BACKGROUND The species status of two closely related Chinese oaks, Quercus liaotungensis and Q. mongolica, has been called into question. The objective of this study was to investigate the species status and to estimate the degree of introgression between the two taxa using different approaches. METHODOLOGY/PRINCIPAL FINDINGS Using SSR (simple sequence repeat) and AFLP (amplified fragment len...

An assessment is made of the repeatability of parasite community structure in space for a marine fish, and in space and time for a freshwater fish from south-eastern Mexico. The marine fish species was the red grouper, Epinephelus morio (collected from 9 localities), and the freshwater species was the cichlid, Cichlasoma urophthalmus (collected from 6 localities: including monthly at 2 localiti...

Plant species have repeatedly evolved recognition systems between pollen and pistils that identify and reject inappropriate matings. Two of the most important systems recognize self-pollen and interspecific pollen. Outstanding questions are whether and how these two recognition systems are linked and if this association could constrain the evolution of mate choice. Our study characterizes varia...

Eyeball structures such as the lens diameter (LD) and axial length are generally assumed to be highly correlated with optically meaningful parameters. However, these optical constraints on eyeball macroanatomy have never been tested explicitly. Tradeoffs between benefits of improved visual performance and cost of adaptation from an increase of tissue production predict that when eyeball size in...

One fundamental signature of reinforcement is elevated prezygotic reproductive isolation between related species in sympatry relative to allopatry. However, this alone is inadequate evidence for reinforcement, as traits conferring reproductive isolation can occur as a by-product of other forces. We conducted crosses between Silene latifolia and S. diclinis, two closely related dioecious floweri...

The ants Aphaenogaster cockerellz and Pogonomyrmex barbatus compete for seed resources in the Chihuahuan desert. Previous work showed that intraspecific competition in P barbatus is more intense between near neighbors with overlapping foraging ranges and depends on colony age. Just before reaching reproductive maturity (3-4 y), colonies are more aggressive and persistent in intraspecific compet...

BACKGROUND The identification of free-living marine nematodes is difficult because of the paucity of easily scorable diagnostic morphological characters. Consequently, molecular identification tools could solve this problem. Unfortunately, hitherto most of these tools relied on 18S rDNA and 28S rDNA sequences, which often lack sufficient resolution at the species level. In contrast, only a few ...

Homologous recombination (HR) and lateral gene transfer are major processes in genome evolution. The combination of the two processes, HR between genes in different species, has been documented but is thought to be restricted to very similar sequences in relatively closely related organisms. Here we report two cases of interspecific HR in the gene encoding the core translational protein transla...

I investigated if primate species assemblages exhibit nestedness in Guyana. In a nested pattern, individual species have a strong tendency to be present in all assemblages of equal or greater size than the smallest one in which they occur. I conducted 1,725 km of surveys to determine primate species composition and distribution patterns at sixteen survey sites in Guyana. The resulting dataset s...

the genetic structure of the genus alburnus is not well known and the phylogenetic relationships among its species are uncertain. in the present study, simple sequence repeats (ssrs or microsatellites) were used to evaluate genetic diversity and genetic differentiation between alburnus mossulensis heckel, 1843 from kashgan river in lorestan province and alburnus caeruleus heckel, 1843 from gama...