Patterns of Testa-imposed Seed Dormancy in Native Australian Legumes

The testa-imposed seed dormancy of 34 native Australian speciesof Faboideae and Mimosoideae was examined immediately afterthe seeds matured and again after 3.5 years of dry storage inthe laboratory. Three groups of dormancy patterns are recognized:17 species (of the Mirbelieae and Acacieae) that have a relativelysmall nondormant fraction (0–10%) of their ripe seedsand that maintain this fraction through time; ten species (ofthe Mirbelieae) that have a relatively large non-dormant fraction(10–40%) of their ripe seeds and that maintain this fractionthrough time; and seven species (of the Bossiaeeae and Phaseoleae)that have a relatively small non-dormant fraction when the seedsripen, and have this fraction increase significantly throughtime. The species in the second group have smaller seeds thando those of the first and third groups, while the species inthe third group have a different testa construction from thosein the first and second groups. For all of the non-dormant seedstested, the water permeability is not localized only at thelens. Leguminosae, Fabaceae, Mimosoideae, Papilionoideae, Faboideae, legume seeds, seed dormancy, hard-seededness, dormancy loss, germination     

Genetic Basis of Mating Preferences in Wild House Mice

This paper reviews work conducted over the last several yearson the effect of genetic differences within the t-complex ofwild house mice on female mating preference. Wild mice are polymorphicfor a mutation within the t complex on chromosome 17. About25% of wild mice are heterozygous (+/t) for a t-haplotype andthe remainder are +/+. These t-haplotypes have a number of deleteriouseffects when homozygous and hence t/t individuals are rarelyfound in wild populations. We have examined preferences of +/+and +/t females for males of both genotypes. We have found that+/t, but not +/+ females have strong preferences for +/+ males.These preferences can be modified by a variety of factors includingestrous condition of the female (the preferences are strongeramong estrous than diestrous females) and the dominance statusof the male (when forced to choose, females give priority tomale dominance status over t complex genotype in choosing males).The restiction of preference to +/t females indicates that geneson t haplotypes modulate these preferences. Because t haplotypesinclude the major histocompatibility complex (MHC) of the mousewe designed a study to ascertain whether the preferences of+/t females were associated with the MHC. Results of the studyindicate that the preferences are independent of the MHC. Furtherwork testing females carrying a partial t-haplotype (t^w18) indicatesthat the genes for mating preference are localized in the regionof the t complex distal to the MHC. A large number of t haplotypesare found in wild mouse populations. Females that are themselves+/t when forced to choose between 2 +/t males (one carryinga haplotype that is the same as their own and one carrying ahaplotype that is different) prefer males carrying t-haplotypesthat differ from their own. Finally, we conclude that matingpreference may only be a weak force regulating the frequencyof t-mutations in wild mouse populations. The impact of matingpreference on population genetics of genes within this regionis muted because of the great importance of male dominance rankin determining mating patterns within interacting social groups.     

Contemporary climate change in the Sonoran Desert favors cold‐adapted species

Impacts of long‐term climate shifts on the dynamics of intact communities within species ranges are not well understood. Here, we show that warming and drying of the Southwestern United States over the last 25 years has corresponded to a shift in the species composition of Sonoran Desert winter annuals, paradoxically favoring species that germinate and grow best in cold temperatures. Winter rains have been arriving later in the season, during December rather than October, leading to the unexpected result that plants are germinating under colder temperatures, shifting community composition to favor slow growing, water‐use efficient, cold‐adapted species. Our results demonstrate how detailed ecophysiological knowledge of individual species, combined with long‐term demographic data, can reveal complex and sometimes unexpected shifts in community composition in response to climate change. Further, these results highlight the potentially overwhelming impact of changes in phenology on the response of biota to a changing climate.     

