Pollination and Breeding System of Vellozia squamata (Liliales: Velloziaceae): A Species of the Brazilian Cerrados

The pollination biology and breeding system of Vellozia squamata (Velloziaceae), a species of cerrado vegetation in Central Brazil, were studied. V. squamata is unusual in being pollinated by a few, generalist bee species despite having very large flowers, and having a distinctive pulsed flowering phenology. The species is self-incompatible but with a late-acting, post-fertilization rejection mechanism.     

The genetic diversity of two brazilian vellozia (velloziaceae) with different patterns of spatial distribution and pollination biology

BACKGROUND AND AIMS: The genetic structure and variability of two species of Vellozia (Velloziaceae) with restricted distribution in high-altitude quartzitic fields in south-eastern Brazil were studied. Vellozia epidendroides is short, grows on pebbly or sandy soil, and is pollinated by bees. Vellozia leptopetala is arborescent, grows on rock outcrops, and is pollinated by bees and hummingbirds. Both are self-incompatible and have a short, massive flowering strategy. The study aimed to associate differences in their genetic diversity and structure with their microhabitat distribution and pollination ecology. METHODS: Leaves from 106 and 139 plants of V. epidendroides and V. leptopetala, respectively, were collected from five patches of each species and prepared for electrophoretic analyses. KEY RESULTS: Five enzyme systems could be reliably scored for both species. Vellozia epidendroides showed 100 % of the loci polymorphic for almost all patches. The average number of alleles per locus ranged between 2.2 and 2.4 among patches. The Wright's fixation index (F) for this species was 0.226. A significant (p) value indicates that there is a reasonable genetic divergence among patches. Vellozia leptopetala presented 47.5 % of polymorphic loci. All levels of P, A, A(p) and of heterozygosities were lower than those of V. epidendroides. Vellozia leptopetala showed high inbreeding within patches. CONCLUSIONS: The relatively high values of genetic diversity indices found for V. epidendroides may be associated with its large and widespread populations. On the other hand, the low values of genetic diversity found for V. leptopetala may be related to physical isolation on outcrops and intensive foraging by territorial hummingbirds, which may hinder gene flow among patches, aggravated by the very restricted seed dispersal characteristic of the genus, that facilitates sibling mating. It is important to stress the need to preserve the specific habitats of these species of Vellozia, in particular those of V. leptopetala that has lower genetic diversity and is restricted to rock outcrop environments.     

Morphological and anatomical differentiation ofVellozia hirsuta populations (Velloziaceae)

The morphological and leaf anatomical differentiation ofVellozia hirsuta is analysed and classified into several types (A1, A2, A4, B3, B5, C3). The species has a relatively wide distribution in the campos rupestres of Minas Gerais in Brazil. The variation of the isolated populations on different mountain ranges is complex, does not follow a clear geographical pattern, and defies taxonomic classification.     

Structure Elucidation,Antimicrobial and Cytotoxic Activities of a Halimane Isolated from Vellozia kolbekii Alves (Velloziaceae)

A new halimane diterpene was isolated from Vellozia kolbekii Alves (Velloziaceae) and identified as (5R,8R,9S,13R)‐halim‐1,10‐ene‐15,16‐diol ( 1 ). It showed cytotoxicity against three human cancer cell lines, SF‐295 (glioblastoma), MDA‐MB‐435 (melanoma), and HCT‐8 (colon adenocarcinoma). In the mechanism of cytotoxic action, halimane 1 interferes in two major phases of the cell cycle: in S phase, in which DNA synthesis occurs and where it is very sensitive to damage, and G2M phase which is the phase of preparation for mitosis and mitosis itself, showing apoptosis‐inducing properties. Antimicrobial activity towards Gram‐positive and Gram‐negative bacteria was studied and, against Bacillus cereus, B. subtilis, Escherichia coli, and Pseudomonas aeruginosa, a MIC value of 0.025 μM was observed for halimane 1 , which is more active than the positive control chloramphenicol.     

Further observations on a Callunetum intensively grazed by mountain hares (Lepus timidus L.)

Summary

Heavy utilisation by mountain hares checked the growth of Calluna so that mean height was only 12 cm thirty years after the 0.2 ha area was burnt. Cover and biomass increased gradually over the thirteen years studied, from 59 to 85% and 300 to 580 g/m² respectively. Differences in sward height were maintained, the greater utilisation of short heather being offset by greater growth. Compared to ruminant-grazed Calluneta, the hare-grazed sward had a distinctive, compact form, and biomass was great relative to cover and height because of the many shoots. Non-ericoid angiosperms had little cover.