Characterization of polymorphic microsatellite markers for the endangered Malagasy radiated tortoise (Geochelone radiata)

The radiated tortoise (Geochelone radiata) is an endangered endemic species from Madagascar that inhabits the semiarid spiny forest of the southern part of the island. Habitat destruction and illegal harvesting greatly threaten this species, as attested by the significant reduction of its distribution area in the past 30 years. In order to undertake appropriate conservation actions, it is essential to acquire a better knowledge of its genetic structure. For this study, 145 blood samples were collected from three populations of radiated tortoises in southwestern Madagascar. Eight microsatellite loci were found to be polymorphic, and allelic diversity and observed heterozygosity were high for all markers.     

SEM studies on vessels in ferns. 11. Ophioglossum

With scanning electron microscopy (SEM), the nature of metaxylem vessel elements and tracheids was examined in Ophioglossum crotalophomides, 0. pendulum subsp. falcatum , and 0. vulgatum roots and rhizomes. Vessels were identified in all species. End walls of vessel elements, which bear perforations, are like lateral wall pitting of those elements in the secondary wall framework and differ only in absence of pit membranes or presence of pit membrane remnants. Some of the perforations contain pit membrane remnants that have large pores, small porosities, or are threadlike or weblike in structure. Dimorphic perforations were found in some vessel elements of rhizomes of 0. pendulum subsp. falcatum. Tracheids are very likely present in addition to vessels in all three species. The secondary wall framework of both tracheids and vessels is basically scalariform, although deviations in pattern are present. Vessel elements of Ophiglossum are entirely comparable to those of leptosporangiate ferns.     

Influence of ultraviolet-B radiation on the drift response of stream invertebrates

1. Recent studies have shown that ultraviolet (UV) radiation (280–400 nm) has increased by ≈ 8% in temperate regions over the past decade, but little effort has been devoted to understanding the ecological effects on temperate ecosystems. This research examined the effects of artificial ultraviolet-B (UVB; 280–320 nm) radiation on the drift response of immature stream insects in laboratory microcosms.
2. Two experiments involved natural populations of stream invertebrates, collected from the Cache la Poudre River (September 1994) and the Arkansas River (October 1995) in Colorado. UVB lamps were turned on from 10.00 to 14.00 h each day, and drifting animals were collected on days 1, 3, 5 and 7 during the exposure period. Levels of artificial UVB used in these experiments were similar to levels that stream organisms experience during clear, mid-day conditions at Fort Collins, Colorado (longitude 105°30'; latitude 40°35').
3. Drift was significantly higher in microcosms exposed to UVB than in controls and was dominated by Baetis sp. (Ephemeroptera: Baetidae), Trichoptera (caddisflies) and Simulium sp. (Diptera: Simuliidae). The increased drift of some stream invertebrates in UVB-exposed streams may be a behavioural response and/or a result of injury.
4. Stream organisms may be particularly sensitive to predicted increases in UV radiation, because streams are generally shallow with clear water. As a result of this potential sensitivity, we recommend that research be directed to understanding the ecological effects of UV radiation on these habitats.     

The outcome of the invasion of Florida lakes by Daphnia lumholtzi

1. We examined 7–12 years of monthly to quarterly historical data from 15 lakes in FL, U.S.A. to determine the extent and outcome of invasion by the alien cladoceran Daphnia lumholtzi Sars. 2. The alien species was found in 10 of the 15 lakes, including Florida’s three largest lakes: Okeechobee, George and Apopka. All the surveyed lakes had resident populations of the smaller native species Daphnia ambigua Scourfield. 3. In most of the lakes, D. ambigua occurred seven to ninefold more often in plankton samples than D. lumholtzi, and at 10‐ to 100‐fold higher maximal densities. One exception was a small lake in central Florida (Lake Jesup), where D. lumholtzi attained high densities on several occasions in the 10 years of sampling. 4. In Lake Okeechobee, where data were of sufficient quality and quantity to perform statistical analyses, the results of canonical correlation analysis indicated that high densities of D. lumholtzi were correlated with lower concentrations of suspended solids, high algal biomass and higher temperature, whereas the opposite conditions were correlated with high densities of D. ambigua. 5. Based on the majority of data, D. lumholtzi has successfully invaded many lakes in Florida, yet it has not become a substantive component of the zooplankton. Additional research is needed to determine whether resources, fish predation or some other factor is responsible for this outcome of invasion.     

Endocrine effects of social stimuli on maturing queens of the dampwood termite Zootermopsis angusticollis

Abstract.  The reproductive physiology of social insects is often highly responsive to social stimuli from nestmates, but the mechanisms underlying this sensitivity are usually poorly understood. The effect of varied social conditions on the endocrinology and ovarian maturation in maturing female primary reproductives of the dampwood termite Zootermopsis angusticollis Hagen is studied to better understand their developmental responses to conspecifics. Newly dealate queens are paired with a reproductive male, with another maturing female, or are allowed to mature in isolation. Developmental responses are tracked by monitoring rates of juvenile hormone (JH) production by corpora allata in vitro , haemolymph ecdysteroids titres and ovarian development after 5, 10, 15 and 30 days of maturation. Significant declines in rates of JH production rates are observed by days 5, 10 and 30, respectively, for females paired with males, left to mature in isolation or paired with a female. Ecdysteroid titres increase by day 5 and stay elevated in females nesting with males. By contrast, for CA from females that are isolated or paired with another female, the titres decline and stay low until at least day 15, but increase significantly by day 30. These hormonal differences correspond to differential rates of physiological maturation, with more rapid ovarian development occurring in females paired with a male, than in those nesting alone or with another female. The results suggest that JH and ecdysteroids modulate the ovarian response of alates to stimuli from nestmates during this period of maturation, and that JH and ecdysteroid titres may be regulated independently during this period of development.