Timing is everything? Phenological synchrony and population variability in leaf‐chewing herbivores of Quercus

Abstract.  1. Specialization on ephemeral resources (e.g. new leaves) should produce large annual variation in herbivore population size when the timing of availability of those resources is unpredictable. Despite considerable evidence for impacts of synchrony with budburst on survival of larval Lepidoptera, previous studies of adult Geometridae and Noctuidae found no correlations between insect phenology and population variability.
2. We surveyed larval Lepidoptera feeding on Quercus alba and Q. velutina in Missouri from 1993 to 2003 and examined population variability, measured as the coefficient of variation of population density (CV), in a subset of abundant species. We compared CV values among species whose larvae feed only in spring, early summer, mid-summer, late summer, or all season. We predicted that univoltine species whose larvae eclose and complete development in spring during leaf expansion would have higher variability than species feeding later in the season, having multiple generations, or having longer development times.
3. As predicted and consistent with hypotheses, spring-feeding species had CV values 32% higher than species feeding in summer months. Coefficients of variation were also 34% higher in leaf-rolling and mining guilds compared with free-feeders, suggesting that mobile species may compensate for asynchrony with budburst by dispersing to higher quality plants or plant parts. Multivoltine species, however, did not differ from univoltine species in population variability.
4. Our results suggest that asynchrony with plant phenology and factors that might exacerbate it, such as climate change, will have the largest impacts on the dynamics of spring-feeding Lepidoptera, particularly species with limited mobility.     

Snail-eating frogs from the Ethiopian highlands: a new anuran specialization

Morphological studies and analysis of gut contents indicate that two species of montane Ethiopian frogs are specialized for selective feeding on terrestrial gastropod mollusks. Certain bony elements of the skull, such as the palatines and prevomers, are reduced and deflected dorsally, while lateral elements of the maxillary arch, such as die quadratojugals and maxillaries, are expanded. The nasal apparatus in both species is situated in an extreme anterior position. The two species are removed from the genus Kassina Girard and placed in die genus Tomierella Ahl. Morphology of the head suggests that these frogs grasp mollusks with their jaws, pull diem from die substrate, and swallow them whole. The sensory cues which trigger feeding are as yet unknown. Apparently, diese frogs are the first terrestrial vertebrates known to feed exclusively on whole mollusks, wimout crushing them or removing the soft parts from the shell.     

Distinguishing Asiatic Black Bears and Sun Bears by Claw Marks on Climbed Trees

Abstract: Asiatic black bears (Ursus thibetanus) and sun bears (Helarctos malayanus) are sympatric in mainland Southeast Asia and face similar threats of habitat loss and commercial poaching. They are rarely seen but leave distinct signs, especially claw marks on climbed trees. These markings, which are potentially valuable indicators of presence, population status, and behavior of black bears and sun bears, have limited usefulness if the 2 species cannot be differentiated. We measured 121 claw mark imprints on climbed trees from 43 known (mainly captive) individual black bears and sun bears of both sexes in Thailand and Cambodia. The span across the markings made by 3, 4, or 5 claws from the hind foot was significantly greater for black bears than sun bears. We developed discriminant function models with these variables and arranged them in a 3-step process that distinguished claw marks as either sun bear, black bear, or indeterminate. This procedure correctly classified 95% of claw marks from the experimental animals. Tested on wild bears (at sites where only one species occurred), the procedure correctly classified 91% of claw marks of black bears in China (n = 94) and 100% of claw marks of sun bears in Indonesia (n = 32). The main limitation of the method was in distinguishing young, small black bears (cubs and yearlings) from sun bears. Nevertheless, application of these findings will be valuable in bear research and monitoring programs throughout Southeast Asia, where sign surveys have, until now, been hampered by the inability to differentiate these 2 ecologically and behaviorally similar species. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):814–821; 2008)     

The Culture of Poverty: An Adjustive Dimension

The "Moynihan controversy" concerning the existence of a subculture of poverty among the Negro poor has been marked by polar positions. There are those who feel that much of the "deviant behavior" of this group is actually normative and transmitted in the socialization process. Others maintain that such behavior is not normative and represents merely situational responses to extreme poverty and other forms of deprivation. The data in this paper, derived from interviews with a sample of the Negro population of Philadelphia, indicate that Negroes living in poverty hold attitudes that can be characterized as a "subculture of poverty." On the other hand, the data also suggest that such attitudes represent but one segment of the total range of attitudes and reference values held by this population, many of which are shared by the larger society. Furthermore, the evidence indicates that these attitudes serve to maintain the mental health of those living in a severely disadvantaged social situation. [deviant behavior, Negro, poverty]     

The Pattern of Reproductive Development in Chenopodium rubrum L.

Individual plants of Chenopodium rubrum were given differentnumbers of inductive cycles in a 12 h photoperiod and the patternof reproductive development was analysed after 40 d of growth.At least 2 inductive cycles are required to form any determinatereproductive organs and at least 12 cycles are required fornormal reproductive development. Individuals given a singleinductive cycle display a loss of apical dominance at thosenodes formed immediately after the treatment without the subsequentformation of any floral structures. Plants given between 2 and12 mductive cycles display both determinate reproductive organsand indeter minate vegetative shoots. The pattern of reproductivedevelopment on such plants depends upon the number of cyclesrelative to the developmental age of newly initiated primordia.It is suggested that the early events of floral induction mayinvolve a radical decrease in the ratio of auxin to cytokinin.     

Evolutionary divergence in common marine ectoparasites Gnathia spp. (Isopoda: Gnathiidae) on the Great Barrier Reef: phylogeography, morphology, and behaviour

The blood‐feeding juvenile stages of gnathiid isopods are important ectoparasites of marine fishes on the Great Barrier Reef (GBR), and are a major component of the diet of cleaner fishes. We report here that these gnathiids have undergone evolutionary diversification, both geographically and temporally (into diurnally and nocturnally active taxa), which has been accompanied by changes in their morphology and behaviour. To perform this analysis, we sequenced a portion of the nuclear ribosomal ITS2 for 47 gnathiids collected from 29 host fishes of 11 species at three locales spanning 2000 km on the GBR. Maximum parsimony and Bayesian phylogenetic analyses both revealed four major clades. There was some degree of geographical structuring in these clades, but there was no evidence supporting host fish specialization, as gnathiids collected from the skin of different teleost taxa did not resolve into distinct clades. The topology of the phylogeny also implied some structuring that was dependent upon collection time (day or night), so we investigated whether there were also behavioural and morphological differences between taxa active at these different times. Nocturnal gnathiids had significantly longer antennules and larger eyes than diurnal gnathiids – two traits presumably adaptive for nocturnal activity. Behavioural tests showed that both nocturnal and diurnal gnathiids use olfaction and vision while foraging, but that nocturnal gnathiids used olfaction more often in dark conditions, and that they were able to perceive movement under extremely low levels of light. Diurnal gnathiids used vision more effectively when there was some ambient light. Our results thus suggest that both phenotypic and genotypic divergence in gnathiids may be influenced by natural selection acting on ecological traits, such as predator avoidance and host detection. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 94 , 569–587.