Sodium‐specific foraging by leafcutter ant workers (Atta cephalotes,Hymenoptera: Formicidae)

1. Sodium is often a limiting nutrient for terrestrial animals, and may be especially sought by herbivores. Leafcutter ants are dominant herbivores in the Neotropics, and leafcutter foraging may be affected by nutritional demands of the colony and/or the demands of their symbiotic fungal mutualists. We hypothesized that leafcutter colonies are sodium limited, and that leafcutter ants will therefore forage specifically for sodium. 2. Previous studies demonstrated that leafcutter Atta cephalotes Linnaeus workers preferentially cut and remove paper baits treated with NaCl relative to water control baits. Atta cephalotes colonies in this study were presented with baits offering NaCl, Na₂SO₄, and KCl to test whether leafcutters forage specifically for sodium. Sucrose and water were used as positive and negative controls, respectively. 3. Atta foragers removed significantly more of the baits treated with NaCl and Na₂SO₄ than the KCl treatment, which did not differ from water. The NaCl and Na₂SO₄ treatments were collected at similar rates. We conclude A. cephalotes forage specifically for sodium rather than for anions (chloride) or solutes in general. This study supports the hypothesis that leafcutter ants are limited by, and preferentially forage for, sodium.     

Terrestrial Activity in Pitheciins (Cacajao,Chiropotes, and Pithecia)

Neotropical monkeys of the genera Cacajao, Chiropotes, and Pithecia (Pitheciidae) are considered to be highly arboreal, spending most of their time feeding and traveling in the upper canopy. Until now, the use of terrestrial substrates has not been analyzed in detail in this group. Here, we review the frequency of terrestrial use among pitheciin taxa to determine the ecological and social conditions that might lead to such behavior. We collated published and unpublished data from 14 taxa in the three genera. Data were gleaned from 53 published studies (including five on multiple pitheciin genera) and personal communications of unpublished data distributed across 31 localities. Terrestrial activity was reported in 61% of Pithecia field studies (11 of 18), in 34% of Chiropotes studies (10 of 29), and 36% of Cacajao studies (4 of 11). Within Pithecia, terrestrial behavior was more frequently reported in smaller species (e.g. P. pithecia) that are vertical clingers and leapers and make extensive use of the understory than in in the larger bodied canopy dwellers of the western Amazon (e.g. P. irrorata). Terrestrial behavior in Pithecia also occurred more frequently and lasted longer than in Cacajao or Chiropotes. An apparent association was found between flooded habitats and terrestrial activity and there is evidence of the development of a “local pattern” of terrestrial use in some populations. Seasonal fruit availability also may stimulate terrestrial behavior. Individuals also descended to the ground when visiting mineral licks, escaping predators, and responding to accidents such as a dropped infant. Overall, the results of this review emphasize that terrestrial use is rare among the pitheciins in general and is usually associated with the exploitation of specific resources or habitat types. Am. J. Primatol. 74:1106‐1127, 2012. © 2012 Wiley Periodicals, Inc.     

Fire effects on insect herbivores in an oak savanna: the role of light and nutrients

Abstract.  1. Environmental heterogeneity created by prescribed burning provided the context for testing whether the distribution of an oak specialist (the lace bug, Corythuca arcuata ) could be explained by stoichiometric mismatches between herbivore and host plant composition.
2. Field observations showed that lace bug density was seven-fold higher in frequently burned than in unburned units.
3. Lace bug density did not increase with leaf nutrient concentrations, but was instead associated with higher light levels, higher concentrations of leaf carbon (C), lignin and total phenolics, and lower levels of cellulose. In addition, lace bugs reared on high-light leaves had higher levels of survivorship than those fed on low-light leaves.
4. Sampling restricted to full-sun leaves was used to test whether fire-related changes in leaf nitrogen (N) and phosphorus (P) concentrations have a secondary influence on lace bug success. This sampling provided only limited evidence for nutrient limitation, as decreases in leaf N and P were associated with an increase in lace bug mass but a decrease in density.
5. It is concluded that burning probably promotes lace bug population growth by increasing canopy openness, light penetration, and the availability of C-based metabolites, and thus simple stoichoimetric mismatches between herbivores and host plants are not of primary importance in this system.     

