Phylogeography of Plathymenia reticulata (Leguminosae) reveals patterns of recent range expansion towards northeastern Brazil and southern Cerrados in Eastern Tropical South America

Little is known about past vegetation dynamics in Eastern Tropical South America (ETSA). Here we describe patterns of chloroplast (cp) DNA variation in Plathymenia reticulata, a widespread tree in the ETSA Atlantic Forest and Cerrado biomes, but not found in the xeromorphic Caatinga. Forty one populations, comprising 220 individuals, were analysed by sequencing the trnS‐trnG and trnL‐trnL‐trnF cpDNA regions. Combined, they resulted in 18 geographically structured haplotypes. The central region of the sampling area, comprising Minas Gerais and Goiás Brazilian states, is a centre of genetic diversity and probably the most longstanding area of the distribution range of the species. In contrast, populations from northeastern Brazil and the southern Cerrados showed very low diversity levels, almost exclusively with common haplotypes which are also found in the central region. Coupled with a long‐branched star‐like network, these patterns suggest a recent range expansion of P. reticulata to those regions from central region sources. The recent origin of the species (in the early Pleistocene) or the extinction of some populations due to drier and cooler climate during the last glacial maximum could have been responsible for that phylogeographic pattern. The populations from northeastern Brazil originated from two colonization routes, one eastern (Atlantic) and one western (inland). Due to its high diversity and complex landscape, the central region, especially central‐north Minas Gerais (between 15°–18° S and 42°–46° W), should be given the highest priority for conservation.     

Tetranucleotide,trinucleotide, and dinucleotide loci from the bobcat (Lynx rufus)

We describe primers and polymerase chain reaction (PCR) conditions to amplify four dinucleotide, one trinucleotide, and three tetranucleotide microsatellite DNA loci from the bobcat (Lynx rufus). The primers were tested on 22 individuals collected from a population located within southwestern Georgia (USA). The primer pairs developed in this study yielded an average of 7.4 alleles per locus (range four to 10), an average observed heterozygosity of 0.60 (range 0.40 to 0.76), and an average polymorphic information content of 0.70 (range 0.51 to 0.78).     

Analysis of the insect community in a stored-maize facility

Maize samples were obtained at two depths [0–30cm (top sample) and 30–60cm (bottom sample) from the maize surface] at 19–28 locations from a naturally infested maize storage facility in Wisconsin, USA. Based on identification of insects in stored-maize samples from 13 weekly sampling events, four topics were addressed: (i) the seasonal fluctuation in the insect community; (ii) ordination analysis was conducted to examine the association among insect taxa and to determine their distribution along abiotic and geographic gradients; (iii) the demographic characteristics of insect communities in maize samples with high abundance of either Plodia interpunctella (Plodia samples) or Sitophilus zeamais (Sitophilus samples); and (iv) to what extent natural enemies were spatially associated with their prey species. We identified a total of 18 different taxa, composed of adults and larvae of 14 determined species, and others identified to genus, family or order. Insect density was significantly higher in top samples compared to bottom samples, and the insect taxa occurred more frequently in top samples compared to bottom samples. In the ordination analysis, the three explanatory variables accounting for eastern, northern and vertical position of maize samples explained the largest part of the total variance. There was a gradual time trend with some of the insect species mainly occurring early or late in the monitoring period. Moisture content of the maize was the weakest of the significant explanatory variables, while temperature in the grain mass did not explain a significant part of the total variance. Plodia samples and Sitophilus samples had significantly different spatial distribution patterns and had markedly different insect species composition. Plodia samples were characterized by low abundance of all granivores and fungivores, except P.interpunctella. Conversely, Sitophilus samples had high abundance of T.castaneum, A.advena, and C.ferrugineus. Consequently, Sitophilus samples seemed to comprise more diverse insect communities than Plodia samples. Natural enemies were not significantly associated with their most common hosts. In a highly homogeneous habitat (stored maize), we demonstrated that stored-product insect species had significantly different distribution patterns mainly along geographic gradients. Stochasticity of the initial infestation process or interspecific competition are two of the possible explanations for the spatial segregation of stored-product insects, and the spatial segregation of insects on the same trophic level may have profound implications for the understanding of how these ecosystems develop over time and thereby how integrated pest management strategies are implemented to control insect pest populations.     

The utilization of heather moorland by territorial Red Grouse Lagopus lagopus scoticus

Although the breeding density of Red Grouse Lagopus lagopus scoticus is related to the density of burned patches of heather Calluna vulgaris , territories appear to offer surplus food, and other factors, especially the risk of predation, may be important. In order to determine how Red Grouse make use of heather moorland, an individually marked population was studied on a moor in northeast Scotland from 1992 to 1994. Territorial birds preferred stands of tall heather during the daytime in autumn and winter, but in spring they increased their use of heterogeneous heather/grass mixtures. Furthermore, in spring, females showed a very strong affinity for edges between heather stands of different ages, where they had easy access to nutritious young heather and good cover. When near the vegetation edge, territorial birds spent most time on the side of the edge providing greater cover. Broods occupied ranges in areas with rather more old heather and with more edge than was available over the entire study site. Within their ranges though, broods clearly preferred heterogeneous areas during the first month after hatching, and showed a further preference for vegetation edge. Their behaviour changed during the second month after hatching, when they utilized tall heather to a greater extent, but edge remained important.     

Variation in safety factors of claws within and among six species of Cancer crabs (Decapoda: Brachyura)

To better understand how safety factors of biological structures evolve, we examined the frequency of claw failure, and the intra‐ and interspecific patterns of variation in maximum biting force and breaking strength in the claws of six species of Cancer (Linnaeus) crabs that live in sympatrv along the coast of the northeastern Pacific: C. antennarius, C. branneri, C. gracilis, C. maguter, C. oregonensis and C. productus. Although the breakage frequencies in natural populations were similar among species (6%), they were higher than predicted based on failure probabilities calculated from laboratory measurements of biting force and breaking strength for healthy pristine claws. The incidence of claw damage was correlated with the degree of wear, suggesting that claws later in the intermolt interval were more likely to fail. Within species, safety factors increased from 3.1 to 4.6 with increasing instar number due primarily to a decline in muscle stress (force per unit area of apodeme). Surprisingly, the lower maximum muscle stress generated by later instars appeared to be due to behavioral restraint, since it was not accompanied by relatively lower muscle mass. In addition, among individuals of the same claw size, lower breaking forces were correlated with lower maximum biting force, and both were correlated with lighter cuticle and closer muscle mass, suggesting a coupling that maintains a more stable safety factor over the moult cycle. In some species, size‐adjusted maximum biting forces were higher for males than females, but this paralleled differences in breaking strength, so safety factors did not differ between the sexes. Among the six Cancer species, one exhibited an unusually high safety factor (C. oregonensis, 7.4) and another an unusually low one (C. maguter, 2.6). The remaining four species were similar to each other and exhibited an intermediate safety factor (3.6). From a phylogenetic perspective, the species with more extreme safety factors appeared to be derived from a common ancestor with an intermediate safety factor. From an ecological perspective, species more closely associated with rocky substrata, and presumably a higher incidence of hard‐shelled prey, exhibited higher safety factors. But safety factors were also correlated with relative claw size, and sexual dimorphism in claw size. Although we cannot say whether habitat, diet or sexual selection are primarily responsible for the differences in safety factors observed among species, the cost of producing a relatively larger claw seems an unlikely explanation because safety‐factors did not differ between males and females in any of the sexually dimorphic species.