DNA barcodes could be a useful tool for plant conservation. Of particular importance is the ability to identify unknown plant material, such as from customs seizures of illegally collected specimens. Mexican cacti are an example of a threatened group, under pressure because of wild collection for the xeriscaping trade and private collectors. Mexican cacti also provide a taxonomically and geogra...

Host-plant specialization plays a key role in insect evolution, but little is known about its molecular basis. A new paper shows that a cactus-feeding fly became restricted to its host by changes in an enzyme that converts dietary sterols into essential hormones.

Sexual selection is often assumed to be strong and consistent, yet increasing research shows it can fluctuate over space and time. Few experimental studies have examined changes in sexual selection in response to natural environmental variation. Here, we use a difference in resource quality to test for the influence of past environmental conditions and current environmental conditions on male a...

The genus Drosophila is the most abundant in the Drosophilidae family. Some species are endemic to certain regions and others are cosmopolitans. In Brazil, there are several ecosystems to explore regarding the composition and ecological aspects of Drosophila. Xerophytic areas are an example. They can be found in the South and Southeast of Brazil as islands, a result of paleoclimatic cycle chang...

Eccentric distance sum (EDS), which can predict biological and physical properties, is a topological index based on the eccentricity of a graph. In this paper we characterize the chain hexagonal cactus with the minimal and the maximal eccentric distance sum among all chain hexagonal cacti of length n, respectively. Moreover, we present exact formulas for EDS of two types of hexagonal cacti.