Climate-based models of spatial patterns of species richness in Egypt's butterfly and mammal fauna

Aim  Identifying areas of high species richness is an important goal of conservation biogeography. In this study we compared alternative methods for generating climate-based estimates of spatial patterns of butterfly and mammal species richness.
Location  Egypt.
Methods  Data on the occurrence of butterflies and mammals in Egypt were taken from an electronic database compiled from museum records and the literature. Using M axent , species distribution models were built with these data and with variables describing climate and habitat. Species richness predictions were made by summing distribution models for individual species and by modelling observed species richness directly using the same environmental variables.
Results  Estimates of species richness from both methods correlated positively with each other and with observed species richness. Protected areas had higher species richness (both predicted and actual) than unprotected areas.
Main conclusions  Our results suggest that climate-based models of species richness could provide a rapid method for selecting potential areas for protection and thus have important implications for biodiversity conservation.     

Involvement of the sun and the magnetic compass of domestic fowl in its spatial orientation

Domestic chicks are able to find a food goal at different times of day, with the sun as the only consistent visual cue. This suggests that domestic chickens may use the sun as a time-compensated compass, rather than as a beacon. An alternative explanation is that the birds might use the earth's magnetic field. In this study, we investigated the role of the sun compass in a spatial orientation task using a clock-shift procedure. Furthermore, we investigated whether domestic chickens use magnetic compass information when tested under sunny conditions.Ten ISA Brown chicks were housed in outdoor pens. A separate test arena comprised an open-topped, opaque-sided, wooden octagonal maze. Eight goal boxes with food pots were attached one to each of the arena sides. A barrier inside each goal box prevented the birds from seeing the food pot before entering. After habituation, we tested in five daily 5-min trials whether chicks were able to find food in an systematically allocated goal direction. We controlled for the use of olfactory cues and intra-maze cues. No external landmarks were visible. All tests were done under sunny conditions. Circular statistics showed that nine chicks significantly oriented goalwards using the sun as the only consistent visual cue during directional testing. Next, these nine chicks were subjected to a clock-shift procedure to test for the role of sun-compass information. The chicks were housed indoors for 6 days on a light-schedule that was 6 h ahead of the natural light–dark schedule. After clock-shifting, the birds were tested again and all birds except one were disrupted in their goalward orientation. For the second experiment, six birds were re-trained and fitted with a tiny, powerful magnet on the head to disrupt their magnetic sense. The magnets did not affect the chicks’ goalward orientation.In conclusion, although the strongest prediction of the sun-compass hypothesis (significant re-orientation after clock-shifting) was neither confirmed nor refuted, our results suggest that domestic chicks use the sun as a compass rather than as a beacon. These findings suggest that hens housed indoors in large non-cage systems may experience difficulties in orientation if adequate alternative cues are unavailable. Further research should elucidate how hens kept in non-cage systems orient in space in relation to available resources.     

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.

Ecohydrology of a seasonal wetland in the Rift Valley: ecological characterization of Lake Solai

The following research describes through an ecohydrological approach, the first assessment of the ecology of Lake Solai, with a particular emphasis on the vegetation. Lake Solai is located 50 km north of Nakuru in the Rift Valley in Kenya at E36°80'–36°84' to N00°05'–00°08'. It is a shallow lake that follows a very peculiar seasonal water regime, and that faces conflicts between agriculture and conservation water users. In the upper catchment, an overview of the agricultural practices was implemented and river water uses were identified to assess river flows. Crops/grassland and woodland/shrubland were the major land uses, covering c. 65% of the catchment. Closer to the lake, vegetation samples were collected around the lake together with samples of environmental factors such as soil and water quality. Thirteen vegetation communities were identified within four main zonations: forest, grassland, river inlet and rocky outcrop. These communities showed abundance, distribution and diversity determined mostly by the human pressures, the flooding periods and the salinity. Cynodon , Cyperus and Sporobolus genera were the most abundant.     

CDKB1;1 Forms a Functional Complex with CYCA2;3 to Suppress Endocycle Onset

The mitosis-to-endocycle transition requires the controlled inactivation of M phase-associated cyclin-dependent kinase (CDK) activity. Previously, the B-type CDKB1;1 was identified as an important negative regulator of endocycle onset. Here, we demonstrate that CDKB1;1 copurifies and associates with the A2-type cyclin CYCA2;3. Coexpression of CYCA2;3 with CDKB1;1 triggered ectopic cell divisions and inhibited endoreduplication. Moreover, the enhanced endoreduplication phenotype observed after overexpression of a dominant-negative allele of CDKB1;1 could be partially complemented by CYCA2;3 co-overexpression, illustrating that both subunits unite in vivo to form a functional complex. CYCA2;3 protein stability was found to be controlled by CCS52A1, an activator of the anaphase-promoting complex. We conclude that CCS52A1 participates in endocycle onset by down-regulating CDKB1;1 activity through the destruction of CYCA2;3.     

