temperature and interacted with UVB. We found, for the first time in a field experiment that epigeic earthworm density and biomass was 36% decreased by warming but remained unaffected by UVB radiation. Our results show that present-day solar UVB radiation and modest warming can adversely affect ecosystem functioning and engineers of this fen. However, results on plant biomass production also showed that treatment manipulations of co-occurring global change factors can be overridden by the local climatic situation in a given study year.