Critical Investigations of Age and Aging in the United States

Aged by Culture . Margaret Morganroth Gullette. Chicago: University of Chicago Press, 2004. 267 pp.
Breaking the Watch: The Meanings of Retirement in America . Joel S. Savishinsky. Ithaca, NY: Cornell University Press, 2000. 281 pp.
My Mother's Hip: Lessons from the World of Eldercare . Luisa Margolies. Philadelphia: Temple University Press, 2004. 339 pp.     

Characterization of 18 SNP markers for sperm whale (Physeter macrocephalus)

We report the characterization of 18 new single nucleotide polymorphism (SNP) markers for an endangered species, the sperm whale (Physeter macrocephalus), developed using a targeted gene approach. SNP markers were derived from autosomal regions of the genome using primers originally characterized for genome mapping in other mammals. These SNP markers are the first to be designed for genotyping sperm whale populations and will provide a necessary addition to the genetic tools employed for understanding population structure on a global scale and for developing a conservation management strategy for this endangered species.     

Effects of sample size,number of markers,and allelic richness on the detection of spatial genetic pattern

The influence of study design on the ability to detect the effects of landscape pattern on gene flow is one of the most pressing methodological gaps in landscape genetic research. To investigate the effect of study design on landscape genetics inference, we used a spatially‐explicit, individual‐based program to simulate gene flow in a spatially continuous population inhabiting a landscape with gradual spatial changes in resistance to movement. We simulated a wide range of combinations of number of loci, number of alleles per locus and number of individuals sampled from the population. We assessed how these three aspects of study design influenced the statistical power to successfully identify the generating process among competing hypotheses of isolation‐by‐distance, isolation‐by‐barrier, and isolation‐by‐landscape resistance using a causal modelling approach with partial Mantel tests. We modelled the statistical power to identify the generating process as a response surface for equilibrium and non‐equilibrium conditions after introduction of isolation‐by‐landscape resistance. All three variables (loci, alleles and sampled individuals) affect the power of causal modelling, but to different degrees. Stronger partial Mantel r correlations between landscape distances and genetic distances were found when more loci were used and when loci were more variable, which makes comparisons of effect size between studies difficult. Number of individuals did not affect the accuracy through mean equilibrium partial Mantel r, but larger samples decreased the uncertainty (increasing the precision) of equilibrium partial Mantel r estimates. We conclude that amplifying more (and more variable) loci is likely to increase the power of landscape genetic inferences more than increasing number of individuals.     

Consequences of habitat loss and change to populations of wintering migratory birds: predicting the local and global effects from studies of individuals

Population models show that the response of migratory bird populations to a reduction in the area, or change in the quality, of their winter feeding areas depends critically on the shape (linear or non-linear) and strength (slope) of the relationship describing how the proportion dying from starvation changes with population density. Yet the parameters that define such density-dependent functions are extremely difficult to estimate from direct measurements of mortality at different population sizes. Even if they could be estimated, there would be uncertainty as to whether or not the relationship would remain the same, and thus provide reliable predictions, in the new circumstances for which forecasts are required. This paper summarizes studies of the Oystercatcher Haematopus ostralegus which aim to derive the shape and strength of the winter density-dependent mortality and emigration function for one estuary, under existing and new circumstances, from the responses of individual birds to each other and to their spatially and seasonally varying food supply. Based on these studies, an individuals-based, physiologically structured game theoretic distribution model has been built which predicts the carrying capacity and numbers of birds dying at different population sizes. The model also can be applied to Oyster-catchers occupying several estuaries distributed throughout their wintering range and can thus be extended to the entire biogeographical or global population. In addition, it can be used to identify some easily measured behavioural and ecological parameters that identify those species, from a wide range of taxa, that are most likely to be affected by habitat loss and change.