Giant Flowers of Southern Magnolia Are Hydrated by the Xylem

Flowering depends upon long-distance transport to supply water for reproductive mechanisms to function. Previous physiological studies suggested that flowers operated uncoupled from stem xylem transport and received water primarily from the phloem. We demonstrate that the water balance of Southern magnolia (Magnolia grandiflora) flowers is regulated in a manner opposite from that of previously examined flowers. We show that flowers of Southern magnolia rely upon relatively efficient xylem hydraulic transport to support high water demand during anthesis. We measured rapid rates of perianth transpiration ranging from twice to 100 times greater than previous studies. We found that relatively efficient xylem pathways existed between the xylem and flower. Perianth hydraulic conductance and the amount of xylem to transpirational surface area ratios of flowers were both approximately one-third those measured for leafy shoots. Furthermore, we observed that perianth tissues underwent significant diurnal depressions in water status during transpiring conditions. Decreases in water potential observed between flowers and vegetative tissues were consistent with water moving from the stem xylem into the flower during anthesis. Xylem hydraulic coupling of flowers to the stem was supported by experiments showing that transpiring flowers were unaffected by bark girdling. With Southern magnolia being a member of a nearly basal evolutionary lineage, our results suggest that flower water balance represents an important functional dimension that influenced early flower evolution.     

The Role of Specific Tomato Volatiles in Tomato-Whitefly Interaction

Bemisia tabaci (whitefly) infestations and the subsequent transfer of viruses are the cause of severe losses in crop production and horticultural practice. To improve biological control of B. tabaci, we investigated repellent properties of plant-produced semiochemicals. The mix of headspace volatiles, collected from naturally repellent wild tomato accessions, influenced B. tabaci initial choice behavior, indicating a role for plant semiochemicals in locating host plants. A collection of wild tomato accessions and introgression lines (Solanum pennellii LA716 × Solanum lycopersicum ‘Moneyberg’) were extensively screened for attractiveness to B. tabaci, and their headspace profiles were determined by means of gas chromatography-mass spectrometry. Correlation analysis revealed that several terpenoids were putatively involved in tomato-whitefly interactions. Several of these candidate compounds conferred repellence to otherwise attractive tomato plants when applied to the plant''s branches on paper cards. The sesquiterpenes zingiberene and curcumene and the monoterpenes p-cymene, α-terpinene, and α-phellandrene had the strongest effects in free-choice bioassays. These terpenes also elicited a response of receptors on the insect''s antennae as determined by electroantennography. Conversely, the monoterpene β-myrcene showed no activity in both assays. B. tabaci apparently uses, besides visual cues, specific plant volatile cues for the initial selection of a host. Altering whitefly choice behavior by manipulation of the terpenoid composition of the host headspace may therefore be feasible.During the last decades, a worldwide spread of the pest insects Bemisia tabaci (Gennadius) and greenhouse whitefly (Trialeurodes vaporariorum) has led to local devastation of vegetable and ornamental crops, resulting in large economic losses. The damage whiteflies cause by their feeding behavior, such as affected biochemistry and development (for review, see Inbar and Gerling, 2008), is far exceeded by the secondary, indirect crop losses due to virus transmission. Specifically B. tabaci outbreaks are associated with the emergence of viruses for which they serve as vectors (Polston and Anderson, 1997). B. tabaci is capable of transmitting >100 different virus species of which the majority belong to the genus Begomovirus, such as Tomato yellow leaf curl virus, Tomato mottle virus (Jones, 2003), and African cassava mosaic virus (Maruthi et al., 2001). Damage caused by virus infection ranges from mild symptoms, such as leaf discolorations, to overall yield reduction, severe fruit necrosis, flower and fruit abortions, and plant death. Viral diseases are particularly severe since no chemical control is available and good sources of virus resistance for interspecific crossing are not always available (Maruthi et al., 2003). To date, only a limited number of virus resistance genes have been identified, and due to high mutation rates, viruses rapidly evolve (Drake and Holland, 1999; García-Andrés et al., 2006) and break monogenic resistances. Herbivores, such as whiteflies and thrips, can apparently benefit from transmitting viruses (Medeiros et al., 2004; Jiu et al., 2007; Belliure et al., 2008).B. tabaci was originally restricted to subtropical regions and greenhouses. However, the new and extremely invasive B and Q biotypes have the ability to rapidly adapt to more temperate zones and new host species (Jones, 2003; Wan et al., 2008). To date, the main control strategy for many crops is the application of insecticides, though effective spraying is complicated because of the insect''s preference for the abaxial side of the leaf (Simmons, 1994). Moreover, B. tabaci is difficult to control chemically due to emerging resistance to active ingredients (Horowitz et al., 2005). A new biological control agent, the phytoseiid predator Typhlodromips swirskii, has only been successful on plants without trichomes in closed greenhouses (Nomikou et al., 2002). The root-knot nematode resistance gene Mi1.2, which confers partial resistance to B. tabaci (Nombela et al., 2003), is widely used in modern tomato (Solanum spp.) varieties but is not sufficient to provide adequate protection against whitefly infestations.During insect host selection, orientation, and landing, both visual and olfactory cues play a predominant role (Visser, 1988). Color is an important factor in host-plant selection, and it was shown that B. tabaci reacts to blue-UV and yellow wavelengths (Van Lenteren and Noldus, 1990). The olfactory stimuli associated with the host plant initiate host targeting, whereas visual cues improve the accuracy of landing. In the initial phase of host targeting, olfaction may cause a positive chemotactic response, i.e. a flight up an odor gradient. Plant odor specificity might be achieved by a particular ratio of constituent volatiles (Bruce et al., 2005a). In the case of whiteflies, the role of olfaction in attraction or repellence has not received much prior attention. After host contact, B. tabaci evaluates host plant quality by labial dabbing and probing using piercing mouthparts. By probing, persistent viruses are transmitted via the insects'' salivary glands and mouthparts (Ghanim et al., 1998; Rosell et al., 1999). Therefore, to avoid virus transmission by B. tabaci, probing should be prevented.Volatile organic compounds released by plants can act as semiochemicals. They play an important role in enabling insects to recognize host plants from a distance (Schütz et al., 1997; Bruce et al., 2005a) or in attracting predators and parasitoids upon herbivory (De Moraes et al., 1998; Van Poecke and Dicke, 2002; Kappers et al., 2005). Moreover, they can play a role in the direct defense against herbivores and pathogens (Kessler and Baldwin, 2001; Shiojiri et al., 2006). A large number of different plant volatiles, with numerous ecological roles, have been identified so far (Sacchettini and Poulter, 1997; Pichersky et al., 2006). The largest class of plant volatiles is derived from the isoprenoid or terpenoid pathway. Solanaceous plants, like tomato, often make use of these terpenes for the defense against herbivores (Snyder et al., 1993; Kennedy, 2003). Some terpenes have been shown to exhibit repellent properties to insects (Peterson et al., 2002; Birkett et al., 2004; Terry et al., 2007). These plant-produced semiochemicals can potentially be used as insect repellents of natural origin, thus providing an alternative to the use of pesticides (Peterson and Coats, 2001). Engineering terpene emission to make crop plants more attractive to herbivore enemies has already been shown to be feasible (Degenhardt et al., 2003; Kappers et al., 2005; Schnee et al., 2006).The aim of this study is to identify the role of plant volatiles in the B. tabaci-tomato host interaction and to identify the terpenes that cause repellence of a selection of wild tomato accessions. The potential of several terpenes as repellent olfactory cues in B. tabaci host-preference behavior has been assessed in behavioral studies and through electroantennography (EAG).     

Changes in concentrations of follistatin in maternal plasma and foetal fluids during pregnancy and parturition in sheep

Studies have shown that follistatin may be involved in the regulation of ovarian development, pregnancy and parturition. The aim of the present study was to measure follistatin levels in maternal plasma and foetal fluids during pregnancy and parturition in sheep. Using a previously described follistatin radioimmunoassay, we found that follistatin in foetal plasma and allantoic fluid was higher in the female than in the male at days 50-75 of gestation. Follistatin concentrations in maternal plasma declined from -9 to -3h before the completion of lamb delivery, and increased from 21 to 39 h after parturition. These results suggest that follistatin may play a role in femaleness development, and that follistatin may be involved in the mechanism of normal parturition and in regulation of the tissue repair after parturition.